Affordable Access

Alterations in myocardial contractility in conscious dogs with dilated cardiomyopathy.

Authors
  • Shannon, R P
  • Komamura, K
  • Stambler, B S
  • Bigaud, M
  • Manders, W T
  • Vatner, S F
Type
Published Article
Journal
The American journal of physiology
Publication Date
Jun 01, 1991
Volume
260
Issue
6 Pt 2
Identifiers
PMID: 2058725
Source
Medline
License
Unknown

Abstract

We investigated the changes in left ventricular (LV) geometry and myocardial contractility in eight conscious chronically instrumented dogs studied before and after the development of dilated cardiomyopathy induced by rapid ventricular pacing. Significant increases (P less than 0.01) were observed in cardiac dimensions in both the LV long and short axes and in end-diastolic volume (control: 53 +/- 1 ml; cardiomyopathy: 76 +/- 2 ml) and end-systolic volume (control: 27 +/- 2 ml; cardiomyopathy: 56 +/- 7 ml). This was associated with the left ventricle assuming a more spherical shape with LV long-to-short axis ratio falling from 1.59 +/- 0.05 to 1.47 +/- 0.04 (P less than 0.05). Both isovolumic (LV dP/dt) and ejection phase indexes (LV mean velocity of circumferential fiber shortening, corrected LV short-axis diameter at point of maximum shortening, and LV ejection fraction) were depressed by 50%. The end-systolic elastance was also depressed significantly (control: 16.6 +/- 0.7 g.cm-2.ml-1; cardiomyopathy: 10.1 +/- 1.7 g.cm-2.ml-1, P less than 0.02). However, cardiac output was maintained at 3 wk due to a compensatory tachycardia (+31 +/- 3 beats/min), plasma volume expansion (+295 +/- 68 ml, P less than 0.05), and greater reliance on the Frank-Starling mechanism. However, in an additional four dogs studied at 4-5 wk, cardiac output fell significantly (P less than 0.05). Thus rapid ventricular pacing results in dilated congestive cardiomyopathy in conscious dogs characterized by globally depressed myocardial systolic function and changes in LV shape.

Report this publication

Statistics

Seen <100 times