Endovascular Repair of Ruptured Hepatic Artery Pseudoaneurysm Secondary to Fibromuscular Dysplasia

Introduction

Fibromuscular dysplasia (FMD) is an idiopathic, nonatherosclerotic, noninflammatory abnormality in the muscular layer of small- and medium-sized arteries ¹ that can lead to various complications, including stenosis, occlusion, dissection, and aneurysm formation. ^{2 -4} Fibromuscular dysplasia is a somewhat uncommon clinical entity, affecting <5% of the general population. ^5,6 However, it can be an important cause of hypertension and stroke due to its predominant localization to the renal and carotid arteries, respectively. ^{2 -5} Over 90% of cases occur in women, and although originally thought to be a disease of young women exclusively, it is typically diagnosed in the middle age.

Fibromuscular dysplasia infrequently affects the mesenteric vasculature. Even more rare are reports of mesenteric arterial complications secondary to FMD. Here, we describe the case of an elderly female patient diagnosed with a common hepatic artery pseudoaneurysm that, upon further investigation, appeared to be secondary to underlying FMD. We also review the literature with respect to mesenteric involvement of FMD and a related entity, segmental arterial mediolysis (SAM).

Case Report

Informed consent was obtained from the patient’s guardian for publication of the case report and accompanying images. An 81-year-old female presented to a local emergency department with her third episode of syncope over the preceding 3 weeks. Her past medical history was notable for hypertension, postural orthostatic tachycardia syndrome, and a prior lower extremity deep venous thrombosis with associated pulmonary embolism (PE) following a knee replacement. As part of the workup, she underwent a computed tomography angiogram (CTA) of her chest to evaluate for recurrent PE. The caudal-most slices of the chest CT demonstrated what appeared to be a ruptured common hepatic artery for which she was urgently transferred to our quaternary care institution.

Upon arrival, she was hemodynamically stable and did not complain of abdominal pain. Laboratory evaluation demonstrated no acute abnormalities, including a normal hemoglobin, and inflammatory markers (ie, erythrocyte sedimentation rate, c-reactive protein) were within normal limits, thus a vasculitis or arteritis was unlikely. A dedicated CTA of the abdomen was performed, which demonstrated a 2.4 cm common hepatic artery pseudoaneurysm with an apparent contained rupture of unknown chronicity (Figure 1). Also seen were multifocal areas of narrowing and aneurysmal dilatation in the celiac trunk extending into the hepatic arterial system consistent with possible underlying FMD (Figure 2). There were similar findings noted in the renal arteries bilaterally, although less pronounced. She later underwent imaging of the carotid arteries with a duplex ultrasound that showed no focal areas of high-grade stenosis but a CTA that revealed a similar pattern of multifocal narrowing and aneurysmal dilatation.

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Figure 1.

Computed tomography angiogram (CTA) demonstrating the common hepatic artery aneurysm with surrounding hematoma, consistent with contained rupture (arrow).

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Figure 2.

Computed tomography (CT) angiogram demonstrating the characteristic multifocal areas of narrowing and aneurysmal dilatation in the celiac trunk extending into the hepatic arterial system (A). 3-D reconstruction of the CT angiogram (B).

In order to address the common hepatic pseudoaneurysm, an endovascular strategy was used. A 7F TourGuide steerable sheath (Medtronic, Minneapolis, Minnesota) was advanced from a right common femoral approach and used to selectively cannulate the celiac trunk. An angled 0.035″ GLIDEWIRE and 0.035″ Glide catheter (Terumo Medical, Somerset, New Jersey) were used to cross the common hepatic artery into the proper hepatic artery with subsequent exchange for a Rosen wire (Cook Medical, Bloomington, Indiana). Digital subtraction angiography identified the pseudoaneurysm with no active extravasation and appropriate seal zones distal to the splenic artery origin and in the distal common hepatic artery proximal to the origin of the gastroduodenal artery (GDA). A 5 × 59 mm VBX balloon expandable covered stent (W. L. Gore and Associates, Flagstaff, Arizona) was deployed to exclude the pseudoaneurysm. Repeat angiography demonstrated successful exclusion of the aneurysm with no further filling of the aneurysm sac and intact flow to the splenic artery, GDA, and hepatic arterial branches.

The patient tolerated the procedure well and was discharged home on postprocedure day 2 on dual antiplatelet therapy with aspirin and clopidogrel. She subsequently returned for a 1-month follow-up appointment, where a CTA demonstrated patency of the common hepatic stent with successful exclusion and thrombosis of the pseudoaneurysm (Figure 3).

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Figure 3.

Three-dimensional reconstruction of a 1-month postoperative computed tomography (CT) angiogram demonstrating patency of the covered stent with continued perfusion of branch arteries and no endoleak.

Discussion

The pathological classification of FMD is based on the arterial layer that is involved (intimal, medial, and adventitial), with medial fibroplasia being the most common. ¹ The characteristic findings on imaging depend on the layer involved and include multifocal areas of stenosis and aneurysmal dilation or the so-called “beads on a string” appearance for medial fibroplasia, focal, concentric stenosis for intimal fibroplasia, and localized tubular areas of stenosis for adventitial hyperplasia. ^{7 -9} Diagnosis is typically made with duplex ultrasonography, CTA, arteriography, or a combination of the above. Concern for FMD should prompt inflammatory marker laboratory test results as well as at least 1 head to pelvis cross-sectional image, either CTA or Magnetic Resonance Arteriography (MRA), to screen for additional disease sites. ¹⁰

This presentation of a common hepatic artery pseudoaneurysm and contained rupture in the setting of possible FMD is interesting for several reasons. First, in the general population, hepatic artery aneurysms occur infrequently (reported incidence of approximately 0.01%), ¹¹ and rupture is rare in the absence of prior hepatobiliary surgery or trauma. ¹² Second, hepatic artery involvement in FMD appears to be quite unusual as well and thus far limited to case reports. Presentation with rupture and intra-abdominal hemorrhage is so rare that the frequency is unknown. ^10,13,14 Prior case reports of FMD affecting the hepatic artery are summarized in Table 1. As with our patient, the diagnosis of FMD in these cases was largely based on imaging, with a histologic diagnosis being impossible to obtain.

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Table 1.

Summary of Case Reports Describing Fibromuscular Dysplasia (FMD) With Hepatic Arterial Involvement.

Case Report	Patient Presentation	Arterial Involvement	Comments
Bermejo et al 15	64-year-old female with common hepatic artery rupture	Common hepatic artery, right/left hepatic arteries	No histology, FMD determined by imaging and history
Jones et al 16	58-year-old female with hepatic artery aneurysm rupture	Common hepatic artery, right/left hepatic arteries	No histology, FMD determined by imaging and history
Yanishi et al 17	22-year-old female with ruptured gastroepiploic and left hepatic artery	Gastroepiploic artery, left hepatic artery	Annular small bowel ulcers resected; pathology consistent with FMD
Cho et al 18	18-year-old female with hemobilia	Right/left hepatic arteries	Histology after cholecystectomy consistent with medial hyperplasia
Shussman et al 19	47-year-old female with hemobilia	Right/left hepatic arteries, proper hepatic artery	No histology, FMD determined by imaging and history
Siegert et al 20	43-year-old female with renal failure and stroke	Hepatic arteries, SMA, right renal artery, splenic artery, right middle cerebral artery	Diagnosis made postmortem; evidence of vasculitis on presentation

Abbreviation: FMD, fibromuscular dysplasia.

Surgical intervention in patients with FMD is usually reserved for symptomatic patients and is aimed at resolution of stenosis. Current recommendations generally call for percutaneous balloon angioplasty alone as the modality of choice. In this case, the presence of the common hepatic artery pseudoaneurysm with possible contained rupture mandated a different approach. Placement of a 5 × 59 mm Gore VBX balloon expandable covered stent provided an effective seal of the pseudoaneurysm while leaving the GDA and the other branches of the celiac axis uncovered (although the splenic artery appears to be covered, there was persistent flow through it at completion). This was appropriately sized to the native hepatic artery, which measured approximately 4.5 mm in diameter. The flexibility of the stent and delivery system allowed smooth tracking through the turn of the celiac axis from a femoral approach. An endovascular approach allowed a faster recovery than would have a traditional, open approach via a laparotomy incision, and the patient was discharged on postoperative day 2. Regarding follow-up, she will undergo CTA at 6 months and then at 1-year intervals thereafter, assuming there is no change in the excluded aneurysm sac (eg, endoleak). She will also have carotid and renal duplex ultrasounds performed yearly to evaluate for disease progression, provided she remains asymptomatic.

Due to the rarity of FMD and lack of long-term data, particularly for visceral disease, follow-up is not standardized. However, this schedule will allow the patient to be followed within standard guidelines for her renal and carotid involvement as well. ^5,21 Management of asymptomatic renal disease typically includes frequent blood pressure measurements and renal function laboratory test results, which will also be performed. ^5,9 With regard to the asymptomatic carotid disease, a European expert consensus paper recommended yearly imaging (MRA and Duplex Ultrasonogrpahy [DUS]), ⁹ although Olin et al have recommended more frequent carotid imaging with DUS every 6 months. ⁵

An alternate diagnosis worth mentioning in this particular case is SAM, another noninflammatory vascular disorder characterized by medial layer lysis in the arterial wall. ^6,15 While vasculitis or arteritis was also considered, we believed them to be less likely as the patient’s laboratory test results were normal. Segmental arterial mediolysis, like FMD, is also very rare with an unknown true prevalence. Segmental arterial mediolysis differs from FMD in that SAM shows no gender preference, ^21,16 is thought to be self-limited, ^6,17 and develops in multiple arterial beds: most commonly in the celiac and mesenteric arteries and renal artery. ^{16 -18} The arterial bed can sometimes help distinguish between SAM and FMD, but the diagnosis can be difficult to differentiate without histology, as SAM can also cause a radiographic “beads on a string” appearance. ^6,17,18 Given these similarities, it is thought that SAM may be a variant of FMD or possibly a precursor. ^16,18 In fact, there are several case reports in the literature of hepatic artery aneurysm secondary to SAM, some even leading to rupture. ^19,20,22,23 Although the hepatic arterial involvement in our patient could potentially point more toward SAM, given the patient’s concomitant carotid involvement and without histologic confirmation, the most likely diagnosis here appears to be FMD.

Conclusion

Fibromuscular dysplasia involving the hepatic artery is rare. When there is associated pathology such as aneurysm, pseudoaneurysm, or even rupture, endovascular intervention with covered stent placement appears to be a safe and viable option for repair.