The hemodynamic effects of adenosine infusion after experimental right heart infarct in young swine

The use of a vasodilator selective to the pulmonary circulation may be bene ficial in cases with right-ventricle failure, as it will decrease right-hea rt afterload without concurrent systemic hypotension. Adenosine has recentl y been advocated as such a drug, although its clinical efficacy in this res pect is still in question. We therefore devised an experimental protocol of right-heart infarct to test the efficacy of adenosine in alleviating sympt oms of right-heart failure. Right-heart infarct was induced experimentally in 17 young pigs. After hemodynamics had stabilized, preload was optimized with a dextrose-based colloid solution. A continuous infusion of adenosine was then begun at doses of 25, 50, 75, and 100 mu g/kg/min in a study group of 10 animals, while the remaining seven were monitored as controls. Hemod ynamic parameters were followed throughout the study, with particular atten tion paid to pulmonary and systemic vascular resistance indices (PVRI and S VRI), right ventricle ejection fraction (REF), cardiac index (CI), and hear t rate (HR). Cardiac index (CI) showed a tendency to increase during the ad enosine infusion, as did REF and stroke index (SI), whereas PVRI and mean p ulmonary pressure (MPAP) were decreased. There was a marked decrease in SVR I as a result of the adenosine, as there was in mean arterial pressure at t he higher infusion rates. HR remained unchanged by the infusion. Discontinu ation of the drug resulted in a rapid increase in MAP, SVRI, MPAP, HR, left ventricle stroke work index (LVSWI), and PVRI and in a modest decrease in CI, The continuous infusion of adenosine appears to cause an effective arte rial vasodilation, with a consequent unloading of right-heart afterload. It s use may be beneficial in the treatment of increased pulmonary vascular re sistance after right-heart failure.