PHARMACOLOGICAL MODULATION OF THE HUMAN COLLATERAL VASCULAR-RESISTANCE IN ACUTE AND CHRONIC CORONARY-OCCLUSION ASSESSED BY INTRACORONARY BLOOD-FLOW VELOCITY ANALYSIS IN AN ANGIOPLASTY MODEL

Background The pharmacological responsiveness of the coronary collater al circulation in humans has been studied only by indirect means. Meth ods and Results Patients with one-vessel disease and recruitable (n=14 ) or spontaneously visible (n=24) collateral vessels were studied duri ng coronary angioplasty. Collateral Bow in the recipient coronary arte ry was determined with a 0.014-in Doppler guide wire during balloon co ronary occlusion and expressed as the diastolic blood flow velocity in tegral (dVi). Collateral blood flow velocity, mean aortic pressure (Pa o) and coronary wedge pressure (Pw) were used to calculate the collate ral vascular resistance index: Rcoll = (Pao - Pw)/dVi (mm Hg/cm) and t he peripheral vascular resistance index of the recipient coronary arte ry: R4=Pw/dVi (mm Hg/cm). Adenosine (12 to 18 mu g) and nitroglycerin (0.2 mg) were injected as a bolus in the donor coronary artery during subsequent balloon inflations to assess their effect on these hemodyna mic variables. The administration of adenosine or nitroglycerin in pat ients with recruitable collateral vessels did not induce a change in d Vi and Pw/Pao ratio. In patients with spontaneously visible collateral vessels, dVi increased from 8.0+/-4.5 to 10.8+/-8.0 cm (P=.01) after adenosine and from 7.4+/-4.5 to 10.3+/-6.9 cm (P=.003) after nitroglyc erin. The Pw/Pao ratio remained unchanged after adenosine and nitrogly cerin. Rcoll decreased from 10.3+/-9.5 to 8.6+/-8.5 mm Hg/cm (P=.01) a fter adenosine and from 11.6+/-10.4 to 8.3+/-8.9 mmHg/cm (P<.001) afte r nitroglycerin. R4 decreased from 7.7+/-5.5 to 5.9+/-5.1 mm Hg/cm (P< .001) after adenosine and from 8.4+/-6.6 to 7.1+/-7.2 mm Hg/cm (P=.01) after nitroglycerin. Conclusions Coronary collateral blood Bow can be increased with adenosine and nitroglycerin in patients with one-vesse l disease and spontaneously visible collateral vessels, which is in co ntrast to patients with recruitable collateral vessels. This effect is the result of a reduction in the collateral vascular resistance and p eripheral vascular resistance of the recipient coronary artery.