Epicardial Approach to Catheter Ablation of Ventricular Tachycardia

The ability to map the epicardial surface of the heart has led to significant advances in our understanding of arrhythmogenic substrates associated with disease-specific etiologies. Access to the pericardial space can be obtained via a percutaneous subxiphoid approach, akin to pericardiocentesis in the vast majority of patients without prior cardiac surgery. In cases where adhesions are anticipated, limited surgical approaches can be used in the electrophysiology laboratory to gain access to the epicardium. Patients with ventricular tachycardia (VT) in settings such as arrhythmogenic right ventricular cardiomyopathy (ARVC), idiopathic dilated cardiomyopathy, and prior myocarditis typically have more epicardial scar than endocardial scar, whereas postmyocardial infarction scar is typically most predominant on the endocardial surface. Because of the complex 3-dimensional nature of VT circuits and nontransmural nature of current ablation technologies, two-sided ablation approaches have been shown to improve freedom from recurrent VT across all scar-related VT substrates. Patients with prior unsuccessful ablation from an endocardial approach typically have higher probability of successful ablation when targeting an epicardial substrate. Knowledge of pericardial anatomy and attention to adjacent structures such as the phrenic nerve, coronaries arteries, and epicardial fat is critically important when implementing an epicardial approach.