Journal of Nippon Medical School: Vol.66 No.6 page.388

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ArticleTitle QT dispersion in premature beats produced by extrastimuli from the right atrium and right ventricle

AuthorList Gui Shu Jin, Norishige Morita, Hirotsugu Atarashi, Yasumi Endoh, Yoshinori Kobayashi, Hirokazu Saitoh, Hiroshi Kishida and Hirokazu Hayakawa

Affiliation First Department of Internal Madicine, Nippon Medical School

Language JA

Volume 66

Issue 6

Year 1999

Page 388-394

Received August 9,1999

Accepted October 4,1999

Keywords QT interval, QT dispersion, premature beats, activation time,12-lead electrocardiogram

Abstract The difference between the maximum and minimum QT interval measured from a12-lead electrocardiogram was defined as an index of spatial inhomogeneous repolarization of the ventricular myocardium. The causal relationship between QT dispersion and incidence of ventricular arrhythmias has been pointed out in various heart diseases, but until now it was discussed mainly related to sinus rhythm. QT dispersion in extrasystole may be more important in the development of arrhythmias. We examined5cases (mean age34 ｱ 12years) with a history of paroxysmal supraventricular tachycardia, who underwent electrophysiologic study. Both atrial and ventricular premature stimuli were given at a basic cycle length of600msec respectively. The QT interval and the ventricular activation time(VAT)(period from premature test stimulus to the summit of QRS)of the premature beats were measured in a simultaneously recorded12-lead electrocardiogram. QT dispersion(the difference between the longest QT interval and the shortest QT interval)and VAT dispersion(the difference between the longest VAT and the shortest VAT)were measured. In atrial premature beats, there were no significant changes in the QT dispersion or VAT dispersion when the coupling interval of the premature beats was shortend. In the ventricular premature beats, however, both the QT dispersion and the VAT dispersion tended to incerase with the shortening of the coupling interval. We concluded that only a short coupled ventricular premature beat induces greater QT and VAT dispersion. A ventricular couplet with short coupling interval may contribute to the development of ventricular tachyarrhythmias.

Correspondence to Hirotsugu Atarashi, MD, First Department of Internal Medicine, Nippon Medical School,1-1-5Sendagi, Bunkyo-ku, Tokyo113-8603, Japan

ArticleTitle	QT dispersion in premature beats produced by extrastimuli from the right atrium and right ventricle
AuthorList	Gui Shu Jin, Norishige Morita, Hirotsugu Atarashi, Yasumi Endoh, Yoshinori Kobayashi, Hirokazu Saitoh, Hiroshi Kishida and Hirokazu Hayakawa
Affiliation	First Department of Internal Madicine, Nippon Medical School
Language	JA
Volume	66
Issue	6
Year	1999
Page	388-394
Received	August 9,1999
Accepted	October 4,1999
Keywords	QT interval, QT dispersion, premature beats, activation time,12-lead electrocardiogram
Abstract	The difference between the maximum and minimum QT interval measured from a12-lead electrocardiogram was defined as an index of spatial inhomogeneous repolarization of the ventricular myocardium. The causal relationship between QT dispersion and incidence of ventricular arrhythmias has been pointed out in various heart diseases, but until now it was discussed mainly related to sinus rhythm. QT dispersion in extrasystole may be more important in the development of arrhythmias. We examined5cases (mean age34 ｱ 12years) with a history of paroxysmal supraventricular tachycardia, who underwent electrophysiologic study. Both atrial and ventricular premature stimuli were given at a basic cycle length of600msec respectively. The QT interval and the ventricular activation time(VAT)(period from premature test stimulus to the summit of QRS)of the premature beats were measured in a simultaneously recorded12-lead electrocardiogram. QT dispersion(the difference between the longest QT interval and the shortest QT interval)and VAT dispersion(the difference between the longest VAT and the shortest VAT)were measured. In atrial premature beats, there were no significant changes in the QT dispersion or VAT dispersion when the coupling interval of the premature beats was shortend. In the ventricular premature beats, however, both the QT dispersion and the VAT dispersion tended to incerase with the shortening of the coupling interval. We concluded that only a short coupled ventricular premature beat induces greater QT and VAT dispersion. A ventricular couplet with short coupling interval may contribute to the development of ventricular tachyarrhythmias.
Correspondence to	Hirotsugu Atarashi, MD, First Department of Internal Medicine, Nippon Medical School,1-1-5Sendagi, Bunkyo-ku, Tokyo113-8603, Japan