Popliteal artery aneurysms. Clinical relevance of dynamics and vulnerability

Knowledge of anatomic variations of the popliteal artery is essential for the management of peripheral vascular disease. It influences the success of femoropopliteal and crural reconstructions and may also be important in orthopedic surgery. Variations may increase the risk of bleeding, dissections, or ischemic complications. Therefore, this thesis will commence in Chapter 2 by describing the variations in anatomy of the popliteal artery. PAAs and AAAs frequently coincide. The frequency and nature of symptoms are different; however, most patients with a PAA will be symptomatic at the time of diagnosis, most frequently with thromboembolic complications, and less than 2% of patients present with a ruptured PAA. In contrast, patients with an AAA are mostly asymptomatic at the time of diagnosis, and when symptomatic, rupture is the most frequently observed symptom. In Chapter 3, the aneurysm wall composition of PAAs and AAAs is assessed. Chapter 4 reports systematic reviews of short-term and long-term results of surgical and endovascular treatment of PAAs. Open surgical treatment with a venous graft is still the treatment of choice for most surgeons. During recent years, endovascular surgery has become an alternative to open surgery. The most commonly performed surgical technique for PAA repair is the medial approach, with proximal and distal aneurysm ligation, followed by autologous vein or polytetrafluroethylene (PTFE) bypass grafting25. This technique does not exclude side branches with their origin in the PAA, which can be responsible for retrograde perfusion in the ligated aneurysm sac and eventually lead to aneurysm enlargement and worse, rupture26-31. An alternative technique is the posterior approach. This technique includes direct opening of the aneurysm sac, interrupting patent side branches of the genicular arteries, and autologous venous or PTFE interposition grafting. Chapter 5 reports a headto- head comparison of the medial and posterior approaches in the treatment of PAA. In Chapter 6, a systematic review summarizes outcomes of acutely thrombosed PAAs treated with thrombolysis or thrombectomy, followed by a bypass. The primary end point in this study was limb salvage, and the secondary end points were mortality and patency of the bypasses. It is not clear which characteristics of an asymptomatic PAA will lead to acute thrombosis; diameter alone might not be the only predicting factor. Chapter 7 examines other possible features that may influence outcome such as the changes in lumen area and the degree of angulation directly proximal and distal of the PAA after flexion and extension of the knee joint. The behavior of arterial disease is different in women and men in terms of anatomy, physiology, and clinical presentation. Combined results of studies focusing on the outcome of bypass surgery in the lower extremity do not show significant differences in primary patency rates, percentage of limb salvage, and survival between men and women32-39. Chapter 8 investigates whether there is an association of gender on the outcome of PAA treatment. Chapter 9 concludes this thesis, providing a general discussion and future perspectives. A summary in Dutch is presented in Chapter 10.