Splanchnic blood flow in essential hypertension and in hypertensive patients with renal artery stenosis

Abstract

Splanchnic blood flow (SBF) was measured simultaneously with cardiac output (dye dilution) and intraarterial blood pressure by constant infusion of indocyanine green in 11 control subjects, 13 patients with essential hypertension (EH) and 7 hypertensive patients with renal artery stenosis (RAS). The cardiac index (CI) was lower (P<0.05) in patients with EH (3.17 ± 0.07 L/min/m2) (mean ± SEM) than in control subjects (3.43 ± 0.09). Associated with the lower CI was a significantly (P<0.01) lower SBF (0.797 ± 0.02 L/min/m2 vs 0.889 ± 0.04). Patients with RAS presented with higher (P<0.01 vs EH, nonsignificant vs control subjects) cardiac index (3.66 ± 0.17) and even lower SBF (0.749 ± 0.02). Furthermore, there was a negative correlation (r = -0.652) between the mean arterial pressure and the SBF when results for all patients were considered. The correlation remained (r = -0.568) in the EH group and the slope of regression line was not different from that for all subjects. The CI and SBF were weakly correlated (r = 0.423) in control subjects and patients with EH, whereas in patients with RAS, a negative correlation was found (r = -0.778). This study indicates that the SBF, although significantly decreased in patients with EH, remains proportional to the CI in control subjects and in essential hypertensive patients. No redistribution of CI in regard to the splanchnic circulation occurs in EH. In contrast, in patients with RAS a dissociation of CI and SBF occurs and the fraction of the CI which passes through the splanchnic vascular bed is markedly reduced. The close correlation between mean arterial pressure and SBF suggests that both parameters are influenced by a common pathophysiological factor.