A desktop computer to visualize the intraluminal velocity profile and its clinical application

Based on our previous study that the outcome of reconstructive surgery for lower limbs could well be predicted by flow waveforms and that this state was defined by variation of wall shear stress (tau) in a cardiac cycle, we set up a desktop computer that could calculate wall shear stress in a given patient. This work is based on a principle of a computational method for simulating pulsating blood flow. The flow data from the patient are sent to the waveform analyzer, where the intraluminal velocity profile as well as the shear stress variation is demonstrated. Our study revealed no late occlusion in patients with flow waveforms over 70 dynes/cm2 in tau-variation, early graft failure in those below 20 dynes/cm2, and late occlusion in considerable numbers of patients whose waveforms were between 70 and 20 dynes/cm2. Intraoperative use of the waveform analyzer disclosed the occult cause of obstruction, which would otherwise be overlooked, leading to a remarkable decrease in the rate of immediate graft failure. Follow-up of outpatients with this approach facilitated early detection of late failure, making it possible to repair the graft with minor surgery. Use of the waveform analyzer proved superior to ankle pressure index in predicting graft failure.