الفهرس 
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Abstract
Object: Myocardial revascularization is performed preferentially with internal mammary artery grafts. Pedicled or Skeletonized preparation and pharmacologic vasodilator treatment vary greatly. Objective measurements are difficult since peripheral and later coronary vascular resistance and possible competitive flow of the native bypassed coronary artery will influence the results significantly.
Our objectives were: (1) Measurement of internal mammary artery (IMA) graft flow and pulsatile index with the transit time flow technique; (2) comparison of two surgical take-down techniques (skeletonizing vs. standard pedicle preparation); (3) quantitation of transit-time flow and pulsatile index during bypass and after coming off bypass.
Method: Consecutive elective cases of coronary artery bypass grafting, performed by two surgeons using routinely either skeletonizing of the internal mammary artery (group S, n = 40) or classical pedicle preparation technique (group P, n = 30), were studied prospectively. Anesthesia, cardiopulmonary bypass, operative and post-operative results were collected compared between the two groups using Transit- time flow (TTF), pulsatile index (PI) and both TTF and PI difference using Medi-Stim® flowmeter where the measurements done after anastomosis of distal end at the following time points: (1; during bypass and (2) after coming off cardiopulmonary bypass.
Results: (1) After coronary grafting, transit-time flow showed significant differences in flow between the two groups (2) No significant differences in pulsatile index between two groups as all cases PI was<5 except one reading in one case during bypass where the PI was 6.6 and (3) Logistic regression analysis for mortality showed that reduced flow after protamine was an independent predictor of mortality (OR 1.269: CI at 95% 1.035-1.556). (4) Receiver Operating characteristic curve (ROC) analysis showed that a flow after protamine 26 or less is 100% sensitive and 97% specific for occurrence of mortality (area under the curve 0.977; P=0.001) while a flow after protamine 61 or less is 88.2% sensitive and 38.9% specific for occurrence of low cardiac output (LCO) (area under the curve 0.843; P=0.001).
Conclusion: (1) Intraoperative transit time flow measurement is a reliable method for assessing quality of grafts. (2) Flow after protamine and PI value< 5 can be used as independent predictor of morbidity and mortality. (3) Skeletonization of IMA has better outcome.