Epicardial ablation: prevention of phrenic nerve damage by pericardial injection of saline and the use of a steerable sheath

Epicardial Ablation Complications

The percutaneous epicardial approach has become an adjunctive tool for electrophysiologists to treat disparate cardiac arrhythmias, including accessory pathways, atrial tachycardia, and particularly ventricular tachycardia. This novel technique prompted a strong impulse to perform epicardial access as an alternative strategy for pacing and defibrillation, left atrial appendage exclusion, heart failure with preserved ejection fraction, and genetically engineered tissue delivery. However, because of the incremental risk of major complications compared with stand-alone endocardial ablation, it is still practiced in a limited number of highly experienced centers across the world.

Phrenic Nerve Limitation During Epicardial Catheter Ablation of Ventricular Tachycardia

OBJECTIVES

This study sought to investigate the incidence of phrenic nerve (PN) limitation and the utility of displacing the PN with a balloon.

BACKGROUND

The PN can limit the epicardial ablation of ventricular tachycardia (VT).

METHODS

From 2010 to 2017, 363 patients undergoing VT epicardial ablation at a single center were studied. Before the ablation, we used high output (20-mA) pacing maneuvers to verify the course of the PN. When we observed its capture, we used 1 of 3 different approaches to protect it: 1) non-balloon strategy (nerve-sparing ablation); 2) PN displacement with a small balloon (6 mm × 20 mm); or 3) PN displacement with a large balloon (20 mm × 45 mm).

RESULTS

PN capture occurred in 25 patients (7%) at the target ablation site. The most common cause was myocarditis (12 patients [48%]), and the incidence of the PN limitation was significantly higher in myocarditis than in other causes (19% vs. 4%, respectively; p = 0.0002). PN displacement was attempted in 7 patients by using large balloons and in 6 patients with small balloons, resulting in successful PN displacements and complete late potential (LP) abolition in 6 patients (86%) and 3 patients (50%), respectively. Among the 12 patients in whom the non-balloon strategy was used, only 1 patient (8%) achieved LP abolition (compared with the large balloon group; p = 0.002), whereas 3 patients experienced PN paralysis.

CONCLUSIONS

The PN limited the epicardial ablation in 7% of patients. Because nerve-sparing ablations often resulted in PN injuries, a possible solution could be to displace the PN with a large balloon, leading to a safer procedure and completion of LP abolition.

Epicardial ablation of ventricular tachycardia using pericardioscopy through submammary minimal thoracotomy

The subxiphoid access became the standard technique for epicardial ablation of ventricular tachycardia. However, it may prove difficult in certain situations. Here, we report an alternative method of epicardial and endocardial ablation performed via submammary minimal thoracotomy guided by pericardioscopy. Two male patients with structural heart disease and incessant ventricular tachycardia were successfully ablated using this technique. The described technique can be considered as an alternative to the standard technique. Moreover, it permits real-time visualization of cardiac vessels and fat tissue, and is safe in terms of damage to the phrenic nerve or potential bleeding complications.

Epicardial phrenic nerve displacement during catheter ablation of atrial and ventricular arrhythmias: procedural experience and outcomes

BACKGROUND

Arrhythmia origin in close proximity to the phrenic nerve (PN) can hinder successful catheter ablation. We describe our approach with epicardial PN displacement in such instances.

METHODS AND RESULTS

PN displacement via percutaneous pericardial access was attempted in 13 patients (age 49±16 years, 9 females) with either atrial tachycardia (6 patients) or atrial fibrillation triggered from a superior vena cava focus (1 patient) adjacent to the right PN or epicardial ventricular tachycardia origin adjacent to the left PN (6 patients). An epicardially placed steerable sheath/4 mm-catheter combination (5 patients) or a vascular or an esophageal balloon (8 patients) was ultimately successful. Balloon placement was often difficult requiring manipulation via a steerable sheath. In 2 ventricular tachycardia cases, absence of PN capture was achieved only once the balloon was directly over the ablation catheter. In 3 atrial tachycardia patients, PN displacement was not possible with a balloon; however, a steerable sheath/catheter combination was ultimately successful. PN displacement allowed acute abolishment of all targeted arrhythmias. No PN injury occurred acutely or in follow up. Two patients developed acute complications (pleuro-pericardial fistula 1 and pericardial bleeding 1). Survival free of target arrhythmia was achieved in all atrial tachycardia patients; however, a nontargeted ventricular tachycardia recurred in 1 patient at a median of 13 months' follow up.

CONCLUSIONS

Arrhythmias originating in close proximity to the PN can be targeted successfully with PN displacement with an epicardially placed steerable sheath/catheter combination, or balloon, but this strategy can be difficult to implement. Better tools for phrenic nerve protection are desirable.