EFFECTS OF INTRACORONARY OR INTRAVENOUS-I NFUSION OF ILOPROST ON CORONARY BLOOD-FLOW VELOCITY IN PATIENTS WITH CORONARY-ARTERY DISEASE

Prostacyclin and its stable analog iloprost (ILO) are able to induce v asomotor effects in smooth muscle cells. These vasodilator effects hav e been demonstrated in several types of vessels, even in coronary arte ries. Bugiardini et al. have previously claimed to have evidence for a coronary steal phenomenon in patients with coronary artery disease re ceiving ILO. They conclude the steal phenomenon from the appearance of angina and ST-segment changes. The aim of our trial was to study the coronary circulation by measuring coronary vessel diameter, coronary b lood flow velocity (CBFV), heart rate and blood pressure in patients w ith high degree LAD stenosis following i.v. and i.c. infusion of ILO a nd papaverine (PAPA i.c.). Infusion of ILO i.v. (2 ng kg(-1) min(-1)) induced no significant change in vessel diameter measured in the steno tic and in normal vessel segments. Following ILO i.c. (0.5 ng kg(-1) m in(-1)) and PAPA coronary vessel diameter increased proximal to the st enosis by 25.8 +/- 5.6 % and 24.8 +/- 4.6 % and within the stenosis by 50.1 +/- 10 % and 56.2 +/- 11 %, respectively (p < 0.01). At the end of the i.c. ILO infusion CBFV increased by 103.7 +/- 24.9 % and was fu rther elevated by PAPA (217 +/- 57.2 %, p < 0.01). The elevated flow v elocity with increased vessel diameter following ILO i.c. (0.5 ng kg(- 1) min(-1)) implicated an increased flow in the stenotic vessel and th us there was no evidence for a decreased perfusion or coronary steal p henomenon.