PATHOPHYSIOLOGY AND NATURAL HISTORY PREEXCITATION Preexcited reciprocating tachycardia in patients with Wolff-Parkinson-White syndrome: incidence and mechanisms

During the electrophysiologic study of 435 patients referred for evaluation of WolffParkinson-White syndrome, 42 (10%) had preexcited reciprocating tachycardia (defined as a macroreentrant tachycardia that used an accessory atrioventricular [AV] pathway for antegrade conduction). The ages of the patients ranged from 9 to 67 years (27 + 14). Thirty-three were male patients, nine female, and eight had Ebstein's anomaly. Preexcited reciprocating tachycardia cycle length was 220 to 430 msec (294 ± 42). Significant hemodynamic compromise in the laboratory directly related to preexcitated reciprocating tachycardia occurred in only one patient. However, in 10 patients a transformation to atrial fibrillation was seen after a spontaneously occurring premature atrial contraction. Only 17 of the 42 patients with preexcited reciprocating tachycardia during electrophysiologic study had the same tachycardia documented clinically. These 17 patients were more often younger with multiple accessory pathways and with no history of orthodromic reciprocating tachycardia when compared with 25 patients in whom preexcited reciprocating tachycardia could be induced only in the laboratory. Preexcited reciprocating tachycardia was induced in the laboratory in 22 of 374 (6%) patients with single accessory pathways and in 20 of 61 (33%) of those with multiple accessory pathways. In the 20 patients with multiple accessory pathways, the spectrum of reentrant circuits included fusion over two or more accessory pathways or fusion over both an accessory pathway and the AV node. In the 22 patients with a single accessory pathway and true antidromic reciprocating tachycardia, all but two episodes were at least 4 cm from the AV node. No patient with true antidromic reciprocating tachycardia had a posterior septal accessory AV pathway. Only in patients with multiple accessory pathways was the posterior septal accessory AV pathway used as the antegrade limb. Circulation 70, No. 3, 377-391, 1984. ORTHODROMIC reciprocating tachycardia and atrial fibrillation are the predominant clinical arrhythmias in patients with Wolff-Parkinson-White syndrome (WPW).' The mechanisms by which they arise have been studied extensively. Antidromic reciprocating tachycardia, however, has not been as well evaluated as the other tachycardias in patients with WPW. Relatively few reported cases of antidromic reciprocating tachycardia are available for study2'7 and, consequently, less is known about the mechanisms by which it From the Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham. Supported in part by Research grants HL-17670 and HL-15190 from the National Heart, Lung and Blood Institute and by National Research Service Award HL-07101. Address for correspondence: Dr. John J. Gallagher, Heineman Medical Research Center and Sanger Clinic, 1960 Randolph Rd., Charlotte, NC 28207. Received July 11, 1983; revision accepted May 24, 1984. *Current address: Gust H. Bardy, M.D., University of Washington, Harborview Medical Center, 325 Ninth Ave., Seattle, WA 98104. Vol. 70, No. 3, September 1984 arises, the electrophysiologic substrates necessary for its occurrence, or its clinical significance. The first reported use of the term "antidromic" reciprocating tachycardia was by Fontaines to define a reentrant circuit in which antegrade excitation proceeded over an accessory atrioventricular (AV) pathway while the His bundle/AV node comprised the retrograde limb of the circuit the reverse of orthodromic reciprocating tachycardia. A variant of true antidromic reciprocating tachycardia also has been described in which retrograde conduction occurs over a second accessory pathway rather than the His bundle/AV node.6t' 10, 12, 3 We use the term preexcited reciprocating tachycardia to include both true antidromic reciprocating tachycardia and any reciprocating tachycardia that uses an accessory AV pathway as an antegrade limb of a reentrant circuit. This report reviews our experience with preexcited reciprocating tachycardia in patients with WPW, the circumstances 377 by gest on July 6, 2017 http://ciajournals.org/ D ow nladed from