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Bruce P. Mindich, MD; Eric H. Bronstein, MD; Mitchell Rubinstein, MD;
Carlos O. Urrutia-S, MD, Enrico Gonzalez, MD
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Purpose:
Graft patency is the crucial end point in CABG surgery. Factors leading to graft failure are well documented with technical errors remaining the most frustrating. In an effort to detect unacceptable grafts in the operating room where correction can be accomplished, ultrasonic flow measurements have been introduced.
Method:
Once flow has been established in a graft, measurements are performed utilizing ultrasonic transit-time technology. The flow probes are placed around the graft and the volume of flow is measured by ultrasonically intersecting the entire width of the vessel both in an upstream and downstream cycle. A printout and acoustic signal are generated which which can be interpreted. If flow is inadequate, an algorithm is established to determine the cause of the problem. The effects of poor run-off, competitive flow and possible spasm are differentiated from technical errors. The latter are then corrected. In patients performed on CPB, in isolated or combined procedures, graft flows are measured while on CPB. The flow characteristics with the heart beating, in fibrillation or asystolic, predict the quality of flow once CPB is discontinued; corrective measures can be instituted at that time. All patients have oximetric Swan-Ganz catheters, TEE probes and ECG event analysis in place during the entire procedure. Curve, representing poor flow are correlated with these parameters.
Results:
The technique has been utilized in over 1,000 cases. The most recent 500 cases were analyzed in an effort to eliminate effects of a learning curve or interpretation of the data. There were 3.2 grafts/patient. Ninety-five (95%) percent of the isolated CABGs were done as OPCABS. Of 1,600 grafts evaluated, 248 demonstrated questionable curves; 82 technic
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