ObjectiveTo analyze two techniques of papaverine application, topical spray on the harvested left internal mammary artery (LIMA) and perivascular injection, to find out their ability to improve LIMA flow.MethodsForty patients were randomized into two groups. In Group 1, papaverine was sprayed on the harvested pedunculated LIMA. In Group 2, papaverine was delivered into the perivascular plane. Drug dosage was the same for both groups. LIMA flow was measured 20 minutes after applying papaverine. Blood flow was recorded for 20 seconds and flow per minute was calculated. The systemic mean pressures were maintained at 70 mmHg during blood collection. The data collected was statistically evaluated and interpreted.ResultsThe LIMA blood flow before papaverine application in the Group 1 was 51.9±13.40 ml/min and in Group 2 it was 55.1±15.70 ml/min. Statistically, LIMA flows were identical in both groups before papaverine application. The LIMA blood flow, post papaverine application, in Group 1 was 87.20±13.46 ml/min and in Group 2 it was 104.7±20.19 ml/min. The Group 2 flows were statistically higher than Group 1 flows.ConclusionPapaverine delivery to LIMA by the perivascular injection method provided statistically significant higher flows when compared to the topical spray method. Hence, the perivascular delivery of papaverine is more efficient than the spray method in improving LIMA blood flow.