Comparative Efficacy and Safety of Pulsed Field Ablation Versus Radiofrequency Ablation of Idiopathic LV Arrhythmias

Radiofrequency-aided venous ethanol vs optimized radiofrequency for primary and repeat ablation of left ventricular summit arrhythmias: A propensity score-matched comparison

BACKGROUND

Radiofrequency (RF) ablation of left ventricular summit arrhythmias (LVSAs) is challenging and may fail due to the anatomical inaccessibility of the substrate. Coronary venous ethanol ablation (CVEA) has been suggested as an alternative ablation strategy for drug- and RF-refractory LVSA.

OBJECTIVE

This study compared venous ethanol with or without adjunctive RF (CVEA ± RF) vs optimized RF (ORF) for primary or repeat ablation of LVSA.

METHODS

After propensity score matching, 41 of 43 patients treated with CVEA ± RF were compared to 41 of 93 patients who underwent ORF ablation.

RESULTS

Patient characteristics were similar for both groups (77% male, median age 65 [56-71] years, median 2 [1-2] previous ablation procedures). The mean pace-match was 97.1 ± 1.7% for venous vs 94.7 ± 3% for conventional mapping (P < .0001). The earliest presystolic signal was -41 ± 11 ms for venous vs -28 ± 10 ms conventional mapping (P < .0001). Acute procedural success was 95% vs 83% for CVEA ± RF and ORF respectively (P = .077). Ventricular premature beat burden decreased by 58% after ORF and by 91% following CVEA ± RF (P = .041). In patients with ventricular tachycardia, ventricular tachycardia burden decreased by 96% after CVEA ± RF (P < .0001), while a 70% reduction was not significant for ORF. After a median follow-up of 24 (12-58) months, 20% of CVEA ± RF patients recurred as compared to 54% following ORF (P = .002). Following ORF ablation, 1 patient developed pericarditis, 1 patient tamponade, and 1 patient atrioventricular block. In the CVEA ± RF group, one patient suffered a vascular access complication. No patients died.

CONCLUSION

When venous mapping supports intramural origin, RF-aided venous ethanol ablation is an effective strategy for the treatment of LVSA also when compared to ORF ablation.

Indirect epicardial targeting of left atrial tachycardia using Bachmann's bundle: A case report of successful ablation from pulmonary artery

Successful rhythm control by standard endocardial methods may become quite challenging in some atrial tachycardia cases, very few of which may need extraordinarily different approaches after the initial failure of extensive endocardial ablation, such as epicardial ablation after subxiphoid puncture, or venous alcohol injection inside the vein of Marshall. With a good understanding of the structures nearby the LA, endocardially failed epicardial ATs can still be successfully ablated without directly entering the pericardial space.

Dose-dependent ventricular lesion formation using a novel large-area pulsed field ablation catheter: A preclinical feasibility study

BACKGROUND

Pulsed field ablation (PFA) has shown promising data in terms of safety and procedural efficiency for pulmonary vein isolation. Large-area focal PFA catheter designs might be suitable to deliver deep and durable lesions in ventricular myocardium.

OBJECTIVE

We aimed to investigate the dose-response of a novel large-area focal 3-dimensional (3D)-enabled map-and-ablate PFA catheter for ventricular ablation in a chronic preclinical swine model.

METHODS

An 8F catheter with a 9-mm hexaspline tip was used for 3D mapping of both ventricles in a porcine model. Using a PFA generator with a proprietary waveform optimized for the catheter, left and right ventricular lesions were placed with either a monopolar or bipolar ablation vector and with 1, 2, or 4 applications per site (2.0 kV/application). Tissue contact was ensured by intracardiac echocardiography and electrograms. The animals were kept alive for 1 week. Ablation lesions were assessed macroscopically after triphenyl tetrazolium chloride staining and by histopathology.

RESULTS

A total of 69 chronic ventricular lesions from 7 pigs were available for analysis. By stacking 4 PFA applications rather than a single application, median chronic lesion depth increased from 4.8 mm (interquartile range [IQR], 4.1-5.6 mm) to 5.5 mm (IQR, 5.0-6.2 mm; P = .06) with bipolar ablation and from 4.9 mm (IQR, 4.4-5.2 mm) to 6.5 mm (IQR, 5.9-6.9 mm; P = .002) with monopolar ablation. On histologic evaluation, lesion borders were clearly demarcated, with vessels and nerves preserved.

CONCLUSION

A novel large-area focal ablation catheter with the ability for 3D mapping and PFA was able to create dose-dependent deep ventricular lesions durable 1 week after ablation.

Feasibility and midterm effectiveness of focal pulsed field ablation for ventricular arrhythmias

BACKGROUND

Pulsed field ablation (PFA) is a promising novel method of atrial ablation, with preclinical data suggesting it to be a viable option for ventricular arrhythmias.

OBJECTIVE

The objective was to report the feasibility, safety, and clinical efficacy of PFA for ventricular arrhythmias.

METHODS

All patients (N = 35) scheduled for ablation of premature ventricular complexes (PVCs; n = 24) or ventricular tachycardia (VT; n = 11) underwent focal PFA by use of a pulsed field generator and irrigated ablation catheters. Procedural and clinical outcomes were evaluated by 3-month Holter monitoring, implantable cardioverter-defibrillator home monitoring, and chart review.

RESULTS

A total of 11 (31%) patients had experienced previously failed radiofrequency ablation. Most PVCs (58%) originated from the outflow tracts, and most VTs were caused by ischemic cardiomyopathy (55%). Average procedure time was 187 ± 59 minutes. Acute procedural success was achieved in 91% of the patients. PFA was delivered combined endocardially and through the cardiac venous system in 25% of the PVC patients. During a mean follow-up of 288 ± 149 days, the success was 75% for PVCs and 45% for VTs. A total of 5 patients were reablated during follow-up (4 VT, 1 PVC). We observed 7 (20%) minor and 2 (6%) major complications including 2 transient conduction system blocks related to pulsed field delivery and 1 stroke and 1 minor stroke.

CONCLUSION

Focal PFA exhibited satisfactory acute effectiveness for PVC and VT, but favorable clinical effectiveness was retained only in PVC patients. More data are needed to establish lesion durability, safety, and limitations of PFA in ventricular tissue.

Improving long-term postoperative survival in a porcine cardiac valve surgery model utilizing cardiopulmonary bypass via left thoracotomy: a single-center experience sharing insights

Objective

The objective of this study was to improve long-term postoperative survival in a porcine cardiac valve surgery model by utilizing cardiopulmonary bypass (CPB) via left thoracotomy. The study aimed to share refined techniques and insights accumulated over years at a single-center animal clinical trial facility.

Method

A total of 196 Chinese Large White pigs weighing between 60 and 75 kg were used in the study. All animals underwent cardiac valve surgeries via left thoracotomy with CPB. Surgical techniques included mitral valve replacement, mitral valve repair, aortic valve replacement, OZAKI procedure, ascending aorta replacement, and left ventricular assist device implantation. Anesthesia and CPB protocols were optimized to minimize stress and complications. Postoperative care was standardized to enhance recovery and survival.

Result

All 196 pigs survived the surgical procedures, with no deaths reported. The mean surgical duration was 168.55 ± 38.75 min, CPB time was 114.89 ± 32.11 min, and aortic cross-clamp time was 76.75 ± 21.33 min. Automatic heart resumption occurred in 63.8% of pigs, while the remainder required electrical defibrillation or cardiac massage. The postoperative mechanical ventilation time was 2.44 ± 0.58 min, and the average drainage volume at 2 h postoperatively was 27.50 ± 9.70 ml. There were no cases of postoperative hemorrhage complications or blood transfusions, and surgical site infections occurred in only 1.5% of pigs.

Conclusion

The surgical approach utilizing left thoracotomy with CPB has proven effective in significantly enhancing long-term survival rates in porcine heart surgeries. The refined techniques and standardized operational procedures described in this study offer valuable insights for researchers aiming to improve the success of porcine heart valve surgical models. However, due to differences in animal anatomy, the applicability of this surgical approach to other animal models still requires further exploration.

Contemporary Trends in Pulsed Field Ablation for Cardiac Arrhythmias

Pulsed field ablation (PFA) is a catheter-based procedure that utilizes short high voltage and short-duration electrical field pulses to induce tissue injury. The last decade has yielded significant scientific progress and quickened interest in PFA as an energy modality leading to the emergence of the clinical use of PFA technologies for the treatment of atrial fibrillation. It is generally agreed that more research is needed to improve our biophysical understanding of PFA for clinical cardiac applications as well as its potential as a potential alternative energy source to thermal ablation modalities for the treatment of other arrhythmias. In this review, we discuss the available preclinical and clinical evidence for PFA for atrial fibrillation, developments for ventricular arrhythmia (VA) ablation, and future perspectives.

Feasibility and safety of pulsed field ablation at the ventricular outflow tract using focal point catheter

BACKGROUND

Ventricular arrhythmias commonly originate from the ventricular outflow tract. It remains unexplored whether pulsed field ablation (PFA) can create durable lesions safely at the ventricular outflow tract.

OBJECTIVE

This study aimed to evaluate the feasibility and safety of a novel PFA catheter to deliver focal ablation to the ventricular outflow tract, especially pulmonary and aortic sinus cusps (PSCs and ASCs).

METHODS

Twelve swine were divided into 3 groups: 24-hour, 2-week, and 4-week post-ablation. PFA was delivered to predefined sites of PSCs and ASCs with a focal point catheter, positioned by a mapping system, fluoroscopy, and intracardiac echocardiography. Electrophysiologic assessment, coronary angiography, transesophageal echocardiography, and gross and histologic examination were performed to evaluate the impact of PFA delivery on cardiac structure and function.

RESULTS

All subjects survived, and no adverse events were observed. There was a significant decrease in voltage amplitude and increase in pacing thresholds at PSCs and ASCs. There were no significant differences in AH or HV intervals between pre-ablation and post-ablation (AH, P = .70; HV, P = .90). After PFA delivery to ASCs, coronary arteries were fully perfused in each heart, without ST-segment elevation observed. No severe valvular dysfunction was observed on intracardiac echocardiography and transesophageal echocardiography. Gross and histologic examination confirmed the creation of well-demarcated lesions at the targeted sites without damage to adjacent structures.

CONCLUSION

PFA delivered by the focal point catheter could create durable lesions at PSCs and ASCs without damage to coronary arteries, atrioventricular block, or valvular dysfunction, indicative of the feasibility and safety of this novel PFA catheter at the ventricular outflow tract.

Efficacy of balloon-expandable extreme-low-temperature ventricular epicardial cryoablation: A preclinical proof of concept evaluation

BACKGROUND

Current epicardial ablation technologies are limited by the inability to create adequate depth lesions and risk of collateral injury to extracardiac structures.

OBJECTIVE

The purpose of this study was to evaluate the feasibility and efficacy of ventricular epicardial ablation with a novel balloon-expandable extreme-low-temperature (XLT) cryoablation catheter with an embedded insulation pontoon for protection of extracardiac structures, which has been specifically designed for epicardial ablation.

METHODS

Ten healthy swine underwent surgical (n = 6) and subxiphoid percutaneous (n = 4) epicardial access. A total of 3-6 sites were targeted in the right and left ventricular wall for different exposure durations. Ablation was performed with a large footprint (surgical) and smaller footprint (percutaneous) version of the HeartPad (Corfigo Inc., Montclair, NJ) XLT system. The system consists of the balloon-expandable cryoablation catheter and a console. The console vaporizes liquid helium (-269°C) and controls continuous delivery of extremely cold helium gas at high flow rates through a high-efficiency ablation element mounted on an expandable insulation pontoon to protect extracardiac structures. Ablation lesions were assessed by gross pathology and histologic examination.

RESULTS

A total of 42 epicardial lesions were created. Mean lesion depth increased progressively with ablation time (surgical catheter: 11 ± 2 mm at ≤30 seconds, 13 ± 4 mm at 60 seconds, 15 ± 3 mm at ≥120 seconds, P = .001; percutaneous catheter: 10 ± 2 mm at 30 seconds, 14 ± 2 mm at 60 seconds, 16 ± 2 mm at 120 seconds, P = .001). Lesion geometry seemed unaffected by presence and thickness of epicardial fat. One episode of ventricular fibrillation occurred after ablation over the atrioventricular groove and 2 adjacent obtuse marginal arteries.

CONCLUSION

Surgical or percutaneous epicardial ablation using the HeartPad XLT cryoablation system is feasible and can efficiently produce deep ventricular lesions in different epicardial locations.

Pulsed Field Ablation: A Comprehensive Update

One of the recent advancements in the field of cardiac electrophysiology is pulsed field ablation (PFA). PFA is a novel energy modality that does not rely on thermal processes to achieve ablation which, in turn, results in limited collateral damage to surrounding structures. In this review, we discuss the mechanisms, safety, efficacy, and clinical applications of PFA for the management of atrial and ventricular arrhythmias. We also summarize the published pre-clinical and clinical studies regarding this new technology.