Doppler ultrasound in the evaluation of experimental microvascular grafts

A study was made to evaluate the accuracy of Doppler ultrasound in assessing patency in experimental microvascular grafts in rats. In 20 animals, pre-operative assessment produced a phasic wave form and audio signal consistent with arterial flow when the Doppler probe was placed over the groin crease. Ten animals then had a sham operation exposing the femoral vessels through a groin crease incision. The remaining 10 had a 10 mm segment of femoral artery excised to simulate an occluded graft. These animals were re-assessed 18 to 20 days later and the wave form and audio signal of arterial flow were detectable in the sham operated animals with the probe placed below the groin incision. No signal was elicited at this site in the animals whose femoral arteries had been excised. When these principles were applied to 20 rats with microvenous grafts and 20 with 1 mm PTFE grafts in the femoral artery we predicted graft patency with 100% accuracy. This non-invasive technique is inexpensive and highly accurate.