Gijsbert F.L. Kapel

Re-Entry Using Anatomically Determined Isthmuses A Curable Ventricular Tachycardia in Repaired Congenital Heart Disease

Background—Ventricular tachycardia (VT) is an important cause of late morbidity and mortality in repaired congenital heart disease. The substrate often includes anatomic isthmuses that can be transected by radiofrequency catheter ablation similar to isthmus block for atrial flutter. This study evaluates the long-term efficacy of isthmus block for treatment of re-entry VT in adults with repaired congenital heart disease. Methods and Results—Thirty-four patients (49±13 years; 74% male) with repaired congenital heart disease who underwent radiofrequency catheter ablation of VT in 2 centers were included. Twenty-two (65%) had a preserved left and right ventricular function. Patients were inducible for 1 (interquartile range, 1–2) VT, median cycle length: 295 ms (interquartile range, 242–346). Ablation aimed to transect anatomic isthmuses containing VT re-entry circuit isthmuses. Procedural success was defined as noninducibility of any VT and transection of the anatomic isthmus and was achieved in 25 (74%) patients. During long-term follow-up (46±29 months), all patients with procedural success (18/25 with internal cardiac defibrillators) were free of VT recurrence but 7 of 18 experienced internal cardiac defibrillator-related complications. One patient with procedural success and depressed cardiac function received an internal cardiac defibrillator shock for ventricular fibrillation. None of the 18 patients (12/18 with internal cardiac defibrillators) with complete success and preserved cardiac function experienced any ventricular arrhythmia. In contrast, VT recurred in 4 of 9 patients without procedural success. Four patients died from nonarrhythmic causes. Conclusions—In patients with repaired congenital heart disease with preserved ventricular function and isthmus-dependent re-entry, VT isthmus ablation can be curative.

Arrhythmogenic anatomical isthmuses identified by electroanatomical mapping are the substrate for ventricular tachycardia in repaired tetralogy of Fallot.

Aims The majority of ventricular tachycardias (VTs) in repaired tetralogy of Fallot (rTOF) are related to anatomically defined isthmuses. We aimed to identify specific electroanatomical characteristics of anatomical isthmuses (AI) related to VT which may allow for individualized risk stratification and tailored ablation. Methods and results Seventy-four consecutive rTOF patients (40 ± 16 years, 63% male) underwent VT induction and right ventricular electroanatomical voltage and activation mapping during sinus rhythm (SR) to identify the presence and characteristics of AI (isthmus width, length and conduction velocity index [CVi]). Twenty-eight patients were inducible for 41 VTs. All 74 patients had at least one AI. However, AI in patients with VT were longer (22 ± 7 vs. 16 ± 7 mm, P = 0.001), narrower (20 ± 8 vs. 28 ± 11 mm, P < 0.001) and had lower CVi (0.36 ± 0.34 vs. 0.78 ± 0.24 m/s, P < 0.001). Thirty-seven VTs in 24 patients were mapped (pace-, entrainment mapping, and/or VT termination by ablation) to 28 AI. All 28 AI related to VT had a CVi < 0.5 m/s (slow conducting AI (SCAI)). In contrast, 87 of 89 AI of the 46 patients without VT had CVi ≥ 0.5 m/s. Sixty-two patients were discharged without the presence of an SCAI (44 had no SCAI at baseline, 18 underwent ablation of the SCAI) and 10 still had an SCAI (no/failed ablation). During follow-up (50 ± 22 months), no patient without SCAI had any VT, which occurred in 5/10 patients with SCAI (P < 0.001). Conclusion In rTOF, slow conducting anatomical isthmuses identified by electroanatomical mapping during SR are the dominant substrate for VT allowing individualized risk stratification and preventive ablation.

Left-Sided Ablation of Ventricular Tachycardia in Adults with Repaired Tetralogy of Fallot: A Case Series

Background—Radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in repaired Tetralogy of Fallot focuses on isthmuses in the right ventricle but may be hampered by hypertrophied myocardium or prosthetic material. These patients may benefit from ablation at the left side of the ventricular septum. Methods and Results—Records from 28 consecutive repaired Tetralogy of Fallot patients from 2 centers who underwent VT ablation were reviewed. Ablation targeted anatomic isthmuses containing VT re-entry circuits, which were identified by 3-dimensional substrate, pace, and entrainment mapping. A left-sided approach was considered beneficial if (1) right-sided RFCA failed, (2) part of the circuit was mapped to the left side, and (3) left-sided RFCA resulted in isthmus transection and prevention of VT induction. In 4 of 28 patients (52±13 years; 75% men), inducible for 1.5 (quartiles, 1.0 – 2.0) VTs (335±58 ms), left-sided RFCA was performed. In 3 patients, RFCA at aortic sites terminated VT related to a septal isthmus and prevented reinduction. In 1 patient, with prior biventricular implantable cardioverter-defibrillator, diastolic activity was recorded at the left side of the septum in proximity to the His-bundle. RFCA prevented VT reinduction with anticipated complete atrioventricular block. The left-sided approach resulted in complete procedural success (transection of anatomic isthmus and noninducibility) and freedom of VT recurrence during follow-up (20±15 months) in all patients. Right-sided RFCA failure was likely because of septal hypertrophy in 2, overlying pulmonary homograft in 1, and overlying ventricular septal defect patch in 1. Conclusions—Left-sided RFCA for VTs dependent on septal anatomic isthmuses improves ablation outcome in repaired Tetralogy of Fallot.

Endocardial or epicardial ventricular tachycardia in nonischemic cardiomyopathy? The role of 12-lead ECG criteria in clinical practice.

BACKGROUND Specific 12-lead ECG criteria have been reported to predict an epicardial site of origin (SoO) of induced ventricular tachycardias (VTs) in left ventricular nonischemic cardiomyopathy. OBJECTIVE The purpose of this study was to (1) determine the value of ECG criteria to predict an epicardial SoO of clinically documented VTs, (2) analyze the effect of VT cycle length (CL) and antiarrhythmic drugs on the accuracy of ECG criteria, and (3) assess interobserver variability. METHODS In 36 consecutive patients with nonischemic left ventricular cardiomyopathy (age 58 ± 16 years, 75% male) who underwent combined endocardial/epicardial VT ablation, all clinically documented and induced right bundle branch block VTs were analyzed for previously reported ECG criteria to determine the SoO, as defined by ≥11/12 pace-map, concealed entrainment, and/or VT termination during ablation. RESULTS In 21 patients with clinically documented (25 mm/s) right bundle branch block VT, none of the ECG criteria differentiated between patients with and those without an epicardial SoO. In induced VTs (100 mm/s), 2 of 4 interval criteria differentiated between an endocardial and epicardial SoO for slow VTs (CL >350 ms) and 2 of 4 criteria in patients on amiodarone, but none for fast VTs (CL ≤350 ms) or patients off amiodarone. The Q wave in lead I was the most accurate criterion for an epicardial SoO (sensitivity 88%, specificity 80%). In both clinically documented and induced VTs, interobserver agreement was poor for pseudodelta wave and moderate for other criteria. CONCLUSION When applied to clinically documented VTs, no ECG criterion could differentiate between patients with and those without an epicardial SoO. Published interval-based ECG criteria do not apply to fast VTs and patients off amiodarone.

Left-Sided Ablation of Ventricular Tachycardia in Adults With Repaired Tetralogy of FallotCLINICAL PERSPECTIVE

Background—Radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in repaired Tetralogy of Fallot focuses on isthmuses in the right ventricle but may be hampered by hypertrophied myocardium or prosthetic material. These patients may benefit from ablation at the left side of the ventricular septum. Methods and Results—Records from 28 consecutive repaired Tetralogy of Fallot patients from 2 centers who underwent VT ablation were reviewed. Ablation targeted anatomic isthmuses containing VT re-entry circuits, which were identified by 3-dimensional substrate, pace, and entrainment mapping. A left-sided approach was considered beneficial if (1) right-sided RFCA failed, (2) part of the circuit was mapped to the left side, and (3) left-sided RFCA resulted in isthmus transection and prevention of VT induction. In 4 of 28 patients (52±13 years; 75% men), inducible for 1.5 (quartiles, 1.0 – 2.0) VTs (335±58 ms), left-sided RFCA was performed. In 3 patients, RFCA at aortic sites terminated VT related to a septal isthmus and prevented reinduction. In 1 patient, with prior biventricular implantable cardioverter-defibrillator, diastolic activity was recorded at the left side of the septum in proximity to the His-bundle. RFCA prevented VT reinduction with anticipated complete atrioventricular block. The left-sided approach resulted in complete procedural success (transection of anatomic isthmus and noninducibility) and freedom of VT recurrence during follow-up (20±15 months) in all patients. Right-sided RFCA failure was likely because of septal hypertrophy in 2, overlying pulmonary homograft in 1, and overlying ventricular septal defect patch in 1. Conclusions—Left-sided RFCA for VTs dependent on septal anatomic isthmuses improves ablation outcome in repaired Tetralogy of Fallot.

Left-Sided Ablation of Ventricular Tachycardia in Adults With Repaired Tetralogy of FallotCLINICAL PERSPECTIVE: A Case Series

Background—Radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in repaired Tetralogy of Fallot focuses on isthmuses in the right ventricle but may be hampered by hypertrophied myocardium or prosthetic material. These patients may benefit from ablation at the left side of the ventricular septum. Methods and Results—Records from 28 consecutive repaired Tetralogy of Fallot patients from 2 centers who underwent VT ablation were reviewed. Ablation targeted anatomic isthmuses containing VT re-entry circuits, which were identified by 3-dimensional substrate, pace, and entrainment mapping. A left-sided approach was considered beneficial if (1) right-sided RFCA failed, (2) part of the circuit was mapped to the left side, and (3) left-sided RFCA resulted in isthmus transection and prevention of VT induction. In 4 of 28 patients (52±13 years; 75% men), inducible for 1.5 (quartiles, 1.0 – 2.0) VTs (335±58 ms), left-sided RFCA was performed. In 3 patients, RFCA at aortic sites terminated VT related to a septal isthmus and prevented reinduction. In 1 patient, with prior biventricular implantable cardioverter-defibrillator, diastolic activity was recorded at the left side of the septum in proximity to the His-bundle. RFCA prevented VT reinduction with anticipated complete atrioventricular block. The left-sided approach resulted in complete procedural success (transection of anatomic isthmus and noninducibility) and freedom of VT recurrence during follow-up (20±15 months) in all patients. Right-sided RFCA failure was likely because of septal hypertrophy in 2, overlying pulmonary homograft in 1, and overlying ventricular septal defect patch in 1. Conclusions—Left-sided RFCA for VTs dependent on septal anatomic isthmuses improves ablation outcome in repaired Tetralogy of Fallot.