Transcatheter structural cardiac intervention: a radiology perspective.

C a r d i o p u l m o n a r y I m a g i n g • R ev i ew Renapurkar et al. Transcatheter Cardiac Intervention

Downloaded from www.ajronline.org by NYU Langone Med Ctr-Sch of Med on 07/03/15 from IP address 128.122.253.212. Copyright ARRS. For personal use only; all rights reserved

Cardiopulmonary Imaging Review

Transcatheter Structural Cardiac Intervention: A Radiology Perspective Rahul D. Renapurkar 1,2 Ahmed H. El-Sherief 1 Lourdes Prieto 3 Samir R. Kapadia3 Paul Schoenhagen2,3 Renapurkar RD, El-Sherief AH, Prieto L, Kapadia SR, Schoenhagen P

OBJECTIVE. Valvular heart disease continues to remain a significant cardiovascular problem worldwide. Imaging techniques, such as echocardiography, CT, and MRI have enabled development of newer transcatheter approaches for cardiovascular diseases. CONCLUSION. In this article, we discuss the commonly seen valvular diseases and various transcatheter valvular intervention techniques. We highlight the roles of CT and MRI in planning these procedures and discuss critical reporting information that needs to be conveyed to the interventionalists.

T

he purpose of this article is to provide an overview of the newer transcatheter techniques that are being used or assessed for the management of structural heart disease. Knowledge of these newer techniques and devices is critical for radiologists interpreting these studies. This article will also discuss the role of imaging, specifically CT and MRI, in clinical decision-making and treatment of valvular heart disorders. Keywords: CT, MRI, valvular heart disease DOI:10.2214/AJR.14.12571 Received January 15, 2014; accepted after revision September 26, 2014. 1

Section of Thoracic Imaging, L10, Imaging Institute, Cleveland Clinic, Cleveland, OH 44195. Address correspondence to R. D. Renapurkar ([email protected]).

2

Cardiovascular Imaging Laboratory, Imaging Institute, Cleveland Clinic, Cleveland, OH.

3 Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH.

Supplemental Data Available online at www.ajronline.org. WEB This is a web exclusive article. AJR 2015; 204:W648–W662 0361–803X/15/2046–W648 © American Roentgen Ray Society

W648

Aortic Valve Disease Aortic stenosis is the most common valvular abnormality and is present in 2–9% of adults more than 75 years old [1]. In adults, the most common causes of aortic stenosis are calcific aortic valve disease (AVD) and rheumatic valve disease, with the incidence of calcific AVD steadily rising. Traditionally, surgery has been the mainstay of treatment for symptomatic patients. However, many of these patients have coexisting morbidities that preclude surgical intervention [2]. The transcatheter aortic valve replacement (TAVR) procedure has emerged as a promising alternative to surgery in inoperable patients. The 1- and 2-year follow-up results from the Placement of Aortic Transcatheter study have shown comparable outcomes in high-risk patients treated with TAVR and those treated with surgical aortic valve replacement [3]. Transcatheter Aortic Valve Replacement The goal of the TAVR procedure is to implant the valve system in the aortic annulus,

causing displacement of the native aortic valve leaflets. In this procedure, the valve prosthesis is mounted on a delivery system that is advanced and placed in the annular region. Two TAVR devices are commonly used for this procedure: the balloon-expandable Edwards Sapien valve (Edwards Lifesci ences), which is available in multiple models and sizes of 20, 23, 26, and 29 mm (commercially available in sizes of 23 and 26 mm); and the self-expandable CoreValve ReValving System (Medtronic), which is available in sizes of 23, 26, 29, and 31 mm (Figs. 1 and 2). The Edwards Sapien prosthesis is 15–19 mm in height and does not extend beyond the sinus, whereas the CoreValve is 52–55 mm in length and, when implanted, extends into the ascending thoracic aorta (Fig. 3). Several approaches can be used to perform TAVR. The retrograde or transfemoral approach is preferred in patients with favorable iliofemoral vascular anatomy. In patients who are not candidates for the transfemoral approach, the Edwards Sapien valve can be implanted through a transapical approach, which requires a thoracotomy. Transaortic, subclavian, and femoral vein approaches have also been used. Preprocedural Imaging CT plays a pivotal role in appropriate patient selection that is crucial to the success of the procedure. At our institution, after contrast administration, retrospective ECG-gated high-resolution images of the aortic root and the heart are obtained, followed by non-

AJR:204, June 2015


Transcatheter Cardiac Intervention ECG-gated imaging of the aorta (3-mm intervals) down to the midthigh level. This retrospective imaging of the aortic root enables functional 4D imaging of the aortic valve and root. In patients with contraindications to contrast administration, unenhanced CT can be used to evaluate the aortoiliac system for calcific atherosclerotic disease; however, measurements of the luminal diameters are suboptimal with this technique. Several modifications of the CT protocol have been tried in attempts to reduce radiation dose. For instance, a prospectively triggered systolic phase study can be performed. With second-generation dual-source scanners, prospectively triggered 4D imaging of the aortic root has shown promising results [4]. In patients with increased risk of contrast nephropathy, CT angiography (CTA) of the iliofemoral arteries with intraarterial injection (direct aortic injection) of the contrast material has been used, although this technique has not gained wide acceptance [5]. ECG-triggered high-pitch spiral dualsource CTA has been shown to provide excellent diagnostic image quality with a reduced contrast dose, supporting the use of this technique when available [6]. Evaluation of iliofemoral access—The femoral transarterial approach for TAVR relies on good vascular access to deliver the prosthesis. The first-generation delivery systems were fairly large, requiring 22to 24-French sheaths (external diameter, 9 mm), and were associated with a high rate of vascular complications (30.7%) [7]. This rate has decreased with the development of improved and smaller delivery systems. Other factors accounting for vascular complications after TAVR include unfavorable anatomy and atherosclerotic disease of the iliofemoral system [8]. Conventional angiography provides limited information on the calcifications and atherosclerotic burden of the vascular system and has therefore been supplanted by CT for this purpose. With multiplanar reconstruction, crosssectional images orthogonal to the vessel course are created and the minimal diameters of the iliofemoral system down to the femoral head are determined [9] (Fig. 4 and Table 1). For the Edwards Sapien device, minimal luminal diameters are 7 mm or greater for the 23-mm size and 8 mm of greater for the 26-mm size. Care should be taken not to overestimate luminal narrowing in areas of dense calcifications, which can lead to blooming artifacts.

The extent of calcifications is also determined. Specifically, areas of circumferential calcifications and calcifications at vessel bifurcations should be highlighted because the presence of these areas is a contraindication to the transfemoral approach. Areas of protruding atherosclerotic plaques and focal dissections are also assessed. Tortuous and kinked calcified segments of vessels carry a high risk of access failure. However, these segments may be straightened and are not necessarily a contraindication to the transfemoral approach. Evaluation of aorta—CT enables comprehensive evaluation of the entire aortic system, which is useful when alternative access sites are being considered. For example, if a subclavian approach is being considered, the CT dataset can be used to evaluate the subclavian artery anatomy and to determine whether the artery is disease free. Similarly, the ascending thoracic aorta can be evaluated for calcifications; significant calcifications in this region could preclude the transaortic approach. Attention should be paid to noncalcified protruding plaques in the aortic arch because these plaques could become dislodged during the procedure and cause embolic strokes [10]. When the CoreValve prosthesis is used, the maximal dimensions of the ascending thoracic aorta must also be measured because the prosthesis extends into the proximal ascending thoracic aorta. Aortic annulus sizing—The functional anatomy of the aortic root can be thought of as a series of true and virtual rings, three circular and one crownlike [11] (Video 1). The crown-shaped ring is formed by the attachment of the aortic leaflets along the length of the root. The base of this crown forms the vir-

tual circular ventricular ring. The middle circular ring is the anatomic ventriculoarterial junction, and the top of the crown forms the superior ring, the sinotubular junction. Sizing of the annulus before TAVR is critical because specific valves are designed for specific aortic annular sizes. In surgical procedures, the aortic annulus can be sized intraoperatively with a sizing probe, but in endovascular procedures, the interventionalist has to rely solely on preprocedure imaging for sizing of the annulus. Conventionally, aortic annulus measurements have been performed using 2D transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), or angiography [12]. Such 2D techniques assess diameter in a single plane and assume a circular shape of the aortic annulus; however, several studies have shown that the annulus is a complex structure and can often be oval in shape [11]. Thus, 3D TEE and MDCT have been found to provide larger annular sizes than 2D TEE, with CT providing the highest measurements of all [13, 14]. Annulus measurements are obtained in CT by reconstructing images orthogonal to the aortic root and measuring just inferior to the nadir of the aortic cusps (corresponding to the basal ring) [15]. Biplane “hinge-tohinge” measurements can be obtained in coronal or sagittal oblique planes similar to 2D echocardiography (Figure 5). A step-wise approach for the measurement of these diameters is highlighted in Figures 6–8. Because biplane measurements do not account for the complex anatomy of the annulus, alternative methods have been proposed for measuring the aortic annulus. The three most commonly used methods are the mean diameter, area-derived diameter, and circumference of

TABLE 1: Manufacturer Recommendations for Various Valve Devices

Valve CoreValve ReValving System

Edwards Sapien Edwards Sapien XT

Aortic Ascending Minimal Annulus Thoracic Sinus Sinus Introducer Luminal Size Diameter Aorta Diameter Height Sheath Diameter (mm) (mm) (mm) (mm) (mm) (French) (mm) 26

20–23

< 40

> 27

> 15

18

6.0

29

23–27

< 43

> 29

> 15

18

6.0 6.0

31

26–29

< 43

> 29

> 15

18

23

18–22

—

—

—

22

7.0

26

21–25

—

—

—

24

8.0

23

18–22

—

—

—

16

6.0

26

21–25

—

—

—

18

6.5

29

24–27

—

—

—

20

7.0

Note—CoreValve ReValving System manufactured by Medtronic. Edwards Sapien and Edwards Sapien XT manufactured by Edwards Lifesciences. Dash indicates not applicable.

AJR:204, June 2015 W649


Renapurkar et al. the annulus [7] (Fig. 9). For the area-derived and circumference-derived diameters, the annulus is assumed to have a spherical shape after valve implantation. Additionally, annular measurements in systolic and diastolic phases are slightly different and larger in systole; systolic measurements are preferred [15]. Manufacturer-based thresholds of the aortic annulus for valve selection are shown in Table 1. However, these recommendations are based on echocardiographic data, and CT-based thresholds are likely to be different [16, 17] (Table 2). Increasing evidence points to the use of CT-derived measurements for selection of both types of valve prosthesis [18–20]. The study recommended selecting a prosthesis 4 mm smaller than the maximum diameter of the aortic annulus on CT and 1.5 mm smaller than the circumference-derived diameter of the aortic annulus [16]. Aortic valve morphology assessment— Oversizing of the prosthesis can lead to the disastrous complication of root rupture [18]. This can be avoided by measuring the root at the sinuses of Valsalva and at the sinotubular junction. Leaflet morphology can be assessed in short-axis projection of the root (Fig. 9). Currently, valve leaflet morphologies other than the usual trileaflet valve are considered contraindications [19]. Four-dimensional cine CT enables evaluation of the leaflet opening and the severity of leaflet excursion (Video 2). Additionally, the valve orifice area can be measured using planimetry, which has shown good correlation with echocardiographic data [19] (Fig. 9). Valve areas are measured in systolic phase datasets. The extent of calcification of the aortic leaflets and the sinotubular junction are noted because they can affect the precise deployment of the stent (Fig. 9). Distance between the annulus and the coronary ostia and the leaflet length—When the prosthesis is expanded in TAVR, the native

leaflets are displaced and crushed, and heavily calcified leaflets can potentially compress coronary arteries and occlude them [20]. To avoid this complication, the distance of the left coronary ostium and the insertion of the left coronary cusp should be calculated using appropriate multiplanar projection. For the Edwards Sapien prosthesis, a distance cutoff of 10–14 mm has been deemed adequate for stent deployment [20] (Fig. 9). The length of the leaflet is assessed from the tip to the base (Fig. 9). Coronary artery anatomy should also be evaluated, specifically for anomalies that could preclude percutaneous intervention. Reconstructed CT images can be used to assess aortic root orientation and axis in relation to the long axis of the body, which can facilitate identification of precise angiographic projection angles and thereby reduce the number of contrast injections [21, 22]. Assessment of left ventricle—Left ventricular (LV) dimensions and function can be evaluated on retrospectively performed ECG-gated studies. Also, the left ventricle can be evaluated for thrombus, which is a contraindication for TAVR [23]. This study can also be used to assess the alignment of the LV apex and its orientation relative to the LV outflow tract, which may be relevant information when determining whether transapical access is possible. Role of MRI—Unenhanced MRI can be used as an alternative to CT in selected patients who have iodine-based contrast allergies or renal insufficiency [24, 25]. LV function can also be comprehensively assessed with cine steadystate free precession (SSFP) imaging. MR angiography (MRA) can be used to assess the iliofemoral anatomy and to quantify areas of stenosis [26]. In patients with renal insufficiency in whom gadolinium cannot be administered, unenhanced MRA techniques, such as 3D balanced SSFP MRA, can be used to evaluate the aortoiliac system [27].

TABLE 2: Manufacturer CT-Based Recommendations for Edwards Sapien and CoreValve Selection Valve

Diameter (mm)

Circumference (mm)

Area (mm2)

Edwards Sapien, 23 mm

19–22

60–69

300–380


23–25

72–78.5

415–490


25–27

81.5–88

530–620

Medtronic CoreValve, 23 mm

18–20

56.5–62.8

254.5–314.2

CoreValve, 26 mm

20–23

62.8–72.3

314.2–415.5

CoreValve, 29 mm

23–27

72.3–84.8

415.5–572.6

CoreValve, 31 mm

26–29

81.7–91.1

530.9–660.5

Note—Data are range. CoreValve devices manufactured by Medtronic. Edwards Sapien devices manufactured by Edwards Lifesciences.

W650

Intraprocedural and Postprocedural Imaging Most of the sequential steps of TAVR and immediate postprocedural assessment are guided by fluoroscopy and TEE. TTE is a valuable tool for assessing long-term complications, such as paravalvular regurgitation; however, because of its superior spatial resolution, CT is better suited to assess stent position and complications, such as stent migration or fractures. The routine use of CT in follow-up is not warranted in uncomplicated cases [15]. Valve-in-Valve TAVR The success of TAVR has fueled interest in performing the procedure in patients with degenerating prosthetic aortic valves [28]. Initial studies have shown excellent technical success with this procedure [29]. In preprocedure planning for valve-in-valve TAVR, the internal diameter of the failed valve is most relevant. The prosthetic valve can be affected by several disease processes, which may lead to calcification and pannus formation. CT and echocardiography can be used to evaluate these factors. One study found that MRI and CT were comparable in their assessments of aortic geometry for valve-in-valve TAVR planning [30]. However, CT should be used in patients with metal strut aortic valve constructions. Mitral Valve Disease Mitral regurgitation is the second most common valvular disease after aortic stenosis. It is estimated that 20% of patients with heart failure and 12% of patients who have experienced a myocardial infarction have at least moderate mitral regurgitation [31, 32]. The causes of mitral regurgitation can be classified into structural or functional causes. Most of the organic causes are related to degeneration of the leaflets or chordae. Functional mitral regurgitation is a consequence of LV and annular dilation, which prevents the coaptation of the leaflets. The mitral valve apparatus consists of the annulus, leaflet, chordae, and papillary muscles. The mitral valve is bileaflet with an anterior “aortic” leaflet and a posterior “mural” leaflet. Each of the leaflets is divided into three scallops (from left to right): A1, A2, and A3 (anterior); and P1, P2, and P3 (posterior) (Fig. 10). The annulus (or atrioventricular junction) is a saddleshaped structure with elevated lateral and septal ends and depressed central zones where the two leaflets appose. Fibroelastic cords support and reinforce the mitral valve leaflets, which are relatively deficient along the posterior aspect. Be-

AJR:204, June 2015


Transcatheter Cardiac Intervention cause of this relatively deficient fibrous support, there is a tendency for annular dilation and calcification along the posterior aspect, causing a disproportionate increase in the septal-to-lateral diameter and lack of leaflet coaptation, resulting in regurgitation [33]. Traditionally, surgical repair has been the treatment of choice for symptomatic organic mitral regurgitation. In cases with annular dilation, the goal is to reduce the septal-to-lateral diameter by at least 8 mm [34]. In patients with regurgitation caused by incomplete coaptation of the leaflets, one of the surgical techniques used is the edge-to-edge technique, or the Alfieri stitch [35]. This technique involves direct suturing of the free edge of the leaflets at the site of regurgitation, resulting in the creation of a valve with two orifices. Transcatheter Procedures Transcatheter procedures for mitral regurgitation are based on principles similar to those described previously. Depending on the mechanism of mitral regurgitation, these techniques can be targeted toward annular remodeling or leaflet repair with the MitraClip device (Abbott Laboratories) [38]. Annular remodeling can be achieved directly by entering the left ventricle or indirectly by placing a device in the coronary sinus or across the atrium-ventricle. Very limited data are available regarding direct annular remodeling techniques, and further studies are needed [37]. In coronary sinus–based indirect annuloplasty techniques, the aim is to place devices across the coronary sinus that exert pressure on the mitral annulus, thus reducing the annular diameter. Several devices have undergone testing for this purpose, including the Mitral Contour System (Contour Systems), PTMA (Viacor), and Monarc System (American Medical Systems). Most clinical experience has involved MitraClip and the Mitral Contour System. The MitraClip device uses an edge-to-edge repair technique similar to the surgical Alfieri technique. The device has three components: a guide catheter (24-French proximally and 22-French near the interatrial septum), a delivery system, and a clip implant (Fig. 11). After transseptal puncture via a femoral approach, a guide catheter is advanced to the left atrium from the femoral vein. Under fluoroscopic and TEE guidance, the clip is advanced into the left ventricle at the site of the regurgitant orifice, and the arms are then withdrawn to grasp both the leaflets, thus creating a double orifice [38] (Fig. 11). More than one clip can be used. For lateral or commis-

sural jets, a paracentral clip can be placed, resulting in a single orifice. The Mitral Contour System is an indirect annuloplasty device that has a proximal and distal anchor connected by a shaping ribbon. This device, which is implanted in the coronary sinus, indirectly reduces the annular dimensions. The use of the MitraClip and Mitral Contour System in the United States is still investigational [39]. Preprocedural Imaging Careful patient selection is crucial to the success of these procedures. Clinicians must also understand the mechanism of mitral regurgitation so that they can determine which technique should be used (edge-to-edge vs indirect annuloplasty techniques). Echocardiography and CT or MRI can play a vital role in evaluating for these factors [40, 41]. Assessment of severity of mitral regurgitation—Echocardiography is a robust technique for evaluating the severity of mitral regurgitation [42]. In addition, 3D echocardiography has improved identification of the mechanism and accurate quantification of mitral regurgitation [43]. MRI can also be used to quantify mitral regurgitation, and velocity-encoded MRI (VEMRI) can be used to quantify transvalvular flow. Three-dimensional VE-MRI with retrospective valve tracking may be more effective because it enables compensation for the mitral annular and leaflet motion [44–46]. Assessment of mitral valve and subvalvular anatomy—CT and echocardiography play complementary roles in the assessment of mitral valve anatomy and evaluation of the mechanism of regurgitation. Echocardiog raphy provides dynamic information about mitral valve leaflets, whereas CT provides the best definition of the anatomy of the valvular and the subvalvular apparatus. Retrospectively ECG-gated CT can be performed, which enables reconstruction of the dataset in both systolic and diastolic phases. A stepwise approach for assessment of the mitral valve leaflets and annulus is shown in Figures 12–14. The anatomy of the valve leaflets is assessed, with each scallop carefully examined. Particular attention is paid to prolapsed and flail segments, which are best assessed with echocardiography. The mitral annulus is systematically evaluated with CT (Fig. 15). First, the annulus is assessed for calcifications because the MitraClip device cannot be used in patients with severe mitral annular calcification. Mitral annu-

lus sizing is performed, with measurements taken of the anteroposterior diameter and the intercommissural distance. The mitral annular area is then measured using planimetry. The anatomic details of the left ventricle and the subvalvular apparatus are usually assessed with echocardiography. Some studies have shown incremental value of CT-derived indexes in assessment of the anatomy and geometry of the mitral valve apparatus [47]. For example, displacement of the papillary muscles is estimated by calculating the distance between the heads of the papillary muscles from the systolic phase data (Fig. 15). The sphericity index of the mitral valve is determined by calculating the distance between the level of the papillary muscles and the mitral annulus [47] (Fig. 15). In the study by Delgado et al. [47], increased sphericity index (1.4 ± 0.3 SD]) was observed in patients without functional mitral regurgitation (vs 1.2 ± 0.3 in patients with functional mitral regurgitation) and was one of the strongest determinants of functional mitral regurgitation severity. Whether these measurements positively affect patient selection and clinical outcomes remains to be seen. Finally, the anatomy of the coronary sinus is examined in detail (Fig. 15). The left circumflex artery courses close to the coronary sinus and may be prone to compression with coronary sinus–based devices [48]. CT can be used to assess the distance to the point of intersection between the left circumflex artery and the coronary sinus [49]. This result determines the length of coronary sinus that can safely be used in the patient. In addition, the success of a coronary sinus annuloplasty approach depends on the proximity of the coronary sinus to the mitral valve annulus and how the exerted force distributes on the annulus. In mitral regurgitation and left atrial dilation, the distance between the coronary sinus and the mitral valve annulus may widen, especially in the posterolateral direction, which may impede the success of the procedure. Three-dimensional SSFP MRA can also be used to assess the relationships between the coronary sinus and the mitral valve annulus and between the coronary sinus and left circumflex artery [50]. Intraprocedural and Postprocedural Imaging TEE and fluoroscopy are used to systematically guide these transcatheter procedures and assess for immediate postprocedural treatment response and complications. In the future, MRI-derived road maps may be

AJR:204, June 2015 W651

Renapurkar et al.


fused on live fluoroscopic data to provide fusion intraprocedural guidance [51]. Pulmonary Valve Disease The vast majority of pulmonary valve lesions are congenital, resulting from abnormal fetal development of the valve or the conotruncal region, resulting in obstruction of the right ventricular outflow tract (RVOT). Surgical intervention for pulmonary valve stenosis is often required in infancy or early childhood. Although pulmonary regurgitation is well tolerated, the deleterious effects of pulmonary regurgitation, such as progressive right ventricular (RV) dilation and right heart failure are eventual indications for pulmonary valve replacement (PVR) [52–54]. Surgically implanted prosthetic pulmonary valves degenerate over time and have an approximate span of 10 years [55]. These patients therefore face the prospect of multiple PVRs over their lifetimes. Until recently, open heart surgery was the only alternative. Therefore, there has been reluctance to perform repeated interventions. Symptoms of right heart failure clearly call for intervention, but strict guidelines in asymptomatic patients are lacking [56–59]. Despite efforts to define thresholds for intervention for pulmonary regurgitation, a subset of these patients do not show improvement in RV ejection fraction or exercise parameters after PVR [60]. Current criteria for intervention are therefore likely too conservative, and transcatheter PVR may enable more aggressive management and improve outcomes. Transcatheter Pulmonary Valve Implantation Procedures The first percutaneous PVR was performed in 2000 [61], and Food and Drug Administration (FDA) approval under Humanitarian Device Exemption status was granted to the Melody Valve (Medtronic) in 2010. The valve is approved for use in surgically implanted dysfunctional conduits, but off-label use in native dysfunctional RVOTs is possible in certain cases (with preapproval from the institutional review board at our institution) provided the size of the RVOT is within the required range. One of the factors associated with valve dysfunction, typically obstruction, is fracture of the stent on which the valve is mounted. Reinforcement of the stent in the newer iteration of the valve and prestenting of the landing zone before valve delivery have resulted in a lower incidence of stent fractures [62]. Additionally, valve dysfunction, which usually manifests as restenosis, can often be treated with either

W652

redilation or implantation of a second percutaneous pulmonary valve [63]. The valve has remained remarkably competent in midterm follow-up [64–67]. The Melody device consists of a trileaflet bovine jugular vein sutured into a platinum-iridium balloon-expandable stent (Fig. 16). The Edwards Sapien valve, which is currently being used for aortic stenosis, is now undergoing trials in the United States for implantation of a second percutaneous pulmonary valve [68]. One factor that has limited the number of patients who can be treated with implantation of a second percutaneous pulmonary valve is the size of the currently available implantation devices. The Melody valve, available in 18-, 20-, and 22-mm diameters, can be implanted in conduits ≥ 16 mm and ≤ 22 mm in diameter at the time of surgical implantation or in larger conduits provided the conduit stenotic area provides a landing zone that is less than 22 mm in diameter. The Edwards Sapien device, available in 23 and 26 mm, can be implanted into slightly larger conduits or outflow tracts. Most native RVOTs are larger, particularly when pulmonary regurgitation is the predominant lesion and therefore are not suitable for implantation of a second percutaneous pulmonary valve. Preprocedural Imaging In preprocedural selection of these patients, imaging is crucial, with echocardiog raphy and MRI most commonly used. CT can also be used as an alternate tool to obtain anatomic information (if MRI is contraindicated). In patients with pulmonary regurgitation as the predominant lesion, RV volume obtained by MRI is one of the most important determinants of timing of implantation of a second percutaneous pulmonary valve. Size and distensibility of the pulmonary trunk—Cross-sectional measurements of the minimal diameter of a surgically implanted conduit or native outflow tract are crucial in assessing the candidacy for PVR. Cine MRI can provide valuable information on RVOT or conduit distensibility. Implantation of a second percutaneous pulmonary valve is contraindicated if the minimal diameter by MRI exceeds 22 mm for the Melody valve or 26 mm for the Edwards Sapien valve (Fig. 17). Care must be taken to measure the minimal cross-sectional diameter at its most distended. Serious complications, such as embolization, may occur if the minimal diameter is underestimated.

RVOT–pulmonary trunk morphology— Catheter-based devices need stable landing zones. Three-dimensional navigator-gated SSFP images can suitably assess RVOT anatomy. A classification system for RVOT morphology has been developed on the basis of MRI assessment [69] (Fig. 17). Type I morphology with a pyramidal shape is seen in patients with transannular patch repair and is unsuitable for treatment with the currently available devices. In general, the more favorable repaired RVOTs are those with parallel walls or a narrower midsection (Fig. 17). Position of coronary arteries—Expanding a stent in the RVOT can compress the coronary arteries and induce ischemia and infarction [65]. Therefore, preprocedural assessment of the spatial relationship between the coronary arteries and the pulmonary trunk is vital and can be reliably performed with 3D SSFP imaging (Fig. 17). Postprocedural Imaging Stent integrity can be assessed with chest radiography (Fig. 18). Nordmeyer et al. [70] classified stent fractures on the basis of chest radiographic appearance (Fig. 19). Type I fractures, which are the most common, are defined as a fracture of one or more struts without loss of integrity. Type II fractures are defined as a loss of stent integrity. Type III fractures are defined as separation of fragments or embolization. Type I fractures are closely monitored, whereas type II fractures may be treated by valve-invalve implantation. Type III fractures require surgical explantation [63]. Although susceptibility artifact from the stent limits assessment of the stent struts with MRI, this modality can be used to assess for flow inside the stent. Echocardiog raphy is routinely performed to assess valve function on follow-up. Tricuspid Valve Disease Tricuspid valve disease is a rare entity in clinical practice. Causes of tricuspid valve disease include congenital conditions, such as Ebstein anomaly, and acquired causes, such as endocarditis, rheumatic disease, and carcinoid disease. To date, experience with percutaneous tricuspid valve replacement (TVR) is limited. The largest series reported involved 15 patients with a dysfunctional surgical bioprosthetic valve who were treated with percutaneous TVR with good success [71]. The expanded use of this technique may reduce the number of repeat surgical procedures necessary in this population. For preprocedural imaging, it

AJR:204, June 2015


Transcatheter Cardiac Intervention is important to make accurate measurements of the internal diameter of the bioprosthetic valve or right atrium–to–right ventricle conduit to ensure an adequate anchor point and enough room for the percutaneous valve to expand. MRI can be used to comprehensively assess the valve and RV function. In patients with contraindications to MRI, CT can be used to define the valve anatomy. Paravalvular Leak Paravalvular leak is a major problem in patients who have undergone surgical replacement of mitral or aortic valves (2–12% and 1–5% of patients, respectively) [72, 73]. Moderate to severe aortic regurgitation may also be seen in up to 17% of patients who have undergone TAVR, with most of these cases classified as paravalvular [74, 75]. Symptomatic patients often require repeat surgery, which has a high recurrence rate [76]. Percutaneous techniques have been used with increasing frequency as treatment options for paravalvular leak. A vascular plug or occluder (most commonly Amplatzer Vascular Plug, St. Jude Medical) is deployed across the leak under fluoroscopic and echocardiographic guidance (Fig. 20). The role of cross-sectional imaging modalities, such as CT or MRI, is limited. At our center, CT has been used as a road map to guide the procedure by overlaying CT data on fluoroscopic projections [77]. Conclusion In summary, transcatheter techniques have expanded considerably for the diagnosis and treatment of valvular heart diseases. With refinement of techniques and devices, the future of interventional techniques holds considerable promise. Radiologists, particularly those involved in cardiothoracic imaging, need to keep abreast of these emerging methods because an understanding of these techniques is crucial for recognizing normal and abnormal imaging appearances. Acknowledgment We thank Megan Griffiths, scientific writer for Imaging Institute, for her editorial assistance. References 1. Faggiano P, Antonini-Canterin F, Baldessin F, Lorusso R, D’Aloia A, Cas LD. Epidemiology and cardiovascular risk factors of aortic stenosis. Cardiovasc Ultrasound 2006; 4:27 2. Iung B, Baron G, Butchart EG, et al. A prospective survey of patients with valvular heart disease in Europe: the Euro Heart Survey on Valvular Heart Disease. Eur Heart J 2003; 24:1231–1243

3. Kodali SK, Williams MR, Smith CR, et al.; PARTNER Trial Investigators. Two-year outcomes after transcatheter or surgical aortic-valve replacement. N Engl J Med 2012; 366:1686–1695 4. Bolen MA, Popovic ZB, Dahiya A, et al. Prospective ECG-triggered, axial 4-D imaging of the aortic root, valvular, and left ventricular structures: a lower radiation dose option for preprocedural TAVR imaging. J Cardiovasc Comput Tomogr 2012; 6:393–398 5. Nietlispach F, Leipsic J, Al-Bugami S, Masson JB, Carere RG, Webb JG. CT of the ilio-femoral arteries using direct aortic contrast injection: proof of feasibility in patients screened towards percutaneous aortic valve replacement. Swiss Med Wkly 2009; 139:458–462 6. Wuest W, Anders K, Schuhbaeck A, et al. Dual source multidetector CT-angiography before trans catheter aortic valve implantation (TAVI) using a high-pitch spiral acquisition mode. Eur Radiol 2012; 22:51–58 7. Leon MB, Smith CR, Mack M, et al.; PARTNER Trial Investigators. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. N Engl J Med 2010; 363:1597–1607 8. Kurra V, Schoenhagen P, Roselli EE, et al. Prevalence of significant peripheral artery disease in patients evaluated for percutaneous aortic valve insertion: preprocedural assessment with multidetector computed tomography. J Thorac Cardiovasc Surg 2009; 137:1258–1264 9. Achenbach S, Delgado V, Hausleiter J, Schoenhagen P, Min JK, Leipsic JA. SCCT expert consensus document on computed tomography imaging before transcatheter aortic valve implantation (TAVI)/ transcatheter aortic valve replacement (TAVR). J Cardiovasc Comput Tomogr 2012; 6:366–380 10. Tamburino C, Capodanno D, Ramondo A, et al. Incidence and predictors of early and late mortality after transcatheter aortic valve implantation in 663 patients with severe aortic stenosis. Circulation 2011; 123:299–308 11. Anderson RH. Clinical anatomy of the aortic root. Heart 2000; 84:670–673 12. Moss RR, Ivens E, Pasupati S, et al. Role of echocardiography in percutaneous aortic valve implantation. JACC Cardiovasc Imaging 2008; 1:15–24 13. Ng AC, Delgado V, van der Kley F, et al. Comparison of aortic root dimensions and geometries before and after transcatheter aortic valve implantation by 2- and 3-dimensional transesophageal echocardiog raphy and multislice computed tomography. Circ Cardiovasc Imaging 2010; 3:94–102 14. Tops LF, Wood DA, Delgado V, et al. Noninvasive evaluation of the aortic root with multislice computed tomography implications for transcatheter aortic valve replacement. JACC Cardiovasc Imaging 2008; 1:321–330 15. Leipsic J, Gurvitch R, Labounty TM, et al. Multi-

detector computed tomography in transcatheter aortic valve implantation. JACC Cardiovasc Imaging 2011; 4:416–429 16. Jilaihawi H, Kashif M, Fontana G, et al. Crosssectional computed tomographic assessment improves accuracy of aortic annular sizing for transcatheter aortic valve replacement and reduces the incidence of paravalvular aortic regurgitation. J Am Coll Cardiol 2012; 59:1275–1286 17. Kasel AM, Cassese S, Bleiziffer S, et al. Standardized imaging for aortic annular sizing: implications for transcatheter valve selection. JACC Cardiovasc Imaging 2013; 6:249–262 18. Blanke P, Russe M, Leipsic J, et al. Conformational pulsatile changes of the aortic annulus: impact on prosthesis sizing by computed tomography for transcatheter aortic valve replacement. JACC Cardiovasc Interv 2012; 5:984–994 19. Rajiah P, Schoenhagen P. The role of computed tomography in pre-procedural planning of cardiovascular surgery and intervention. Insights Imaging. 2013; 4:671–689 20. Masson JB, Kovac J, Schuler G, et al. Transcatheter aortic valve implantation: review of the nature, management, and avoidance of procedural complications. JACC Cardiovasc Interv 2009; 2:811–820 21. Kurra V, Kapadia SR, Tuzcu EM, et al. Pre-procedural imaging of aortic root orientation and dimensions: comparison between x-ray angiographic planar imaging and 3-dimensional multidetector row computed tomography. JACC Cardiovasc Interv 2010; 3:105–113 22. Schoenhagen P, Tuzcu EM, Kapadia SR, Desai MY, Svensson LG. Three-dimensional imaging of the aortic valve and aortic root with computed tomography: new standards in an era of transcatheter valve repair/implantation. Eur Heart J 2009; 30:2079–2086 23. Vahanian A, Alfieri O, Al-Attar N, et al.; European Association of Cardio-Thoracic Surgery, European Society of Cardiology, European Association of Percutaneous Cardiovascular Interventions. Transcatheter valve implantation for patients with aortic stenosis: a position statement from the European Association of Cardio-Thoracic Surgery (EACTS) and the European Society of Cardiology (ESC), in collaboration with the European Association of Percutaneous Cardiovascular Interventions (EAPCI). Eur Heart J 2008; 29:1463–1470 24. Jabbour A, Ismail TF, Moat N, et al. Multimodality imaging in transcatheter aortic valve implantation and post-procedural aortic regurgitation: comparison among cardiovascular magnetic resonance, cardiac computed tomography, and echocardiography. J Am Coll Cardiol 2011; 58:2165–2173 25. Koos R, Altiok E, Mahnken AH, et al. Evaluation of aortic root for definition of prosthesis size by magnetic resonance imaging and cardiac computed to-

AJR:204, June 2015 W653


Renapurkar et al. mography: implications for transcatheter aortic valve implantation. Int J Cardiol 2012; 158:353–358 26. Swan JS, Kennell TW, Acher CW, et al. Magnetic resonance angiography of aorto-iliac disease. Am J Surg 2000; 180:6–12 27. Miyazaki M, Lee VS. Nonenhanced MR angiography. Radiology 2008; 248:20–43 28. Gurvitch R, Cheung A, Ye J, et al. Transcatheter valve-in-valve implantation for failed surgical bioprosthetic valves. J Am Coll Cardiol 2011; 58:2196–2209 29. Eggebrecht H, Schäfer U, Treede H, et al. Valvein-valve transcatheter aortic valve implantation for degenerated bioprosthetic heart valves. JACC Cardiovasc Interv 2011; 4:1218–1227 30. Quail MA, Nordmeyer J, Schievano S, Reinthaler M, Mullen MJ, Taylor AM. Use of cardiovascular magnetic resonance imaging for TAVR assessment in patients with bioprosthetic aortic valves: comparison with computed tomography. Eur J Radiol 2012; 81:3912–3917 31. Robbins JD, Maniar PB, Cotts W, Parker MA, Bonow RO, Gheorghiade M. Prevalence and severity of mitral regurgitation in chronic systolic heart failure. Am J Cardiol 2003; 91:360–362 32. Bursi F, Enriquez-Sarano M, Nkomo VT, et al. Heart failure and death after myocardial infarction in the community: the emerging role of mitral regurgitation. Circulation 2005; 111:295–301 33. Van Mieghem NM, Piazza N, Anderson RH, et al. Anatomy of the mitral valvular complex and its implications for transcatheter interventions for mitral regurgitation. J Am Coll Cardiol 2010; 56:617–626 34. Daimon M, Fukuda S, Adams DH, et al. Mitral valve repair with Carpentier-McCarthy-Adams IMR ETlogix annuloplasty ring for ischemic mitral regurgitation: early echocardiographic results from a multi-center study. Circulation 2006; 114(1 suppl):I588–I593 35. Alfieri O, Elefteriades JA, Chapolini RJ, et al. Novel suture device for beating-heart mitral leaflet approximation. Ann Thorac Surg 2002; 74:1488–1493 36. Delgado V, Kapadia S, Marsan NA, Schalij MJ, Tuzcu EM, Bax JJ. Multimodality imaging before, during, and after percutaneous mitral valve repair. Heart 2011; 97:1704–1714 37. Aybek T, Risteski P, Miskovic A, et al. Seven years’ experience with suture annuloplasty for mitral valve repair. J Thorac Cardiovasc Surg 2006; 131:99–106 38. St. Goar FG, Fann JI, Komtebedde J, et al. Endovascular edge-to-edge mitral valve repair: shortterm results in a porcine model. Circulation 2003; 108:1990–1993 39. Gillinov AM, Liddicoat JR. Percutaneous mitral valve repair. Semin Thorac Cardiovasc Surg 2006; 18:115–121 40. Mauri L, Garg P, Massaro JM, et al. The EVEREST

W654

II trial: design and rationale for a randomized study of the evalve mitraclip system compared with mitral valve surgery for mitral regurgitation. Am Heart J 2010; 160:23–29 41. Cavalcante JL, Rodriguez LL, Kapadia S, Tuzcu EM, Stewart WJ. Role of echocardiography in percutaneous mitral valve interventions. JACC Cardiovasc Imaging 2012; 5:733–746 42. Marsan NA, Westenberg JJ, Ypenburg C, et al. Quantification of functional mitral regurgitation by real-time 3D echocardiography: comparison with 3D velocity-encoded cardiac magnetic resonance. JACC Cardiovasc Imaging 2009; 2:1245–1252 43. Kayser HW, Stoel BC, van der Wall EE, van der Geest RJ, de Roos A. MR velocity mapping of tricuspid flow: correction for through-plane motion. J Magn Reson Imaging 1997; 7:669–673 44. Westenberg JJ, Danilouchkine MG, Doornbos J, et al. Accurate and reproducible mitral valvular blood flow measurement with three-directional velocity-encoded magnetic resonance imaging. J Cardiovasc Magn Reson 2004; 6:767–776 45. Westenberg JJ, Doornbos J, Versteegh MI, et al. Accurate quantitation of regurgitant volume with MRI in patients selected for mitral valve repair. Eur J Cardiothorac Surg 2005; 27:462–466 46. Westenberg JJ, Roes SD, Ajmone Marsan N, et al. Mitral valve and tricuspid valve blood flow: accurate quantification with 3D velocity-encoded MR imaging with retrospective valve tracking. Radiology 2008; 249:792–800 47. Delgado V, Tops LF, Schuijf JD, et al. Assessment of mitral valve anatomy and geometry with multislice computed tomography. JACC Cardiovasc Imaging 2009; 2:556–565 48. Tops LF, Van de Veire NR, Schuijf JD, et al. Noninvasive evaluation of coronary sinus anatomy and its relation to the mitral valve annulus: implications for percutaneous mitral annuloplasty. Circulation 2007; 115:1426–1432 49. Choure AJ, Garcia MJ, Hesse B, et al. In vivo analysis of the anatomical relationship of coronary sinus to mitral annulus and left circumflex coronary artery using cardiac multidetector computed tomography: implications for percutaneous coronary sinus mitral annuloplasty. J Am Coll Cardiol 2006; 48:1938–1945 50. Chiribiri A, Kelle S, Köhler U, et al. Magnetic resonance cardiac vein imaging: relation to mitral valve annulus and left circumflex coronary artery. JACC Cardiovasc Imaging 2008; 1:729–738 51. Kim JH, Kocaturk O, Ozturk C, et al. Mitral cerclage annuloplasty, a novel transcatheter treatment for secondary mitral valve regurgitation: initial results in swine. J Am Coll Cardiol 2009; 54:638–651 52. Therrien J, Provost Y, Merchant N, Williams W, Colman J, Webb G. Optimal timing for pulmonary valve replacement in adults after tetralogy of

Fallot repair. Am J Cardiol 2005; 95:779–782 53. Oosterhof T, Van Straten A, Vliegen HW, et al. Preoperative thresholds for pulmonary valve replacement in patients with corrected tetralogy of Fallot using cardiovascular magnetic resonance. Circulation 2007; 116:545–551 54. Warnes CA, Williams RG, Bashore TM, et al. ACC/AHA 2008 guidelines for the management of adults with congenital heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to develop guidelines on the management of adults with congenital heart disease). Circulation 2008; 118:e714–e833 55. Razzouk AJ, Williams WG, Cleveland DC, et al. Surgical connections from ventricle to pulmonary artery: comparison of four types of valved implants. Circulation 1992; 86(5 suppl):II154–II158 56. Geva T. Indications and timing of pulmonary valve replacement after tetralogy of Fallot repair. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2006; 2009:11–22 57. Gatzoulis MA, Balaji S, Webber SA, et al. Risk factors for arrhythmia and sudden cardiac death late after repair of tetralogy of Fallot: a multicentre study. Lancet 2000; 356:975–981 58. Knauth AL, Gauvreau K, Powell AJ, et al. Ventricular size and function assessed by cardiac MRI predict major adverse clinical outcomes late after tetralogy of Fallot repair. Heart 2008; 94:211–216 59. Scherptong RW, Hazekamp MG, Mulder BJ, et al. Follow up after pulmonary valve replacement in adults with tetralogy of Fallot: association between QRS duration and outcome. J Am Coll Cardiol 2010; 56:1486–1492 60. Therrien J, Siu SC, McLaughlin PR, Liu PP, Williams WG, Webb GD. Pulmonary valve replacement in adults late after repair of tetralogy of Fallot: are we operating too late? J Am Coll Cardiol 2000; 36:1670–1675 61. Bonhoeffer P, Boudjemline Y, Saliba Z, et al. Percutaneous replacement of pulmonary valve in a right-ventricle to pulmonary-artery prosthetic conduit with valve dysfunction. Lancet 2000; 356:1403–1405 62. Nordmeyer J, Lurz P, Khambadkone S, et al. Prestenting with a bare metal stent before percutaneous pulmonary valve implantation: acute and 1-year outcomes. Heart 2011; 97:118–123 63. Nordmeyer J, Coats L, Lurz P, et al. Percutaneous pulmonary valve-in-valve implantation: a successful treatment concept for early device failure. Eur Heart J 2008; 29:810–815 64. Lurz P, Coats L, Khambadkone S, et al. Percutaneous pulmonary valve implantation: impact of evolving technology and learning curve on clinical outcome. Circulation 2008; 117:1964–1972 65. McElhinney DB, Hellenbrand WE, Zahn EM, et

AJR:204, June 2015


Transcatheter Cardiac Intervention al. Short- and medium-term outcomes after transcatheter pulmonary valve placement in the expanded multicenter US Melody valve trial. Circulation 2010; 122:507–516 66. Vezmar M, Chaturvedi R, Lee KJ, et al. Percutaneous pulmonary valve implantation in the young 2-year follow-up. JACC Cardiovasc Interv 2010; 3:439–448 67. Eicken A, Ewert P, Hager A, et al. Percutaneous pulmonary valve implantation: two-centre experience with more than 100 patients. Eur Heart J 2011; 32:1260–1265 68. Kenny D, Hijazi ZM, Kar S, et al. Percutaneous implantation of the Edwards SAPIEN transcatheter heart valve for conduit failure in the pulmonary position: early phase 1 results from an international multicenter clinical trial. J Am Coll Cardiol 2011; 58:2248–2256 69. Schievano S, Coats L, Migliavacca F, et al. Varia-

tions in right ventricular outflow tract morphology following repair of congenital heart disease: implications for percutaneous pulmonary valve implantation. J Cardiovasc Magn Reson 2007; 9:687–695 70. Nordmeyer J, Khambadkone S, Coats L, et al. Risk stratification, systematic classification, and anticipatory management strategies for stent fracture after percutaneous pulmonary valve implantation. Circulation 2007; 115:1392–1397 71. Roberts PA, Boudjemline Y, Cheatham JP, et al. Percutaneous tricuspid valve replacement in congenital and acquired heart disease. J Am Coll Cardiol 2011; 58:117–122 72. Jindani A, Neville EM, Venn G, Williams BT. Paraprosthetic leak: a complication of cardiac valve replacement. J Cardiovasc Surg (Torino) 1991; 32:503–508 73. Hammermeister K, Sethi GK, Henderson WG, Grover FL, Oprian C, Rahimtoola SH. Outcomes

Fig. 1—Edwards Sapien Valve (Edwards Lifesciences). Axial CT image in 81-year-old woman shows appropriately positioned Edwards Sapien valve in aortic position (arrow).

15 years after valve replacement with a mechanical versus a bioprosthetic valve: final report of the Veterans Affairs randomized trial. J Am Coll Cardiol 2000; 36:1152–1158 74. Ionescu A, Fraser AG, Butchart EG. Prevalence and clinical significance of incidental paraprosthetic valvar regurgitation: a prospective study using transoesophageal echocardiography. Heart 2003; 89:1316–1321 75. Rodés-Cabau J. Transcatheter aortic valve implantation: current and future approaches. Nat Rev Cardiol 2011; 9:15–29 76. Echevarria JR, Bernal JM, Rabasa JM, Morales D, Revilla Y, Revuelta JM. Reoperation for bioprosthetic valve dysfunction: a decade of clinical experience. Eur J Cardiothorac Surg 1991; 5:523–526 77. Krishnaswamy A, Kapadia SR, Tuzcu EM. Percutaneous paravalvular leak closure: imaging, techniques, and outcomes. Circ J 2013; 77:19–27

Fig. 2—Photograph shows Edwards Sapien heart valve (Edwards Lifesciences). (Reprinted with permission from Edwards Lifesciences LLC)

Fig. 3—Photograph shows CoreValve System (Medtronic). This system is not commercially available in all countries and is investigational device in other countries, including United States. (Reprinted with permission from Medtronic).

AJR:204, June 2015 W655


Renapurkar et al.

A

B

Fig. 4—Measurement of iliofemoral diameter. A–C, Multiplanar reconstructed CT images in 66-year-old man with aortic stenosis show measurement of left common iliac artery in shortaxis dimension. Intersecting lines represent cross hairs that have been aligned to create a true crosssectional image.

C

Fig. 5—Biplanar hinge-to-hinge measurement of aortic annulus in 85-year-old man with aortic stenosis. Coronal oblique view is shown. These measurements may be performed in sagittal oblique or in three-chambered view similar to long-axis echocardiographic view. See also Video 1 and Figure 6.

W656

AJR:204, June 2015


Transcatheter Cardiac Intervention Fig. 6—Stepwise guide to techniques of measurement of aortic annulus. First step: Scroll dataset to level of aortic valve. On axial image, place crosshair in center of aortic valve (asterisk).

Fig. 7—Stepwise guide to techniques of measurement of aortic annulus. Second step: On original coronal image, rotate orange line so it crosses through center of left ventricular outflow tract. Asterisk indicates center of aortic valve.

Fig. 8—Stepwise guide to techniques of measurement of aortic annulus. Step three: On original sagittal image, rotate blue line so it crosses through center of left ventricular outflow tract. Asterisk indicates center of aortic valve.

AJR:204, June 2015 W657


Renapurkar et al.

A

B

C

D

E

F

Fig. 9—Preprocedural assessment of aortic root and valve on CT in 85-year-old man with aortic stenosis. A, Mean diameter can be calculated using long- and short-axis diameters (arrows). B and C, Area- (B) and circumference-(C) derived diameters can be calculated assuming circular shape of annulus after valve implantation. Significance of mean diameter and area- and circumference-derived diameters in selection of prosthesis is shown in Table 2. D, Short-axis reconstructed image in systolic phase dataset shows measurement of valve area using planimetry (segmented area). Aortic valve area has been used to quantify aortic stenosis. Normal area of aortic valve is 3–4 cm2 , which decreases with progressively worsening aortic stenosis. In severe aortic stenosis, area is less than 1 cm2 . CT-derived aortic valve area has shown good correlation with measurements derived from transesophageal echocardiography and cardiac catheterization. E, Coronal oblique image shows measurement of distance between inferior aspect of left coronary ostium and annulus (white line). F, Coronal oblique image shows measurement of leaflet length (white line).

Fig. 10—Diagram shows anatomy of mitral valve and its relationships to structures at left atrioventricular junction. Mitral valve apparatus consists of annulus, leaflet, chordae, and papillary muscles. Mitral valve is bileaflet with anterior “aortic” leaflet and posterior “mural” leaflet. Each of the leaflets is divided into three scallops: A1, A 2 , and A 3 (anterior); and P1, P 2 , and P 3 (posterior).

W658

AJR:204, June 2015


Transcatheter Cardiac Intervention

Fig. 11—Photograph shows MitraClip system, and accompanying drawings show placement techniques with resultant creation of double-orifice valve. (Photograph of MitraClip device reprinted with permission from Abbott Vascular)

Fig. 12—Stepwise guide to assessment of mitral valve and annulus with CT. First step: Scroll to level of mitral valve. On axial image, place crosshair in center of mitral valve (asterisk).

Fig. 13—Stepwise guide to assessment of mitral valve and annulus with CT. Second step: On axial image, rotate orange line so that it is parallel to interventricular septum and crosses through apex of left ventricle. Asterisk indicates center of mitral valve.

Fig. 14—Stepwise guide to assessment of mitral valve and annulus with CT. Third step: On original sagittal image, rotate purple line so that it crosses through apex of left ventricle (asterisk). Original coronal image has been transformed into short-axis view of mitral valve.

AJR:204, June 2015 W659


Renapurkar et al.

A

B

C

D

Fig. 15—Preprocedural assessment of mitral valvar and subvalvular apparatus using CT in 74-year-old man with mitral valve disease. A, Reconstructed short-axis CT image of mitral annulus shows measurements of anteroposterior diameter (black line) and intercommissural distance (blue line). B, Reconstructed long-axis view of left ventricle shows measurement of displacement of heads of papillary muscles (intersecting lines). C, Calculation of sphericity index of mitral valve by measuring distance between bases of papillary muscles (A) and dividing by distance between this level and mitral annular plane (B). Increased sphericity index (1.4 ± 0.3) is observed in patients with functional mitral regurgitation and is one of strongest determinants of functional mitral regurgitation severity. D, Reconstructed short-axis image at level of mitral annulus shows relationship of great cardiac vein (GCV) to left circumflex artery (LCx). Proximity of coronary sinus and GCV to LCx (as in this case) may predispose to coronary compression during placement of coronary sinus–based devices.

W660

AJR:204, June 2015

Transcatheter Cardiac Intervention


Fig. 16—Photograph shows Melody Valve device (Medtronic).

A

C

B

D

E

Fig. 17—Preprocedural assessment of pulmonary valve and right ventricular outflow tract (RVOT) with MRI in 21-year-old patient with repaired tetralogy of Fallot. A, Measurement of minimal distance of RVOT conduit. Short-axis steady-state free precession (SSFP) image at level of RVOT shows measurement of minimal distance (green line). Implantation of a percutaneous pulmonary valve is contraindicated if minimal distance exceeds 22 mm for Melody (Medtronic) device placement. In this patient, minimal diameter was 17 mm and was within acceptable range. Patient underwent successful implantation of percutaneous pulmonary valve. B, Schematic diagram of types of RVOT morphology on basis of MRI assessment. C and D, Reconstructed 3D SSFP MR angiography (MRA) images of RVOT show type II (C) and type V (D) RVOT shapes. These RVOT shapes with narrower or parallel midsections are more suitable for implantation of a percutaneous pulmonary valve. E, Measurement of relationship of coronary arteries to RVOT. Axial maximum-intensity-projection SSFP MRA image shows close relationship of left anterior descending artery (white arrow) to RVOT conduit (black arrow). Expanding stent in RVOT can cause compression of adjacent coronary arteries and induce ischemia.

AJR:204, June 2015 W661


Renapurkar et al.

Fig. 18—Lateral chest radiograph shows wellpositioned Melody valve (Medtronic) (arrow). See also Figure 16.

Fig. 19—Classification of Melody stent fractures: Pictorial diagram shows types of stent fractures (types I, II, and III from top to bottom) on basis of radiographic appearance.

Fig. 20—54-year-old woman with rheumatic valve disease after mitral valve replacement and transcatheter repair of paravalvular leak. Lateral chest radiograph shows position of Amplatzer (St. Jude Medical) plug (arrow) along posteroinferior aspect of mitral annulus.

F O R YO U R I N F O R M AT I O N

The videos accompanying this web exclusive article can be viewed by clicking “Supplemental” at the top of the article.

W662

AJR:204, June 2015

Film-less Radiology - A Future Perspective.

Patient care in interventional radiology: a perspective.

Transcatheter Aortic Valve Replacement: a Kidney's Perspective.

[Research in Radiology: our perspective].

Human IgG4: a structural perspective.

Severe acute respiratory syndrome: 11 years later--a radiology perspective.

Setting up a transcatheter aortic valve implantation program: Indian perspective.

Transcatheter therapies for mitral regurgitation: a surgeon's perspective.

Transcatheter tricuspid valve intervention: the next frontier.

Computer Vision Techniques for Transcatheter Intervention.

Transcatheter intervention in a child with scimitar syndrome.

Sphingosine-1-phosphate metabolism: A structural perspective.

A Clinical Perspective on Sudden Cardiac Death.

Radiology of the pleural fissures: an historical perspective.

Goldenhar syndrome: Cardiac anesthesiologist's perspective.

Chaperone-dependent Neurodegeneration: A Molecular Perspective on Therapeutic Intervention.

Thoracolumbar burst fractures. Surgical intervention from a nursing perspective.

Innovation in intervention: transcatheter aortic valve replacement focus issue.

Transcatheter therapeutic intervention in adult coarctation of the aorta.

Bacterial sigma factors: a historical, structural, and genomic perspective.

A systems life cycle approach to managing the radiology profession: an Australian perspective.

Lessons learned at the Radiology Leadership Institute-Kellogg leadership development program: a resident's perspective.

Pilins in gram-positive bacteria: A structural perspective.

Orphans and new gene origination, a structural and evolutionary perspective.