title: Alterations in left ventricular relaxation, early diastolic filling and passive viscoelastic properties during postpacing ischemia.
abstract: Alterations in left ventricular relaxation, early diastolic filling, regional myocardial dynamics and passive viscoelastic properties during postpacing ischemia were studied in 9 patients with coronary artery disease. In all patients typical anginal pain developed during pacing tachycardia, and in the postpacing beat, left ventricular end-diastolic pressure increased from 14 +/- 4 to 26 +/- 5 mm Hg (mean +/- standard deviation, p less than 0.01), relaxation time constant increased from 44 +/- 9 to 59 +/- 7 ms (p less than 0.01) and ejection fraction diminished from 63.1 +/- 9.1 to 52.8 +/- 10.8% (p less than 0.01). However, peak rate of early left ventricular filling obtained from frame-by-frame analysis of left ventriculograms did not change significantly. The time difference from segmental peak lengthening to left ventricular peak filling increased significantly in the ischemic segment (32 +/- 30 vs 77 +/- 49 ms, p less than 0.05). Chamber stiffness constant of a viscoelastic model increased significantly from 0.0177 +/- 0.01 to 0.0354 +/- 0.015 (p less than 0.01) without change in chamber viscosity constant. In the ischemic segment, peak rate of lengthening decreased by 45% with ischemia, and peak rate of lengthening normalized for the end-diastolic segment length by 36%. However, peak rate of lengthening normalized for the extent of systolic shortening did not change. The control segment showed a tendency to increase in these 3 parameters, but the changes were not statistically significant. Thus, peak rate of segmental myocardial lengthening decreased with ischemia because of a decrease in segmental shortening.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Internal Medicine, Faculty of Medicine, Kyoto University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: S
authors.initials: S
authors.lastname: Sasayama
authors.forename: H
authors.initials: H
authors.lastname: Nonogi
authors.forename: T
authors.initials: T
authors.lastname: Murakami
authors.forename: C
authors.initials: C
authors.lastname: Kawai
mesh_terms: D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000209:etiology / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects; D017023:Coronary Angiography; D003971:Diastole; D004548:Elasticity; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction