Intracoronary adenosine and papaverine do not increase myocardial systolic thickening

Study objective - The aim was to determine if myocardial systolic thickening increases when coronary flow is augmented by infusing intracoronary vasodilators (adenosine and papaverine).Design - Systolic thickening fraction was measured with pulsed Doppler crystals and sonomicrometer crystals before and during the intracoronary infusion of adenosine and papaverine.Subjects - Sixteen anaethetised mongrel dogs were studied.Measurements and main results - Intracoronary adenosine did not alter systemic haemodynamics, but did induce a three- to fourfold increase in myocardial blood flow. Intracoronary papaverine caused a slight decrease in systemic arterial pressure and rise in heart rate. Neither intracoronary adenosine nor intracoronary papaverine increased systolic thickening: control thickening fraction (TF%) = 20 (SEM 1)%, adenosine TF% = 18(1)%; control TF% = 22(2)%, papaverine TF% = 20(2)%.Conclusions - These experiments do not support the hypothesis that an increase in myocardial blood flow induced by intracoronary vasodilators causes an increase in myocardial systolic function.