title: Usefulness of tissue Doppler imaging for demonstrating altered septal contraction sequence during dual-chamber pacing in obstructive hypertrophic cardiomyopathy.
abstract: Dual-chamber pacing reduces left ventricular (LV) outflow obstruction in patients with obstructive hypertrophic cardiomyopathy (HC), the mechanism of which lies in pacing-induced paradoxic septal motion. This study was conducted to test the hypothesis that tissue Doppler imaging (TDI) could demonstrate changes in the septal contraction sequence during dual-chamber pacing in patients with HC. TDI was performed in 16 patients (5 women; mean age 63+/-11 years) who underwent dual-chamber pacing for 7.6+/-2.1 year. With and without pacing, the time to peak systolic myocardial velocity was measured from the basal, mid, and distal segments in the 4 different LV walls. Without pacing, there was almost no longitudinal segmental asynchrony. During pacing, however, marked longitudinal segmental asynchrony appeared, especially in the anteroseptal wall (from p=NS to p<0.01 by analysis of variance) and the ventricular septum (from p<0.05 to p<0.01), with the time to peak velocity extremely prolonged at the distal segments. This was associated with a modest but significant decrease in the LV pressure gradient (from 20+/-8 to 14+/-7 mm Hg, p<0.01). In patients with obstructive HC, altered septal contraction sequence accounts for the reduced LV outflow obstruction during dual-chamber pacing, which was clearly demonstrated by TDI.
authors.affiliation: The Third Division, Department of Internal Medicine, Osaka Medical College, Takatsuki, Osaka, Japan. in3016@poh.osaka-med.ac.jp
authors.forename: Takahide
authors.initials: T
authors.lastname: Ito
authors.forename: Michihiro
authors.initials: M
authors.lastname: Suwa
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Sakai
authors.forename: Tomomi
authors.initials: T
authors.lastname: Hozumi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kitaura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity / Q000502:physiology; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy; D018450:Disease Progression; D018619:Echocardiography, Doppler, Pulsed; D005260:Female; D005500:Follow-Up Studies; D006346:Heart Septum / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D015588:Observer Variation; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology; D017725:Ventricular Pressure / Q000502:physiology