Modulation of left ventricular diastolic distensibility by collateral flowrecruitment during balloon coronary occlusion

OBJECTIVES The goals of this study were to elucidate the scaffolding effect of blood-filled coronary vasculature and to determine the functional role of recruited collateral flow in modulating left ventricular (LV) distensibi lity during balloon coronary occlusion (BCO). BACKGROUND Although LV distensibility is an important factor affecting acut e dilation after myocardial infarction, the response of LV diastolic pressu re-volume (P-V) relations to coronary occlusion is inconsistent in humans. METHODS Micromanometer and conductance derived LV P-V loops were serially o btained from 16 patients undergoing percutaneous transluminal coronary angi oplasty. Coronary collateral flow recruitment was angiographically evaluate d by contralateral and ipsilateral contrast injection during BCO. RESULTS In the group with poor collateral flow (grades 0-I; n = 8), BCO res ulted in a downward and rightward shift of the diastolic P-V relations, whe re end-diastolic volume (EDV) increased by 13% (p < 0.05) without appreciab le change in end-diastolic pressure (EDP; 18 +/- 6 to 18 +/- 8 mm Hg). In c ontrast, BCO in the group with good collateral flow (grades II-III; n = 8) shifted the diastolic P-V relations upward to the right with a concomitant increase in minimal pressure (min-P; 6 +/- 4 to 10 +/- 5 mm Hg, p < 0.05), EDP (15 +/- 7 to 21 +/- 9 mm Hg, p < 0.05) and EDV (+10%, p < 0.05). Reacti ve hyperemia after balloon deflation caused a rapid and parallel upward shi ft of the diastolic P-V relations with a marked increase in min-P and EDP, especially in the group with poor collateral flow, before any improvement i n LV contraction or relaxation abnormalities. CONCLUSIONS Grades of coronary filling, either retrograde or anterograde, a bruptly modulate LV distensibility through the rapid scaffolding effect of coronary vascular turgor. (C) 1999 by the American College of Cardiology.