The Evaluation of In Vitro Effects of Dipyridamole on Coronary Artery Bypass Grafts

Objective: The aim of this study is to evaluate the efficacy of dipyridamole in relieving the vasospasm of coronary artery bypass grafts. Material and Methods: Twenty two patients who underwent elective coronary artery bypass grafting (CABG) were admitted to the study (Men/Women:14/8, mean age: 62.4±8.8 years). Ten samples from left internal mammary(LIMA), radial arterial (RA) and saphenous vein (SV) grafts were collected for each. The samples were transported to the vascular laboratory in 4°C Krebs solution. Submaximal smooth muscle contraction was achieved first by 10-7M of phenylephrine solution. Dipyridamole was then added, starting from a concentration of 10-9M to a concentration of 10-3.5M in two minutes intervals and half logarithmic dose increments. The concentration-response curves were obtained of the vasodilatation response relative to the begining. Results: In the LIMA graft samples, the vasodilation response to dipyridamole was 43.2±1.6% and 97.6±4.1% at concentrations of 10-6M and 10-3.5M respectively. In RA graft samples, the vasodilation response to dipyridamole was 36.3±1.8% and 95.3± 2.7% at concentrations of 10-6M and 10-3.5M respectively. In SV graft samples, however, the vasodilation response to dipyridamole was 43.2±1.4 % and 96.6± 2.2% at concentrations of 10-6M and 10-3.5M respectively. Conclusions: The amplitude of relaxation response to dipyridamole of all grafts samples were similar, without statistically significant difference among the IMA, RA and SV grafts in the in vitro tissue bath system. These results prove that dipyridamole has a potential use as a vasodilatatory drug in all graft types.