Endovascular Transvenous Femoropopliteal Bypass and its Effectiveness Compared to Open Bypass in the Treatment of Long Segment Superficial Femoral Artery Occlusion

Lower extremity peripheral artery disease (PAD) is among the most common manifestations of atherosclerosis. Due to aging of population, this pathology is only expected to rise in prevalence. It causes significant reduction of quality of life and, in case of critical limb ischemia, poses serious threat to limb and patient’s life. Superficial femoral artery (SFA) is often severely affected by atherosclerosis, making it the focus of extensive research and innovation in vascular technology. Short and simple lesions can be managed effectively by standard endovascular modalities, whereas long and complex SFA pathologies historically were treated by open femoropopliteal bypass. However, patients with severe SFA disease are usually in advanced age, often frail, highly comorbid and thus have increased risk for open surgery. For the past two decades, vascular surgeons and invasive radiologists have debated and studied the question of which revascularisation method is superior in case of long and complex SFA lesions. Advocates of endovascular technique state lower periprocedural morbidity and mortality, shorter length of hospital stay and less wound complications. Proponents of open surgery claim higher long-term patency, less secondary interventions and lower rates of amputation. In an effort to combine the benefits of both approaches, endovascular transvenous femoropopliteal (ETFP) bypass was introduced. In this endovascular procedure, bypass from proximal SFA to above-the-knee popliteal artery is created through the deep venous system. This novel technique was investigated thoroughly in different aspects. The study was conducted in Pauls Stradiņš Clinical University Hospital between 2015 and 2020. It comprised of 52 patients (54 procedures) in study group and two control groups – 83 patients in prosthetic and 48 patients in venous bypass group. Patients with Rutherford 3–5, ankle-brachial-index (ABI) < 0.7, long (> 10 cm) TASC C and D lesions and at least one patent crural vessel were included in study group. Only patients for whom both open and endovascular treatment was feasible were included in this study. All procedures were performed by a designated team of vascular surgeons and interventional radiologists. Control groups were formed of patients with long SFA lesions who were not eligible for ETFP bypass procedure and who agreed to take part in this follow-up patency study. Following all procedures and open surgeries, control visits were performed with 6-month intervals for a total duration of 3 years. During visits, clinical assessment, plethysmography (study group) and Duplex ultrasound (DUS) was performed to assess graft patency, inflow and outflow vessels, and venous system in patients with transvenous grafts. Transvenous bypass group received dual antiplatelet treatment throughout the 3-year follow-up. Patients in control groups received either standard aspirin monotherapy, dual antiplatelet therapy, or anticoagulants if indicated by coronary artery disease or arrhythmia, respectively. The dissertation is organised as a collection of four peer-reviewed publications. First of all, we analysed and published long term venous results, which consisted of clinical and physiology assessment. Secondly, we published data regarding ETFP bypass patency. This allows us to compare it to other endovascular treatment methods. Following that, we compared the results of ETFP bypass to open surgery, both with saphenous vein and prosthetic bypass. In parallel, we conducted a study analysing DUS and ABI in the follow-up surveillance of patients after ETFP bypass. To the best of my knowledge, there are no publications reporting venous system physiology data in the context of ETFP bypass. Our results indicate that ETFP bypass does not significantly alter venous clinical symptoms and function within 3-year follow-up period. Venous system is capable of adaptation to a large stent-graft without reducing functional performance. Although we noted and early increase in venous symptoms, these changes were transient and returned to baseline by 6-months. Risk of symptomatic deep vein thrombosis following ETFP bypass is low. However, significant number of patients developed asymptomatic non-occlusive thrombi on stent-graft. Therefore, we recommend adding a low-dose anticoagulant to postprocedural medical regimen for one year. We were among the few centres in the world to publish patency data of this innovative technique. In our centre, primary patency was acceptable at 12-months (72.2 %) but reduced to 43.8 % at 3 years. Secondary patency was 92.6 % at 12 months and remained high during the study period (73.9 % at 3 years). This indicates the need for stringent surveillance and secondary interventions to maintain optimal patency of this novel device. Comparison with open femoropopliteal bypass gave us valuable practical insight. Our results demonstrate superiority of venous bypass over ETFP and prosthetic open bypass. ETFP bypass is an option with comparable primary-assisted and secondary patency to venous bypass, but will require reinterventions to provide favourable results. Whenever adequate saphenous vein is available and surgery can be tolerated, it should be the first-line option for above-the-knee open revascularisation. Prosthetic bypass should only be used if no other options are available. Diagnostic modalities used for follow-up were DUS and ABI measurements. Our study results indicate that both of these tools in combination provide the best opportunity to diagnose device-related and vascular problems. Timely diagnosis and intervention are necessary to improve our results. In summary, ETFP bypass is the method of choice for patients with infection and inadequate vein for bypass, as well as for severely adipose patients. In addition, dense scar tissue are present following previous irradiation and open surgery, thus ETFP bypass should be considered in these situations as well.