Major advances have been made in the field of interventional cardiac electrophysiology (EP) over the past three decades. Catheter-based ablation enables minimally invasive therapeutic options in the management of various tachyarrhythmias. Ablation is often guided by EP study and mapping to diagnose the arrhythmia and localize the arrhythmogenic substrate that is to be targeted for ablation. Catheter ablation requires expertise and constitutes a major procedural component, in addition to implantation and management of cardiac electronic devices, within the subspecialty of clinical cardiac electrophysiology. In this chapter, we discuss (1) general technical considerations for catheter ablation, (2) specifics related to ablation of different arrhythmias, and (3) potential complications of ablation.
EP study and catheter ablation are performed in the clinical EP laboratory, yet prior review of the specific arrhythmia and medical background, especially cardiac function and anatomy, is fundamental. General anesthesia facilitates patient comfort and safety during the procedure, which typically require 4 to 8 hours without significant patient motion. Certain arrhythmias are driven in part by sympathetic/catecholaminergic axes and can be rendered noninducible by anesthetic agents. This can preclude identification of the culprit rhythm, and inhaled anesthetic gases, benzodiazepines, and opioids are commonly avoided, while propofol or ketamine are less suppressive of arrhythmia.
Most EP studies and ablation procedures require percutaneous access to the heart with multiple catheters. These catheters contain multiple electrodes for recording intracardiac electrical signals and in addition are capable of electrical stimulation of the myocardium (Fig. 88–1), and are inserted through sheaths placed in the femoral, jugular, or subclavian veins. Mapping of the relevant electrophysiologic substrate is performed by repositioning and recording of the constellation of electrical signals throughout the relevant sections of the heart. Current catheter technology typically provides a soft, deflectable 1- to 5-mm mapping electrode that can be maneuvered throughout the atria, ventricles, coronary sinus, pulmonary veins, and above and below the atrioventricular and semi-lunar valves. Left-sided chambers are accessed with a trans-interatrial septal puncture or femoral arterial access for retroaortic mapping of the left ventricle and/or the sinuses of Valsalva. Epicardial mapping is performed through the coronary vein branches of the coronary sinus, or by direct percutaneous access to the pericardial space from the subxiphoid region (Fig. 88–2).1
Standard intracardiac catheter positioning and recordings for an electrophysiology study and supraventricular tachycardia ablation. A. A right anterior oblique fluoroscopic image of a typical initial catheter setup. Catheters are placed via the femoral vein. There is a quadripolar catheter in the high right atrium (HRA) and in the right ventricular apex (RVA). There is another quadripolar catheter positioned to measure a His bundle (His) electrogram and a decapolar catheter in the coronary sinus (CS). B. Baseline conduction intervals in sinus rhythm with a normal HV interval of 44 ms. Note that atrial activation times with the P wave ...