Status of surgery for ventricular arrhythmias.

IN 1913, MINES' demonstrated that a circulating wave of excitation in a closed ring of myocardial tissue could be interrupted by dividing the ring at some point. He foretold the role of surgery for reentrant rhythms when he stated, ". . . the best test for a circulating excitation is to cut through the ring at one point . . . the vigorous circulating wave and its instantaneous arrest by section of the ring is a sight not easily forgotten."2 The clinical demonstration of this phenomenon came in 1969 when Sealy and co-workers divided an accessory pathway in a patient with WolffParkinson-White syndrome subjected to recurrent reentrant supraventricular tachycardia.3 Interest has continued in devising methods to localize and divide circuits of reentry that underly other reentrant rhythms in man.4 Excluding surgical treatment of the preexcitation syndromes, interest has centered on the potential for surgery to ablate or modify the site of origin of recurrent ventricular arrhythmias. This communication will consider the status of surgical treatment for ventricular arrhythmias. We will consider the mechanisms underlying ventricular arrhythmias, clarify the method used for the localization, and discuss the rationale of surgical approaches based on the mechanism and location of the arrhythmia. Our understanding in each of these areas is incomplete. Judging from animal models, for example, a spectrum of different mechanisms of ventricular arrhythmias may exist, depending on the etiology of the arrhythmia and the stage of the disease process. Although such phenomena as reentry, automaticity and "triggered" activity experimentally appear reasonable to consider as mechanisms, our ability to discriminate between them at the clinical level is limited. Nonetheless, there appears to be a growing tendency, however unjustified, to ascribe tentatively the mechanism of reentry to rhythms that can be initiated and terminated by programmed stimulation. Empirically, this differentiation has value in that it provides 1) a means to assess medical management, 2) a rationale for pacemaker devices, and, most relevant to this discussion, 3) some assurance that the rhythm can be evoked for investigative purposes at the time of surgery. It further appears that programmed stimulation may identify patients in whom surgery is likely to