Case example provided by Dr. Michael Yacob, Kingston General Hospital, Kingston, Ontario, Canada.
Comments from Dr. Yacob regarding Transit Time Flow Measurement (TTFM) as quality assessment of the graft patency:
“Really great information intra-OP that changed how I performed today and will hopefully prolong the patency of this long segment bypass.”
Fem-Pop bypass with in-situ vein graft
In this case the surgeon wanted to perform the procedure as minimally invasive as possible. The bypass was performed by using the great saphenous vein (SVG) in situ and ligating all the side branches endoscopically. The surgeon did the completion control with TTFM to confirm adequate flow distally and the lack of side branches. He then performed an angiogram according to his previous routine to verify that the findings with TTFM were correct as his intention was to be able to skip angio and the use of contrast media in the future when doing this procedure.
- 57-year-old male
- Diagnosis: Critical limb threatening ischemia (CLTI) due to occlusion of the superficial femoral and popliteal arteries
After vein mapping and locating the sites for the proximal and distal anastomosis, 10 cm incisions were made proximally and distally, Figure 1. The side branches on the SVG were ligated endoscopically and valve lysis was performed, Figure 1 and 2.
Completion control with TTFM
After completion of the proximal and distal anastomosis, the surgeon placed a 4 mm flow probe on the vessel at the proximal site showing 133 ml/min with a PI of 1.7, Figure 3 and 4. To check for presence of side branches, he occluded the graft percutaneously several times with his finger while moving the pressure point distally along the graft and at the same time measuring the flow volume at the proximal site. A strong reduction in flow each time he occluded the graft confirmed that all the side branches were clipped.
3 minutes after he had measured the flow proximally, TTFM was performed at the distal site showing adequate flow of 156 ml/min with a PI of 1.3, Figure 5 and 6.
Comparing Doppler vs. TTFM as completion control
The surgeon completed an open bypass procedure as normal on another patient and was satisfied with the Doppler signal at the end of the case. He then used TTFM and noticed low flow at the distal site, 89 ml/min with a PI of 1.5, Figure 7.
After a critical review of the bypass, it was detected that one area had an intermittent pulse. He opened the side branch and noticed there was a retained valve. The valve was removed and the side branch was closed. Flow volume was then remeasured which had increased to 110 ml/min with a PI of 1.9, Figure 8.
Medistim VeriQTM System with Medistim QuickFitTM TTFM probes 3 and 4 mm.