QRS supraventricular tachycardia

To determine the value of alternation of QRS morphology in determining the site of origin of sustained narrow QRS supraventricular tachycardia (SVT), we retrospectively studied 163 distinct tachycardias in 161 patients (ages 4 to 91 years) in whom the site of origin of SVT was proven by intracardiac electrophysiologic study. Sustained SVT was defined as lasting longer than 30 sec. Narrow QRS was defined as QRS width less than 0.12 sec. Atrial fibrillation and flutter were excluded. The presence or absence of QRS altemation was judged at least 10 sec after initiation of SVT. Circus movement tachycardia with anterograde AV node conduction and a retrograde accessory AV pathway was seen in 89 patients (58 with Wolff-Parkinson-White syndrome, 31 with concealed accessory pathway); intra-AV nodal reentrant tachycardia (AVNT) was present in 57 cases, and 17 tachycardias were atrial in origin. QRS alternation was present in 36 of 163 cases (22%). In only eight of these 36 did RR interval length alternation accompany alternation in QRS morphology. Thirty-three of 36 (92%) tachycardias with QRS alternation were circus movement tachycardias. Two were atrial in origin and one was AVNT. We conclude that the presence of QRS alternation during sustained narrow QRS SVT is highly indicative of a retrograde accessory AV pathway in the tachycardia circuit. Circulation 68, No. 2, 368-373, 1983. ACCURACY in determining the site of origin of supraventricular tachycardia (SVT) with the 12-lead electrocardiogram (ECG) is important for correct treatment of the arrhythmia. Having seen electrical alternans of the QRS complex in patients with SVT, we wondered whether this finding could be of help in determining the site of origin of the tachycardia. Therefore we undertook a study to evaluate the diagnostic value of QRS alternation in patients with sustained SVT and a narrow QRS complex. Patients and methods All electrocardiographic tracings of all patients studied for SVT in Maastricht, The Netherlands, between February 1977 and December 1982 were retrospectively analyzed. In all patients the mechanism and site of origin of sustained narrow QRS tachycardia had been ascertained by an intracardiac electrophysiologic study, which included programmed electrical stimulation of the heart. Sustained tachycardia was defined as lastFrom the Department of Cardiology, University of Limburg, Maastricht, The Netherlands. Supported by the Deutsche Forschungsgemeinschaft (M. W.). Address for correspondence: Hein J. J. Wellens, M.D., Department of Cardiology, University of Limburg, Maastricht, The Netherlands. Received March 15, 1983; accepted April 21, 1983. Dr. Green was a Fellow of the Medical Research of Canada during the performance of this work. Dr. Abdollah is a Research Fellow of the Ontario Heart Foundation. *Present address: Division of Cardiology, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada. 368 ing longer than 30 sec, and narrow QRS was defined as a QRS width of less than 0.12 sec. Atrial fibrillation and atrial flutter were excluded. Our methods of stimulation, recording, and analysis of tracings have been previously described. ' The site of origin (intra-AV nodal reentrant tachycardia, atrial tachycardia, or orthodromic circus movement tachycardia with anterograde AV node conduction and a retrograde accessory atrioventricular pathway) was determined according to previously defined criteria.2 A total of 161 patients met the entry criteria and were included in the study population. There were 71 women and 90 men (mean age 39 years). Two patients had more than one type of tachycardia and as a result there are 163 cases of tachycardia included in the study. One patient had two accessory AV pathways, and the tachycardia with the right-sided retrograde accessory pathway was considered separately from that with the retrograde left-sided pathway. One patient had a tachycardia with a concealed accessory pathway and an atrial tachycardia, and both had been documented clinically. Data on patients and their tachycardias are summarized in table 1. There were 89 circus movement tachycardias, incorporating a retrograde accessory AV pathway and the AV node in the anterograde direction. Fifty-eight patients had Wolff-Parkinson-White syndrome and 31 had a concealed accessory pathway. Reentry within the AV node was present in 57 cases, and the remaining 17 tachycardias were atrial in origin. All available leads in all recorded episodes of tachycardia were examined by the same observer for the presence or absence of QRS alternation. To avoid confusion by changes in QRS morphology seen at the initiation of tachycardia, QRS alternation was judged to be present only if it persisted for at least 10 sec and occurred at least 10 sec after the initiation of tachycardia. CIRCULATION by gest on N ovem er 2, 2017 http://ciajournals.org/ D ow nladed from DIAGNOSTIC METHODS-ELECTROCARDIOGRAPHY TABLE 1 Data on the patients and their tachycardias Age (yr) Cycle length (msec) Range Mean+ 1SD Range Mean+ 1SD CMT (n = 89) 4-70 34.2± 14.2 230-510 342±63.5 AVNT (n = 57) 23-91 48.2 ± 14.8 260-480 336 ± 62.5 AT (n = 17) 5-73 36.5±25.7 310-490 381+50.9 Total (n 163) 4-91 38.9 17.4 230-510 350 ± 63.0 CMT = orthodromic circus movement tachycardia (retrograde accessory pathway); AVNT = intra-AV nodal reentrant tachycardia; AT = atrial tachycardia. The groups were compared for continuous and discrete variables by Student's t tests for unpaired data and chi-square tests, respectively.