Significance of the Right Ventricular Free Wall in Dogs with and without Pulmonary Constriction.

Abstract

M., KANAZAWA, M., HANEDA, T. and TAKISHIMA, T. Significance of the Right Ventricular Free Wall in Dogs with and without Pulmonary Constriction. Tohoku J. Exp. Med., 1995, 177 (2), [93][94][95][96][97][98][99][100][101][102][103][104][105][106] To evaluate the role of the right ventricular (RV) free wall in cardiac function, RV and left ventricular (LV) wall segment lengths were measured by ultrasonic crystals in 10 open chest dogs with the pericardium preserved. Right coronary artery (RCA) was perfused separately by own blood and the flow was reduced stepwise until active shortening (aL) of the RV segment disappeared or RCA flow became zero (Ischemia). The experiment was repeated with and without pulmonary stenosis (PS). At Ischemia, RV and LV systolic pressures decreased. RV end-diastolic length increased and RVaL decreased. LV enddiastolic length and LVaL were reduced. LV stroke volume concurrently fell. These changes became more prominant with PS. The critical level of RCA flow, at which RVaL began to change, was higher with PS (5.27±2.85 ml/min, mean± S.D.) than without PS (1.44± 1.16, p <0.01). Based on the relationships between RVaL and percent changes in RV developed pressure and stroke volume, the degree of the decreases in RV developed pressure and stroke volume at RVAL of zero were estimated to be about 20%. These results indicate that the RV free wall partly contributes to maintaining the RV function, especially during RV pressure overload, critical coronary flow; pressure load; right ventricular function; stroke volumeThe significance of the right ventricular free wall in cardiac function has long been questioned. Following a report by Starr et al. (1943), the right ventricular free wall has been thought not to participate in maintaining cardiac function. In contrast, right ventricular infarction sometimes shows a severely depressed state of cardiac function in the clinical settings (Cohn et al. 1974;Coma-Canella et al. 1979;Lorell et al. 1979;Coma-Canella and Lopez-Sendon 1980;Lloyd et al. 1981;Lopez-Sendon et al. 1981). In addition, the right ventricular stroke volume is known to be mainly maintained by bellows action, which consists of the cooperative movements of both the right ventricular free wall and the interventricular septum (Rushmer et al. 1953). Thus, it appears that the right ventricular free wall partly contributes to maintaining right ventricular function. Therefore, the present study was designed to clarify the significance of the right ventricular free wall in cardiac function. We induced a depression of right ventricular free wall function through the stepwise reduction in right coronary artery flow, and examined the changes in cardiac function, especially changes in the right ventricular developed pressure and left ventricular stroke volume in relation to the right ventricular free wall movement, under conditions with and without pulmonary stenosis. MATERIALS AND METHODS Surgical preparationsTen mongrel dogs weighing from 13.6 to 23.5 kg (mean 17.9 kg) were anesthetized with intra...

Two‐Dimensional Assessment of Right Ventricular Function: An Echocardiographic–MRI Correlative Study

“…Nevertheless, we did not show a strong association between TAM and RVEF; marked differences in ranges may also explain the poor relationship between these two variables. Our findings suggest that the degree of RV longitudinal shortening does not appear to contribute significantly to RV ejection; this is also supported by animal models and human studies of RV function 13,14 …”

“…That TFC correlated poorly with RVEF was surprising in light of evidence supporting a dominant role for transverse systolic shortening 14 . Nevertheless, the relationship between transverse shortening and RVEF may only be linear in patients with normal or slightly impaired RV function 13 .…”

Right Ventricular Ejection Function Assessed by Cineangiography. Importance of Bellows Action.

“…However, an experimental study indicated that contraction of the right ventricular free wall contributed to maintenance of right ventricular ejection function. 18 Active contraction of the free wall may result in a bellows action, which of course may also be influenced by the movement of the ventricular septum and indirectly by that of the left ventricular free wall. In addition, it seems that these myocardial movements depend on bi-ventricular pressures and volumes.…”