Splenic Artery Aneurysm


Article Author:
Mohammed Kassem


Article Editor:
Lorena Gonzalez


Editors In Chief:
Ritesh Menezes


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Frank Smeeks
Kristina Soman-Faulkner
Trevor Nezwek
Radia Jamil
Patrick Le
Sobhan Daneshfar
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
6/29/2019 1:54:49 PM

Introduction

The splenic artery is defined as aneurysmal when a focal dilation is observed in its diameter of greater than 50% compared to the normal vessel diameter. The normal diameter of the splenic artery varies and ranges from 0.43 cm to 0.49 cm. True splenic artery aneurysms (SAAs) involve all layers of the wall, each of which is intact and thinning. Pseudoaneurysms are the result of a tear in the vessel wall intima with subsequent blood dissection into a false lumen and periarterial hematoma formation. They develop secondary to trauma or inflammation of the splenic artery, such as in cases of pancreatitis. The SAA is the most common visceral artery aneurysm reported. SAA represents 60% to 70% of patients diagnosed with visceral artery aneurysms (VAAs). Hepatic artery aneurysms have been reported in 20%, while celiac or mesenteric artery aneurysms represent 10% of all reported cases of VAAs.[1][2][3]

Etiology

Modifiable risk factors include atherosclerosis, portal hypertension, liver transplantation, pregnancy, and connective tissue disorders such as Marfan or Ehler-Danlos syndrome. Recent studies demonstrate splenic pseudoaneurysms occur in up to 21% of patients diagnosed with chronic pancreatitis. Non-modifiable risk factors include advanced age and female gender. Splenic artery pseudoaneurysms have been associated with blunt and penetrating trauma as well as iatrogenic trauma during instrumentation.[4]

Epidemiology

The prevalence of SAA in general population is reportedto be less than 1%, as most of the SAAs remain asymptomatic and therefore go undetected. A recent retrospective study found that 78% of SAAs occur in women. Mortality because of splenic aneurysm rupture in non-pregnant patients ranges from 25% to 40%. However, maternal mortality due to SAA rupture increases up to 75%, and fetal mortality increases as high as 95%.[5][6] 

Pathophysiology

The exact etiology of visceral aneurysms is not established. Recent literature has suggested that true aneurysms develop secondary to arterial wall weakness due to several causes. These include atherosclerosis (32%), medial degeneration or dysplasia (24%), abdominal trauma (10%), hypertension, connective tissue diseases, and necrotizing vasculitides such as polyarteritis nodosa or Wegner granulomatosis. Pseudoaneurysms are periarterial hematomas that develop as a consequence of iatrogenic trauma or inflammatory processes such as chronic pancreatitis. Pseudoaneurysms lack a true wall hence they are more prone to rupture.

Toxicokinetics

The splenic artery is one of the major branches of the celiac axis.  It courses along the superior aspect of the body, and the tail of the pancreas towards the splenic hilum arises, but its course can be variable. The artery is commonly tortuous, dividing into separate branches that provide a segmental blood supply to the spleen. Aneurysms arise in the middle or distal third of the splenic artery near its bifurcation. SAAs are usually saccular as opposed to fusiform.

History and Physical

The most common presenting symptom is vague epigastric or left upper quadrant abdominal pain that may radiate toward the left shoulder. Other symptoms include gastrointestinal hemorrhage with subsequent hematemesis or hematochezia, or hemorrhage into the pancreatic duct with subsequent hemobilia.True aneurysms can be silent and asymptomatic; however, pseudoaneurysms are always symptomatic. Rupture is a rare but serious complication of SAA which may manifest by acute diffuse abdominal pain and hypovolemic shock with signs and symptoms of an acute surgical abdomen. Rupture incidence increases in multiparous women and patients with portal hypertension due to increased portal blood flow. The reported risk of SAA rupture is 2% to 10%, which is increased to 76% to 83% in symptomatic patients.

Evaluation

Multi-slice abdominal computerized tomography (CT scan) with IV contrast is the ideal diagnostic imaging modality to diagnose SAA and other visceral aneurysms. CT is useful in detecting small SAAs and assessing anatomy for operative planning. Magnetic resonance imaging (MRI) is an alternative to CT, especially in patients with chronic renal insufficiency. Contrast angiography (CA) is the most specific imaging test to identify SAAs and may also be therapeutic. Endoscopic ultrasound can reliably distinguish SAAs from other extrinsic lesions such as pancreatic pseudocysts. [7][8]

Treatment / Management

Due to the increased risk of aneurysmal rupture, intervention rather than a watchful waiting is advised for aneurysms greater than 2 cm in diameter. Other indications for intervention include: symptomatic patients, women of childbearing years, concomitant pregnancy, and cirrhotic patients planning to undergo orthotopic liver transplantation or Porto venous shunting procedures.[9][10]

Open surgical approach: Open surgical intervention is considered the gold standard approach for SAA repair. Techniques involving resection of an aneurysm with interposition bypass are ideal for aneurysms located in the proximal to the mid-splenic artery. Resection of an aneurysm can be combined with splenectomy in cases of a hostile abdomen or distal aneurysms located near the splenic hilum. Patients with ruptured splenic aneurysms should undergo urgent laparotomy and control of hemorrhage with ligation of an aneurysm. Preservation of the spleen is encouraged when possible, but splenectomy should be performed if adequate hemostasis is impossible to achieve otherwise.

Endovascular approach: Endovascular intervention has gained a lot of popularity recently in managing aneurysms. Techniques vary according to the type of an aneurysm, location, whether preserving the splenic artery will be preserved, and the condition of collaterals. Fusiform true aneurysms are better treated with a stent graft (covered stent), while tortuous, saccular aneurysms are treated with aneurysmal coiling techniques. Pseudoaneurysms can be treated with embolization using liquid embolic agents to thrombose the inflow and outflow arteries or filling the sac itself. Distal splenic embolization should be avoided.

Minimally invasive laparoscopic approach:  The laparoscopic approach is a safe therapeutic alternative for cases of elective splenic aneurysm repair. Different techniques have been employed including ligation of the mid-splenic artery via stapling or clipping to splenectomy alone for distal SAAs near the hilum. Splenectomy with distal pancreatectomy may be necessary when the aneurysmal wall is severely inflamed and adherent to the tail of the pancreas. The laparoscopic approach carries the advantage of the rapid recovery, shorter hospital stay, and less postoperative pain compared with the open approach. The laparoscopic approach is also suitable and safe in pregnant SAA patients. Compared with the open approach, laparoscopic splenic aneurysm repair has a lower risk of preterm labor in these patients due to minimal manipulation of intra-abdominal contents.

Pearls and Other Issues

SAA in Pregnancy

SAAs occur predominantly in multiparous women. The true prevalence of SAA in pregnancy is unknown. Fifty percent of SAAs that occur in pregnancy eventually rupture during pregnancy.

Two-thirds of SAA rupture in the third trimester and typically in the last two weeks of pregnancy. Multiple factors have been linked to increased SAA incidence particularly in pregnant women.

One hypothesis suggests that the increased blood flow and cardiac output in pregnancy may result in increased force against the vessel wall. Another hormonal hypothesis suggests that increased estrogen and progesterone presumably result in medial degeneration of the vessel wall.

Elevated levels of relaxin during pregnancy may enhance the elasticity of splenic artery leading to aneurysmal dilation. Additionally, increased frequency of SAAs rupturing in late pregnancy is presumably linked to an increased mechanical pressure of the enlarging gravid uterus.

Enhancing Healthcare Team Outcomes

Splenic artery aneurysms are the most visceral aneurysms and may be either true or false. With more frequent use of imaging studies, these aneurysms are now being discovered incidentally. However, because of the risk of rupture, it is important that healthcare professionals including nurse practitioners promptly refer these patients to a surgeon or an interventional radiologist. Today, endovascular therapy is increasingly used to manage these aneurysms with a high success rate. For splenic artery aneurysms that rupture, the mortality rates are very high. The highest risk of rupture is during pregnancy and unfortunately, despite the best efforts, often leads to a loss of two lives.[11][7]


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Splenic Artery Aneurysm - Questions

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Which is true regarding a splenic artery aneurysm?



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Which of the following is not a true claim about splenic artery aneurysms?



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Splenic artery aneurysm is associated with all except which of the following?



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A middle-aged female was being worked up for intermittent claudication. The radiologist evaluated the upper and lower abdomen, and one of the static images is shown below. The patient has a history of hypertension, chronic obstructive pulmonary disease, and gout. She is on enalapril, albuterol, and allopurinol. She is a smoker and drinks alcohol socially. After discussing her condition found in the image below, she would like to know what she can do to avoid future complications. Which of the following is most important?

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Splenic Artery Aneurysm - References

References

Arghami A,Krajewski AC,Gloviczki P,Leduc C,Lin PT, Open staged repair of splenic and extensive superior mesenteric artery aneurysms. Journal of vascular surgery. 2018 Oct 3     [PubMed]
Qiu P,Zhu H, Endovascular Repair of Anomalous Splenic Artery Aneurysm with Systemic Lupus Erythematosus. Annals of vascular surgery. 2018 Sep 11     [PubMed]
Therakathu J,Panwala HK,Bhargava S,Eapen A,Keshava SN,David D, Contrast-enhanced Computed Tomography Imaging of Splenic Artery Aneurysms and Pseudoaneurysms: A Single-center Experience. Journal of clinical imaging science. 2018     [PubMed]
van Rijn MJ,Ten Raa S,Hendriks JM,Verhagen HJ, Visceral aneurysms: Old paradigms, new insights? Best practice     [PubMed]
Kaya M,Baran Ş,Güya C,Kaplan MA, Prevalence and predictive factors for development of splenic artery aneurysms in cirrhosis. Indian journal of gastroenterology : official journal of the Indian Society of Gastroenterology. 2016 May     [PubMed]
Veluppillai C,Perreve S,de Kerviler B,Ducarme G, [Splenic arterial aneurysm and pregnancy: A review]. Presse medicale (Paris, France : 1983). 2015 Oct     [PubMed]
Fang G,Chen B,Fu W,Guo D,Xu X,Jiang J,Luo J,Dong Z, Strategies for endovascular treatment of complicated splenic artery aneurysms. Journal of vascular surgery. 2018 Sep     [PubMed]
Özdemir M,Ökten RS,Küçükay F,Ereren M,Özdemir FAE,Akdoğan M,Kaçar S,Bostancı EB, Multidetector Computed Tomography Findings of Splenic Artery Aneurysms Associated With Liver Involvement in Wilson's Disease. Transplantation proceedings. 2017 Oct     [PubMed]
Venturini M,Marra P,Colarieti A,Agostini G,Lanza C,Augello L,Gusmini S,Salvioni M,Melissano G,Fiorina P,Chiesa R,De Cobelli F,Del Maschio A, Covered stenting and transcatheter embolization of splenic artery aneurysms in diabetic patients: A review of endovascular treatment of visceral artery aneurysms in the current era. Pharmacological research. 2018 Sep     [PubMed]
Ouchi T,Kato N,Nakajima K,Higashigawa T,Hashimoto T,Chino S,Sakuma H, Splenic Artery Aneurysm Treated With Endovascular Stent Grafting: A Case Report and Review of Literature. Vascular and endovascular surgery. 2018 Nov     [PubMed]
Nasser HA,Kansoun AH,Sleiman YA,Mendes VM,Van Vyve E,Kachi A,Berjawi T,Hamdan WS,El Nakadi I, Different laparoscopic treatment modalities for splenic artery aneurysms: about 3 cases with review of the literature. Acta chirurgica Belgica. 2018 Aug     [PubMed]

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