Mycotic Celiac Artery Aneurysm Following Infective Endocarditis: Successful Treatment Using N-butyl Cyanoacrylate with Embolization Coils

Abstract

Mycotic celiac artery aneurysm following infective endocarditis is extremely rare and, to our knowledge, only four cases have been reported in the literature to date. We describe the case of a 60 year-old man who developed a mycotic aneurysm of the celiac artery, which was detected by computed tomography (CT) following an episode of infective endocarditis. He successfully underwent endovascular isolation and packing of the aneurysm using N-butyl cyanoacrylate (NBCA) with embolization coils.

Introduction

Aneurysm of the celiac artery accounts for 4% of all visceral artery aneurysms (VAA).¹⁾ Mycotic celiac artery aneurysm is extremely rare and, to our knowledge, only four cases have been reported in the literature to date.^3–6) We present a case of mycotic celiac artery aneurysm following an episode of infectious endocarditis. The aneurysm was detected on computed tomography (CT) and successfully treated by endovascular therapy using N-butyl cyanoacrylate (NBCA) with embolization coils.

Case Report

A 60 year-old man who was a healthy and had no previous diseases. The patient was referred to our hospital with a history of persistent fever since four months developed a headache, in addition to the fever. Cranial magnetic resonance imaging (MRI) revealed chronic, multiple cerebellar infarcts. Blood tests performed on admission revealed a high white blood cell counts (14000/μl; normal, <9000/μl) and high C-reactive protein levels(5.767 mg/dl; normal, <0.5 mg/dl). The patient was diagnosed with infective endocarditis on the basis of echocardiographic findings, which revealed vegetation in the anterior mitral leaflet and aortic valve. Initial CT scans performed on admission did not reveal any abnormal findings (Fig. 1A). Blood culture revealed the presence of Streptococcus; consequently, a course of antibiotics (ampicillin+gentamicin) was initiated. On the seventh day after admission, the patient complained of abdominal pain. An abdominal X-ray indicated ileus and blood tests revealed mildly elevated liver function; however, abdominal ultrasound imaging showed no abnormal findings. Hazy mesenteric fat around the celiac artery was observed on CT images (Fig. 1B), which was later identified as the first sign of inflammation. The ileus improved with conservative treatment.

Fig. 1.

Computed tomography imaging.

A: Computed tomography imaging at the time of hospitalization. There are no abnormal findings. B: Seventh day after hospitalization. Hazy fat density is observed around the celiac artery (arrow). C: Thirtieth day after hospitalization. A celiac artery aneurysm (arrow) with a diameter of 17 mm is observed. D: Nine months after hospitalization. Expansion of the celiac artery aneurysm (from17 mm to 50 mm) is observed. The aneurysm was suspected a pseudoaneurysm, and there is sever adhesion among surrounding tissues.

On the thirteenth day after admission, aortic and mitral valve replacement surgery was performed. Aortic valve was replaced by mechanical valve (CarboMedics Top Hat valve, 23 mm, CarboMedics, Inc., Austin, TX, USA). Mitral valve was also replaced mechanical valve (CarboMedics standard mitral valve, 25 mm, CarboMedics, Inc., Austin, Tx, USA). The cultures of those valves were negative.

CT imaging prior to surgery revealed an aneurysm of approximately 17 mm in diameter in the celiac artery (Fig. 1C). Although the clinical course of the patient indicated the diagnosis of a mycotic aneurysm, we decided to keep the patient under strict observation. The patients was given antibiotics via an intravenous route for two weeks following valve replacement surgery and wasswitched to an oral route thereafter. Postoperative CT imaging was performed at regular intervals, but no change was observed in the size of the aneurysm. His postoperative course was uneventful, and he was discharged on the sixteenth postoperative day.

A CT scan (Fig. 1D) performed eight months after valve replacement surgery (9 months after admission) revealed a sudden enlargement of the aneurysm (from 17 mm to 50 mm), leading to the suspicion of a pseudoaneurysm (Fig. 2). He had no symptoms and no fever. Blood tests performed on admission revealed a normal white blood cell counts (6300/μl; normal, <9000/μl) and normal C-reactive protein levels(0.57 mg/dl; normal, <0.5 mg/dl). The aneurysm was large enough to alter the shape of the pancreas. We suspected the pseudoaneurysm. There is the sever adhesion among the celiac artery aneurysm and surrounding tissues. (Fig. 1D). Because he took Warfarin and Aspirin, he had a greater risk of bleeding. We thought open surgical repairs were difficult. Therefore, endovascular embolization was attempted using an approach via the right femoral artery. There were no abnormalities in the superior mesenteric artery (SMA) and portal vein. Celiac angiography revealed a fusiform aneurysm in the trunk of the celiac artery and a pseudoaneurysm located below it (Fig. 3A). The common hepatic and splenic arteries diverged at the fusiform aneurysm, and the left gastric artery branched off the celiac artery from the proximal side of the aneurysm (Fig. 3A).

Fig. 2.

Three-dimensional computed tomography nine months after hospitalization

Three-dimensional computed tomography reveals a celiac artery aneurysm (arrow head) and a pseudoaneurysm located below it (※).

CHA: common hepatic artery; LGA: left gastric artery; SpA: splenic artery; SMA: superior mesenteric artery

Fig. 3.

A: Primary selective angiography of the celiac trunk.

B: After isolation and packing of the aneurysm, collaterals to the liver (arrow) and the spleen via the patent left gastric artery are identified.

CHA: common hepatic artery; LGA: left gastric artery; SpA: splenic artery

First, we performed the embolization of the common hepatic artery using an interlocking detachable coil system (IDC system; Boston Scientific Corp., Massachusetts, USA) and fibered IDC system (Boston Scientific Corp.). Similarly, selective embolization of the splenic artery was performed using the IDC system. For tight packing of the aneurysm, we injected iodized oil (Lipiodol; Guerbet, Aulnay-sous-Bois, France) and NBCA (Histoacryl; B.Braun Melsungen AG, Melsungen, Germany) in a 1:1 ratio into a nest of detachable coils(Cook Medical, Indiana, USA) in the celiac axis under temporary balloon occlusion (3.3F; Fuji Systems Corporation, Tokyo, Japan) to prevent glue migration. Finally, embolization of the celiac axis distal to the left gastric artery was performed using the fibered IDC system, and isolation and packing of the whole aneurysm was completed (Fig. 3B). Postoperatively, normal perfusion to the liver and spleen via a collateral circulation was observed; in addition, there were no postoperative complications. Follow-up MRI revealed shrinkage of the aneurysm; moreover, there was no recurrent infection or recanalization of the aneurysm twelve months after the embolization procedure.

Discussion

Celiac artery aneurysms, which account for approximately 4% of all VAAs,¹⁾ may extend to involve the major branches of the celiac artery to varying degrees.²⁾ Mycotic aneurysms, on the other hand, tend to be multiple, with the most common site of involvement being the femoral artery. However, most mycotic VAAs occur in SMA.^4,6) Mycotic celiac artery aneurysm due to infective endocarditis is extremely rare, and, to our knowledge, only four cases have been reported in the literature to date. (Sweany, 1919; Zeppa, 1966; Jatene, 1990; and Dor 1993)^3–6)

Celiac artery aneurysms presumably arise as a result of arteriosclerosis and medial degeneration; however, trauma, dissection, and Takayasu arteritis can also be causes.²⁾ Because our patient had a medical history of infective endocarditis, we deduced that he developed a pseudoaneurysm subsequent to inflammation of the visceral wall, which was induced by septic emboli.

Early recognition and accurate characterization of this vascular anomaly are essential because the operative mortality rate increases from approximately 5% to 40% if the aneurysm ruptures during surgical intervention.⁷⁾ Because of the rarity of these aneurysms, their natural history is poorly understood. Criteria for intervention in asymptomatic patients should include the following: aneurysms >2 cm in diameter with reasonable operative risk, radiologic evidence of increasing aneurysm size, or size >3–4 times the original diameter of the vessel (8 mm).⁷⁾

Even so, a mycotic celiac artery aneurysm that ruptured on attaining a size of 1.5 cm has been reported.²⁾ However, these were small studies; as a consequence, no strict size criterion has been identified as a risk for rupture. In our case, the earliest CT finding (Fig. 1) was that of hazy mesenteric fat around the celiac artery. Retrospectively, we believe this hazy mesenteric fat be the first sign of inflammation.⁸⁾ Thus, we advocate frequent CT scanning to check for the appearance of hazy mesenteric fat around visceral arteries and to evaluate the possible formation of VAA.

Treatment options for VAA include conventional open surgery and less invasive catheter-based techniques. Several reports document low morbidity and mortality rates with endovascular intervention for VAA, with technical success rates reportedly ranging from 75% to 100%.⁹⁾ Saltzberg et al.⁹⁾ recommended endovascular repair as a first line of treatment for VAAs in anatomically suitable cases, excluding those with lesions located in the distal splenic artery. Endovascular techniques confer many possible advantages: anatomic localization; ability to perform with local anesthesia; easy assessment of collateral circulation; decreased postoperative complications including ileus obstruction, abscess, bleeding, wound infection, and pancreatitis; and shorter hospital stays. However, complications of coil embolization include end organ infarction, sacrifice of the visceral vessel aneurysm recurrence, abscess, arterial disruption, contrast-induced acute kidney injury, pain, fever, embolism, infarction, and access site hematomas.⁷⁾ Occlusion of the celiac trunk should be avoided if the portal vein or SMA are not patent or in cases of liver dysfunction. Occlusion of the gastroduodenal artery also presents a relative contraindication.¹⁰⁾

According to classical surgical considerations, implantation of prosthetic material in an infected environment could hamper a favorable long-term outcome. However, endovascular treatment with appropriate antibiotic therapy can also be a definitive line of treatment, with the advantages of reduced invasiveness in patients with extensive comorbidities. However, regular follow-ups with blood analysis and ultrasonography to check for additional aneurysm formation due to recurrent infection is mandatory after endovascular treatment.

In this case, we were able to safely perform distal embolization with packing within the aneurysmal sac and proximal embolization of the celiac axis. Packing of the aneurysm, using both coils and NBCA, was extremely effective in terms of cost and procedure time. Moreover, it is safer to use NBCA with coils because it tends to aggregate in the coil nest. In addition, decreased blood flow under temporary balloon occlusion prevents the distal embolization of glue. This combination decreases the amount of NBCA injected and the number of expensive coils delivered around the aneurysm. Limiting the number of coils delivered into the aneurysm is also important to reduce the risk of periprocedural aneurysm rupture due to enlargement of the aneurysm.¹¹⁾

An important potential risk of endovascular treatment is postoperative recanalization or regrowth of the aneurysm. However, because artifacts from the metallic coils disrupt postoperative CT surveillance,²⁾ long-term follow up may require duplex ultrasonography, MRI/angiography, or conventional, digital subtraction angiography.

Endovascular treatment of celiac artery aneurysms is now recognized as a relatively safe and effective method, even for mycotic aneurysms. In future, randomized controlled studies with long-term follow-up after endovascular treatment should be considered to establish the indications for endovascular treatment as an alternative to surgical intervention.

Conclusion

Few reports exist on the clinical course of mycotic celiac artery aneurysms. The initial CT sign of a mycotic aneurysm is a hazy fat density, which is indicative of fat in the periarterial tissue. Periodic follow-up CT imaging should be performed at short intervals, in addition to a strict antibiotic regimen, when this finding is detected on initial CT. If the aneurysm appears to be expanding, treatment must be promptly initiated irrespective of size. In this case, endovascular therapy was both effective and safe. Strict follow-up observations are necessary to reduce the possibility of recurrent infection, which may lead to the formation of additional aneurysms.

Disclosure Statement

The authors disclose no conflicts of interest.