AJP - Heart and Circulatory Physiology, Vol 253, Issue 2 347-H357, Copyright © 1987 by American Physiological Society
Chronic pressure overload hypertrophy decreases direct ventricular interaction
B. K. Slinker, A. C. Chagas and S. A. Glantz
We studied the relative roles of direct (via the interventricular septum)
and series (via the pulmonary circulation) ventricular interaction in
hearts with concentric left ventricular hypertrophy by using statistical
models to analyze the transient responses in right and left ventricular
pressures and dimensions to occlusions of the venae cava and pulmonary
artery in five open-chest anesthetized dogs. The left ventricles of these
dogs had moderate concentric hypertrophy (31% increase in mass) induced by
3 mo of renovascular hypertension [peak left ventricular pressure = 160 +/-
13 (SD) mmHg]. At end diastole we found that direct interaction was only
about one-tenth as important as series interaction in determining left
ventricular size with the pericardium around the heart. At end systole we
found that direct interaction was about one-fifth as important as the
end-systolic pressure-volume relationship in determining left ventricular
size. Removing the pericardium decreased the importance of direct
interaction. Direct interaction is less important in these hearts than in
normal hearts, probably because the septum is thicker and, hence, less
distensible. This change in the relative importance of direct ventricular
interaction with hypertrophy complicates comparison of pressure-volume
relationships between normal and hypertrophied hearts.
