title: Acute effect of percutaneous transluminal mitral commissurotomy on QT interval: possible role of afterload in contraction-excitation feedback.
abstract: Percutaneous balloon valvuloplasty for pulmonary or aortic stenosis results in QT prolongation, a finding supporting the presence of contraction-excitation feedback in man. Though afterload reduction alters the QT interval, the effect of changes in preload on ventricular repolarization is yet unknown. To test whether diastolic stretch modified ventricular repolarization, the change in the QT interval was determined in 15 patients who underwent percutaneous transluminal mitral commissurotomy (PTMC) for mitral stenosis. After successful PTMC, the QT interval was prolonged in five, shortened in two, and was unchanged in eight patients, but the mean QT interval in 15 patients did not change (406 +/- 31 msec versus 412 +/- 40 msec, p = NS). However, linear regression analysis revealed a strong correlation between changes in the QT interval and those in systemic vascular resistance (r = -0.83, p less than 0.01). These data indicated that changes in the QT interval after PTMC were small compared with those seen with valvuloplasty for pulmonary or aortic stenosis, and were dependent on afterload but not on preload.
authors.affiliation: Second Department of Internal Medicine, Tokyo University Hospital, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamashita
authors.forename: H
authors.initials: H
authors.lastname: Inoue
authors.forename: M
authors.initials: M
authors.lastname: Usui
authors.forename: T
authors.initials: T
authors.lastname: Kuo
authors.forename: S
authors.initials: S
authors.lastname: Saihara
authors.forename: A
authors.initials: A
authors.lastname: Nozaki
authors.forename: S
authors.initials: S
authors.lastname: Momomura
authors.forename: T
authors.initials: T
authors.lastname: Serizawa
authors.forename: M
authors.initials: M
authors.lastname: Iizuka
authors.forename: T
authors.initials: T
authors.lastname: Sugimoto
mesh_terms: D000328:Adult; D000368:Aged; D002404:Catheterization; D004562:Electrocardiography; D005246:Feedback; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008946:Mitral Valve Stenosis / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D009200:Myocardial Contraction; D013997:Time Factors