Conquest of Ventricular Tachycardia: Insights Into Mechanisms, Innovations in Management: Contribution of Mark E. Josephson, MD, to Clinical Electrophysiology.

Abstract

### Mohammad Shenasa, MD Cardiac mapping has always been an integral part of basic and clinical electrophysiology. Indeed, direct cardiac mapping with recording of local electrograms has been used since the early 19th century, well before intracardiac catheter mapping.1,2 Walter H. Gaskell measured cardiac contraction to investigate the sequence of cardiac activation.1 Thomas Lewis used direct electrogram mapping in a dog model with atrial and ventricular arrhythmias (Figure 1).2 Intraoperative direct epicardial and endocardial mapping was later reported in patients with preexcitation syndromes and conduction disturbances, initially by the Amsterdam group3; however, systematic use of endocardial and epicardial mapping for ventricular tachycardia (VT) was pioneered by Josephson and colleagues at the University of Pennsylvania, although epicardial mapping was reported earlier by Fontaine et al.4–8 These reports greatly improved our understanding of pathophysiology and mechanisms of VT initially in patients with coronary artery disease and previous myocardial infarction. Intraoperative endocardial mapping revealed that reentry circuits were often localized on the endocardial surface or subendocardially and that resection of those regions eliminated the substrate of VT.9,10 These intraoperative studies led directly to the techniques we use in catheter ablation of VT today and has been applied to other VT substrates. Figure 1. Thomas Lewis’s activation map for direct electrogram recording in a dog heart.2 DBL indicates descending branch of left (coronary artery); DBR, descending branch of right (coronary artery); IVC, inferior vena cava; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; and SVC, superior vena cava. In modern interventional electrophysiology, cardiac mapping and imaging are integrated, and this merging is critical for success in complex ablation procedures. However, electrogram mapping remains an essential part of physiological understanding of the mechanism(s) of VT. The Penn group has set standards for …