Splenic artery aneurysm is a rare but dangerous condition with female predominance. It is poorly treatable, is usually asymptomatic, and often ruptures spontaneously.
Visceral artery aneurysm is a rarity among arterial aneurysms, accounting for 0.1-2%. With 60%, the lienal artery is the main localization of visceral aneurysms, followed by the hepatica communis artery with 20-30%. It is the only thoracoabdominal aneurysm that occurs more frequently (4:1) in women than in men, especially in pregnant women and multipara [1,2]. The morphology of lienal artery aneurysm verum is fusiform or sacciform, the occurrence solitary or multiple, extra- or intrasplenic. To be distinguished from this are pseudoaneurysms that result from vascular erosion (pancreatitis) or as a complication of endovascular, hepatobiliary procedures [2,3].
Case studies
Case 1: A 58-year-old female patient was sonographically diagnosed with a mass in the left upper abdomen as an incidental finding. A suspected diagnosis of splenic artery aneurysm was made by duplex sonography and confirmed by CTA. At diagnosis, the solitary aneurysm had a size of 18×13×15 mm (Fig. 1).
Due to the distal location of the aneurysm and good accessibility, an endovascular approach was favored. As part of the challenging procedure, the aneurysm was eliminated from the systemic circulation by implanting a covered stent (5×50 mm) into the lienal artery (Fig. 2). Dual platelet aggregation with ASA and clopidogrel was prescribed for eight weeks. Duplex sonographic controls were unremarkable postintervention.
Case 2: During gastrointestinal diagnostic workup, a 43-year-old multipara (eight children) was incidentally diagnosed with splenic artery aneurysm by duplex sonography. Three aneurysms of the lienal artery close to the hilus were detected by CTA, the largest of which had a diameter of 19 mm (Fig. 3). The multiple and hilar manifestations indicated surgical intervention (Fig. 4) . Three weeks after diagnosis, laparoscopic splenectomy was performed. Postoperatively, the patient was discontinued on ASA.
Pathogenesis and natural history
The pathogenesis is predominantly arteriosclerotic in nature. Other causes include fibromuscular dysplasia, inflammatory and infectious processes, and hereditary connective tissue defects. Cirrhosis of the liver with portal hypertension appears to influence the development of splenic artery aneurysm.
The predominance of female sex is not yet fully understood, but pregnancy-associated hemodynamics with portal hypertension, pendulum flow in the portal vein, and blood flow augmentation play a role, as do hormonal influences on blood flow and damage to elastic fibers of the vessel wall. A pregnancy-associated hypertensive component (preeclampsia, gestational hypertension) is discussed [2–4]. Pregnant women and postmenopausal multipara are thus risk groups for the development of splenic artery aneurysm.
Data on the natural history of splenic artery aneurysm are sparse. Predictors of rupture include aneurysm size of >2 cm (rupture rate 30-40%) and sacciform morphology, rapid growth, and hormonal and hemodynamic changes during pregnancy. 20-45% of splenic artery aneurysms rupture during pregnancy, most commonly in the third trimester and immediately after delivery (69%). Maternal (75%) and fetal (95%) mortality is notably high in this setting [2,5–8].
Clinic and diagnostics
The clinical course is usually asymptomatic, with 95% of pregnant women becoming symptomatic in the third trimester. Occurring symptoms are variable, usually an expression of a complication and difficult to distinguish from pregnancy-associated complaints. The clinic ranges from left upper abdominal pain to acute abdomen with hemorrhagic shock (blood pressure and Hb drop) with spontaneous rupture [2,5–8].
Generally, asymptomatic splenic artery aneurysms are diagnosed by a flow murmur in the left upper abdomen, a calcific shadow on abdominal plain radiography, or by color-coded duplex sonography (pulsatile/perfused tumor); symptomatic ones are diagnosed by workup of gastrointestinal symptoms. The method of choice is CTA, which allows reliable assessment of vessel morphology (wall and course pathologies) and existing complications (occlusion, embolism, compression, fistulation with bleeding and rupture). Intra-arterial mesentericography visualizes collateral circulation (Aa. gastricae breves), aids in treatment planning, and allows for an endovascular approach in the same session.
In pregnant women, the suspected diagnosis of splenic artery aneurysm is predominantly made sonographically and by color-coded duplex sonography. Radiation exposure should be avoided, with only a vital maternal threat justifying the use of CTA or mesenteric imaging. Alternatively, the use of MRI or MRA should be considered. The same applies to young women who want to have children.
Splenic artery aneurysm therapy
Individualized, risk-adapted therapy for splenic artery aneurysm is surgical or endovascular. The goal is to eliminate the aneurysm from the systemic circulation to avoid rupture or complications.
The choice of therapeutic procedure is influenced by the location and morphology of the aneurysm, complications that have occurred, existing gravidity, and the patient’s wishes. Treatment indications are generally symptomatic aneurysm, aneurysm size >2 cm and rapid size increase (wall weakness). Consideration is also given to aneurysm morphology, as sacciform aneurysms are more likely to rupture than fusiform ones. Some authors recommend elimination of the aneurysm when the size is three to four times the original vessel diameter. Pseudoaneurysms are treated regardless of size because of the high risk of rupture [2,6,9].
A wait-and-see approach is indicated in small, asymptomatic aneurysms without significant size increase and in inoperable patients who cannot be treated endovascularly. If the size increases to 5 cm, action must be taken [2]. Aneurysm rupture is an emergency indication for immediate care. Similarly, mycotic splenic artery aneurysm does not allow time deferral [1,2,6–9].
Surgical procedures include laparotomy and laparoscopy, which are associated with major surgical trauma. Aneurysm manifestation (solitary, multilocular), location (extra-, intrasplenic), and collateral circulation determine the possibility of organ preservation. Various techniques (end-to-end anastomoses, interposition, aneurysmorrhaphy) are used. If organ preservation is not possible, splenectomy is performed. The laparoscopic approach allows surgical repair even in high-risk patients. Patients treated surgically are considered cured [2,6,9].
The advantage of endovascular procedures (coils, covered stents) is minimal invasiveness and the ability to treat inoperable high-risk patients with organ preservation. Disadvantages include radiation and contrast agent exposure. Technical realization may fail due to pronounced vascular tortuosity. In case of rupture, endovascular coiling of the lienal artery or catheter blockade is possible. The endovascular approach is potentially associated with recurrent procedures [2,5,7,10].
Pregnant women should be surgically rehabilitated after the first trimester because embryogenesis is complete and uterine size does not yet interfere with the surgical procedure. Endovascular procedures are contraindicated due to radiation exposure [2,8]. If rehabilitation is not possible in a high-risk pregnancy with maternal inoperability, this requires intensive interdisciplinary observation, especially in the last trimester. In pregnant women and multipara, the indication for therapy should be rather generous because of the high spontaneous rupture rate [2,9,10].
Take-Home Messages
- The lienal artery is the most common site of visceral aneurysms with predominance of females.
- Splenic artery aneurysm is poorly treatable, usually asymptomatic, and often ruptures spontaneously primary in pregnant women and multipara.
- Gravidity is a pathogenetic factor of splenic artery aneurysm.Diagnosis is usually made incidentally by abdominal ultrasonography and color-coded duplex sonography, with pancreatic pseudocyst being the most common differential diagnosis.
- In pregnant women, the treatment of choice is surgical repair at the beginning of the second trimester.
Acknowledgments: I would like to thank Prof. Dr. med. Sven Mutze, Director of the Institute of Radiology and Neuroradiology at Unfallkrankenhaus Berlin and Head of the Institute of Radiology at Sana Klinikum Lichtenberg, for providing the image material used (Fig. 1 and 2). I would also like to thank Jens Nickel, MD, senior physician at the Institute for X-ray Diagnostics at Asklepios Klinikum Pasewalk, for the image documentation provided (Figs. 3 and 4).
Literature:
- German Society for Vascular Surgery: Aneurysms of the coeliac trunk, lienal, hepatic and mesenteric arteries (S2). In: Guidelines for Diagnostics and Therapy in Vascular Surgery. Berlin/Heidelberg: Springer, 2010: 41-45.
- Meyer A, Lang W: Visceral artery aneurysms. Vascular Surgery 2011; 16: 355-362.
- Sessa C, et al: Treatment of visceral artery aneurysms: description of a retrospective series of 42 aneurysms in 34 patients. Ann Vasc Surg 2004; 18: 695-703.
- Anders S, et al: Sudden death in ruptured splenic artery aneurysm. Forensic Medicine 2000; 10(6): 201-206.
- Croner RS, et al: Aneurysms of visceral arteries. Dtsch Arztebl 2006; 103(20): A1367-1371.
- Hanschke D, Eberhardt E: Giant aneurysm of the lienal artery – a casuistry. Vascular Surgery 2002; 7(2): 70-73.
- Guillon R, et al: Management of Splenic Artery Aneurysms and False Aneurysms with Endovascular Treatment. Cardiovasc Intervent Radiol 2003; 26(3): 256-260.
- Grotemeyer D, et al: The mycotic visceral artery aneurysm. Surgeon 2004; 75: 533-540.
- Lauschke H, et al: The visceral artery aneurysm. Zentralbl Chir 2002; 127(6): 538-542.
- Carr SC, et al: Visceral artery aneurysm rupture. J Vasc Surg 2001; 33(4): 806-811.
CARDIOVASC 2018; 17(4): 3-6
