Retrograde Pressures and Flows in Coronary Arterial Disease

Antegrade and retrograde pressures and flows have been measured in the coronary arteries distal to an obstructive lesion and the retrograde flow and pressure correlated with the arteriographically determined degree of stenosis and extent of collateral circulation. Antegrade pressure and flow were roughly proportional to the estimated degree of proximal obstruction, with little change being noted below 70% obstruction. Below 90% obstruction, minimal collateral flow was demonstrable either by arteriogram or by retrograde flow measurement. Retrograde pressures proved to be surprisingly low, usually being about one-third of the systemic pressure and almost never over 30 mm. Hg. Retrograde pressures were relatively independent of the degree of proximal stenosis or of arteriographically demonstrable collateral circulation. Retrograde flows likewise proved to be surprisingly small, even though the method of measurement allowed for absolutely maximal backflow. Retrograde flow, however, did correlate well with the degree of collateral circulation demonstrated in the arteriograms. Patients with the preinfarction syndrome had the lowest antegrade flows and retrograde flows, which were usually too small to be measured.