Myocardial relaxation in the regionally stunned left ventricle.
Leite-Moreira, Adelino F., and Thierry C. Gillebert.
Department of Physiology and Medicine, University of Antwerpen,
B2020 Antwerpen, Belgium
APStracts 2:0341H, 1995.
Myocardial Relaxation in the Stunned Left Ventricle Load regulation of
pressure fall was analyzed in regionally stunned left ventricles (LV)
of anesthetized dogs. Stunning delayed and slowed pressure fall. When
partial aortic occlusions elevated systolic pressure by 12.5+/-0.4
mmHg, the rate of pressure fall remained unchanged at baseline but
slowed after stunning. This different response after stunning could
be attributed entirely to decreased contractility and decreased
development of peak isovolumetric pressure. Total aortic occlusions
were then performed at various timings during ejection. With early
occlusions and isovolumetric heart beats, systolic pressure was lower
after stunning, but pressure fall slowed to the same extent. With mid
occlusions the stunned LV developed relatively more systolic pressure
and pressure fall slowed more. This suggested a delayed transition
from contraction to relaxation. With late occlusions pressure fall
did not slow as with earlier occlusions, but initial pressure fall
accelerated both at baseline and after stunning. The data suggested
that load dependence was preserved with stunning and that, even if
myocardial inactivation might be delayed, this delay did not
contribute to the observed slowing of pressure fall.
Received 7 April 1995; accepted in final form 3 August 1995.
APS Manuscript Number H339-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 August 1995.