Reversal of preexisting vasospasm in coronary artery conduits

Background. To reverse preexisting coronary graft spasm, we investigated th e vasodilative effect of the average therapeutic plasma concentration of ni troglycerin (NTG) alone and various calcium antagonists in combination with NTG in human arterial and venous conduits. Methods. Vasodilative effects of 2 x 10(-8) mol/L NTG alone and 10(-8) mol/ L NTG in combination with 2.2 x 10(-7) mol/L diltiazem, 2.8 x 10-7 mol/L ni fedipine, 10-7 mol/L verapamil, or 5.6 x 10(-8) mol/L nicardipine were asse ssed in human radial artery, internal thoracic artery, and saphenous vein s egments precontracted with a mixture of ten times the maximum plasma concen trations of endothelin-1 (8.6 x 10(-13) mol/L), angiotensin II (36 x 10(-11 ) mol/L), 5-hydroxytryptamine (3.4 x 10(-7) mol/L), and norepinephrine (1.7 x 10(-8) mol/L). The studies were done in organ baths. Results. The therapeutic concentration of NTG alone or nifedipine, verapami l, diltiazem, or nicardipine in combination with NTG caused equal relaxatio n in a particular group of vascular segments (average vasodilation: radial artery, 83% to 95% [p = 0.7608 by analysis of variance]; saphenous vein, 47 % to 70% [p = 0.3142]; internal thoracic artery, 54% to 79% [p = 0.2783]). These combinations were not equally effective when compared between differe nt groups of vascular segments (vasodilation; radial artery > internal thor acic artery > saphenous vein [p < 0.0001 by analysis of variance]). Althoug h not significant, in comparison with NTG alone, NTG in combination with a calcium antagonist caused less vasodilation in any group of vascular segmen ts. Conclusions. Nitroglycerin alone or in combination with nifedipine, verapam il, diltiazem, or nicardipine effectively reverses preexisting vasospasm in coronary artery conduits. (C) 2001 by The Society of Thoracic Surgeons.