Accepted Manuscript Title: What every Radiologist should know about Pediatric Echocardiography Author: Erich Sorantin Bernd Heinzl PII: DOI: Reference:
S0720-048X(14)00267-8 http://dx.doi.org/doi:10.1016/j.ejrad.2014.05.030 EURR 6801
To appear in:
European Journal of Radiology
Received date: Revised date: Accepted date:
8-5-2014 14-5-2014 18-5-2014
Please cite this article as: Sorantin E, Heinzl B, What every Radiologist should know about Pediatric Echocardiography, European Journal of Radiology (2014), http://dx.doi.org/10.1016/j.ejrad.2014.05.030 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
What every Radiologist should know about Pediatric Echocardiography
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Erich Sorantin1, Bernd Heinzl2
Division of Pediatric Radiology
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Department of Radiology Medical University Graz Auenbruggerplatz 34
Division of Pediatric Cardiology
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2:
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A – 8036 Graz
Department of Pediatric and Adolescent Medicine
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Medical University Graz
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A – 8036 Graz
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Auenbruggerplatz 34
Corresponding Author:
Univ.-Prof.Dr.Erich Sorantin
Division of Pediatric Radiology
Department of Radiology Medical University Graz Auenbruggerplatz 34 A – 8036 Graz Tel.:
+43 316 385 14202
Fax
+43 316 385 14299
Email: [email protected]
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What every Radiologist should know about Echocardiography
Abstract:
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Congenital heart defects (CHD) occur in less than one percent of all newborns. Echocardiography represents the imaging modality of choice for morphological and functional assessment. In
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childhood the different CHD types can be diagnosed trustfully and can be performed bedside. In the
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follow-up of CHD cross sectional imaging plays an important role and therefore it is essential for the radiologist to know the features, challenges and limitations of echocardiography. Within this
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review article a a systematic approach for morphological and functional assessment of the heart will is given along with representative example images. In addition, typical echocardiographic findings
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in commen CHD is presented. In older children, adolescents and grown-ups with CHD (GUCH) echocardiography suffers from limitations – partially due to skeletal deformations and lung
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emphysema. In particular right ventricular function assessment is not always possible by
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echocardiography. Therefore strengths and limitations of echocardiography will be discussed an the
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role of cardiac Magnetic Resonance Imaging (cMRI) and cardiac Computed Tomography (cCT) emphasized.
Keywords: heart defects congenital, echocardiography, children, cardiology
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Introduction About one percent of all newborn suffer from congenital heart disease (CHD), half of them are represented by defects with shunts like the ventricular septum defect (VSD), atrial septum defect (ASD) and the persistent Ductus Arteriosus Botalli (PDA) (1). The most frequent other types are
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(aortic) coarctation, pulmonary stenosis, aortic valve stenosis and Tetralogy of Fallot (details are found in Table 1).
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There are several possibilities to classify CHD – according to anatomy (obstruction of left or right
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heart, septal or vascular malformation, and complex CHD with anomalies of origin of the great arteries - Table 2) or due to shunts (left to right, right to left, bidirectional shunt, or no shunt).
in simple, moderate or severe are given in Table 4.
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Moreover, CHD types with and without cyanosis can be discriminated (Table 3). CHD stratification
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Currently a change in CHD epidemiology can be observed. Improved treatment options in combination with declining birth rate in western countries as well as terminated pregnancies in
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severe malformations lead to the fact, that today there are more adults with CHD than children
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(GUCH = grown-up congenital disease) (2). Therefore congenital heart defects do not only refer
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anymore to paediatric radiologists and paediatric cardiologists, but an increasing number of patients are within the adult population.
Besides chest x-ray, echocardiography has become the most important non-invasive imaging modality of choice for evaluation of the cardiovascular system, providing morphological diagnosis as well as functional assessment.
The purpose of this article is to present principles and limitations of echocardiography, diagnostic echocardiographic features of common CHD types, as well as the role of other imaging modalities like cardiac catheterization, cardiac magnetic resonance imaging (cMRI) and cardiac CT (cCT). Though there are two major types of echocardiography depending on the access [trans-thoracic and trans-oesophageal echocardiography (TEE)] this article will focus on the more common and basic trans-thoracic echocardiography.
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Patient preparation and positioning For trans-thoracic echocardiography there is no special preparation necessary. In rare cases sedation (peroral, using chloral hydrate or midazolam) may be necessary in order to obtain diagnostic
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information. The patient is positioned on his left side down, in a reclined position in order to move their heart away from the sternum (Fig.1). For supra-sternal views, the neck has to be overextended
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in order to place the transducer within the jugular fossa.
Technical requirements
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Sector transducers with a frequency range from five to twelve megahertz (MHz) are needed for proper near field view in premature / newborn infants, for older children one to five MHz are
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appropriate. Moreover, linear transducers are helpful especially in the assessment of the mediastinum and the supra-aortic vessels in neonates and infants.
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Besides two-dimensional (2D) ultrasound (US), the machine should support M-Mode, Pulsed Wave
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Doppler (PW) Sonography, Colour Doppler Sonography (CDS), Continuous Wave Doppler (CW)
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Sonography and TEE. Further add-ons are three-dimensional (3D) and four-dimensional (4D) echocardiography as well as Tissue Doppler Imaging.
Standardized course of examination of trans-thoracic 2D echocardiography There are three basic planes: a) Long axis plane (parallel to the major axis of the left ventricle), b) short axis plane (orthogonal to major axis of left ventricle) and c) coronal plane through the cardiac apex (four chamber view showing both ventricle and both atria). The US transducer is positioned on four different places in order to obtain the standard planes (Fig.2a): para-sternal area near the sternum in the second to fourth intercostal space, at the region of the cardiac apex, as well as within the subcostal region and the supra-sternal notch. Long and short axis planes can be generated in each of these areas (Fig.2b). Additional views can be obtained by
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tilting the transducer von right to left, to superior and inferior, and rotating clock- or counter clockwise. The standardized examination protocol defines the visceral situs (where is the heart apex), followed by description of the relationship between the descending aorta and inferior vena cava (IVC),
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definition of position and morphology of atria, assessment of the systemic and pulmonary venous return, hepatic veins, continuity of IVC, as well as inter-atrial and inter-ventricular septum.
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Determination of atrio-ventricular junction (which atrium is in front of which ventricle) as well as
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the ventricular arterial junction (which ventricle gives outlet to which great artery) is essential for
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classification of several complex heart defects.
Normal two-dimensional, trans-thoracic echocardiographic findings
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In the para-sternal long axis view the transducers orientated along the major axis of the heart (eg. from the left hip to right shoulder). In infants visualization is improved due to the thymus. Using
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this plane, the inter-ventricular septum, the left ventricle and atrium, the inflow portion of the left
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ventricle including the mitral valve, as well as the outflow portion of the aortic valve and ascending
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aorta can be visualized (Fig.3).
The para-sternal short axis view is obtained by rotating the transducer 90 degrees clockwise from the long axis view. From the base of the heart to the apical region several short axis planes can be generated and different anatomic structures like cardiac apex, papillary muscles, mitral valve, heart base, as well as the origin of great vessels can be assessed (Fig.4). By angulating the transducer to the left, the right ventricular outflow tract and the main pulmonary artery with its bifurcation is depicted (Fig.5). The origin of the coronary arteries can be evaluated at the base of the heart (Fig.6). For the apical four chamber views the transducer is applied on the pulsating cardiac apex and rotated perpendicular to the inter-ventricular and inter-atrial septum. Using this approach, all four cardiac chambers, the mitral- and tricuspid valve, as well as the inter-atrial and inter-ventricular septa can be visualized. Moreover, the more apical insertion of the tricuspidal valve is depicted
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clearly using this view (Fig.7). By slight anterior angulation of the transducer the left ventricular outflow tract and the ascending aorta can be assessed. Subcostal views can be achieved in sagittal plan in order to evaluate the descending aorta left to the IVC. The subcostal four chamber view can be generated by turning the transducer from the
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subcostal sagittal view 90 degrees counter clockwise. It allows for visualisation of all four cardiac chambers, especially in newborns and infants, additionally the inter-atrial septum and pulmonary
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veins can be shown.
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Supra-sternal views are obtained by placing the transducer on the suprasternal notch with overextended neck. Using this approach the entire aortic arch and the supra-aortic vessels can be
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inspected, as well as the right pulmonary artery in cross section. This approach is particularly helpful for differentiation between a left or a right aortic arch.
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Moreover, the entrance of the inferior cava vein into right atrium should be assessed in all studies.
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M (motion) – Mode Echocardiography
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A single US beam is sent through the heart and is reflected on the different structures. A strip chart
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is generated by plotting these echoes against time, thus depicting the movement of cardiac structures at that particular position (Fig.8). M-Mode echocardiography allows measuring diameters of cardiac chambers, vessels and septa more accurately. Moreover, left ventricular systolic function can be quantified using the shortening fraction (Fig.9), as well as motion of the valves and the intraventricular septum can be studied.
Doppler Sonography CDS allows visualizing the blood flow within the heart and great vessels, to assess the direction of internal and external cardiac shunts, as well as to depict jets in valvular stenosis and regurgitation. PW- and CW-Doppler enable measuring blood flow velocity. PW-Doppler is limited by the Nyquist frequency of the transducer and therefore there is a trade-off between the B-Mode 2DUS
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geometrical resolution and maximum speed encoding capability for Doppler studies. CW-Doppler does not suffer from that limitation and therefore can be used for assessment of high speed blood velocities in shunts or valvular stenosis. Based on the modified Bernoulli Equation pressure gradients in stenotic areas can be estimated. In
P1 -P2 = 4v2 mmHg (Eq. 1)
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general, the pressure difference between across a stenotic area is given according Equation 1 (3):
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At the beginning of the systolic heart phase blood flow velocity equals zero and therefore Eq.1 can
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be reduced to Eq.2: δP = 4 v2 mmHg (Eq. 2)
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For example, if the maximum blood flow velocity across the aortic wave is measured to be 3.0 m/s,
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the pressure gradient will be calculated to be 4 x (3)2 mmHg = 4 x 9 mmHg = 36 mm Hg.
Assessment of cardiac function
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Left systolic function: two indices can be calculated
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a) Shorting fraction (SF): representing the change of the left ventricular internal diameter during the
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systolic phase - normal values between 28% to 44% (Fig.9) and b) Ejection fraction (EF) indicating the change of the left ventricular cavity - from the diastolic to the systolic phase in percent. Normal values are 55% to 75%. EF can be calculated and based on MMode tracings, left ventricular area as well as from 2D echocardiography, volumetric based ones can be achieved by 3D/4DUS.
Assessment of right ventricular systolic function: the tricuspid annular systolic excursion (TAPSE) is derived from M-Mode tracings and characterizes a displacement of the right ventricular base during systolic and diastolic phase. Estimation of the right ventricular ejection fraction by echocardiography is not reliable due to the complex shape of the right ventricle, reminding a banana. Measurements are usually normalized to body surface area (BSA) and can be obtained from the
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internet under http://parameterz.blogspot.co.at/
Special echocardiographic techniques Transoesophageal echocardiography (TEE) is a semi-invasive procedure where a transducer is
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inserted into the oesophagus. In children TEE indications include intra- or peri-operative echocardiography, exact evaluation of morphology defects within the inter-atrial septum, guidance
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of interventional procedures during cardiac catheterization with limited thoracic US window (4).
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3DUS is now available and has become a valuable tool for calculating ventricular volumes, assessment of valve anatomy or heart function as well as wall motion disorders. In future 4DUS
improve results from former 3DUS applications.
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may play a role in the exact tomographic evaluation of complex congenital anomalies and will
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Tissue Doppler Imaging is a relatively new technique which allows measuring the velocity of
function.
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myocardial motion thus enabling a better characterization of ventricular systolic and diastolic
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Contrast-enhanced US, using physiologic saline or dedicated US contrast media (“microbubbles”)
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enable detection and characterization of right to left shunts, but no US contrast-media is licensed for paediatric use worldwide.
Echocardiographic findings of common CHD types Atrial septum defect (ASD): several types are known, the septum secundum defect being the most frequent one (Fig.10). Patent foramen ovale (PFO) can be demonstrated in neonates as a flap-like opening. In 30% of adults PFO can be demonstrated by valvasalva manoeuvre combined with contrast enhancement by injection of physiologic saline, application of US contrast media can be an option (5,6,7). Sinus venosus defects (superior vena cava defect, shunt in superior/posterior part of inter-atrial septum) are often associated with anomalous pulmonary venous drainage. Atrioventricular septal defects (AVSD) are characterized by a common atrio-ventricular valve (AV-valve)
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with one or two separate openings. Contradictionary to the normal case, valve leaflets insert at the same ventricular level. AV-valve regurgitation can occur due to commissures between leaflets (“clefts”). Inter-atrial septum is best assessed by subcostal und apical 4 chamber views. Since the inter-atrial
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septum is thin it can be difficult to distinguish from artifacts. For common AV-valves the parasternal short axis views are helpful too.
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PW-Doppler and CDS can be used for demonstration of left to right shunt in ASD, which leads to
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right ventricular volume overload and increased sized of the right ventricular outflow tract as well as the pulmonary arteries. Due to the minor pressure gradient between both atria, pulmonary
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hypertension is occurring only within the third decade of life.
Ventricular septum defects (VSD): most common CHD, a major proportion of VSDs are located
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within the membranous part (Fig.11), if the muscular septum is involved then the VSD is called a “perimembranous VSD”. CDS enables detection of small or multiple VSD. Using CW-Doppler and
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the modified Bernoulli Equation (Eq.2) the pressure gradient can be measured and, in case of
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the following formula (8):
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simultaneously measured blood pressure, the systolic right ventricular pressure can be estimated by
right ventricular systolic pressure = systolic blood pressure – pressure gradient (Eq.3) Due to the left to right shunt in VSD the left atrium, the left ventricle and the pulmonary arteries are dilated, followed by right ventricle dilatation later in the course. In VSD there is a high pressure gradient between left and right ventricle and therefore pulmonary hypertension develops already in infancy in those defects with significant shunt. Patent Ductus Arteriosus Botalli (PDA): Occurs in preterm infants, isolated or in combination with other CHD types. PDA is best assessed from high left parasternal views or parasternal short axis sections (“ductus view”), where the main pulmonary artery divides in three vessels: right and left pulmonary artery and PDA (Fig.12). Due to the left-to-right shunt, volume overload of the lung and the left heart exists, thus leading to dilatation of left atrium and ventricle.
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Aortic Coarctation: The aortic arch is best examined by hyerextended neck placing the transducer on the suprasternal notch. Care must be taken to image the whole aortic arch, since there can be a hypoplastic or interrupted arch. Axial and oblique scans of the neck are helpful for assessing the position of the brachio-cephalic trunk.
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CDS depicts the high velocity jet distal to the coarctation (Fig.13), PW- / CW-Doppler allows measurement of the velocity and computation of the pressure gradient using the modified Bernoulli
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Equation (Eq.1).
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Due to upper extremity hypertension, left ventricular myocardium thickening (indicating left ventricular hypertrophy) can be found on M-Mode and 2D-echocardiography.
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Tetralogy of Fallot (TOF) and variants eg. Pulmonary Atresia with VSD: TOF represents the most common cyanotic congenital heart defect (9). TOF is characterized by right ventricular outflow
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tract obstruction causing right ventricular hypertrophy, a large VSD located within the outflow tract causing the Aorta to get blood supply from both ventricles – therefore the name “overriding Aorta”.
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Para-sternal long axis views can be exploited to imagine the VSD and the overriding aorta
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(Fig.14a). Para-sternal and subcostal short axis views allow assessment of subpulmonary stenosis,
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morphology and size of the pulmonary valve, as well as of the main pulmonary artery. Bifurcation of main pulmonary artery and branches are best depicted by para-sternal short axis views and from the supra-sternal transducer position. In 25% of TOF patients there is a right aortic arch with a right descending aorta, which can be evaluated by transversal subcostal planes. CDS enables visualization of the ejection jet from pulmonary stenosis (Fig.14b). And it demonstrates the predominant right-left shunt caused by the VSD. CW-Doppler enables determination of the pressure gradient across the right ventricular outflow tract. After surgical correction patients suffer from right ventricular dilatation due to pulmonary insufficiency later in life. Transposition of the Great Arteries (TGA): Several types are known, in the simple case (d-TGA) the aorta originates anteriorly from the right ventricle and the main pulmonary artery posteriorly from
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the left ventricle – therefore it is called ventriculo-arterial disconcordance. As a consequence, systemic and pulmonary circulation are in parallel. Venous return from the superior and inferior cava vein drains into the right atrium and is expelled via the right ventricle into the aorta. Therefore no oxygenated blood arrives in the systemic circulation. In the untreated case, survival depends on
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shunts like ASD, VSD and PDA. In l-TGA the ventricles are inverted too (atrio-ventricular disconcordance) and thus the morphologic right ventricle functions as the systemic ventricle and the
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morphologic left ventricle as the subpulmonary one. These patients get symptomatic in the third to
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fourth decade due to the insufficiency of the systemic ventricle (equals morphologic systemic ventricle).
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In d-TGA aorta and main pulmonary artery are in a sagittal position (“double flint position”). Therefore - on para-sternal long axis views and supra-sternal transducer positions - both arteries can
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be seen on sagittal scans (Fig.15). Using the subcostal four chamber view the connection of the left ventricle with the main pulmonary artery can be demonstrated. CDS enables demonstration of
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shunts and stenosis jets in associated defects such as VSD, coarctation or outflow tract obstruction.
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It has to be kept in mind that shunts between systemic and pulmonary circulation (eg. PDA) change
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arterial blood flow – in case of a PDA, aorto-pulmonary window or aortic insufficiency, the diastolic flow will be in opposite direction of the systolic one (Fig 16). The opposite direction of the diastolic flow can cause troubles at interpretation of cranial PW-Doppler findings, eg. in grading brain oedema. In this situation the additional Doppler interrogation of the carotid arteries, the abdominal aorta and renal arteries is helpful.
Role of other imaging modalities: A general overview of the indications can be found in the recent guidelines of the “Task Force on the Management of Grown-up Congenital Heart Disease of the European Society of Cardiology (ESC); Association for European Paediatric Cardiology (AEPC); ESC Committee for Practice Guidelines (CPG)” (10).
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Cardiac Catherisation: Was regarded as gold standard for morphological and functional cardiac assessment for a long time, but it suffers from considerable radiation burden and is invasive. However, cardiac catherisation enables direct pressure measurements and oxymetry for shunt quantification and thus cannot be replaced completely by other imaging. In addition, interventional
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procedures can be performed in the same session.
Cardiac Magnetic Resonance Imaging (cMRI) and Computed Tomography (cCT): Beyond infancy,
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in CHD adolescents and GUCH patients, echocardiography is more difficult to perform due
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restricted access, eg. by chest wall deformities, scoliosis, lung emphysema and more. Therefore an optimal insonation is not always possible. cMRI provides a non-invasive, radiation free imaging
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modality, which depicts cardiac morphology and function with high accuracy (11). Images planes are in the same orientation - such as short axis or four chamber view (Fig.17). Moreover, left and
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right ventricular function assessment can be done, and the ejection fraction can be calculated without any geometrical assumption. Therefore ventricular shape does not impair results. Based on
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“Velocity Encoded Imaging (VENC)” valve pressure gradients can be calculated as well as the
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regurgitation fraction in valve insufficiency (Fig.18). VENC from the tricuspidal valve allows
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estimating right ventricular compliance. Cardiac stress examinations can be done using intravenous Dopamin injection or physical stress (12). Additionally, several Gadolinium (Gd) free Magnetic Resonance Angiography (MRA) techniques are available for imaging of the cardio-vascular system (Fig. 19a).
Using intravenous injection of Gd-based contrast media vitality imaging of the myocardium can be achieved, and patterns of delayed enhancement allow differential diagnosis of ischaemic versus other cardiomyopathies, storage diseases – just to name a few (Fig. 19b). Moreover, based on Gd injection, MRA can performed with high temporal and geometrical resolution (12). cCT presently represents the imaging modality of choice for depicting coronary arteries in infants and children (eg. Kawasaki Syndrome), since in routine MRA complete imaging of those vessels needs expertise and - due to simultaneous ECG and respiratory gating - a cooperative patient (or
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general anaesthesia with long breath hold sessions). Assessment of dissecting aneurysms (eg. Marfan Syndrome) represents another cCT indication. Estimation of ventricular function in patients with MRI contraindications (eg., peacemaker), evaluation of valve morphology, and determination
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of the opening/closing area in valve diseases are further applications of cCT.
Conclusion
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In conclusion, after basic patient evaluation (anamnesis, physical examination, ECG)
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echocardiography still is and will stay the first line imaging method in childhood cardio-vascular disease. In neonates, infants and children CHD types can be diagnosed by echocardiography, and
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functional heart evaluation can be done at the bed side, only right ventricular assessment is more challenging. In older children, adolescents and GUCH patients, echocardiography suffers from
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limitations, where cMRI and cCT offer many options for complete morphological and functional
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heart assessment.
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Literature:
1. Allen HD, Driscoll DJ, Shaddy RE, et al. Heart Disease in Infants, Children and Adolescents. 8th
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Edition 2013, Lippincott Williams and Wilkins, Philadelphia, 32-52
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2. Kaemmerer H, Bauer U, De Haan F, et al. Recommendations for improving the quality of the interdisciplinary medical care of grown-ups with congenital heart disease (GUCH). Int J Cardiol
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2011;150(1):59-64.
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3. Zhang Y, Nitter-Hauge S. Determination of the mean pressure gradient in aortic stenosis by
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Doppler echocardiography. Eur Heart J 1985;6(12):999-1005.
4. Hahn RT, Abraham T, Adams MS, et al. Guidelines for performing a comprehensive
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transesophageal echocardiographic examination: recommendations from the American Society of
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2013;26(9):921-64.
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Echocardiography and the Society of Cardiovascular Anesthesiologists. J Am Soc Echocardiogr
5. Van Hare GF, Silverman NH. Contrast two-dimensional echocardiography in congenital heart disease: techniques, indications and clinical utility. J Am Coll 1989;13:673-86.
6. Mulvagh SL, Rakowski H, Vannan MA, et al.
American Society of Echocardiography
Consensus Statement on the Clinical Applications of Ultrasonic Contrast Agents in Echocardiography. J Am Soc Echocardiogr 2008;21(11):1179-1201.
7. Fisher DC, Fisher EA, Budd JH, et al. The incidence of patent foramen ovale in 1,000 consecutive patients. A contrast transesophageal echocardiography study. Chest 1995;107(6):1504-
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9.
8. Murphy DJ, Ludomirsky A, Huhta JC. Continous wave doppler in children with ventricular septal defect: non invasive estimation of interventricular pressure gradient. Am J Cardiol 1986;
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57:428-32.
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9. Apitz C, Webb GD, Redington AN. Tetralogy of Fallot. Lancet 2009;374:1462-71.
10. Baumgartner H, Bonhoeffer P, De Groot NM, et al. ESC Guidelines for the management of
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grown-up congenital heart disease (new version 2010). Eur Heart J 2010;31(23):2915-57.
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11. Kilner PJ, Geva T, Kaemmerer H, et al. Recommendations for cardiovascular magnetic resonance in adults with congenital heart disease from the respective working groups of the
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European Society of Cardiology. European Heart Journal 2010;31(7):794-805.
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12. Marterer R, Sorantin E, Nagel B. Evaluation of the pulmonary valve function under physical stress using cMRI - could it be a prognostic factor in the follow-up of TOF patients? Pediatric Radiology 2011;41(Suppl 1):S257.
12. Ntsinjana HN, Tann O, Taylor AM. Trends in pediatric cardiovascular magnetic resonance imaging. Acta Radiologica 2013;54(9):1063-74.
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Type
Frequency 30%
Atrial Septum Defect (ASD)
10%
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Ventricular Sepumt Defect (VSD)
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Tables:
Persistent Ductus Arteriosus Botalli (PDA)
10%
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Coarctation (CoA)
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Pulmonary Stenosis Aortic Stenosis
7% 6% 6% 4%
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Transposition of Great Arteries
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Tetralogy of Fallot (TOF)
7%
Tab. 1
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Left heart obstruction
Anomaly
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Anatomical cause
Valvular, sub-/supravalvular aortic stenosis (AS)
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Hypoplastic left heart syndrome
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Coarctation of aorta (CoA), interrupted aortic arch
Congenital mitral valve stenosis
Valvular, sub-/supravalvular pulmonic stenosis (PS)
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Right heart obstruction
Pulmonary atresia (PA)
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Tetralogy of Fallot (TOF) Tricuspid atresia (TA)
anomalous pulmonary venous drainage)
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malformations
Atrial septal defect (ASD I, ASD II, ASD with partial
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Septal and vascular
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Ebstein anomaly
Ventricular septal defect (VSD) Total atrioventricular canal (AVC) Patent ductus arteriosus (PDA) Total anomalous pulmonary venous drainage (TAPVD) Truncus arteriosus communis (TAC)
Complex congenital heart disease Complete transposition of the great arteries (d-TGA) / anomalous origins of great
Corrected transposition of the great arteries (l-TGA)
arteries
Double-outlet right ventricle (DORV) Univentricular heart (UVH), single ventricle (SV)
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Lung perfusion
Decreased
Normal
PS
VSD
Increased
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Lung perfusion
Decreased
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ASD
With cyanosis
AS
TGA
CoA
TAPVD
PA
DORV (without PS)
DORV and PS
UVH
UVH without PS
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Increased
Without cyanosis
Tab. 3
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PDA
TOF
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Type
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Degree of severity ASD, VSD, PDA
“Moderately severe” anomalies
AVC, valvular insufficiencies, CoA, ASD
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“Simple” anomalies
type I, right ventricular outflow tract stenosis Cyanotic heart defects, valvular atresias,
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“Severe” anomalies
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TGA, UVH
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Tab. 4
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Legends:
Figure 1: Patient positioning for echocardiography
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Patient is lying on left side.
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Figure 2: Planes and transducer positions for echocardiography: a) Transducer positions are depicted – A corresponds to jugular position, B for short axis, C for four chamber view and D for
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subcostal approach.
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b) Scheme demonstrates the different planes for Echocardiography.
Figure 3: Male, 10 years, parasternal view, long axis:
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LA – left atrium, LV – left ventricle, Ao – aorta: simultaneous imaging of left ventricular inflow and
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outflow tract.
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Figure 4: Male, 10 years, parasternal view, short axis
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a) at level of mitral valve (white arrows) – leaflets have the appearance of a fish mouth, b) level of the left ventricular papillary muscles (arrows).
Figure 5: Male, 3 months, parasternal view, short axis at the base of the heart: Ao – aorta, PApulmonary artery: the bifurcation of the main pulmonary artery is visualized.
Figure 6: Female, 8 years, short axis view at the base of the heart. Arrows mark origin of a) left coronary artery b) right one.
Figure 7: Male, 4 years, apical four chamber view LV – left ventricle, LA – left atrium, RV – right ventricle, RA – right atrium, PV – pulmonary vein:
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all four cardiac chambers are visualized simultaneously.
Figure 8: Male 12 years, M-Mode echocardiogram obtained from a parasternal short axis view The right ventricle (RV) is shown anteriorly and the left ventricle (LV) posteriorly, change in
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Figure 9: Male, 10 years, M-Mode tracing through left ventricle,
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diameter indicates heart contraction.
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In the upper part of the image the 2D cut is displayed (LV-left ventricle, LA-left atrium, AO-aorta, RV-right ventricle), in the lower part the M-Mode tracing with markings of the inter-ventricular thickness and posterior left ventricular wall thickness (green lines). Additionally, the
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septum
internal diameter of the left ventricle in the diastolic (LVIDd-left ventricular internal, diastolic
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diameter) and systolic phase (LVIDs-left ventricular internal, systolic diameter) is depicted. Right, lower part depicts derived left ventricular function parameters.
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Used abbreviations in systolic(s) and diastolic(d) phase: LVPW-left ventricular wall thickness,
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LVID-left ventricular internal diameter, IVS-inter-ventricular septum thickness, EDV-enddiastolic
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volume, LV Masse-left ventricular mass, IVS%-relative intravenricular septum thickening during systole, FS-fractional shortening, ESV-left ventricular endsystolic volume, EF-ejection fraction, LVPW%-relative left ventricular wall thickening during systole in percent).
Figure 10: Female, 7 months, four chamber view. * indicates the ASD II defect.
Figure 11: Female, 1 year, parasternal view, long axis, CDS, Arrow points to left to right shunt via a perimembranous VSD.
Figure 12: Male, 1 year
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a) parasternal view, short axis at the base of the heart, CDS demonstrates shunt from descending aorta to pulmonary artery (PA) by a PDA (AO-aortic bulb, AO-Desc-descending aorta). b) CW Doppler tracing demonstrates typical high flow systolic-diastolic flow pattern.
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Figure 13: Male, 7 days, suprasternal view, CDS.
Arrow marks area of Coarctation, CDS demonstrates increased blood flow velocity (AO-Arch –
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aortic arch).
Figure 14: Male, 1 month, TOF, CDS
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a) parasternal, long axis view showing the VSD (asterix) and the overriding aorta receiving blood from left (LV) and right (RV) ventricle.
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b) Short axis view, base of the heart, arrow points to the turbulent blood flow caused by the
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Figure 15: Female, 4 days, d-TGA
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pulmonary stenosis.
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Suprasternal view depicting the parallel alignment of ascending aorta (+) and pulmonary artery (*).
Figure 16: pathologic, retrograde flow in aorta caused by aortic insufficiency. a) Suprasternal view, CDS of descending aorta. According the colour bar at right, upper image corner, red coded flow indicates flow towards the transducer thus meaning retrograde (opposite to systolic) flow.
b) Doppler tracings of descending aorta, for quantification of diastolic flow the scale is set to a low value of ±61.6 cm/s. The x symbol marks the systolic, antegrade flow (away from transducer), the arrow points to the reverted systolic tracings due to aliasing, wheras the symbol * depicts the pathologic, retrograde flow with a maximum velocity of 79.0 cm/s and mean velocity of 47.0cm/s.
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Figure 17: Male 20 years, operated TOF follow up, cardiac MRI. a) Short axis view demonstrating both ventricles (RV-right ventricle, LV-left ventricle), * marks right ventricular outflow tract aneurysm – a typical complication in the later course. b) Same patient, four chamber view – right ventricle (RV) forms cardiac apex due to enlargement
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caused by the pulmonary insufficiency (LV-left ventricle, RV-right ventricle, LA-left atrium, RA-
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right atrium).
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Figure 18: Same patient as in Figure 18, cardiac MRI, VENC Imaging within the pulmonary artery. a) Chart demonstrating forward (dark grey) and backward (light grey) blood flow due to pulmonary
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insufficiency.
b) Results from calculation the forward and reverse volume (marked by grey rectangle) – in this
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patient the forward volume was computed with 112.44ml and backward volume with 43.68ml. Therefore the regurgitation fraction can be simply calculated by: 43.68ml/112.44ml = 38.8%,
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indicating that 38.8% of right ventricular stroke volume is running back to the right ventricle during
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the diastolic phase thus leading to right ventricular enlargement.
Figure 19: Female, 28 years, Gd-free MRA, follow-up of Coarctation. a) “Handy Cane View” of aortic arch. Note high contrast display of vessels. Gothic aortic arch configuration is depicted as well as the reduced vessel diameter within the Coarctation area. b) Female, 15 years, embolic myocardial infarction due to a huge arterio-venous malformation of the lung, cardiac MRI after Gd injection, delayed enhancement technique, short axis cut: arrows point to bright areas within the myocardium representing the necrotic, transmural areas (“Bright is Dead”).
Table 1: Incidence and types of most frequent congenital heart defects.
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Table 2: Systematic classification of CHD, based on the underlying anatomic defect
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allowing categorization in left and right heart obstruction, septal and vascular malformations as well as complex CHD.
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Table 3: Based on cyanosis and lung perfusion in chest X-Ray another useful CHD classification
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can be achieved.
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Table 4: CHD categorization based on the necessary treatment intensity – simple, moderate and
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severe types can be discriminated.
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S0720-048X(14)00267-8 http://dx.doi.org/doi:10.1016/j.ejrad.2014.05.030 EURR 6801
To appear in:
European Journal of Radiology
Received date: Revised date: Accepted date:
8-5-2014 14-5-2014 18-5-2014
Please cite this article as: Sorantin E, Heinzl B, What every Radiologist should know about Pediatric Echocardiography, European Journal of Radiology (2014), http://dx.doi.org/10.1016/j.ejrad.2014.05.030 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
What every Radiologist should know about Pediatric Echocardiography
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Erich Sorantin1, Bernd Heinzl2
Division of Pediatric Radiology
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Department of Radiology Medical University Graz Auenbruggerplatz 34
Division of Pediatric Cardiology
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2:
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A – 8036 Graz
Department of Pediatric and Adolescent Medicine
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Medical University Graz
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A – 8036 Graz
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Auenbruggerplatz 34
Corresponding Author:
Univ.-Prof.Dr.Erich Sorantin
Division of Pediatric Radiology
Department of Radiology Medical University Graz Auenbruggerplatz 34 A – 8036 Graz Tel.:
+43 316 385 14202
Fax
+43 316 385 14299
Email: [email protected]
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What every Radiologist should know about Echocardiography
Abstract:
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Congenital heart defects (CHD) occur in less than one percent of all newborns. Echocardiography represents the imaging modality of choice for morphological and functional assessment. In
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childhood the different CHD types can be diagnosed trustfully and can be performed bedside. In the
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follow-up of CHD cross sectional imaging plays an important role and therefore it is essential for the radiologist to know the features, challenges and limitations of echocardiography. Within this
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review article a a systematic approach for morphological and functional assessment of the heart will is given along with representative example images. In addition, typical echocardiographic findings
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in commen CHD is presented. In older children, adolescents and grown-ups with CHD (GUCH) echocardiography suffers from limitations – partially due to skeletal deformations and lung
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emphysema. In particular right ventricular function assessment is not always possible by
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echocardiography. Therefore strengths and limitations of echocardiography will be discussed an the
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role of cardiac Magnetic Resonance Imaging (cMRI) and cardiac Computed Tomography (cCT) emphasized.
Keywords: heart defects congenital, echocardiography, children, cardiology
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Introduction About one percent of all newborn suffer from congenital heart disease (CHD), half of them are represented by defects with shunts like the ventricular septum defect (VSD), atrial septum defect (ASD) and the persistent Ductus Arteriosus Botalli (PDA) (1). The most frequent other types are
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(aortic) coarctation, pulmonary stenosis, aortic valve stenosis and Tetralogy of Fallot (details are found in Table 1).
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There are several possibilities to classify CHD – according to anatomy (obstruction of left or right
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heart, septal or vascular malformation, and complex CHD with anomalies of origin of the great arteries - Table 2) or due to shunts (left to right, right to left, bidirectional shunt, or no shunt).
in simple, moderate or severe are given in Table 4.
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Moreover, CHD types with and without cyanosis can be discriminated (Table 3). CHD stratification
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Currently a change in CHD epidemiology can be observed. Improved treatment options in combination with declining birth rate in western countries as well as terminated pregnancies in
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severe malformations lead to the fact, that today there are more adults with CHD than children
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(GUCH = grown-up congenital disease) (2). Therefore congenital heart defects do not only refer
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anymore to paediatric radiologists and paediatric cardiologists, but an increasing number of patients are within the adult population.
Besides chest x-ray, echocardiography has become the most important non-invasive imaging modality of choice for evaluation of the cardiovascular system, providing morphological diagnosis as well as functional assessment.
The purpose of this article is to present principles and limitations of echocardiography, diagnostic echocardiographic features of common CHD types, as well as the role of other imaging modalities like cardiac catheterization, cardiac magnetic resonance imaging (cMRI) and cardiac CT (cCT). Though there are two major types of echocardiography depending on the access [trans-thoracic and trans-oesophageal echocardiography (TEE)] this article will focus on the more common and basic trans-thoracic echocardiography.
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Patient preparation and positioning For trans-thoracic echocardiography there is no special preparation necessary. In rare cases sedation (peroral, using chloral hydrate or midazolam) may be necessary in order to obtain diagnostic
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information. The patient is positioned on his left side down, in a reclined position in order to move their heart away from the sternum (Fig.1). For supra-sternal views, the neck has to be overextended
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in order to place the transducer within the jugular fossa.
Technical requirements
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Sector transducers with a frequency range from five to twelve megahertz (MHz) are needed for proper near field view in premature / newborn infants, for older children one to five MHz are
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appropriate. Moreover, linear transducers are helpful especially in the assessment of the mediastinum and the supra-aortic vessels in neonates and infants.
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Besides two-dimensional (2D) ultrasound (US), the machine should support M-Mode, Pulsed Wave
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Doppler (PW) Sonography, Colour Doppler Sonography (CDS), Continuous Wave Doppler (CW)
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Sonography and TEE. Further add-ons are three-dimensional (3D) and four-dimensional (4D) echocardiography as well as Tissue Doppler Imaging.
Standardized course of examination of trans-thoracic 2D echocardiography There are three basic planes: a) Long axis plane (parallel to the major axis of the left ventricle), b) short axis plane (orthogonal to major axis of left ventricle) and c) coronal plane through the cardiac apex (four chamber view showing both ventricle and both atria). The US transducer is positioned on four different places in order to obtain the standard planes (Fig.2a): para-sternal area near the sternum in the second to fourth intercostal space, at the region of the cardiac apex, as well as within the subcostal region and the supra-sternal notch. Long and short axis planes can be generated in each of these areas (Fig.2b). Additional views can be obtained by
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tilting the transducer von right to left, to superior and inferior, and rotating clock- or counter clockwise. The standardized examination protocol defines the visceral situs (where is the heart apex), followed by description of the relationship between the descending aorta and inferior vena cava (IVC),
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definition of position and morphology of atria, assessment of the systemic and pulmonary venous return, hepatic veins, continuity of IVC, as well as inter-atrial and inter-ventricular septum.
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Determination of atrio-ventricular junction (which atrium is in front of which ventricle) as well as
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the ventricular arterial junction (which ventricle gives outlet to which great artery) is essential for
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classification of several complex heart defects.
Normal two-dimensional, trans-thoracic echocardiographic findings
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In the para-sternal long axis view the transducers orientated along the major axis of the heart (eg. from the left hip to right shoulder). In infants visualization is improved due to the thymus. Using
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this plane, the inter-ventricular septum, the left ventricle and atrium, the inflow portion of the left
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ventricle including the mitral valve, as well as the outflow portion of the aortic valve and ascending
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aorta can be visualized (Fig.3).
The para-sternal short axis view is obtained by rotating the transducer 90 degrees clockwise from the long axis view. From the base of the heart to the apical region several short axis planes can be generated and different anatomic structures like cardiac apex, papillary muscles, mitral valve, heart base, as well as the origin of great vessels can be assessed (Fig.4). By angulating the transducer to the left, the right ventricular outflow tract and the main pulmonary artery with its bifurcation is depicted (Fig.5). The origin of the coronary arteries can be evaluated at the base of the heart (Fig.6). For the apical four chamber views the transducer is applied on the pulsating cardiac apex and rotated perpendicular to the inter-ventricular and inter-atrial septum. Using this approach, all four cardiac chambers, the mitral- and tricuspid valve, as well as the inter-atrial and inter-ventricular septa can be visualized. Moreover, the more apical insertion of the tricuspidal valve is depicted
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clearly using this view (Fig.7). By slight anterior angulation of the transducer the left ventricular outflow tract and the ascending aorta can be assessed. Subcostal views can be achieved in sagittal plan in order to evaluate the descending aorta left to the IVC. The subcostal four chamber view can be generated by turning the transducer from the
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subcostal sagittal view 90 degrees counter clockwise. It allows for visualisation of all four cardiac chambers, especially in newborns and infants, additionally the inter-atrial septum and pulmonary
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veins can be shown.
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Supra-sternal views are obtained by placing the transducer on the suprasternal notch with overextended neck. Using this approach the entire aortic arch and the supra-aortic vessels can be
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inspected, as well as the right pulmonary artery in cross section. This approach is particularly helpful for differentiation between a left or a right aortic arch.
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Moreover, the entrance of the inferior cava vein into right atrium should be assessed in all studies.
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M (motion) – Mode Echocardiography
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A single US beam is sent through the heart and is reflected on the different structures. A strip chart
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is generated by plotting these echoes against time, thus depicting the movement of cardiac structures at that particular position (Fig.8). M-Mode echocardiography allows measuring diameters of cardiac chambers, vessels and septa more accurately. Moreover, left ventricular systolic function can be quantified using the shortening fraction (Fig.9), as well as motion of the valves and the intraventricular septum can be studied.
Doppler Sonography CDS allows visualizing the blood flow within the heart and great vessels, to assess the direction of internal and external cardiac shunts, as well as to depict jets in valvular stenosis and regurgitation. PW- and CW-Doppler enable measuring blood flow velocity. PW-Doppler is limited by the Nyquist frequency of the transducer and therefore there is a trade-off between the B-Mode 2DUS
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geometrical resolution and maximum speed encoding capability for Doppler studies. CW-Doppler does not suffer from that limitation and therefore can be used for assessment of high speed blood velocities in shunts or valvular stenosis. Based on the modified Bernoulli Equation pressure gradients in stenotic areas can be estimated. In
P1 -P2 = 4v2 mmHg (Eq. 1)
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general, the pressure difference between across a stenotic area is given according Equation 1 (3):
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At the beginning of the systolic heart phase blood flow velocity equals zero and therefore Eq.1 can
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be reduced to Eq.2: δP = 4 v2 mmHg (Eq. 2)
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For example, if the maximum blood flow velocity across the aortic wave is measured to be 3.0 m/s,
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the pressure gradient will be calculated to be 4 x (3)2 mmHg = 4 x 9 mmHg = 36 mm Hg.
Assessment of cardiac function
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Left systolic function: two indices can be calculated
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a) Shorting fraction (SF): representing the change of the left ventricular internal diameter during the
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systolic phase - normal values between 28% to 44% (Fig.9) and b) Ejection fraction (EF) indicating the change of the left ventricular cavity - from the diastolic to the systolic phase in percent. Normal values are 55% to 75%. EF can be calculated and based on MMode tracings, left ventricular area as well as from 2D echocardiography, volumetric based ones can be achieved by 3D/4DUS.
Assessment of right ventricular systolic function: the tricuspid annular systolic excursion (TAPSE) is derived from M-Mode tracings and characterizes a displacement of the right ventricular base during systolic and diastolic phase. Estimation of the right ventricular ejection fraction by echocardiography is not reliable due to the complex shape of the right ventricle, reminding a banana. Measurements are usually normalized to body surface area (BSA) and can be obtained from the
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internet under http://parameterz.blogspot.co.at/
Special echocardiographic techniques Transoesophageal echocardiography (TEE) is a semi-invasive procedure where a transducer is
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inserted into the oesophagus. In children TEE indications include intra- or peri-operative echocardiography, exact evaluation of morphology defects within the inter-atrial septum, guidance
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of interventional procedures during cardiac catheterization with limited thoracic US window (4).
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3DUS is now available and has become a valuable tool for calculating ventricular volumes, assessment of valve anatomy or heart function as well as wall motion disorders. In future 4DUS
improve results from former 3DUS applications.
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may play a role in the exact tomographic evaluation of complex congenital anomalies and will
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Tissue Doppler Imaging is a relatively new technique which allows measuring the velocity of
function.
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myocardial motion thus enabling a better characterization of ventricular systolic and diastolic
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Contrast-enhanced US, using physiologic saline or dedicated US contrast media (“microbubbles”)
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enable detection and characterization of right to left shunts, but no US contrast-media is licensed for paediatric use worldwide.
Echocardiographic findings of common CHD types Atrial septum defect (ASD): several types are known, the septum secundum defect being the most frequent one (Fig.10). Patent foramen ovale (PFO) can be demonstrated in neonates as a flap-like opening. In 30% of adults PFO can be demonstrated by valvasalva manoeuvre combined with contrast enhancement by injection of physiologic saline, application of US contrast media can be an option (5,6,7). Sinus venosus defects (superior vena cava defect, shunt in superior/posterior part of inter-atrial septum) are often associated with anomalous pulmonary venous drainage. Atrioventricular septal defects (AVSD) are characterized by a common atrio-ventricular valve (AV-valve)
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with one or two separate openings. Contradictionary to the normal case, valve leaflets insert at the same ventricular level. AV-valve regurgitation can occur due to commissures between leaflets (“clefts”). Inter-atrial septum is best assessed by subcostal und apical 4 chamber views. Since the inter-atrial
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septum is thin it can be difficult to distinguish from artifacts. For common AV-valves the parasternal short axis views are helpful too.
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PW-Doppler and CDS can be used for demonstration of left to right shunt in ASD, which leads to
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right ventricular volume overload and increased sized of the right ventricular outflow tract as well as the pulmonary arteries. Due to the minor pressure gradient between both atria, pulmonary
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hypertension is occurring only within the third decade of life.
Ventricular septum defects (VSD): most common CHD, a major proportion of VSDs are located
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within the membranous part (Fig.11), if the muscular septum is involved then the VSD is called a “perimembranous VSD”. CDS enables detection of small or multiple VSD. Using CW-Doppler and
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the modified Bernoulli Equation (Eq.2) the pressure gradient can be measured and, in case of
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the following formula (8):
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simultaneously measured blood pressure, the systolic right ventricular pressure can be estimated by
right ventricular systolic pressure = systolic blood pressure – pressure gradient (Eq.3) Due to the left to right shunt in VSD the left atrium, the left ventricle and the pulmonary arteries are dilated, followed by right ventricle dilatation later in the course. In VSD there is a high pressure gradient between left and right ventricle and therefore pulmonary hypertension develops already in infancy in those defects with significant shunt. Patent Ductus Arteriosus Botalli (PDA): Occurs in preterm infants, isolated or in combination with other CHD types. PDA is best assessed from high left parasternal views or parasternal short axis sections (“ductus view”), where the main pulmonary artery divides in three vessels: right and left pulmonary artery and PDA (Fig.12). Due to the left-to-right shunt, volume overload of the lung and the left heart exists, thus leading to dilatation of left atrium and ventricle.
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Aortic Coarctation: The aortic arch is best examined by hyerextended neck placing the transducer on the suprasternal notch. Care must be taken to image the whole aortic arch, since there can be a hypoplastic or interrupted arch. Axial and oblique scans of the neck are helpful for assessing the position of the brachio-cephalic trunk.
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CDS depicts the high velocity jet distal to the coarctation (Fig.13), PW- / CW-Doppler allows measurement of the velocity and computation of the pressure gradient using the modified Bernoulli
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Equation (Eq.1).
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Due to upper extremity hypertension, left ventricular myocardium thickening (indicating left ventricular hypertrophy) can be found on M-Mode and 2D-echocardiography.
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Tetralogy of Fallot (TOF) and variants eg. Pulmonary Atresia with VSD: TOF represents the most common cyanotic congenital heart defect (9). TOF is characterized by right ventricular outflow
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tract obstruction causing right ventricular hypertrophy, a large VSD located within the outflow tract causing the Aorta to get blood supply from both ventricles – therefore the name “overriding Aorta”.
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Para-sternal long axis views can be exploited to imagine the VSD and the overriding aorta
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(Fig.14a). Para-sternal and subcostal short axis views allow assessment of subpulmonary stenosis,
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morphology and size of the pulmonary valve, as well as of the main pulmonary artery. Bifurcation of main pulmonary artery and branches are best depicted by para-sternal short axis views and from the supra-sternal transducer position. In 25% of TOF patients there is a right aortic arch with a right descending aorta, which can be evaluated by transversal subcostal planes. CDS enables visualization of the ejection jet from pulmonary stenosis (Fig.14b). And it demonstrates the predominant right-left shunt caused by the VSD. CW-Doppler enables determination of the pressure gradient across the right ventricular outflow tract. After surgical correction patients suffer from right ventricular dilatation due to pulmonary insufficiency later in life. Transposition of the Great Arteries (TGA): Several types are known, in the simple case (d-TGA) the aorta originates anteriorly from the right ventricle and the main pulmonary artery posteriorly from
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the left ventricle – therefore it is called ventriculo-arterial disconcordance. As a consequence, systemic and pulmonary circulation are in parallel. Venous return from the superior and inferior cava vein drains into the right atrium and is expelled via the right ventricle into the aorta. Therefore no oxygenated blood arrives in the systemic circulation. In the untreated case, survival depends on
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shunts like ASD, VSD and PDA. In l-TGA the ventricles are inverted too (atrio-ventricular disconcordance) and thus the morphologic right ventricle functions as the systemic ventricle and the
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morphologic left ventricle as the subpulmonary one. These patients get symptomatic in the third to
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fourth decade due to the insufficiency of the systemic ventricle (equals morphologic systemic ventricle).
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In d-TGA aorta and main pulmonary artery are in a sagittal position (“double flint position”). Therefore - on para-sternal long axis views and supra-sternal transducer positions - both arteries can
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be seen on sagittal scans (Fig.15). Using the subcostal four chamber view the connection of the left ventricle with the main pulmonary artery can be demonstrated. CDS enables demonstration of
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shunts and stenosis jets in associated defects such as VSD, coarctation or outflow tract obstruction.
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It has to be kept in mind that shunts between systemic and pulmonary circulation (eg. PDA) change
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arterial blood flow – in case of a PDA, aorto-pulmonary window or aortic insufficiency, the diastolic flow will be in opposite direction of the systolic one (Fig 16). The opposite direction of the diastolic flow can cause troubles at interpretation of cranial PW-Doppler findings, eg. in grading brain oedema. In this situation the additional Doppler interrogation of the carotid arteries, the abdominal aorta and renal arteries is helpful.
Role of other imaging modalities: A general overview of the indications can be found in the recent guidelines of the “Task Force on the Management of Grown-up Congenital Heart Disease of the European Society of Cardiology (ESC); Association for European Paediatric Cardiology (AEPC); ESC Committee for Practice Guidelines (CPG)” (10).
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Cardiac Catherisation: Was regarded as gold standard for morphological and functional cardiac assessment for a long time, but it suffers from considerable radiation burden and is invasive. However, cardiac catherisation enables direct pressure measurements and oxymetry for shunt quantification and thus cannot be replaced completely by other imaging. In addition, interventional
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procedures can be performed in the same session.
Cardiac Magnetic Resonance Imaging (cMRI) and Computed Tomography (cCT): Beyond infancy,
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in CHD adolescents and GUCH patients, echocardiography is more difficult to perform due
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restricted access, eg. by chest wall deformities, scoliosis, lung emphysema and more. Therefore an optimal insonation is not always possible. cMRI provides a non-invasive, radiation free imaging
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modality, which depicts cardiac morphology and function with high accuracy (11). Images planes are in the same orientation - such as short axis or four chamber view (Fig.17). Moreover, left and
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right ventricular function assessment can be done, and the ejection fraction can be calculated without any geometrical assumption. Therefore ventricular shape does not impair results. Based on
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“Velocity Encoded Imaging (VENC)” valve pressure gradients can be calculated as well as the
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regurgitation fraction in valve insufficiency (Fig.18). VENC from the tricuspidal valve allows
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estimating right ventricular compliance. Cardiac stress examinations can be done using intravenous Dopamin injection or physical stress (12). Additionally, several Gadolinium (Gd) free Magnetic Resonance Angiography (MRA) techniques are available for imaging of the cardio-vascular system (Fig. 19a).
Using intravenous injection of Gd-based contrast media vitality imaging of the myocardium can be achieved, and patterns of delayed enhancement allow differential diagnosis of ischaemic versus other cardiomyopathies, storage diseases – just to name a few (Fig. 19b). Moreover, based on Gd injection, MRA can performed with high temporal and geometrical resolution (12). cCT presently represents the imaging modality of choice for depicting coronary arteries in infants and children (eg. Kawasaki Syndrome), since in routine MRA complete imaging of those vessels needs expertise and - due to simultaneous ECG and respiratory gating - a cooperative patient (or
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general anaesthesia with long breath hold sessions). Assessment of dissecting aneurysms (eg. Marfan Syndrome) represents another cCT indication. Estimation of ventricular function in patients with MRI contraindications (eg., peacemaker), evaluation of valve morphology, and determination
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of the opening/closing area in valve diseases are further applications of cCT.
Conclusion
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In conclusion, after basic patient evaluation (anamnesis, physical examination, ECG)
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echocardiography still is and will stay the first line imaging method in childhood cardio-vascular disease. In neonates, infants and children CHD types can be diagnosed by echocardiography, and
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functional heart evaluation can be done at the bed side, only right ventricular assessment is more challenging. In older children, adolescents and GUCH patients, echocardiography suffers from
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limitations, where cMRI and cCT offer many options for complete morphological and functional
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heart assessment.
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Literature:
1. Allen HD, Driscoll DJ, Shaddy RE, et al. Heart Disease in Infants, Children and Adolescents. 8th
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Edition 2013, Lippincott Williams and Wilkins, Philadelphia, 32-52
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2. Kaemmerer H, Bauer U, De Haan F, et al. Recommendations for improving the quality of the interdisciplinary medical care of grown-ups with congenital heart disease (GUCH). Int J Cardiol
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2011;150(1):59-64.
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3. Zhang Y, Nitter-Hauge S. Determination of the mean pressure gradient in aortic stenosis by
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Doppler echocardiography. Eur Heart J 1985;6(12):999-1005.
4. Hahn RT, Abraham T, Adams MS, et al. Guidelines for performing a comprehensive
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transesophageal echocardiographic examination: recommendations from the American Society of
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2013;26(9):921-64.
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Echocardiography and the Society of Cardiovascular Anesthesiologists. J Am Soc Echocardiogr
5. Van Hare GF, Silverman NH. Contrast two-dimensional echocardiography in congenital heart disease: techniques, indications and clinical utility. J Am Coll 1989;13:673-86.
6. Mulvagh SL, Rakowski H, Vannan MA, et al.
American Society of Echocardiography
Consensus Statement on the Clinical Applications of Ultrasonic Contrast Agents in Echocardiography. J Am Soc Echocardiogr 2008;21(11):1179-1201.
7. Fisher DC, Fisher EA, Budd JH, et al. The incidence of patent foramen ovale in 1,000 consecutive patients. A contrast transesophageal echocardiography study. Chest 1995;107(6):1504-
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9.
8. Murphy DJ, Ludomirsky A, Huhta JC. Continous wave doppler in children with ventricular septal defect: non invasive estimation of interventricular pressure gradient. Am J Cardiol 1986;
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57:428-32.
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9. Apitz C, Webb GD, Redington AN. Tetralogy of Fallot. Lancet 2009;374:1462-71.
10. Baumgartner H, Bonhoeffer P, De Groot NM, et al. ESC Guidelines for the management of
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grown-up congenital heart disease (new version 2010). Eur Heart J 2010;31(23):2915-57.
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11. Kilner PJ, Geva T, Kaemmerer H, et al. Recommendations for cardiovascular magnetic resonance in adults with congenital heart disease from the respective working groups of the
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European Society of Cardiology. European Heart Journal 2010;31(7):794-805.
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12. Marterer R, Sorantin E, Nagel B. Evaluation of the pulmonary valve function under physical stress using cMRI - could it be a prognostic factor in the follow-up of TOF patients? Pediatric Radiology 2011;41(Suppl 1):S257.
12. Ntsinjana HN, Tann O, Taylor AM. Trends in pediatric cardiovascular magnetic resonance imaging. Acta Radiologica 2013;54(9):1063-74.
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Type
Frequency 30%
Atrial Septum Defect (ASD)
10%
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Ventricular Sepumt Defect (VSD)
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Tables:
Persistent Ductus Arteriosus Botalli (PDA)
10%
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Coarctation (CoA)
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Pulmonary Stenosis Aortic Stenosis
7% 6% 6% 4%
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Transposition of Great Arteries
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Tetralogy of Fallot (TOF)
7%
Tab. 1
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Left heart obstruction
Anomaly
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Anatomical cause
Valvular, sub-/supravalvular aortic stenosis (AS)
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Hypoplastic left heart syndrome
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Coarctation of aorta (CoA), interrupted aortic arch
Congenital mitral valve stenosis
Valvular, sub-/supravalvular pulmonic stenosis (PS)
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Right heart obstruction
Pulmonary atresia (PA)
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Tetralogy of Fallot (TOF) Tricuspid atresia (TA)
anomalous pulmonary venous drainage)
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malformations
Atrial septal defect (ASD I, ASD II, ASD with partial
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Septal and vascular
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Ebstein anomaly
Ventricular septal defect (VSD) Total atrioventricular canal (AVC) Patent ductus arteriosus (PDA) Total anomalous pulmonary venous drainage (TAPVD) Truncus arteriosus communis (TAC)
Complex congenital heart disease Complete transposition of the great arteries (d-TGA) / anomalous origins of great
Corrected transposition of the great arteries (l-TGA)
arteries
Double-outlet right ventricle (DORV) Univentricular heart (UVH), single ventricle (SV)
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Lung perfusion
Decreased
Normal
PS
VSD
Increased
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Lung perfusion
Decreased
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ASD
With cyanosis
AS
TGA
CoA
TAPVD
PA
DORV (without PS)
DORV and PS
UVH
UVH without PS
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Increased
Without cyanosis
Tab. 3
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PDA
TOF
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Type
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Degree of severity ASD, VSD, PDA
“Moderately severe” anomalies
AVC, valvular insufficiencies, CoA, ASD
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“Simple” anomalies
type I, right ventricular outflow tract stenosis Cyanotic heart defects, valvular atresias,
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“Severe” anomalies
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TGA, UVH
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Tab. 4
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Legends:
Figure 1: Patient positioning for echocardiography
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Patient is lying on left side.
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Figure 2: Planes and transducer positions for echocardiography: a) Transducer positions are depicted – A corresponds to jugular position, B for short axis, C for four chamber view and D for
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subcostal approach.
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b) Scheme demonstrates the different planes for Echocardiography.
Figure 3: Male, 10 years, parasternal view, long axis:
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LA – left atrium, LV – left ventricle, Ao – aorta: simultaneous imaging of left ventricular inflow and
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outflow tract.
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Figure 4: Male, 10 years, parasternal view, short axis
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a) at level of mitral valve (white arrows) – leaflets have the appearance of a fish mouth, b) level of the left ventricular papillary muscles (arrows).
Figure 5: Male, 3 months, parasternal view, short axis at the base of the heart: Ao – aorta, PApulmonary artery: the bifurcation of the main pulmonary artery is visualized.
Figure 6: Female, 8 years, short axis view at the base of the heart. Arrows mark origin of a) left coronary artery b) right one.
Figure 7: Male, 4 years, apical four chamber view LV – left ventricle, LA – left atrium, RV – right ventricle, RA – right atrium, PV – pulmonary vein:
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all four cardiac chambers are visualized simultaneously.
Figure 8: Male 12 years, M-Mode echocardiogram obtained from a parasternal short axis view The right ventricle (RV) is shown anteriorly and the left ventricle (LV) posteriorly, change in
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Figure 9: Male, 10 years, M-Mode tracing through left ventricle,
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diameter indicates heart contraction.
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In the upper part of the image the 2D cut is displayed (LV-left ventricle, LA-left atrium, AO-aorta, RV-right ventricle), in the lower part the M-Mode tracing with markings of the inter-ventricular thickness and posterior left ventricular wall thickness (green lines). Additionally, the
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internal diameter of the left ventricle in the diastolic (LVIDd-left ventricular internal, diastolic
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diameter) and systolic phase (LVIDs-left ventricular internal, systolic diameter) is depicted. Right, lower part depicts derived left ventricular function parameters.
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LVID-left ventricular internal diameter, IVS-inter-ventricular septum thickness, EDV-enddiastolic
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volume, LV Masse-left ventricular mass, IVS%-relative intravenricular septum thickening during systole, FS-fractional shortening, ESV-left ventricular endsystolic volume, EF-ejection fraction, LVPW%-relative left ventricular wall thickening during systole in percent).
Figure 10: Female, 7 months, four chamber view. * indicates the ASD II defect.
Figure 11: Female, 1 year, parasternal view, long axis, CDS, Arrow points to left to right shunt via a perimembranous VSD.
Figure 12: Male, 1 year
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a) parasternal view, short axis at the base of the heart, CDS demonstrates shunt from descending aorta to pulmonary artery (PA) by a PDA (AO-aortic bulb, AO-Desc-descending aorta). b) CW Doppler tracing demonstrates typical high flow systolic-diastolic flow pattern.
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Figure 13: Male, 7 days, suprasternal view, CDS.
Arrow marks area of Coarctation, CDS demonstrates increased blood flow velocity (AO-Arch –
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aortic arch).
Figure 14: Male, 1 month, TOF, CDS
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a) parasternal, long axis view showing the VSD (asterix) and the overriding aorta receiving blood from left (LV) and right (RV) ventricle.
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b) Short axis view, base of the heart, arrow points to the turbulent blood flow caused by the
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Figure 15: Female, 4 days, d-TGA
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pulmonary stenosis.
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Suprasternal view depicting the parallel alignment of ascending aorta (+) and pulmonary artery (*).
Figure 16: pathologic, retrograde flow in aorta caused by aortic insufficiency. a) Suprasternal view, CDS of descending aorta. According the colour bar at right, upper image corner, red coded flow indicates flow towards the transducer thus meaning retrograde (opposite to systolic) flow.
b) Doppler tracings of descending aorta, for quantification of diastolic flow the scale is set to a low value of ±61.6 cm/s. The x symbol marks the systolic, antegrade flow (away from transducer), the arrow points to the reverted systolic tracings due to aliasing, wheras the symbol * depicts the pathologic, retrograde flow with a maximum velocity of 79.0 cm/s and mean velocity of 47.0cm/s.
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Figure 17: Male 20 years, operated TOF follow up, cardiac MRI. a) Short axis view demonstrating both ventricles (RV-right ventricle, LV-left ventricle), * marks right ventricular outflow tract aneurysm – a typical complication in the later course. b) Same patient, four chamber view – right ventricle (RV) forms cardiac apex due to enlargement
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caused by the pulmonary insufficiency (LV-left ventricle, RV-right ventricle, LA-left atrium, RA-
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right atrium).
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Figure 18: Same patient as in Figure 18, cardiac MRI, VENC Imaging within the pulmonary artery. a) Chart demonstrating forward (dark grey) and backward (light grey) blood flow due to pulmonary
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insufficiency.
b) Results from calculation the forward and reverse volume (marked by grey rectangle) – in this
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patient the forward volume was computed with 112.44ml and backward volume with 43.68ml. Therefore the regurgitation fraction can be simply calculated by: 43.68ml/112.44ml = 38.8%,
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indicating that 38.8% of right ventricular stroke volume is running back to the right ventricle during
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the diastolic phase thus leading to right ventricular enlargement.
Figure 19: Female, 28 years, Gd-free MRA, follow-up of Coarctation. a) “Handy Cane View” of aortic arch. Note high contrast display of vessels. Gothic aortic arch configuration is depicted as well as the reduced vessel diameter within the Coarctation area. b) Female, 15 years, embolic myocardial infarction due to a huge arterio-venous malformation of the lung, cardiac MRI after Gd injection, delayed enhancement technique, short axis cut: arrows point to bright areas within the myocardium representing the necrotic, transmural areas (“Bright is Dead”).
Table 1: Incidence and types of most frequent congenital heart defects.
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Table 2: Systematic classification of CHD, based on the underlying anatomic defect
– thus
allowing categorization in left and right heart obstruction, septal and vascular malformations as well as complex CHD.
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Table 3: Based on cyanosis and lung perfusion in chest X-Ray another useful CHD classification
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Table 4: CHD categorization based on the necessary treatment intensity – simple, moderate and
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severe types can be discriminated.
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