AJP - Heart and Circulatory Physiology, Vol 248, Issue 1 132-H142, Copyright © 1985 by American Physiological Society
Aortic bulb-aortic orifice hemodynamics in left ventricle-systemic arterial interaction
K. B. Campbell, J. A. Ringo, P. A. Klavano, J. D. Robinette and J. E. Alexander
Experiments were conducted in open-chest dogs in which ascending aortic
blood flow (Q) was measured with an electromagnetic flow probe, and
pressure was measured in the left ventricle (LV) and ascending aorta. The
aorta just distal to the flow probe was occluded suddenly, causing the
aortic bulb (AB) to be the only part of the arterial system to be in
communication with the LV during clamped beats. Pressure and flow data from
preocclusion, occlusion, and occlusion-release periods were analyzed to
assess AB compliance (CAB) and the longitudinal impedance properties of
inertance (LVO) and resistance (RVO) in the AB-aortic orifice region. In
five dogs (avg wt 24.2 kg), the mean and range of values were as follows:
CAB = 45 (31-55) X 10(-4) cm5/dyn; LVO = 1.86 (0.76-2.88) dyn X s2 X cm-5,
RVO = 4.07 (0.66-8.55) dyn X s X cm-5. The volume-accommodating actions of
CAB caused actual LV outflow to be characteristically different from Q and
aortic-clamped beats to be nonisovolumic. Actions of the AB were found to
be important in the estimation of arterial characteristic impedance as a
component of LV afterload and in the estimation of the LV pump properties
of time-varying elastance and internal resistance.
