New mechanoenergetic evaluation of left ventricular contractility in in situ rat hearts.
We recorded a series of ejecting left ventricular (LV) pressure (P)-volume (V) loops of in situ rat hearts during a gradual ascending aortic occlusion. The end-systolic (ES) P-V relationship (ESPVR) was upward convex curvilinear regardless of LV contractility. The ESPVR was shifted upward in an enhanced contractility by dobutamine and downward in a depressed contractility by propranolol; ESP at a midrange V of 0.1 ml/g LV on each ESPVR increased from 131 +/- 11 to 192 +/- 17 mmHg and decreased from 136 +/- 10 to 110 +/- 7 mmHg, respectively. Furthermore, we obtained an upward concave curvilinear pressure-volume area (PVA; a measure of total mechanical energy)-V (preload) relationship to assess LV work capability in each contractility. This relationship also shifted upward in enhanced contractility and downward in depressed contractility; the PVA at midrange V increased from 7.9 +/- 1.2 to 12.3 +/- 1.5 mmHg. ml.beat-1.g-1 and decreased from 8.2 +/- 0.9 to 6.4 +/- 0.8 mmHg.ml.beat-1.g-1. We conclude that the heights of the ESPVR and PVA-V relationship curves can evaluate LV contractility mechanoenergetically.
Tachibana
H
H
Department of Physiology II, Okayama University Medical School, Japan.
Takaki
M
M
Lee
S
S
Ito
H
H
Yamaguchi
H
H
Suga
H
H
D000818:Animals; D001018:Aortic Diseases / Q000503:physiopathology; D002316:Cardiotonic Agents / Q000494:pharmacology; D003251:Constriction, Pathologic; D004280:Dobutamine / Q000494:pharmacology; D004734:Energy Metabolism; D006321:Heart / Q000187:drug effects / Q000503:physiopathology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D011312:Pressure; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013318:Stroke Volume / Q000187:drug effects; D013599:Systole; D016277:Ventricular Function, Left
D002316:Cardiotonic Agents; D004280:Dobutamine; D011433:Propranolol