Giant Splenic Artery Aneurysm

Introduction

Splenic artery aneurysm (SAA) is an infrequent occurrence, but it is important to evaluate the size and the location of the aneurysm to prevent life-threatening complications. SAA is more common in women than in men. Pregnancy is a major risk factor for rupture. The patient presented here had a very poor general condition, with acute pancreatitis and other severe comorbid conditions. There was a high risk of SAA rupture, owing to the huge size. Angioembolization of SAA was performed successfully with metallic coils. Endovascular procedures are currently the first choice of treatment for SAA. Open surgeries for this condition are now performed less often.

Case Report

A 57-year-old man with a history of obesity, diabetes, hypercholesterolemia, and chronic alcoholism was admitted because of pain in the epigastrium and left flank. Laboratory tests showed normal liver functions. The patient had leukocytosis and elevated serum amylase and lipase levels. At admission, the patient had four Ransom’s criteria. The initial computerized axial tomography (CT) scan confirmed the features of acute pancreatitis and a diverticulosis of the left colon. There was also an inflammatory mass in the left upper quadrant of the abdomen. A tortuous SAA measuring 5 cm with a wide neck was identified. In the lower lobe of the left lung, there was a large infiltrate. Echocardiography revealed a patent foramen ovale. Taking into consideration the acute pancreatitis and other comorbid conditions, a decision was made to perform angioembolization. The procedure was performed through the right groin with puncture of the right femoral artery. A catheter (Cook, Bloomington, Indiana) was used through a 5-Fr sheath. An angiogram to delineate the aneurysm and position of the catheter was done. The aneurysm was occluded by embolization through a tracker catheter using multiple detachable metallic coils. The post-procedure CT scan showed a partial thrombosis and a follow-up CT scan demonstrated complete thrombosis of the aneurysm. Supportive care in the form of intravenous fluids, total parenteral nutrition (TPN), control of diabetes, and antibiotics was continued until acute pancreatitis and pneumonia subsided. The patient was discharged in stable condition. CT scans 6 months and 1 year after discharge showed persistence of the complete thromboses of the aneurysm

Discussion

SAA constitute 60% of all splanchnic aneurysms. SAA are second in frequency to femoroiliac artery aneurysms. SAA larger than 3 cm are rare,¹ but giant aneurysms, measuring 10 cm or more have been reported.² An aneurysm of 5 cm, as in our case, raised serious concerns regarding the risk of rupture and bleeding. SAA may present with mild symptoms, such as vague pain in the left upper quadrant of the abdomen or epigastrium. These aneurysms can be asymptomatic.⁴ Complications, such as ruptures, are life threatening. In women, pregnancy is a major risk factor for rupture; approximately 95% of them occur in the second trimester. The maternal mortality in these cases is 75% and the fetal mortality is as high as 95%.³ Pancreatitis, either chronic or acute, can be a direct cause of SAA. Other causes include fibrodysplasia, hormonal changes associated with pregnancy, portal hypertension, trauma, and orthotropic liver transplantation. Splenic artery pseudoaneurysms have been described in association with pancreatitis and particularly with pancreatic pseudocysts.⁴ Bleeding from SAA may initially be contained in the lesser sac, which later can rupture into the general peritoneal cavity, thus creating the so-called double-rupture phenomenon. In cases of the rupture of pseudoaneurysms due to pancreatitis, bleeding occurs more commonly in the gastrointestinal tract. A pseudocyst can lead to the formation of an SAA. If it erodes into the stomach, the patient may present with hematemesis.⁵

Pseudoaneurysms in the spleen carry a very high chance of rupture. Hemorrhagic complications of aneurysms or pseudoaneurysms in association with pseudocysts are life threatening.6 Differentiation of a pseudoaneurysm from a ruptured aneurysm into a post pancreatitis pseudocyst may be difficult. CT scans are important in the initial evaluation of this condition. Plain abdominal radiographs occasionally show signet ring calcifications. Although color Doppler studies are usually not done initially in most of the cases, Doppler studies done for other reasons may pick CT incidentally. Some authors consider this modality very reliable in diagnosis.⁷ Certainly these tests have great potential as follow-up tools. Many different management strategies have been proposed for aneurysms and pseudoaneurysms of the splenic artery. The choice is governed by the condition of the patient, the exact morphology of the aneurysm, and the availability of the resources. The current data support the use of endovascular procedures as first choice of treatment for SAA.

Angiography and possibly angioembolization should be considered for all patients who are hemodynamically stable.⁸ A consideration to preserve the spleen and its function should be made in all cases. Beta blockers can be helpful in preventing the growth of the aneurysms.⁹ Female patients with SAA who are likely to get pregnant and patients who are candidates for orthotopic liver transplant should get preventive treatment.¹⁰ Open surgery is reserved mostly for the treatment of complications in relatively stable patients. Ruptured aneurysms require aggressive attempts at resuscitation and surgical exploration if interventional radiology is not available or fails.^11,12 The location on the artery of the aneurysm makes a serious difference in surgical management. If the aneurysm is located in the distal third of the artery and the aneurysm has to be resected, the patient may ultimately require a splenectomy. If the aneurysm is located in the proximal third of the artery, splenic conservation should be attempted.¹³ If surgery is performed, difficulties that can be encountered are the presence of a phlegmon, inability to find the plane of dissection, excessive bleeding, and inadvertent injury to the viscera.

For ruptured aneurysms and pseudoaneurysms, splenectomy or splenopancreatectomy may be necessary.^14,15 Dense adhesions to the surrounding structures sometimes make exclusion of the aneurysm necessary by proximal and distal ligation of the artery. Proximal control of the splenic artery in this situation is sometimes difficult.¹⁶ In cases when the aneurysm is adherent to the pancreas and no dissection plane is defined, it is reasonable to open the aneurysm and leave its posterior wall in situ.¹⁷ Pulli at al¹⁸ restored arterial continuity in 10 cases of SAA. Their series included patients who underwent surgery between 1982 and 2000, when interventional radiology was not widely available.¹⁸ Open surgery remains an option when the patient is allergic to contrast medium, when angiography has failed, or when patients with chronic renal insufficiency need urgent intervention. Laparoscopic surgery for SAA has also been attempted but requires an operator with advanced skills.¹⁹ Endovascular interventions have been performed with increased frequency in the last decade. Stent grafts also have been used successfully.²⁰ Pilleul and Dugougeat²¹ published a series of 25 transcatheter embolizations. In their series, 8 patients had complete embolization; in the remaining patients, only partial occlusion was achieved. The authors concluded that in cases of large aneurysms, embolization is likely to be incomplete.²¹ Davis at al²² emphasized the need for aggressive use of embolization in cases of splenic artery pseudoaneurysms that develop after blunt trauma. Their success rate was 61%.²² Endovascular interventions are also the favored approach for patients who are immunocompromised.²² Cyanoarylate glue has been successfully used in occluding aneurysms.²³ Coil embolization has been used with good results in mycotic SAA and in cases of wide-mouthed aneurysms, such as the one reported here.²⁴ Splenic infarcts can occur after embolization.²⁵ Some authors consider that catheter embolization is best used as a temporary measure to stop bleeding from ruptured SAA, stressing the need for formal intervention at a later time. Others exclude any endovascular intervention in cases of giant SAA with extreme tortuosity. We feel that in such cases the choice of procedure should be considered individually. The skill and experience of the interventional radiologist and the availability of facilities are key factors. Three-dimensional CT scans and colored Doppler sonography have been the favored investigational tools for the follow up of a SAA endovascular procedure.

Conclusion

Endovascular interventions should be considered as first choice in both emergency and elective treatment of SAA. Controversy and questions exist regarding the effectiveness of different types of endovascular procedures and the need for surgical interventions after successful embolization. Recanalization of the aneurysm managed by embolization is a real possibility. All such patients need a close follow up. Considering the nature of SAA and their infrequent occurrence, it is unlikely that controlled studies will ever be done.

Acknowledgement

The authors would like to thank Dr. Eugene Albu for his great help.