© 2014, Wiley Periodicals, Inc. DOI: 10.1111/echo.12714

Echocardiography

Utility of Intracardiac Echocardiography for Catheter Ablation of Complex Cardiac Arrhythmias in a Medium-Volume Training Center  n-Castrejo  n, M.D.,* David Filgueiras-Rama, M.D., Ph.D,*†1 Fernando de Torres-Alba, M.D.,*1 Sergio Castrejo  ~  pez, M.D.,* Alejandro Estrada, M.D.,* Jorge Figueroa, M.D.,* Oscar Salvador-Montan es, M.D.,* Teresa Lo  pez Sendo  n, M.D., Ph.D.,* and Jos Mar Moreno-Yanguela, M.D.,* Jos e L. Lo e L. Merino, M.D., Ph.D.* *Department of Cardiology, La Paz University Hospital, Madrid, Spain; and †Atherothrombosis, Imaging and Epidemiology Department, National Center for Cardiovascular Research (CNIC), Madrid, Spain

Aims and Objectives: New electrophysiology tools like intracardiac echocardiography (ICE) might help to minimize and early detect complications during cardiac ablation procedures. The aim of the study was to assess the utility and vascular safety of ICE during catheter ablation of complex cardiac arrhythmias in a medium-volume training center. Methods: Prospective, observational study consisted of consecutive patients who underwent catheter-based ablation of complex cardiac arrhythmias. All procedures were performed using three-dimensional electro-anatomical mapping and routine cannulation of right and left femoral veins. The ICE probe was initially positioned at the mid-level of the right atrium and properly moved to monitor different steps of the procedure and identify complications. All procedure-related vascular complications were registered. Results: One hundred two patients (age 61.4  13.1 years, 69 male) underwent 110 ablation procedures. Pulmonary vein isolation was the most common ablation substrate (55.4%). Ventricular tachycardia (17.2%) and left atrial flutter procedures (16.4%) were also common. The use of ICE enabled us to early initiate anticoagulation and to optimize the transseptal puncture. It also provided the capability to early detect life-threatening complications such as tamponade (3.6%), along with important information during the procedure such as exact catheter location, lesion formation, and stability during radiofrequency delivery. Such benefits were not associated with a higher number of vascular complications. Conclusion: The use of ICE during catheter-based ablation of complex cardiac substrates provides technical features that may decrease complications and increase accuracy while applying radiofrequency, especially in training centers where fellows start to perform complex procedures. (Echocardiography 2015;32:660–670) Key words: intracardiac echocardiography, ablation, complex arrhythmias, complications Catheter ablation has become a well-established therapeutic option for a wide variety of complex cardiac arrhythmias. However, complications during complex ablation procedures are still a major concern,1,2 which makes it necessary to continuously develop electrophysiological tools to minimize them. The latter is especially relevant considering the increasing number of electrophysiology laboratories and operators that are currently performing ablation procedures.2 Thus, cardiac imaging is a very promising tool to minimize complications. Three-dimensional electro-anatomical mapping systems have already 1 Equal contribution to this work. Address for correspondence and reprint requests: David Filgueiras-Rama, Atherothrombosis, Imaging and Epidemiology Department. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernandez Almagro, 3. 28029. Madrid. Spain. Fax: +34-91-4531265; E-mail: david.fi[email protected]

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provided highly reliable anatomical reconstruction of the cardiac chambers and a significant decrease to x-ray exposure during mapping and ablation.3 However, they do not provide real time visualization of other cardiac structures involved in the development of serious complications, such as the pericardium or direct visualization of lesion formation and potential signs of alarm during radiofrequency delivery. Such limitations may be overcome by the use of intracardiac echocardiography (ICE) imaging, which allows direct and real time visualization of catheters, radiofrequency lesions, and most of nearby cardiac structures.4 Moreover, recent data suggest that the use of ICE might minimize major complications during pulmonary vein (PV) isolation.5 However, the role of ICE during ablation of complex cardiac arrhythmias beyond PV isolation is not completely established. The main aim of

Intracardiac Echocardiograhy during Catheter Ablation

this study was to evaluate the usefulness of ICE at different steps during catheter ablation of complex arrhythmias in a medium-volume training center. The second aim was to assess procedurerelated complications and to describe the potential benefit of ICE on complication rates. Methods: Patients Selection: A prospective, nonrandomized observational study conducted in a medium-volume tertiary teaching center, in which electrophysiology fellows regularly cannulate femoral veins. Second year fellows also begin to do transseptal puncture (TSP) and part of the ablation. A senior staff or a second year fellow usually manipulates the ICE probe. The study consisted of consecutive patients who underwent catheter-based ablation of complex cardiac arrhythmias or any noncomplex procedure, in which a TSP (i.e. leftsided accessory pathways) was attempted. All procedures were performed using continuous ICE monitoring. Complex arrhythmias included atrial fibrillation (AF), LA (left atrial) flutter and ventricular tachycardia originating from either the right or the left ventricle. The study complies with the Declaration of Helsinki. We obtained informed consent from all the patients before the procedure. Intra-procedure complications were prospectively registered in a specific institutional database. All vascular complications occurred before hospital discharge and any postdischarge readmission due to procedure-derived complications were registered. Catheter Ablation Procedures: All procedures were performed using right and left vein femoral accesses. For PV isolation and LA flutter procedures, we routinely placed 2 sheath introducers into the right femoral vein and 3 more into the left femoral vein. The latter was used to position a 10-pole catheter into de coronary sinus, a screw-in catheter in the interatrial septum (IAS) and the ICE probe (ViewFlex PLUS Ultrasound Catheter, 9F, St. Jude Medical, Irvin, CA, USA) into the right atrium. Six-F introducers were used for the formers and a 10-F introducer for the latter. The right femoral vein was used to perform the TSP by properly positioning a transseptal needle (Brockenbrough curved needle) through a standard long sheath (8F Mullins introducer). A single TSP technique was used in the majority of cases, in such way that an open-irrigated ablation catheter was first positioned into the LA immediately after the TSP and parallel to the wire-guide. Afterward, a 24-pole catheter (7F, Inquiry Optima Plus, St. Jude Medical or 6F, Orbiter, Bard Electrophysiology, Lowell, MA,

USA) was introduced into the LA through the long sheath. Ventricular tachycardia ablation was performed using the same left femoral vein settings for the 10-pole catheter located into the coronary sinus and the initial positions of the ICE probe into the right atrium. Unlike PV isolation and LA flutter procedures, the screw-in catheter was positioned in the right interventricular septum. Right vein femoral access was used for introducing either a 4-pole catheter in the right ventricular apex or the ablation catheter, for left or right ventricular substrates, respectively. Transseptal access was only attempted when a conventional retrograde aortic approach was not feasible or led to difficulties for complete and accurate mapping of the left ventricle. In noncomplex procedures requiring TSP, only one left femoral vein access was obtained to place the ICE probe. Right femoral vein access was used to position a 10-pole catheter into the coronary sinus and a 4-pole catheter in the His position, along with the transseptal sheath for the ablation catheter. All procedures were performed using an electro-anatomical mapping system (CARTO3; Biosense Webster, Diamond Bar, CA, USA or NavX, St. Jude Medical, St. Paul, MN, USA). Remote magnetic navigation using the Catheter Guidance Control and Imaging (CGCI, Magnetecs Inc. Inglewood, CA, USA) system was also used in several complex cases as described elsewhere.6 Patients were mildly sedated with an initial midazolam bolus for induction, and propofol continuous infusion for maintenance. Additional intravenous boluses of morphine-hydrochloride were administered throughout the procedure. Radiofrequency energy was applied using either 3.5 or 4-mm open-irrigated-tip catheters (Navistar Thermocool; Biosense Webster, Cool Flex; St. Jude Medical or MagnoFlush; MedFact € rrach, GerEngineering GmbH, Hammerstr, Lo many), but in very few cases of left accessory pathway ablation and right ventricular outflow tract tachycardia, in which a 4-mm nonirrigated tip catheter was used. Appropriate temperature and power ablation settings were used as described elsewhere.5,7 An activated clotting time of 250–350 second was routinely maintained throughout the procedure in all cases of PV isolation, LA flutter, and left ventricular substrates. ICE Imaging: The intracardiac echocardiography probe was advanced through the inferior vena cava to the mid-level of the right aitrum to its initial position facing the tricuspid valve. Visualization of the IAS was straightforward from the mid-right aitrum, 661

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usually after slightly rotating clockwise the tip of the ultrasound catheter. The IAS was classified in 6 different categories: (1) thickened, when IAS thickness was >5 mm and homogeneously distributed; (2) lipomatous hypertrophy, when IAS thickness was >20 mm and presented the typical bright echogenicity and “dumbbell” morphology sparing the fossa ovalis; (3) redundant, when the IAS showed a floppy anatomy due to abnormal redundancy of the septal membranes, and the excursion movement was 10 mm beyond the plane of the IAS; (5) calcified, when the IAS showed extensive enhanced echogenicity with posterior acoustic shadow, and (6) normal, when none of these characteristics were present (See Fig. 1 for representative images of the different categories).8–10 Transseptal puncture was performed using conventional fluoroscopy guidance and continuous ICE monitoring to optimize the protrusion of the transseptal needle on the IAS. Any difficulties

during transseptal access were registered. In all cases, counterclockwise rotation of the ultrasound catheter was performed before any TSP attempt to evaluate the presence of pericardial effusion at baseline. Such maneuver allowed seeing the lateral side of the right atrioventricular groove and the basal-lateral wall of the right ventricle. The same maneuver was repeated immediately after TSP and intermittently during the procedure to evaluate the appearance of pericardial effusion and its severity.11 During mapping and ablation, ICE was used to monitor for thrombi formation either inside the cardiac cavities or at the tip of the catheter sheath and catheter itself. Thrombi were defined as echo-dense reflecting masses with defined margins and distinct from the underlying endocardium, observed in more than one imaging plane, and not related to pectinate muscles, false tendons or trabeculae.8 The appearance of spontaneous echo contrast due to low-flow conditions preceding thrombus formation was also assessed.

A

B

C

D

E

F

Figure 1. Anatomy of the interatrial septum (IAS). The same disposition of the left (LA) and right atrium (RA) is shown in all panels. A. Normal IAS (yellow arrowhead). B. Redundant IAS. Note the floppy anatomy, and the excursion movement (purple arrowed line) 10 mm beyond the plane of the IAS (blue line). D. Lipomatous hypertrophy. Note the typical bright echogenicity and “dumbbell” morphology (yellow arrowheads) sparing the fossa ovalis (red arrowheads). E. Thickened IAS. Note the thickness of the IAS (yellow arrowhead) compared with the normal IAS in A. F. Calcified IAS. Note the enhanced echogenicity (green arrowheads) inside the IAS.

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Intracardiac Echocardiograhy during Catheter Ablation

For LA procedures, progressive clockwise rotation of the ICE probe from the initial position allowed visualizing diagnostic and ablation catheters, and their relationship with LA structures such as the mitral valve, the left atrial appendage, the left inferior PV, the aorta, the left superior PV, the esophagus and posterior wall, and the right PVs.12 The relationship of the esophagus lumen with the LA and PVs was routinely documented and further represented on the electro-anatomical reconstruction of the LA. Any indirect signs of excessive rise in tissue temperature, such as local increase in cardiac echogenicity (“whitening” of the catheter tip and adjacent cardiac tissue) or abrupt increase in micro bubbles (presteam pop sign), led to immediately stop radiofrequency application. PV isolation and LA flutter procedures were occasionally complemented with either isolation of the superior vena cava or radiofrequency delivery at the cavo-tricuspid isthmus. Slight removal of the ICE probe to the inferior vena cava, along with counterclockwise rotation from the initial position was used to properly visualize the Eustaquian ridge, the cavo-tricuspid isthmus, and its relationship with the right coronary artery. Deflection of the ICE catheter and orientation of the ultrasound tip superiorly toward the superior vena cava also allowed direct visualization during its isolation. Left and right ventricles, aortic root, right and left ventricle outflow tract were routinely visualized during ventricular tachycardia and premature ventricular complexes ablation. Right ventricular outflow tract and aortic root were well visualized, either on the long or the short-axis view, by positioning the echocardiography probe into the right atrium. Direct and more accurate visualization of the distal part of the right ventricular outflow tract, pulmonary valve, and pulmonary artery was obtained by positioning the echocardiography probe into the right ventricular outflow tract. Visualization of the left ventricle was achieved by moving the tip of the ultrasound catheter along the right ventricular septum. ICE imaging was also used at operator discretion to confirm catheter position, contact, and stability before radiofrequency delivery at certain anatomical positions, such as the right ventricular outflow tract, the aortic root, and the left ventricle. Statistical Analysis: Continuous variables are expressed as means standard deviations after testing for normality of the distribution. Categorical variables are expressed as absolute values and percentages. All statistical analyses were performed using PASW Statistics Version 18.0 (SPSS Inc., Chicago, IL, USA).

Results: One hundred ten procedures were performed in 102 patients included for analysis. The mean age was 61.4  13.1 years, and 69 patients (62.7%) were male. Catheter ablation procedures were mainly focused on paroxysmal and persistent AF (43.6% and 11.8%, respectively). Ventricular tachycardia and premature ventricular complexes ablation were the second most common substrates (17.2% and 5.5%, respectively). A similar number of procedures was performed to eliminate LA flutter (16.4%). PV isolation and LA flutter procedures were further complemented with cavo-tricuspid isthmus ablation in 13 (11.8%) and 6 (5.4%) cases, respectively. However, complementary isolation of the superior vena cava was only performed in 3 PV isolation procedures (2.7%). Remote magnetic navigation was used in 11 patients undergoing PV isolation (18%) and 5 patients who underwent LA flutter ablation (27.7%). Types of procedures performed are listed in Table I. Interatrial Septum Assessment and Transseptal Puncture Optimization: Interatrial septum was evaluated in 86 patients (84.3%), in whom TSP was necessary to access to the left chambers. The IAS was considered normal in 74.4% of patients. Beyond normal classification, the most common anatomical characteristic was the presence of a redundant IAS in 9 patients (10.4%). Anatomical characteristics of the IAS are summarized in Table II and documented in Figure 1A–F. A second procedure TABLE I Basaline Characteristics All Procedures (n = 110) Age, mean SD, years Sex Male, n (%) Female, n (%) Type of procedure Ischemic VT, n (%) VT in dilated cardiomyopathy, n (%) Epicardial VT, n (%) Other VT (RVOT, LVOT, fascicular VT) or PVC, n (%) Paroxysmal AF, n (%) Persistent AF, n (%) Left atrial flutter, n (%) Other (WPW, AT, AVRT), n (%)

61.4  13.1 69 (62.7) 41 (37.3) 15 (13.6) 1 (0.9) 3 (2.7) 6 (5.5) 48 (43.6) 13 (11.8) 18 (16.4) 6 (5.5)

VT = ventricular tachycardia; RVOT = right ventricular outflow tract; LVOT = left ventricular outflow tract; PVC = premature ventricular complexes; AF = atrial fibrillation; WPW = WolffParkinson-White syndrome; AT = atrial tachycardia; AVRT = atrioventricular reentrant tachycardia.

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(n = 4) did not change the initial IAS classification despite healing up of the first septal orifice. Transseptal puncture was considered difficult (more than 2 TSP attempts) in 11 procedures (12.7%) despite routine optimization of the puncture site (Fig. 2A). All patients with calcified, aneurysmal IAS, and the presence of a septal closure device were classified as difficult. Two patients with redundant IAS, 1 with thickened IAS, and 3 with echocardiographic-based normal IAS were also considered difficult for TSP. Radiofrequency delivery at the tip of the transseptal needle was necessary in 3 patients to finally access to the LA (Fig. 2B). Radiofrequency was considered after at least 3 previous unsuccessful attempts performed by a senior staff member. In two patients a dissection of the IAS occurred (Fig. 2C and D), which did not result in any further complication. Pericardial Effusion and Tamponade: Intracardiac echocardiography detected procedure-related pericardial effusion in 13 procedures (11.8%). Such a diagnosis was related to PV isolation (n = 10, 76.9%) and ventricular tachycardia ablation (n = 3, 23.1%). Pericardial effusions were graded as small (Fig. 3A, echo-free space in diastole

Utility of intracardiac echocardiography for catheter ablation of complex cardiac arrhythmias in a medium-volume training center.

New electrophysiology tools like intracardiac echocardiography (ICE) might help to minimize and early detect complications during cardiac ablation pro...
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