Left ventricular mechanics in arrested dog heart: effects of ventricular interaction and vascular volumes

Abstract

The present study was designed to determine the effects of right heart pressure on the compliance of the left ventricle (LV). The studies were conducted on isolated, blood-perfused, potassium-arrested dog hearts with vasomotor tone either present (n = 5) or absent (n = 8). A balloon was used to control LV volume, whereas right heart (RHP) or coronary sinus (CSP) pressures were controlled via a column placed in the right heart or coronary sinus, respectively. Control of CSP independently of RHP allowed us to assess the relative contribution of coronary venous pressure to changes in LV compliance under conditions of elevated RHP. LV volume and compliance at a LV pressure of 15 mmHg (V15 and C15, respectively) were calculated to quantify the shift and slope changes of the LV pressure-volume (P-V) relationships. V15 and C15 decreased with vasomotor tone present from 52.8 +/- 1.4 ml and 1.7 +/- 0.1 ml/mmHg at control, to 43.3 +/- 2.1 ml and 1.4 +/- 0.1 ml/mmHg (P < 0.05) with RHP = 0 and 20 mmHg, respectively. Similar effects were obtained with vasodilation, but C15 was significantly lower relative to autoregulation but C15 was significantly lower relative to autoregulation (1.0 +/- 0.1 at control RHP, P < 0.05). Elevation of CSP with vasomotor tone resulted in an upward shift in the LV P-V relationship: V15 decreased from 53.4 +/- 2.1 at CSP = 0 mmHg to 50.9 +/- 1.6 ml at CSP = 20 mmHg (P < 0.05). After vasodilation there was no detectable shift in the LV P-V relationship with elevation of CSP.

Antihypertensive and anti-arrhythmic effects of an extract of Radix Stephaniae Tetrandrae in the rat

“…In agreement with the previous findings of Xu & Rao (1995), the LVEDP increased with the LV balloon volume and the curve was shifted to the left in the group subjected to DOCA-salt treatment (Figure 4), indicating greater increase in LV pressure with changes in volume and a decrease in myocardial compliance (Horowitz et al 1986;Amrani et al 1994;Manor et al 1995). In DOCA-salt- 118 treated groups fed with tetrandrine or the RST extract, the increases in pressure with volume changes were significantly attenuated; the effect of the RST extract was related to the dose (Figure 4).…”