Journal of Nippon Medical School: Vol.69 No.6 page.525

Journal of Nippon Medical School

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ArticleTitle Clinical Significance of Wide QRS Complexes at the Termination of Paroxysmal Supraventricular Tachycardias

AuthorList Yasumi Endoh, Hirotsugu Atarashi, Hirokazu Hayakawa, Kouichi Nagasawa, Hiroshi Kishida and Teruo Takano

Affiliation First Department of Internal Medicine, Nippon Medical School

Language EN

Volume 69

Issue 6

Year 2002

Page 525-533

Received February 5, 2002

Accepted May 24, 2002

Keywords paroxysmal supraventricular tachycardia, wide QRS complex, vagal tone, antiarrhythmic drug, ventricular premature contraction

Abstract
Background: A wide QRS complex is not a rare electrocardiographic phenomenon at the termination of paroxysmal supraventricular tachycardia (PSVT), but no plausible underlying mechanism has yet been proposed. The purpose of the present study was to elucidate the frequency and the underlying mechanism of the wide QRS complexes at the termination of PSVT.
Methods: We retrospectively reviewed 305 electrocardiograms (ECGs) from 100 patients, on which PSVT termination was recorded. The frequency of the wide QRS complexes was analyzed in 181 ECGs to avoid duplication, because there were 124 ECGs obtained from the same patients with same methods. The 181 ECGs were divided by morphology into three groups: Type A, termination with wide QRS complex without pause; Type B, wide QRS complex following initial pause after termination; Type C, wide QRS complex following the first narrow QRS after termination.
Results: The wide QRS complex was recorded in 81/181 (44.8%) ECGs (Type A; 3/81 (3.7%), Type B; 44/81 (54.3%), Type C; 62/81 (55.6%) ) and its frequency was not dependent on the mechanism of PSVT. It was more frequently observed after a long pause, and was frequently induced by procedures that increase vagal tone, such as intravenous adenosine 5'-triphosphate administration (16/22: 72.7%) and vagal stimulation maneuvers (16/32: 50%). There were a total of 41 wide QRS complexes (44.6%) which had a preceding sinus P wave, out of a total of 92 wide QRS complexes in all three types. These 41 wide QRS complexes included 30/44 (68.2%) Type B wide QRS, and 11 (24.4%) Type C wide QRS complexes. Conclusion. The aberrant conduction or escaped ventricular contraction was suggested to be the underlying mechanism of the majority of wide QRS complexes and ventricular premature contraction is less frequent.

Correspondence to Yasumi Endoh, MD, First Department of Internal Medicine, Tama-Nagayama Hospital, Nippon Medical School, 1-7-1 Nagayama, Tama-shi, Tokyo 206-8512, Japan

ArticleTitle	Clinical Significance of Wide QRS Complexes at the Termination of Paroxysmal Supraventricular Tachycardias
AuthorList	Yasumi Endoh, Hirotsugu Atarashi, Hirokazu Hayakawa, Kouichi Nagasawa, Hiroshi Kishida and Teruo Takano
Affiliation	First Department of Internal Medicine, Nippon Medical School
Language	EN
Volume	69
Issue	6
Year	2002
Page	525-533
Received	February 5, 2002
Accepted	May 24, 2002
Keywords	paroxysmal supraventricular tachycardia, wide QRS complex, vagal tone, antiarrhythmic drug, ventricular premature contraction
Abstract	Background: A wide QRS complex is not a rare electrocardiographic phenomenon at the termination of paroxysmal supraventricular tachycardia (PSVT), but no plausible underlying mechanism has yet been proposed. The purpose of the present study was to elucidate the frequency and the underlying mechanism of the wide QRS complexes at the termination of PSVT. Methods: We retrospectively reviewed 305 electrocardiograms (ECGs) from 100 patients, on which PSVT termination was recorded. The frequency of the wide QRS complexes was analyzed in 181 ECGs to avoid duplication, because there were 124 ECGs obtained from the same patients with same methods. The 181 ECGs were divided by morphology into three groups: Type A, termination with wide QRS complex without pause; Type B, wide QRS complex following initial pause after termination; Type C, wide QRS complex following the first narrow QRS after termination. Results: The wide QRS complex was recorded in 81/181 (44.8%) ECGs (Type A; 3/81 (3.7%), Type B; 44/81 (54.3%), Type C; 62/81 (55.6%) ) and its frequency was not dependent on the mechanism of PSVT. It was more frequently observed after a long pause, and was frequently induced by procedures that increase vagal tone, such as intravenous adenosine 5'-triphosphate administration (16/22: 72.7%) and vagal stimulation maneuvers (16/32: 50%). There were a total of 41 wide QRS complexes (44.6%) which had a preceding sinus P wave, out of a total of 92 wide QRS complexes in all three types. These 41 wide QRS complexes included 30/44 (68.2%) Type B wide QRS, and 11 (24.4%) Type C wide QRS complexes. Conclusion. The aberrant conduction or escaped ventricular contraction was suggested to be the underlying mechanism of the majority of wide QRS complexes and ventricular premature contraction is less frequent.
Correspondence to	Yasumi Endoh, MD, First Department of Internal Medicine, Tama-Nagayama Hospital, Nippon Medical School, 1-7-1 Nagayama, Tama-shi, Tokyo 206-8512, Japan