Evaluation of coronary artery bypass grafts by intraoperative transit time flow measurement

Background: This study was conducted to evaluate the efficacy of transit time flowmetery in determining graft related problems per-operatively while performing coronary artery bypass grafting. Method: From May 2001 to January 2002 transit time flowmetery was performed on 442 grafts in 185 consecutive patients. A fixed protocol was used to assess the flow indices. Grafts were considered blocked if the pulsatility index was more than 5 and a systolic spike was present. Results: Abnormal flowmetery was observed in 10 grafts (2.26%). The mean flows for left internal mammary artery, radial and saphenous vein grafts were 28.24±18.12 ml/min., 37.57±21.81 ml/min., 28.8±17.17 ml/min. respectively. Nine of these grafts were revised with return of flow indices to normal. In one case the native vessel was small and of poor quality and revision was not possible. The 30-day mortality was 1.08%. There was no death attributable to graft malperfusion. Conclusion: Transit time flowmeter is a valuable tool in detecting graft related problems per-operatively. These problems can be corrected immediately thus reducing mortality and morbidity.