Intraoperative flow rate measurements of T-grafts: calculating a flow reserve.

OBJECTIVE

To evaluate the inflow of the left internal thoracic artery (LITA) and the effect of adding a radial artery T-graft to distal LITA flow, and to calculate the LITA flow reserve.

METHODS

Twenty-two patients underwent myocardial revascularization using the radial artery-LITA T-graft in which intraoperative flow measurements were recorded. An ultrasonic flowmeter was used to directly measure flow rates in the T-graft: 1) before completion of the distal anastomoses to measure maximum flow rates (free flow), and 2) after completion of distal anastomoses.

RESULTS

The mean free flow rates of the LITA alone, radial artery graft alone, and T-graft (total flow) were 104 +/- 70, 151 +/- 89, and 230 +/- 102 ml/min, respectively. The mean flow rates on bypass of the distal LITA, radial artery graft, and T-graft after the distal anastomoses were completed were 24 +/- 16, 32 +/- 27, and 63 +/- 29 ml/min, respectively. The mean T-graft flow off bypass was 66 +/- 29 ml/min. The mean flow reserve was 70%.

CONCLUSION

The LITA has a flow reserve by which proximal flow rates will increase to accommodate the addition of a radial artery T-graft without compromising LITA flow distal to the T anastomosis.