© Springer International Publishing Switzerland 2017Tulio Pinho Navarro, Alan Dardik, Daniela Junqueira and Ligia Cisneros (eds.)Vascular Diseases for the Non-Specialist10.1007/978-3-319-46059-8_9
9. Peripheral and Visceral Aneurysm
Department of Surgery, Hospital das Clínicas Universidade Federal de Minas Gerais, Avenida Professor Alfredo Balena, 110. Santa Efigênia, Belo Horizonte, Minas Gerais, 30130-100, Brazil
Department of Surgery, Faculdade de Medicina da Universidade Federal de Minas Gerais, Avenida Professor Alfredo Balena, 110, Belo Horizonte, Minas Gerais, 30130-100, Brazil
Hospital Risoleta Tolentino Neves, Rua Das Gabirobas, 1. Vila Cloris, Belo Horizonte, Minas Gerais, 31744-012, Brazil
Peripheral arterial aneurysms are abnormal dilations of the peripheral arteries caused by weakening of the arterial wall, usually caused by atherosclerosis, trauma, infection, or poststenotic abnormalities. By definition, the “peripheral artery aneurysm” excludes aortic, aorto-iliac, cerebral, and coronary vessels. The exact pathogenic mechanism of aneurysm formation is as yet still unknown. Conventional risk factors, including environmental and genetic factors, may be influenced by mechanical or hemodynamic factors, (including poststenotic flow changes) with gradual expansion over time and increasing risk of rupture or thrombosis, distal embolization, and local compression symptoms. The most common peripheral arterial aneurysm is the popliteal artery aneurysm, and the main complication is thrombosis. Visceral arterial aneurysms are abnormal dilations of the visceral arteries caused by weakening of the arterial wall, usually caused by atherosclerosis, trauma, infection, or poststenotic abnormalities. The most common visceral arterial aneurysm is splenic arterial aneurysm, and the main complication is rupture. Greater caution is needed in patients with visceral aneurysms, especially in pregnant women. Expert opinion in a timely manner is desirable in these circumstances.
KeywordsFemoral arterial aneurysmPopliteal artery aneurysmSubclavian artery aneurysmSplenic artery aneurysmHepatic artery aneurysmSuperior mesenteric artery aneurysmCeliac artery aneurysmRenal arteries aneurysm
This chapter is dedicated to peripheral and visceral aneurysms. Peripheral arteries aneurysms have thrombosis and visceral arterial aneurysm have rupture as main complication.
Femoral Artery Aneurysms
The diameter of the common femoral artery increases with age during growth and also in adults; it is related to age, body size, and sex, with diameter larger in males than females. The incidence of true aneurysms of the femoral artery is low, and femoral artery aneurysms are usually associated with other aortic or peripheral aneurysms. Pseudoaneurysms or false aneurysms of the femoral artery are more common, perhaps due to the increasing number of percutaneous diagnostic and therapeutic vascular interventions being performed. Increasing number of femoral pseudoaneurysms is also due to injection by drug abusers, frequently associated with infection . True and false aneurysms of the femoral artery may result in thrombosis, rupture, and embolization. Femoral artery aneurysm may be confined to the common femoral artery in 80 % or may involve the proximal superficial femoral artery in 15 % or profunda femoral artery in 5 % [2, 3]. Femoral arterial aneurysm is 20 fold more common in men than women. It is estimated that up to 60 % of patients with femoral aneurysms have associated distal occlusive disease. Femoral artery aneurysm main risk factor is smoking, and the main complication is thrombosis. Most of the patients are asymptomatic, and they may have acute ischemia in the affected limb as initial symptom. They are usually associated with popliteal artery aneurysms. Diagnosis is suspected when there is increased femoral pulses amplitude, and it can be confirmed with vascular Doppler ultrasound. Surgery is indicated when greater than 2 cm or intraluminal thrombus presence . Despite rapid improvement in endovascular technology, the common femoral artery still presents major challenges for stent graft exclusion. Its short length, the need for sealing zones, its close proximity to the inguinal ligament during hip flexion, repetitive stent compression and bending with normal movement, and the need to preserve flow to the superficial femoral artery and profunda femoral artery are important considerations. Open surgery with interposition of graft or vein of bypass surgery is commonly indicated [3, 4]. There is a limited literature-based evidence to use thrombin injection to treat post-puncture pseudoaneurysms . Usual approaches consist of compression (blind or ultrasound-guided) as first-line treatment. When the compression technique fails, thrombin can be used . It is feasibly endovascular treatment of true superficial artery aneurysm, but the open surgery is commonly indicated. Rupture of profunda femoral artery aneurysm is more frequently then thrombosis. There is no evidence for endovascular intervention in profunda femoral artery aneurysm and stenting at this time, but this may be safely performed in the appropriate anatomical setting. In some cases, revascularization is recommended, but only arterial ligation can be performed .
Popliteal Artery Aneurysm
The most commonly occurring aneurysms in the periphery are those involving the popliteal artery. They comprise up to 85 % of all such aneurysms, occur almost exclusively in men, and are diagnosed at an average age of 65 years. The popliteal artery is said to be aneurysmal when its diameter is greater than 2 cm. These aneurysms are frequently bilateral (53 %) and are associated with abdominal aortic aneurysms 40–50 % of the time. In the past, only 1–2 % of patients with abdominal aortic aneurysms were found to harbor popliteal aneurysms. However, the incidence reported in contemporary series based on routine ultrasound scanning is higher (14 %) [6, 7]. Between 50 to 75 % of patients found to have popliteal artery aneurysms are symptomatic on presentation. Diagnosis is suspected when there is increased popliteal pulses amplitude, and it is confirmed with vascular Doppler ultrasound . It presents surgical indication when larger than 2 cm or intraluminal thrombus presence . The most common acute symptoms include lower extremity ischemia (claudication or rest pain) caused by thrombosis of the aneurysm or distal embolization of intra-aneurysmal thrombus . Alternatively, chronic symptoms can develop when aneurysms thrombose or embolize in the presence of adequate collateral vessels. Compression of adjacent structures such as nerves and veins can cause leg pain and calf swelling, respectively. Uncommonly, popliteal artery aneurysms rupture leading to a limb-threatening circumstance and an amputation rate approaching 50–70 %. If the patient is young and active, early bypass graft using vein is recommended. Endovascular surgery may offer better results for the patients with severe clinical status . Medium term benefits of endovascular and open surgery are similar for the treatment of popliteal arterial aneurysm. However, short-term complications like thrombosis are significantly greater in the endovascular surgery. The comparison between endovascular and open surgery is currently controversial, and the unknown long-term results .
Subclavian Artery Aneurysm
Subclavian aneurysm is related with repetitive trauma in the region especially in cases of shoulder girdle vascular compression syndromes (thoracic outlet syndrome). There are three forms of thoracic outlet syndrome depending on the predominating compression of the brachial plexus roots, the subclavian vein or the artery, with neurogenic the most frequent clinical expression. Despite the fact that arterial thoracic outlet syndrome is the least frequent 1–5 % of all cases, it is most severe due to damage to the arterial wall by repetitive local trauma leading to a stenosis and/or poststenotic aneurysmatic dilation, eventually causing distal embolization and limb-threatening secondary ischemia. Aneurismatic dilatation is seems in 36 % of arterial thoracic outlet syndrome . Diagnosis can be confirmed with Doppler vascular ultrasound . In some cases, it may be necessary to conduct computerized angiotomography or magnetic ressonance image . Subclavian artery aneurysm should be treated when encountered; there is no size criterion, but the majority are large or symptomatic at diagnosis. It can be well treated with both open and endovascular technique in the elective situation, but mortality is high in emergency situations. The durability of endovascular techniques is as yet unproven, and there are no data to support its preferential use. Open surgery with exposure of the proximal subclavian artery aneurysm is associated with increased morbidity and mortality, but open surgery remains the only method with proven durability and, should, therefore, be the treatment of choice in the majority of patients .
Visceral Artery Aneurysms
Splenic Artery Aneurysms
Splenic artery aneurysms are the second most common in the abdominal cavity excluding aorto-iliac aneurysms and they respond for 60 % of visceral aneurysms. The typical age presentation is between 60 to 70 years old. It has a 4:1 female:male predominance and is frequently encountered in women with multiple pregnancies. Hormonal changes during pregnancy may be associated with structural weakening and increased arterial wall stress. A similar underlying pathophysiology is thought to be involved in the formation of splenic artery aneurysms in patients with portal hypertension. Although splenic artery aneurysm is four times more common in women, splenic artery aneurysm is approximately three times more likely to rupture in men . Splenic pseudoaneurysms have a slight male predominance, probably related to pancreatitis and pancreatic pseudocyst . True aneurysms of the splenic artery are usually smaller than 3 cm at diagnosis and calcification, and mural thrombus may frequently occur. However, calcification does not appear to protect against rupture and recent clinical studies suggest that the risk of rupture is low, perhaps close to 2–3 %. Rupture risk is increased with liver transplantation, portal hypertension, and pregnancy, with a high mortality to both mother and fetus . There is no firm consensus on the aneurysm size for intervention in asymptomatic patients, but there is general agreement that aneurysms greater than 2.0 cm in good-risk patients should be repaired . An endovascular first approach is recommended, especially in patients with pseudoaneurysms. Open surgical intervention is still the treatment of choice in cases of aneurysm rupture and hemodynamic instability, and those with unfavorable anatomy for the endovascular option .