Figure 8From: Cardiac reflections and natural vibrations: Force-frequency relation recording system in the stress echo labDipyridamole stress has the well known coronary vasodilator effects mediated by the inhibition of adenosine cellular transport, eventually leading to extra cellular adenosine accumulation and steal phenomena. There is a mild catecholamine release that is responsible for the inotropic effect of the drug: normal contractile reserve is present if the force-frequency relation is up sloping instead that abnormal negative. Lower panels. The ventricular force is expressed as SP/ESV assessed by echocardiography in the stress echo lab. Left, the mild increase in heart rate at peak stress is accompanied by a mild decrease in systolic pressure without decrease of the end-systolic volume. The Δ rest-peak SP/ESV index is <0 mmHg/ml/m2 (negative contractile reserve). Right, the mild increase in heart rate is accompanied by a mild decrease in systolic pressure with a more pronounced decrease of the end-systolic volume. The Δ rest-peak SP/ESV index is >0 mmHg/ml/m2 (normal contractile reserve). Upper panels. Sensor built force-frequency relation simultaneously recorded in the same patients in which standard echo force-frequency relation was built. Left, abnormal negative force-frequency relation: the Δ rest-peak force is less than 0.35 g * 10-3 (0.35 g * 10-3 = cut-off value for positive vs. negative contractile reserve in DIP stress). Right, normal contractile reserve: the Δ rest-peak force is >0.35 g * 10-3.Back to article page