Therapy available for the treatment of heart rhythm disorders continues to go through significant evolution. Although previously limited to pharmacologic therapy, the transformation and adaptation of surgical procedures to a minimally invasive catheter-based approach and subsequent hybridization of the approach have led to new possibilities in arrhythmia management. A fundamental understanding of the invasive diagnostic and therapeutic strategy for treating heart rhythm disorders is critical to surgical specialties exposed to these rhythm disorders.
The recording of intracardiac signals through electrodes, and subsequent stimulation of the cardiac tissue, allowed for the concept of ablation. In 1967, Durrer and associates described reproducible initiation and termination of tachycardia in a patient with atrioventricular re-entrant tachycardia (AVRT) using a bypass tract.1 In 1969, the His bundle was first reproducibly recorded using a transvenous electrode catheter.2 The continued advancements allowing localization of intracardiac signals led to the study of a variety of tachyarrhythmias.
The idea emerged that critical regions of cardiac tissue were necessary for the initiation and propagation of tachyarrhythmias. If these regions could be interrupted, the tachyarrhythmia could then be cured. Once catheter mapping could localize arrhythmogenic foci, surgical excision was contemplated. In 1968, a description of such a surgical procedure for the elimination of an accessory pathway was first published.3 This heralded an era of nonpharmacologic treatment of tachyarrhythmias.
A variety of arrhythmogenic foci and circuits were successfully mapped and ablated using surgical techniques in the 1970s. Resection of an atrial focus felt to be responsible for an atrial tachycardia was reported in 1973.4 Identification of re-entry circuits within the atrioventricular (AV) node allowed surgical dissection to treat AV nodal re-entrant tachycardia (AVNRT) without causing complete heart block.5 Although surgical ablation was therapeutic for a variety of tachyarrhythmias, the morbidity and mortality associated with thoracotomy and open-heart surgery limited its widespread application. Because most supraventricular tachycardias (SVTs) are not life threatening, the risk of the procedure was hard to justify. Rather, ablation procedures were an option of last resort in highly symptomatic patients refractory to medical therapy.
In attempts to minimize the morbidity associated with ablation, a method of using a catheter to delivery energy to achieve local cardiac injury was sought. In 1981, Scheinman and colleagues reported the first catheter-based ablation procedure, describing the ablation of the His bundle in dogs.6 This same group performed the first closed-chest ablation procedure in a human. A patient with atrial fibrillation and rate control refractory to medical therapy, under general anesthesia, had a catheter advanced to the His bundle region. Using a standard external direct-current (DC) defibrillator, they attached one of the defibrillator pads to the intracardiac catheter and used the second defibrillator pad as a cutaneous grounding pad. A series of DC shocks was delivered between the two pads and complete heart block, and thereby rate control, was achieved.7...