AJP - Heart and Circulatory Physiology, Vol 259, Issue 2 457-H463, Copyright © 1990 by American Physiological Society
Relationship between diastolic shape (eccentricity) and passive elastic properties in canine left ventricle
S. D. Nikolic, E. L. Yellin, M. Dahm, O. Pajaro and R. W. Frater
Department of Cardiothoracic Surgery, Albert Einstein College of Medicine, Bronx, New York 10461.
This study was designed to investigate the relationship between left
ventricular (LV) eccentricity, volume, and passive elastic properties.
Eight open-chest fentanyl-anesthetized dogs were instrumented with an LV
micromanometer, a remote-controlled mitral valve occluder, and two pairs of
ultrasonic crystals to measure anterior-posterior and base-apex dimensions.
We identified the presence of elastic recoil forces with negative LV
diastolic pressure in nonfilling diastoles (end-systolic volume clamp).
Using linear regression analysis we related midwall eccentricity to volume
in nonfilling diastoles at the time of LVPmin and at end diastole, and in
normal beats at end systole at LVPmin and at end-diastole. Intersection of
the end-systolic and end-diastolic lines (transitional volume, Vt = 38.0 +
6.4 ml) divides cycles with and without the presence of elastic recoil
forces. Vt is analogous to the equilibrium volume (V0), determined as the
volume intercept of the logarithmic passive pressure-volume (P-V)
relationship using LV volume estimated from LV weights (V0 nl = 37.6 + 4.4
ml), or the volume intercept of the linearized P-V relationship calculated
from a prolate spheroidal model using measured minor and major diameters
(V0 l = 44.5 + 3.5 ml). Linear regression analysis was also used to relate
the square of peak mitral flow (MF2) with the corresponding
atrioventricular pressure gradient (delta P); the slope represents a
dissipative constant for the cycles without, P = 0.00058(MF)2 + 0.35 (n =
48, r = 0.73), and with elastic recoil P = 0.00035(MF)2 + 0.21 (n = 24, r =
0.81).(ABSTRACT TRUNCATED AT 250 WORDS)
