PHYSIOLOGICAL ASSESSMENT OF THE CORONARY COLLATERAL CIRCULATION IN TRANSPLANTED HUMAN HEARTS

Coronary arteries of transplanted hearts frequently develop a vasculop athy characterized by severe lumenal narrowing in the distal coronary arteries. It has been thought, on the basis of angiographic studies, t hat the coronary circulation of transplaned hearts with vasculopathy f ails to develop collateral vessels normally. To determine the extent o f the collateral circulation in transplanted hearts with a significant coronary stenosis, we measured an index of the collateral circulation , the coronary artery occlusion pressure, during single-vessel coronar y angioplasty in seven patients with allograft vasculopathy and 18 pat ients with atherosclerotic disease who did not undergo transplantation . Aortic and coronary artery pressure distal to the stenosis in the ep icardial artery were measured during balloon occlusion (greater-than-o r-equal-to 45 seconds). Measurement variability for determination of c oronary occlusion pressure was assessed by measuring occlusion pressur e on two separate balloon inflations (n = 17). The severity of the dil ated stenotic lesion was assessed with quantitative angiography (Reibe r-PIE Data method). The indexes of stenosis severity were similar in c oronary arteries of transplanted and native hearts. Coronary occlusion pressure measurements were highly reproducible (mean absolute differe nce between measurements, 1 +/- 1 mm Hg, r = 0.98). Coronary occlusion pressure in transplanted hearts (32 +/- 4 mm Hg) was nearly identical to that measured in coronary arteries of native hearts (29 +/- 2 mm H g). When vessels with total occlusion were excluded and corrections we re made for minor differences in hemodynamics (heart rate and blood pr essure) were made, the coronary occlusion pressure in transplanted hea rts remained nearly identical to native hearts. These data suggest tha t, in the setting of allograft vasculopathy and a severe coronary sten osis, the coronary circulation of transplanted hearts is capable of no rmally developing collateral vessels.