TY - JOUR
T1 - Origin of regional pressure gradients in the left ventricle during early diastole
AU - Nikolic, S. D.
AU - Feneley, M. P.
AU - Pajaro, O. E.
AU - Rankin, J. S.
AU - Yellin, E. L.
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1995
Y1 - 1995
N2 - Left ventricular (LV) pressure (P)-diameter, LVP-area, or LVP-volume relationships used to evaluate LV diastolic function assume uniform LV wall motion and constant LVP. Contrary to these assumptions, there are significant differences in ventricular dynamic geometry and in LV pressures measured simultaneously in different parts of the LV, particularly during early diastole. We instrumented six anesthetized open-chest dogs with three pairs of orthogonal ultrasonic crystals (anterior-posterior and septal-free wall minor axes, and base-apex major axis) and two micromanometers (in the apex and in the LV base). The mitral valve occluder was implanted during standard cardiopulmonary bypass in the mitral annulus. Data were recorded during 11 transient vena caval occlusions. The mitral valve was occluded for 1 beat every 6-8 beats during each vena caval occlusion to produce nonfilling diastole. With the decrease of the LV end-systolic volume (V(es)) below the equilibrium volume V(eq) (volume of the completely relaxed LV at LVP = 0), the minimum negative LVP in nonfilling beats increases, the shape of the ventricle is more ellipsoidal in both filling and nonfilling beats, and the base-to-apex pressure gradient at the time of LVP minimum increases regardless of the presence or absence of filling. Thus heterogeneous myocardial stresses during isovolumic relaxation and early diastole result in ventricular shape changes, intraventricular redistribution of chamber volume, local accelerations of blood, and associated intraventricular LVP gradients. The role of elastic recoil assumes greater importance at V(es) smaller than V(eq), when the left ventricle becomes more ellipsoidal in shape during isovolumic relaxation, leading, in turn, to greater shape changes and greater LVP gradient.
AB - Left ventricular (LV) pressure (P)-diameter, LVP-area, or LVP-volume relationships used to evaluate LV diastolic function assume uniform LV wall motion and constant LVP. Contrary to these assumptions, there are significant differences in ventricular dynamic geometry and in LV pressures measured simultaneously in different parts of the LV, particularly during early diastole. We instrumented six anesthetized open-chest dogs with three pairs of orthogonal ultrasonic crystals (anterior-posterior and septal-free wall minor axes, and base-apex major axis) and two micromanometers (in the apex and in the LV base). The mitral valve occluder was implanted during standard cardiopulmonary bypass in the mitral annulus. Data were recorded during 11 transient vena caval occlusions. The mitral valve was occluded for 1 beat every 6-8 beats during each vena caval occlusion to produce nonfilling diastole. With the decrease of the LV end-systolic volume (V(es)) below the equilibrium volume V(eq) (volume of the completely relaxed LV at LVP = 0), the minimum negative LVP in nonfilling beats increases, the shape of the ventricle is more ellipsoidal in both filling and nonfilling beats, and the base-to-apex pressure gradient at the time of LVP minimum increases regardless of the presence or absence of filling. Thus heterogeneous myocardial stresses during isovolumic relaxation and early diastole result in ventricular shape changes, intraventricular redistribution of chamber volume, local accelerations of blood, and associated intraventricular LVP gradients. The role of elastic recoil assumes greater importance at V(es) smaller than V(eq), when the left ventricle becomes more ellipsoidal in shape during isovolumic relaxation, leading, in turn, to greater shape changes and greater LVP gradient.
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U2 - 10.1152/ajpheart.1995.268.2.h550
DO - 10.1152/ajpheart.1995.268.2.h550
M3 - Article
C2 - 7864179
AN - SCOPUS:0028963523
SN - 0363-6135
VL - 268
SP - H550-H557
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 2 37-2
ER -