Long term clinical and functional venous outcomes after endovascular transvenous femoro-popliteal bypass.

BACKGROUND: Peripheral artery disease is widespread in Western societies affecting around 13% of the population above 50 years of age. Despite recent improvements of endovascular treatment, open surgical bypass is still recommended as the treatment of choice for long segment TASC D lesions. The DETOUR procedure was introduced as an endovascular alternative in cases of long-segment superficial femoral artery occlusion. This unconventional technique raises several questions regarding the effect of the bypass graft on femoral venous physiology. METHODS: We conducted a 3-year follow-up study of subjects enrolled and treated in the prospective, multicenter DETOUR study at the Pauls Stradins clinical university hospital, Riga, Latvia. In total, 52 consecutive patients (54 procedures) were enrolled in this study from 2015 until 2019. We performed Venous Clinical Severity Score (VCSS) and Villalta (VS) Score assessments, Duplex ultrasound measuring femoral and popliteal vein diameters, venous occlusion plethysmography and digital photoplethysmography to assess and compare venous physiology at baseline and at follow-up visits every 6 months. RESULTS: At baseline mean femoral vein diameter was 11.1 mm (SD=1.5). At 36-months following intraluminal stent-graft placement, mean femoral vein diameter was 11.1 mm (SD=1.7) with no evidence of enlargement of the femoral vein (P=0.2). Popliteal vein diameter was not significantly changed during 24-months of follow-up (P=0.12) but showed a small (0.02 mm) statistically significant decrease in diameter at 36-months compared to baseline. During the study period, only one patient (1.9%) developed clinically significant ipsilateral DVT 1-month after surgery. Clinically silent femoral venous thrombosis was documented in 8 legs during 36-month follow-up. In one case the thrombus was occlusive and in 7 cases the thrombus was non-occlusive. At baseline, 48 of 52 patients (92%) had no or minor venous symptoms ([VCSS 0-2] with clinically significant venous symptoms in only 4 patients [VCSS≥3]). At one-month follow-up, the venous clinical severity score increased in all patients compared to baseline. At 6-month follow-up, the VCSS had returned to baseline in the majority of patients with no significant changes during the 3-year follow-up period. At baseline, all patients had a VS of 0-2 indicating minor or no venous symptoms (mean 0.4 [SD 0.7]). At the 1-month follow-up visit 3 patients (5.8%) had a VS≥3 (two patients had a score of 3 and one patient a score of 4), indicating significant venous symptoms. At the 6-month visit and thereafter, all the VS in all patients had returned to baseline. Transvenous endovascular procedure did not significantly alter venous physiology in treated leg. CONCLUSIONS: Percutaneous transvenous femoropopliteal bypass provided safe and effective lower-extremity revascularization with minimal effect on long-term venous function. The femoral and popliteal vein remained patent with no compensatory enlargement in response to the presence of the bypass graft within the femoral vein. During 3-year follow-up there were no significant changes in venous symptom scores or physiologic function.

Bilateral photoplethysmography studies of the leg arterial stenosis.

A newly developed portable multi-channel photoplethysmography (PPG) device has been used for comparative studies of 20 healthy control subjects and 45 patients with diagnosed arterial stenosis in a leg. The peripheral blood pulsations were detected simultaneously at four body sites-the same fingers and toes of both arms and legs. The PPG pulses recorded at the periphery of the stenotic leg, if compared with those of the healthy leg, were much weaker, with delayed arrival as a consequence of increased pulse wave transit time (PWTT) due to higher vascular resistance. The specific PWTT delays for the occluded legs were in the range of 20-80 ms, while in the case of healthy subjects the leg PPG signals arrived without delays or with smaller time-shifts not exceeding 14 ms. The reference bilateral PPG signals detected at the fingertips did not show any notable PWTT delays in both groups. Parallel measurements of local blood pressures by means of the oscillometry method with subsequent calculation of the ankle-brachial index were performed. Convincing correlation between the bilateral differences in the local blood pressure (a routine tool for diagnostics of leg stenosis) and in the corresponding PWTT delay (Pearson's coefficient r = 0.93), as well as between the PWTT delay and the ankle-brachial index (r = -0.96) has been established. From the point of view of PWTT delay, the average value of leg stenosis diagnostic threshold was established to be in the range of 23 +/- 9 ms, with full reliability above 32 ms. The obtained data may find further applications in alternative methodologies for detection and/or assessment of arterial occlusions in human extremities.