Lessons learned – trust your flow numbers!

Case

In this case, an experienced surgeon in Ontario, Canada, who was relatively new to utilizing flow measurement technology, made a critical decision not to rely on his initial flow measurement findings, which indicated a potential issue with the graft. Subsequent information further suggested that the graft was not patent, compelling him to put the patient back on pump and undertake a graft revision. 

Initially, flow measurement was conducted on the LIMA-LAD graft while the patient was on-pump (Picture 1). The reading was deemed “acceptable,” albeit with the pulsatility index (PI) slightly exceeding the optimal threshold (<0.4). Looking back, this marginally elevated PI should have served as an early indicator of potential graft complications, though it was initially perceived as satisfactory.

With the patient off pump and arterial pressure as expected the surgeon could feel a strong pulse in the graft, yet the flow measurement was poor. Mean flow was 6 mL/min, PI was 5.2 and DF% was 67% (Picture 2). As the surgeon was confident in his work, he chose to not trust the TTFM. However, after going fully off pump TEE and aesthesia also started raising concerns that the heart was not performing as expected.

The surgeon then decided to revise the graft and the patient was put back on pump. The issue had been the angle of the LIMA coming into the heart. By trimming back some of the LIMA and opening the LAD more to allow for a longer anastomosis the graft could lay flatter on the heart and perform much better. Post-revision flow measurements showed a very good improvement (Picture 3). Mean flow is up to 122 mL/min, PI down to 1.5, and DF% up to 73% with no backflow.

 

After seeing this improvement, the surgeon admitted that the technology is worth the investment and that he will trust it and use it routinely from here on.