Electrocardiographic and Electrophysiological Characteristics of Idiopathic Ventricular Arrhythmias Ablated Through Percutaneous Trans-Pericardial Approach

BackgroundIdiopathic epicardial ventricular arrhythmias (VAs) are clustered in the areas of the summit and crux.ObjectiveTo report a group of idiopathic epicardial VAs remote from the summit and crux areas.MethodsIn total, 9 patients (6 males, mean age 32{plus minus}13 years) were enrolled. The locations were identified by epicardial mapping and ablation. The electrocardiographic and electrophysiological characteristics were compared to those of 9 patients who had VAs ablated at the opposite endocardial site.ResultsVAs were identified at the epicardium, with 4 patients had VAs located at the inferior wall, one at the anterior wall, one at the apex and 3 patients had VAs at the lateral wall. A QS type at the location-related leads was the only identified surface electrocardiogram indication suggesting epicardial origin (compared to that of the controls, 100% vs 0%, p<0.001). Endocardial and epicardial mapping revealed pre-maturities of -11{plus minus}4 ms and -25{plus minus}8 ms, respectively (VS. -28{plus minus}8 ms revealed by endocardial mapping in control patients, p<0.001 and p=0.389, respectively). All of the study cases demonstrated an rS pattern in the endocardial unipolar electrogram. Acute and long-term successful ablation (a median of 11 months of follow-up) was achieved in all patients without complications.ConclusionA distinct group of idiopathic VAs remote from the summit and crux areas warranting ablation by a subxiphoid approach were identified. Morphological ECG features of a QS type among the location-related grouped leads combined with the mapping findings helped in the identification of the epicardial site of origin.