EXPERIMENTAL AND CLINICAL TRANSPLANTATION

The development of aortic aneurysms in post-transplant patients is a rare but potentially lethal problem. De novo aortic aneurysm formation and rapid growth are postulated to result from an imbalance between pro- and anti-inflammatory vascular endothelial factors after transplant. Here, we present a case of de novo thoracic aneurysm formation within 2 months of orthotopic liver transplant. Prompt clinical recognition allowed for successful endovas-cular repair. Transplant clinicians should be aware of this potentially life-threatening complication and monitor at-risk recipients accordingly.

Key words : Aortic aneurysm, Endovascular repair, Pseudoaneurysm

The incidence, natural history, and treatment options for aortic aneurysms in posttransplant patients have become better defined.^1-3These studies have shown increased aortic aneurysm growth rate and risk of aneurysm rupture in this patient population. We present a case of a postoperative liver transplant patient who developed a large thoracic aneurysm soon after the transplant was completed.

A 61-year-old woman was transferred to our institution with a 3-day history of worsening fatigue, nausea, and vomiting. She also indicated left-upper quadrant abdominal pain with radiation to her scapula for 10 days prior to her admission. Her past medical history was notable for hepatitis C virus-related decompensated cirrhosis that was com-plicated by type 1 hepatorenal syndrome requiring hemodialysis. She underwent orthotopic liver transplant with a standard-criteria deceased-donor graft 2 months before presentation. The transplant operation was uncomplicated; warm ischemia time was 24 minutes, and cold ischemia time was 2 hours and 7 minutes. She was discharged on postoperative day 8 with maintenance immunosuppression consisting of tacrolimus (2 mg twice daily), mycophenolate mofetil (500 mg twice daily), and prednisone (20 mg daily). Her renal function rapidly improved after the transplant and renal-replacement therapy was discontinued. A review of her postdischarge weekly laboratory tests showed normal allograft function and that target tacrolimus levels (average 7.5 ng/dL) were achieved.

On examination after transfer to our facility, she was afebrile and hemodynamically stable. Although she had reported left-upper quadrant abdominal pain with radiation to her back and scapula, her abdomen was soft without guarding, rebound, or shifting dullness. Laboratory tests showed that she had a normal white blood cell count, normal liver enzyme levels, and normal lipase levels. A multiphasic computed tomography (CT) scan revealed a large pseudoaneurysm arising from her distal descending thoracic aorta measuring 6.5 cm × 4.7 cm with a large surrounding area of peripheral thrombus (Figure 1). Of note, the patient had undergone CT scanning of her chest and abdomen as part of her transplant evaluation 3 months earlier, and these scans revealed normal caliber thoracic and abdominal aorta. In addition, a pretransplant echocardiogram showed a normal ejection fraction, no valvular abnormalities other than mild aortic regurgitation, and a normal aortic outflow.

The patient underwent emergent thoracic endovascular aortic repair. An intraoperative thoracic aortogram confirmed the CT scan findings of a large descending thoracic pseudoaneurysm. A 28 mm × 28 mm × 100 mm Valiant stent graft device (Medtronic, Minneapolis, MN, USA) was deployed distal to the left subclavian artery over the aneurysm. Given residual flow into the aneurysm, a second similar graft was placed with extension further distally. A repeat aortogram revealed a completely excluded aneurysm with no evidence of either type 1 or type 2 endoleaks (Figure 2). Her postoperative course was unremarkable, and she was discharged 5 days later. She has had normal allograft function over 6 months since transplant.

In a single-center retrospective study of 3216 abdominal-organ transplant patients, 34 patients (1.1%) and 23 patients (0.7%) had abdominal and thoracic aneurysms, respectively.¹ This study further showed that liver transplant recipients only represented a small fraction of the population with aneurysms. Another investigation of transplant recipients found an average aortic aneurysm growth rate of 1.00 cm/year and an average aortic aneurysm rupture rate of 22.5%/year, which were both significantly higher than in the nontransplant patient population.²

Aortic aneurysm formation is postulated to result from an imbalance between pro- and anti-inflam-matory vascular endothelial factors. In a case study of a kidney transplant patient with a ruptured aortic aneurysm, histologic evaluation of the aneurysm wall showed complete absence of T cells, B cells, and neutrophils, which were cells found at high levels in a nonimmunosuppressed control patient.⁴ Notably, this kidney transplant patient had calcineurin-based immunosuppression therapy similar to our patient.

To the best of our knowledge, we have reported the first case of use of endovascular repair for a thoracic aortic aneurysm in a liver transplant patient. Endovascular repair of aortic aneurysms with stent grafts has been used increasingly over the past 2 decades in lieu of the traditional open approach, and this procedure was recently found to account for 75% of aortic aneurysm repairs.5 The procedure has shown similar technical success and 1-year-survival rates in the afflicted kidney transplant population versus the afflicted general population, which has led to its use in kidney transplant patients with aortic aneurysms.³

Our case is also remarkable for the rapidity of the patient’s aneurysmal development, given that her pretransplant CT scan revealed no evidence of aneurysmal dilation. Clinicians of this unique patient population should maintain a high index of sus-picion for an unusual cause of a common complaint like that reported here.

Volume: 19 Issue: 2 February 2021

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