Epicardial Interventions in Electrophysiology

The utility of the pericardial space in the electrophysiology laboratory for mapping and ablation was not appreciated by cardiac electrophysiologists until percutaneous access to the epicardial space for catheter ablation of ventricular tachycardia (VT) was first described by Sosa and colleagues in patients with Chagasic cardiomyopathy in 1997.1 Long regarded as an area accessed only if procedural complications developed, the epicardial space has now become the new frontier in expanding the role of cardiac catheter ablation and therapeutics.2,3 For many years patients with arrhythmias (which could not be ablated endocardially) were treated with an open surgical approach, reminiscent of the first bypass tract surgical resection in a Wolff-Parkinson-White patient in 1969.4,5 The focus of this article is to review the development of epicardial interventions in electrophysiology in the past decade and a half and to provide an update on the current status and future prospects in this field. The anatomy of the epicardial space is discussed initially, because this provides a basis for a review of the relevant imaging aspects. The technique of accessing the space, initially developed for drainage of pericardial effusions by pericardiocentesis and subsequently modified for accessing a normal pericardial space, will also be outlined. We will also discuss mapping and ablation of arrhythmias from the epicardial surface of the heart. The majority of epicardial clinical studies have involved ventricular arrhythmias, with only small series or case reports for supraventricular arrhythmias. The most recent European Heart Rhythm Association/ Heart Rhythm Society consensus document reported that the epicardial space was accessed in 17% of VT ablation procedures, based on a survey of VT tertiary referral centers.6 A recent multicenter study from tertiary referral centers found an overall epicardial access rate of 19% for patients undergoing VT ablation procedures.7 This …