Interventional therapies for the treatment of heart rhythm disorders have rapidly evolved over the past three decades, and continue to go through significant evolution. Though management options for cardiac arrhythmias were previously limited to pharmacologic therapy, the transformation and adaptation of surgical procedures to less invasive catheter-based approaches have led to a new paradigm in arrhythmia management. A fundamental understanding of diagnostic and therapeutic strategies 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 concept emerged that critical regions of cardiac tissue were necessary for the initiation and propagation of tachyarrhythmias, and that if these regions could be interrupted, the tachyarrhythmia could be cured. Once catheter-based mapping strategies were developed to localize arrhythmogenic foci, surgical excision was contemplated. In 1968, a description of such a surgical procedure for the elimination of an accessory pathway (AP) 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 reentry 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 limited its routine adoption. Surgical ablation was therefore limited to highly symptomatic patients refractory to medical therapy.
In order to minimize the morbidity associated with surgical ablation, a method of using a transvenous catheter for the delivery of energy directly to cardiac tissue 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; in a patient with atrial fibrillation (AF) and rate control refractory to medical therapy, a transvenous catheter was 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 ...