Mycotic Aneurysm of the Hepatic Artery: A Case Report and its Management

INTRODUCTION

Cholecystectomies are one of the most common surgical procedures performed in the United States, with over 300,000 laparoscopic cholecystectomies performed every year.^[1] The complication rates of cholecystectomies range from 1.56% to 6%. Common complications include bleeding from adjacent tissues or the cystic artery, iatrogenic perforations of the gallbladder, injuries to the bile duct, and infection, including abscess formation.^[2] We submit a case of a post- cholecystectomy patient who presented with a ruptured hepatic artery mycotic aneurysm from an abscess within the porta hepatis ultimately requiring endovascular treatment.

Topical thrombin is a common tool utilized by physicians in the treatment to achieve hemostasis. Its use has even expanded to the treatment of superficial pseudoaneurysm. However, there have been only a few cases of catheter-directed endovascular use of thrombin. This case presentation describes the transarterial use of thrombin in the treatment of the aneurysm.

PATIENT CASE

This case involves a 71-year-old male with a past medical history of depression, complex regional pain syndrome, and non-insulin dependent diabetes mellitus Type 2 who presented with abdominal pain and found to have symptomatic cholelithiasis requiring laparoscopic cholecystectomy followed by a complex course, including acute blood loss of approximately 350 cc intraoperatively.

He returned to the emergency department (ED) approximately 2 weeks post-discharge with complaints of worsening abdominal pain, nausea, and vomiting. Contrast-enhanced CT of the abdomen and pelvis (CT A/P) demonstrated multiple large subscapular hepatic abscesses [Figure 1a and b]. Drainage catheters were subsequently placed in two abscesses [Figure 2a and b]. On repeat, contrast-enhanced CT A/P demonstrated new focal dilatation in the right hepatic artery concerning the development of a mycotic pseudoaneurysm [Figure 3].

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Figure 1:

71-year-old male with a recent cholecystectomy who presents with abdominal pain (a) axial contrast-enhanced CT of the abdomen and pelvis demonstrates a large abscess in the right hepatic lobe (arrow). (b) Coronal contrast-enhanced CT of the abdomen and pelvis (right image) demonstrates another large abscess at the base of the right hepatic lobe (arrow) with a medial smaller abscess (arrowhead).

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Figure 2:

71-year-old male with a recent cholecystectomy complicated by multiple abdominal abscesses who presents with abdominal pain. (a) Axial contrast-enhanced CT of the abdomen and pelvis (left image) demonstrates placement of drainage catheter in the right hepatic lobe abscess (arrow). (b) Coronal contrast- enhanced CT of the abdomen and pelvis (right image) demonstrates a drainage catheter in the inferior hepatic abscess (arrow) with interval growth of the more medial abscess (arrowhead).

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Figure 3:

71-year-old male with a recent cholecystectomy complicated by multiple abdominal abscesses who presents with abdominal pain. Coronal contrast-enhanced CT of the Abdomen and pelvis demonstrates a subtle aneurysmal dilatation of the proper hepatic artery (arrow) concerning for a mycotic aneurysm.

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A visceral angiogram was performed, which demonstrated aneurysmal dilation at the distal portion of the proper hepatic artery measuring approximately 1.5 cm [Figure 4]. A collaborative decision was made to conservatively treat the aneurysm with medical management due to the high risk of inducing liver failure with coil embolization. The patient was later discharged on oral antibiotics.

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Figure 4:

71 year old male with a recent cholecystectomy complicated by multiple abdominal abscesses who presents with worsening abdominal pain. Angiogram of the hepatic artery demonstrating an aneurysm at the distal hepatic artery (arrow) with no evidence of active bleeding.

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He returned to the ED approximately a week later with worsening of his symptoms, and a repeat CT A/P demonstrated a new fluid collection within the porta hepatis with interval enlargement of the pseudoaneurysm [Figure 5]. The patient acutely decompensated and suffered cardiac arrest requiring multiple rounds of cardiopulmonary resuscitation. It was presumed that there was active bleeding from the known hepatic artery aneurysm. Bleeding was presumed secondary to a rupture of the known mycotic aneurysm which required massive transfusion protocol with approximately 10 units of PRBC and vasopressors. The patient was immediately taken to the interventional radiology suite.

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Figure 5:

71 year old male with a known mycotic pseudoaneurysm of the hepatic artery presents with worsening abdominal pain. Axial contrast-enhanced image of the abdomen demonstrates interval growth of the mycotic aneurysm (arrow).

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The celiac artery was cannulated with an SOS catheter. An angiogram was performed demonstrating frank extravasation just after the origin of the proper hepatic artery [Figure 6]. No distal flow into the liver parenchyma was identified past the rupture. A microcatheter and microwire were used to obtain access past the gastroduodenal artery (GDA) into the stump of the proper hepatic artery, which was then embolized with coils up to the confluence of the proper hepatic artery and GDA branches. Despite the placement of multiple coils, there was continued visualization of active hemorrhage [Figure 7]. The continued hemorrhage was presumed to be from evolving DIC a transfusion-related coagulopathy.

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Figure 6:

71-year-old male with a known mycotic pseudoaneurysm of the hepatic artery who recently coded on multiple vasopressors. (a) Angiogram at the celiac artery demonstrates no distal flow to the hepatic artery with large active hemorrhage (arrow). (b) Microcatheter was advanced to the distal hepatic artery (arrowhead), with angiogram demonstrating massive active hemorrhage (arrow).

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Figure 7:

71-year-old male with a known mycotic pseudoaneurysm of the hepatic artery who recently coded on multiple vasopressors. Angiogram demonstrating multiple coils deployed into the gastroduodenal and proximal proper hepatic artery. Despite the placement of the coils, there is still active contrast extravasation from the aneurysm (arrow).

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Given lack of other suitable embolic agents available at the time, at a regional community hospital, a decision was made to inject thrombin into the coil mass. The microcatheter was advanced into the proximal coils, positioning was verified with an injection of contrast, and subsequently, 1000 units of reconstituted thrombin were injected. The microcatheter was then removed, the 5 French catheters was aspirated and flushed, and a repeat angiogram through the 5 French catheters demonstrated successful embolization [Figure 8]. Unfortunately, due to multiorgan failure and persistent shock-like physiology from bacteremia, the patient was pronounced dead 3 days after the procedure.

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Figure 8:

71-year-old male with a known mycotic pseudoaneurysm of the hepatic artery who recently coded on multiple vasopressors. After the direct administration of thrombin through the catheter, an angiogram of the celiac artery demonstrates successful embolization and no further extravasation (arrow).

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DISCUSSION

Mycotic aneurysms, commonly referred to as infected aneurysms, are rare in their frequency. However, they can be life-threatening with a high incidence of arterial rupture and recurrence even after treatment. The term “mycotic,” which usually means fungus, was coined by physician Sir William Osler in 1885 when he described the gross pathological appearance of two small saccular aortic aneurysms and not the underlying pathological organism responsible for its development.^[3,4]

Mycotic aneurysms normally arise from bacterial invasion into the arterial wall through hematogenous spread usually in immunocompromised patients such as those with diabetes mellitus, liver cirrhosis, and acquired immune deficiency syndrome or with patient switch arterial luminal defects such as atherosclerotic plaque, ulceration, and preexisting aneurysm. Common locations for the development of mycotic aneurysms include the thoracic and abdominal aorta, abdominal visceral arteries, lower extremity arteries, and intracranial arteries. In the case of our patient, the presence of the abscess within the porta hepatis allowed for the proliferation of the mycotic aneurysm.

Aneurysms of the hepatic artery are uncommon. They tend to be saccular and multiple. Causes typically include infection, arteriosclerosis, trauma, and vasculitis. Post-liver transplantation patients can have pseudoaneurysm formation of the hepatic artery and its branch vessels, these usually occur within the 1^st month of transplantation. A vasculitis such as polyarteritis nodosa has been reported to result in the formation of aneurysms.^[5] Pseudoaneurysm formation can occur after trauma to the hepatic artery; furthermore, there have even been cases of pseudoaneurysm formation trauma from a percutaneous biopsy.^[6]

CONCLUSION

While the complications of cholecystectomy are well known, some of the adverse outcomes may result in complex and life-threatening complications, often requiring a multidisciplinary approach in treatment such as in the case of our patient which required medical, surgical, and interventional collaboration.

The treatment of our patient’s ruptured aneurysm required the use of thrombin, an agent which is rarely used endovascularly as a means of hemostasis, allowing for hemodynamic stability. Post-surgical complications after cholecystectomy and other similar procedures may necessitate the use of endovascular intervention to aid in the patient’s care, often in highly complex and life-threatening conditions. Depending on the clinical situation and availability of resources, the use of novel or atypical agents such as thrombin may be the difference between life or death for patients.