The relationship between drug-induced changes in central and regional hemodynamics in congestive heart failure

Sixty-one patients with moderate to severe congestive heart failure underwent simultaneous central and regional hemodynamic measurements before and after the intravenous or oral administration of one of a number of vasoactive agents including nitroglycerin, nitroprusside, isosorbide dinitrate, hydralazine, prazosin, clonidine, indoramin, and nifedipine. The relationship between changes in cardiac output and concomitant changes in regional (limb, hepatic, and renal) blood flow was determined and analyzed. For the entire population, the aforementioned vasoactive drugs (as a group) effected changes in regional blood flow which correlated poorly with changes in cardiac output; the correlation coefficient (r) between changes in cardiac output and limb blood flow was 0.16 (p = NS), hepatic blood flow 0.04 (p = NS), and renal blood flow 0.42 (p less than 0.05). When individual drugs were analyzed, only hydralazine's alterations in renal blood flow corresponded to simultaneous changes in cardiac output (r = 0.81, r2 = 0.65, p less than 0.05). The results of this study well demonstrate the complex pathophysiologic mechanisms which determine the distribution of blood flow in congestive heart failure, and the wide individual variability of hemodynamic responses to most vasoactive agents.