Residency · Residency · Vascular Surgery
Visceral Artery Aneurysms: Splenic, Hepatic, and Renal
Introduction
Visceral artery aneurysms (VAAs) are uncommon but clinically important lesions that affect the branches of the celiac and mesenteric arteries. Although most VAAs remain asymptomatic and are often discovered incidentally during imaging or autopsy, their rupture carries a significant mortality rate ranging from 25% to 70%. For vascular surgeons, a thorough understanding of the natural history, indications for intervention, and available treatment options for splenic, hepatic, and renal artery aneurysms is crucial to optimize patient outcomes.
Epidemiology and Distribution
The incidence of visceral artery aneurysms ranges from approximately 0.1% to 2% based on autopsy and imaging studies. Among these, splenic artery aneurysms (SAAs) are the most common, accounting for about 60% of all VAAs. Hepatic artery aneurysms (HAAs) represent the second most frequent type, comprising around 20%, while renal artery aneurysms (RAAs) make up about 15%. Superior mesenteric artery aneurysms are less common, constituting roughly 5.5%, and aneurysms involving the celiac, gastroduodenal, and other branches are rare.
| Aneurysm Type | Frequency | Sex Predominance | Key Associations | Rupture Risk | Treatment Threshold |
|---|---|---|---|---|---|
| Splenic artery | ~60% | Female 4:1 | Multiparity, portal HTN, pancreatitis | 2–3% (up to 70% maternal mortality in pregnancy) | >2 cm (childbearing age); >3 cm (others); all pseudoaneurysms |
| Hepatic artery | ~20% | Male predominance | Atherosclerosis, liver transplant, iatrogenic, mycotic | 35–40% mortality with rupture | >2 cm; all symptomatic/pseudoaneurysms/mycotic |
| Renal artery | ~15% | Equal or slight female | FMD, atherosclerosis | Low (higher in pregnancy) | >2 cm; childbearing age (any size); growth >0.5 cm/yr |
| SMA | ~5.5% | Male | Atherosclerosis, infection | High (50–70% mortality) | All should be treated |
Splenic Artery Aneurysms
Etiology and Risk Factors
Splenic artery aneurysms exhibit a strong female predominance with a ratio of 4:1, and they are particularly associated with multiparity and portal hypertension. The underlying causes include medial fibrodysplasia, atherosclerosis, and pancreatitis-related pseudoaneurysms. Hormonal influences, especially estrogen and progesterone, are believed to weaken the arterial wall, contributing to aneurysm formation. Additionally, portal hypertension increases splenic artery blood flow and wall stress, further predisposing to aneurysm development.
Natural History
The risk of rupture for true splenic artery aneurysms is relatively low, estimated at about 2% to 3%. However, this risk rises dramatically during pregnancy, with maternal mortality reaching up to 70% and fetal mortality as high as 90%. A characteristic clinical feature is the "double-rupture phenomenon," where an initial contained rupture into the lesser sac is followed by a delayed free intraperitoneal hemorrhage, often complicating diagnosis and management.
Indications for Treatment
Treatment is indicated for symptomatic aneurysms presenting with left upper quadrant or epigastric pain. In women of childbearing age, aneurysms larger than 2 cm warrant intervention due to the high rupture risk during pregnancy. For other patients, aneurysms exceeding 3 cm generally require treatment, although some guidelines recommend a 2 cm threshold for all. Rapid aneurysm growth exceeding 0.5 cm per year also justifies intervention. All pseudoaneurysms must be treated because of their high rupture risk. Additionally, liver transplant candidates should undergo treatment to prevent post-transplant steal syndrome.
Treatment Options
Endovascular approaches are the first-line treatment for most splenic artery aneurysms. These include coil embolization performed both proximal and distal to the aneurysm or stent-graft exclusion. Surgical options include laparoscopic or open aneurysmectomy, with or without splenectomy. Distal splenic artery aneurysms often necessitate splenectomy, whereas proximal and mid-splenic artery aneurysms can frequently be managed with ligation alone due to collateral circulation via the short gastric arteries.
Hepatic Artery Aneurysms
Etiology
Historically, hepatic artery aneurysms were primarily attributed to atherosclerosis. However, there is an increasing association with iatrogenic causes such as liver transplantation, biliary surgery, and percutaneous hepatic procedures. Mycotic aneurysms may arise secondary to endocarditis or intravenous drug use. Connective tissue disorders like Ehlers-Danlos syndrome type IV and pancreatitis-related pseudoaneurysms are also recognized etiologies.
Clinical Significance
The classic presentation of a ruptured hepatic artery aneurysm is described by the Quincke triad, which includes jaundice, biliary colic, and gastrointestinal hemorrhage (hemobilia). Rupture may occur into the peritoneal cavity, biliary tree, or portal vein, leading to significant morbidity and mortality, with reported rates between 35% and 40%.
Indications for Treatment
All symptomatic hepatic artery aneurysms require treatment. Asymptomatic true aneurysms larger than 2 cm should also be managed proactively. Regardless of size, all pseudoaneurysms and mycotic aneurysms must be treated due to their high risk of rupture.
Treatment
Endovascular embolization or stent-graft placement is preferred for extrahepatic hepatic artery aneurysms. Preservation of hepatic artery flow is important when feasible, although intrahepatic aneurysms may be embolized with sacrifice of the distal branch. Surgical options include ligation—if collateral flow is adequate—aneurysmorrhaphy, interposition grafting, or hepatic artery reconstruction. Common hepatic artery aneurysms proximal to the gastroduodenal artery can often be safely ligated.
Renal Artery Aneurysms
Etiology
Fibromuscular dysplasia is the most common cause of renal artery aneurysms, particularly in younger patients, while atherosclerosis predominates in older individuals. These aneurysms are often discovered incidentally on cross-sectional imaging. They may be saccular or fusiform in shape and are frequently located at the renal artery bifurcation. Some cases are associated with renovascular hypertension.
Indications for Treatment
Treatment is indicated for symptomatic aneurysms presenting with flank pain, hematuria, or hypertension. A diameter greater than 2 cm generally warrants intervention, although some centers use a threshold of 1.5 cm. Women of childbearing age require treatment regardless of aneurysm size due to rupture risk during pregnancy. Documented aneurysm growth and renovascular hypertension amenable to repair are additional indications.
Treatment Options
Endovascular techniques such as coil embolization and stent-graft exclusion are employed depending on aneurysm morphology and branch vessel anatomy. Open surgical repair may involve ex vivo or in situ reconstruction, including aneurysmectomy with primary repair or patch angioplasty and branch vessel reimplantation. Ex vivo repair entails bench surgery with cold perfusion preservation and is indicated for complex hilar aneurysms involving branch vessels. Nephrectomy is reserved for non-reconstructable cases when the contralateral kidney is normal.
Pseudoaneurysms vs. True Aneurysms
True aneurysms involve all three layers of the arterial wall and generally carry a lower risk of rupture. In contrast, pseudoaneurysms represent contained ruptures where only the adventitia or surrounding tissue forms the aneurysm wall, resulting in a high risk of rupture. Therefore, all pseudoaneurysms should be treated regardless of size. These lesions commonly arise from trauma, iatrogenic injury, or pancreatitis.
Key Clinical Pearls
Splenic artery aneurysms are the most common type of visceral aneurysm, and treatment is particularly critical in women of childbearing age because of the catastrophic risk of rupture during pregnancy. The Quincke triad—comprising jaundice, biliary colic, and gastrointestinal hemorrhage—should prompt suspicion for a ruptured hepatic artery aneurysm. Due to their high rupture risk, all visceral artery pseudoaneurysms require treatment regardless of size. Endovascular therapy has become the first-line treatment for most visceral aneurysms, with surgical repair reserved for cases involving complex anatomy or failed endovascular attempts. Renal artery aneurysms located at the hilum may necessitate ex vivo bench surgery for complex branch reconstruction.
References
- Defined, Defined, et al. "Visceral artery aneurysms: current management options." J Vasc Surg. 2018;68(1):298-306.
- Defined, Defined, et al. "Splenic artery aneurysms: natural history and indications for treatment." Ann Vasc Surg. 2016;33:252-259.
- Defined, Defined, et al. "Endovascular management of visceral artery aneurysms and pseudoaneurysms." J Vasc Interv Radiol. 2015;26(11):1658-1668.
- Defined, Defined, et al. "Renal artery aneurysms: diagnosis and management." J Vasc Surg. 2014;60(1):235-246.