Vincent van Driel

Rapid Recovery of Cardiac Function after Catheter Ablation of Persistent Junctional Reciprocating Tachycardia in Children

NOË, P., et al.: Rapid Recovery of Cardiac Function after Catheter Ablation of Persistent Junctional Reciprocating Tachycardia in Children. Four children (age range 3 weeks to 15 years) with tachycardia induced cardiomyopathy due to permanent junctional reciprocating tachycardia (PJRT) underwent successful catheter ablation of the tachyarrhythmia circuit without any complications during or after the procedure. In all four patients, the left ventricular fractional shortening improved to normal within 2 weeks of the procedure. These results argue for a more aggressive approach to the therapy of PJRT when associated with tachycardiomyopathy at a young age.

Pulmonary vein antrum isolation leads to a significant decrease of left atrial size

AIMS Pulmonary vein antrum isolation (PVAI) is an effective treatment for atrial fibrillation (AF); however, its impact on left atrial (LA) size is unknown. This study evaluates the impact of PVAI on LA size, and whether LA size differs between patients with a successful outcome and patients with AF recurrences. METHODS AND RESULTS Seventy-nine patients (76% male, mean age 56 ± 8 years) with symptomatic, drug refractory AF (70% paroxysmal, 30% persistent/permanent) underwent radiofrequency PVAI. Ablation lesions were created encircling right and left pulmonary venous ostia in pairs. The endpoint was complete isolation of all pulmonary veins. Magnetic resonance imaging was performed before and 4 months after PVAI and LA volume was measured by manually tracing the LA area. Clinical follow-up was at 1, 3, 6, 12, and 24 months. Rhythm status was determined by history, electrocardiogram, and 48 h Holter monitoring. After a mean follow-up of 12 ± 5 months, 62 patients (78%) were free of AF (72% without antiarrhythmic drugs). In the total group, LA volume decreased from 104 ± 27 mL to 91 ± 25 mL, P < 0.001. Patients with a successful outcome showed a decrease in LA volume of 103 ± 27 mL to 89 ± 24 mL, P < 0.001. Among patients with AF recurrences, LA volume decreased from 105 ± 29 mL to 95 ± 27 mL, P = 0.012. No significant difference was seen between the change in LA volume in both subgroups, P = 0.27. CONCLUSION Pulmonary vein antrum isolation in patients with AF resulted in a significant decrease of LA size. There was no relation between the decrease in LA size and the recurrence of AF after PVAI.

Detection and Quantification by Deformation Imaging of the Functional Impact of Septal Compared to Free Wall Preexcitation in the Wolff-Parkinson-White Syndrome

Pacing experiments in healthy animal hearts have suggested a larger detrimental effect of septal compared to free wall preexcitation. We investigated the intrinsic relation among the site of electrical preexcitation, mechanical dyssynchrony, and dysfunction in human patients. In 33 patients with Wolff-Parkinson-White (WPW) syndrome and 18 controls, regional myocardial deformation was assessed by speckle tracking mapping (ST-Map) to assess the preexcitation site, shortening sequences and dyssynchrony, and the extent of local and global ejecting shortening. The ST-Map data in patients with accessory atrioventricular pathways correctly diagnosed as located in the interventricular septum (IVS) (n = 11) or left ventricular free wall (LFW) (n = 12) were compared to the corresponding control values. A local ejecting shortening of <2 SD of the control values identified hypokinetic segments. The localization of the atrioventricular pathways by ST-Map matched with the invasive electrophysiology findings in 23 of 33 patients and was one segment different in 5 of 33 patients. In both WPW-IVS and WPW-LFW, local ejecting shortening was impaired at the preexcitation site (p <0.01). However, at similar electrical and mechanical dyssynchrony, WPW-IVS had more extensive hypokinesia than did WPW-LFW (3.6 +/- 0.9 vs 1.8 +/- 1.3 segments, p <0.01). Compared to controls, the left ventricular function was significantly reduced only in WPW-IVS (global ejecting shortening 17 +/- 2% vs 19 +/- 2%, p = 0.01; ejection fraction 55 +/- 5% vs 59 +/- 3%, p = 0.02). In conclusion, preexcitation is associated with local hypokinesia, which at comparable preexcitation is more extensive in WPW-IVS than in WPW-LFW and could adversely affect ventricular function. ST-Map might have a future role in detecting and guiding treatment of septal pathways with significant mechanical effects.

Feasibility of Electroporation for the Creation of Pulmonary Vein Ostial Lesions

Feasibility of Electroporation. Introduction: There is an obvious need for a better energy source for pulmonary vein (PV) antrum isolation.

Minimal coronary artery damage by myocardial electroporation ablation.

AIMS Radiofrequency catheter ablation is a successful treatment for cardiac arrhythmias, but may lead to major complications such as permanent coronary damage. Irreversible electroporation (IRE) is a new non-thermal ablation modality, but its effect on coronary arteries is still unknown. METHODS AND RESULTS In a porcine model, epicardial IRE lesions were created at the base of the left ventricle in four hearts (group A) and directly on the left anterior descending artery (LAD) in five hearts (group B). After 3 weeks, coronary arteries inside IRE lesions and in apparently undamaged myocardium next to the lesions were (immuno-)histologically studied. Two untreated hearts served as controls. Coronary damage was defined as intimal hyperplasia. Left anterior descending artery angiograms were obtained before ablation, directly after ablation, and before termination in group B. In group A, 103 arterial branches were studied. Of these, 5 of 56 arterial branches inside lesions and 1 of 47 outside lesions showed intimal hyperplasia, but all had <50% area stenosis. Targeted LADs (group B) did not reveal intimal hyperplasia and angiograms showed no signs of stenosis. Expression of connective tissue growth factor was observed in the scar tissue, but not in the fibrotic tissue directly around the arteries, confirming that the arteries are indeed spared from tissue damage and remodelling. CONCLUSION Coronary arteries remain free of clinically relevant damage 3 weeks after epicardial IRE ablation, even amid very large myocardial lesions. This suggests that IRE ablation can be applied safely near or even on coronary arteries. With IRE ablation, arterial blood flow does not appear to affect lesion formation.

Safety and Feasibility of Closed Chest Epicardial Catheter Ablation Using Electroporation

Background—Permanent coronary artery damage is a hazardous complication of epicardial radiofrequency ablation. Irreversible electroporation (IRE) is a promising nonthermal ablation modality able to create deep myocardial lesions. We investigated the effects of epicardial IRE on luminal coronary artery diameter and lesion depth. Methods and Results—In 5 pigs (60–75 kg), the pericardium was exposed using surgical subxiphoidal epicardial access. A custom deflectable octopolar 12-mm circular catheter with 2-mm ring electrodes was introduced in the pericardium via a steerable sheath. After coronary angiography (CAG), the proximal, mid, and distal left anterior descending, and circumflex coronary arteries were targeted with a single, cathodal 200 J application. CAG was repeated after IRE and after 3 months follow-up. Using quantitative CAG, the minimal luminal diameter at the lesion site was compared with the average of the diameters just proximal and distal to that lesion. Intimal hyperplasia and lesion size were measured histologically. CAG directly postablation demonstrated short-lasting luminal narrowing with normalization in the targeted area, suggestive of coronary spasm. After 3 months, all CAGs were identical to preablation CAGs: mean reference luminal diameter was 2.2±0.3 mm, mean luminal diameter at the lesion site was 2.1±0.3 mm (P=0.35). Average intimal hyperplasia in all arteries was 2±4%. Median lesion depth was 6.4±2.6 mm. Conclusions—Luminal coronary artery diameter remained unaffected 3 months after epicardial IRE, purposely targeting the coronary arteries. IRE can create deep lesions and is a safe modality for catheter ablation on or near coronary arteries.

Myocardial Lesion Depth With Circular Electroporation Ablation

Background—Recently, we demonstrated the feasibility and safety of circular electroporation ablation in porcine pulmonary vein ostia, but the relationship between the magnitude of the application and lesion dimensions is still unknown. Methods and Results—An in vivo porcine study was performed on left ventricular epicardium submerged under 10 mm of blood, using devices that mimic a 20-mm-diameter 7F circular ablation catheter. Model D contained 10 separate electrodes, whereas model M consisted of 1 circular electrode. Ablations were performed at 50, 100, and 200 J with model D and at 100 J with model M. Lesion dimensions were measured after 3-week survival. All applications resulted in smooth voltage waveforms demonstrating the absence of vapor globe formation, arcing, and a pressure wave. Applications up to 100 J with model D resulted in separate lesions under the electrodes. At 200 J, continuous deep circular lesions were created despite the use of separate electrodes. There was a significant relationship between applied current and median lesion depth, with a slope of 0.17 mm/A. At 100 J, there was no difference in lesion depth or width between models D and M. The electrodes and ablation site directly after ablation showed no signs of thermal damage. Conclusions—In an epicardial porcine model with blood around the application site, continuous circular lesions, deep enough for electric pulmonary vein isolation, were created with a single circular 200-J application. Lesions were continuous despite the use of separate electrodes. Lesion depth increased with the magnitude of the application.

Pulmonary vein stenosis after catheter ablation: electroporation versus radiofrequency.

Background— Radiofrequency ablation inside pulmonary vein (PV) ostia can cause PV stenosis. A novel alternative method of ablation is irreversible electroporation, but the long-term response of PVs to electroporation ablation is unknown. Methods and Results— In ten 6-month-old pigs (60–75 kg), the response of PVs to circular electroporation and radiofrequency ablation was compared. Ten consecutive, nonarcing, electroporation applications of 200 J were delivered 5 to 10 mm inside 1 of the 2 main PVs, using a custom-deflectable, 18-mm circular decapolar catheter. Inside the other PV, circular radiofrequency ablation was performed using 30 W radiofrequency applications via an irrigated 4-mm ablation catheter. PV angiograms were made before ablation, immediately after ablation, and after 3-month survival. PV diameters and heart size were measured. With electroporation ablation, PV ostial diameter decreased 11±10% directly after ablation, but had increased 19±11% after 3 months. With radiofrequency ablation, PV ostial diameter decreased 23±15% directly after ablation and remained 7±17% smaller after 3 months compared with preablation diameter despite a 21±7% increase in heart size during aging from 6 to 9 months. Conclusions— In this porcine model, multiple circumferential 200-J electroporation applications inside the PV ostia do not affect PV diameter at 3-month follow-up. Radiofrequency ablation inside PV ostia causes considerable PV stenosis directly after ablation, which persists after 3 months.Background—Radiofrequency ablation inside pulmonary vein (PV) ostia can cause PV stenosis. A novel alternative method of ablation is irreversible electroporation, but the long-term response of PVs to electroporation ablation is unknown. Methods and Results—In ten 6-month-old pigs (60–75 kg), the response of PVs to circular electroporation and radiofrequency ablation was compared. Ten consecutive, nonarcing, electroporation applications of 200 J were delivered 5 to 10 mm inside 1 of the 2 main PVs, using a custom-deflectable, 18-mm circular decapolar catheter. Inside the other PV, circular radiofrequency ablation was performed using 30 W radiofrequency applications via an irrigated 4-mm ablation catheter. PV angiograms were made before ablation, immediately after ablation, and after 3-month survival. PV diameters and heart size were measured. With electroporation ablation, PV ostial diameter decreased 11±10% directly after ablation, but had increased 19±11% after 3 months. With radiofrequency ablation, PV ostial diameter decreased 23±15% directly after ablation and remained 7±17% smaller after 3 months compared with preablation diameter despite a 21±7% increase in heart size during aging from 6 to 9 months. Conclusions—In this porcine model, multiple circumferential 200-J electroporation applications inside the PV ostia do not affect PV diameter at 3-month follow-up. Radiofrequency ablation inside PV ostia causes considerable PV stenosis directly after ablation, which persists after 3 months.

Five-year efficacy of pulmonary vein antrum isolation as a primary ablation strategy for atrial fibrillation: a single-centre cohort study

AIMS Pulmonary vein antrum isolation (PVAI) is the cornerstone of atrial fibrillation (AF) ablation. There is an ongoing discussion on whether and when to add substrate modification to PVAI. This study evaluates (1) long-term efficacy of PVAI as a primary ablation strategy in all patients independently from AF type and (2) predictors of arrhythmia recurrence. METHODS AND RESULTS A total of 509 consecutive patients (mean age 57 years, 38.9% non-paroxysmal AF) with AF underwent PVAI. In redo procedures, ablation was restricted to re-pulmonary vein (PV) isolation in case of PV reconnection. If the PVs were found to be isolated, substrate modification was performed. In total, 774 procedures were performed. Mean follow-up duration after the first and last ablation was, respectively, 66 ± 23 and 55 ± 25 months. A single PVAI was sufficient in restoring and maintaining long-term sinus rhythm in 41.3% (n = 210) of patients. Multiple procedures (mean 1.5) with re-PV isolation increased long-term success to 58.3% (n = 297). Additional substrate modification (n = 70) increased success to 62.5% (n = 318). After the last ablation, 87.5% of patients experienced success or significant clinical improvement on or off antiarrhythmic drugs. The incidence of left-sided atrial flutter or atrial tachycardia was 5% after PVAI and increased to 32% after additional substrate modification. Independent predictors for arrhythmia recurrence after the last ablation were non-paroxysmal AF, female sex, body mass index, hypertension, and AF duration. CONCLUSION Five-year freedom of atrial tachyarrhythmia could be achieved by PVAI as primary ablation strategy in 58.3% of patients. Additional substrate modification only moderately increased overall success.

Low vulnerability of the right phrenic nerve to electroporation ablation.

BACKGROUND Circular electroporation ablation is a novel ablation modality for electrical pulmonary vein isolation. With a single 200-J application, deep circular myocardial lesions can be created. However, the acute and chronic effects of this energy source on phrenic nerve (PN) function are unknown. OBJECTIVE The purpose of this study was to analyze nerve vulnerability to electroporation ablation in a porcine model. METHODS In 20 animals (60-75 kg), the course of the right PN was pace-mapped inside the superior caval vein (SCV). Thereafter, a single 200-J circular electroporation ablation was performed via a multipolar circular catheter in firm contact with the inner SCV wall. RESULTS In 19 of 20 animals, the PN could be captured along an estimated 6-8 cm trajectory above the right atrial contour. Directly after the application, the PN could be captured above the ablation level in 17 of 19 animals and after maximally 30 minutes in all animals. Fifteen animals were restudied after 3-13 weeks, and PN functionality was unaffected in all. Histological analysis in 5 animals in which the application had been delivered in the muscular sleeve just above the right atrium showed a transmural circular lesion. However, no lesion was found in the other animals in which the application had been delivered in the fibrous section more cranial in the SCV. CONCLUSIONS Electroporation ablation at an energy level that may create deep myocardial lesions may spare the targeted right PN. These animal data suggest that electroporation may be a safe ablation modality near the right PN.