Assessment of right ventricular diastolic suction in dogs with the use of wave intensity analysis.
Diastolic suction (DS) can be defined as that property of the ventricle by means of which it tends to refill itself during early diastole, independent of any force from the atrium. Although thought to be significant in the left ventricle (LV), DS in the right ventricle (RV) has received little attention, probably because of RV geometry. Our recent LV studies have shown that DS is related to both decreased elastance (i.e., tau, the relaxation time constant) and end-systolic volume (V(LVES)), thus reconciling the two mechanisms that have been used to explain the concept of DS. We hypothesized that RV DS would similarly depend on tau and V(RVES). In six anesthetized open-chest dogs, aortic, RV, right atrial (RA), pulmonary arterial (PA), and RV pericardial pressure, tricuspid velocity, and PA flow were measured. V(RVES) was calculated by measuring distances between eight ultrasonic crystals. An empirical index of relaxation, tau', and V(RVES) were manipulated by volume loading/caval constriction and isoproterenol/esmolol. We calculated the total energy (I(W-)) of the backward expansion wave generated during RV relaxation and that component causing DS [I(W-(DS))]; i.e., the energy remaining after tricuspid valve opening. I(W-) [I(W-(DS)) also] was found to be inversely related to tau' and to V(RVES) {i.e., I(W-) = -8.85.e((-0.0423tau')).e([-0.0665(%V(RVES))])}. Thus, as for the LV, the energy of the backward-going wave generated by the RV during relaxation depends on both the rate at which elastance decreases and the completeness of ejection. Despite the thin wall and nonspherical shape of the RV, DS appears to be an important mechanism.
Sun
Yichun
Y
Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
Belenkie
Israel
I
Wang
Jiun-Jr
JJ
Tyberg
John V
JV
D000818:Animals; D001775:Blood Circulation / Q000502:physiology; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology*; D002316:Cardiotonic Agents / Q000494:pharmacology; D004285:Dogs; D015150:Echocardiography, Doppler / Q000379:methods*; D004548:Elasticity; D004734:Energy Metabolism; D007545:Isoproterenol / Q000494:pharmacology; D008962:Models, Theoretical; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology; D014261:Tricuspid Valve / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology*
D002316:Cardiotonic Agents; D007545:Isoproterenol