Reoperative repair of recurrent anastomotic pseudoaneurysm following aorto-aortic bypass for middle aortic syndrome

Abstract

Middle aortic syndrome is a rare disorder characterized by narrowing of the distal thoracic and/or abdominal aorta, often involving the visceral and renal arteries, and presenting with refractory hypertension at a young age. Open surgical repair with aorto-aortic bypass remains the gold standard treatment, although late complications such as anastomotic pseudoaneurysm may occur and may be life threatening. Here, we report the case of a surgically complex 55-year-old female who presented with an enlarging recurrent pseudoaneurysm of the distal anastomosis of an aorto-aortic bypass graft performed for a history of abdominal aortic coarctation causing middle aortic syndrome and who had successful open surgical repair with resection of the pseudoaneurysm and reconstruction of the distal aorta and bilateral iliac arteries.

First described in 1963, middle aortic syndrome (MAS) is a rare vascular disorder characterized by segmental or diffuse narrowing of the distal thoracic and/or abdominal aorta.¹ The resulting aortic coarctation typically involves the visceral and/or renal arteries.^1,2 Hypertension at a young age is the most common presenting manifestation,³ and refractory hypertension remains one of the main indications for surgical intervention.^4,5 Open surgical repair is considered the gold standard for treatment, with aorto-aortic bypass representing the most commonly performed surgical intervention.3, 4, 5 Anastomotic pseudoaneurysm is a potential long-term complication following an aorto-aortic bypass repair and results from progressive weakening at the graft suture line, leading to the formation and enlargement of a contained sac.⁶ We present the case of a surgically complex 55-year-old female who presented with an enlarging recurrent pseudoaneurysm of the distal anastomosis of an aorto-aortic bypass graft performed for a history of abdominal aortic coarctation causing MAS. The patient provided informed consent for the report of her case details and imaging studies.

Case report

A 55-year-old female presented with an enlarging recurrent distal anastomotic pseudoaneurysm of an aorto-aortic bypass graft. Her medical history was significant for coarctation of the abdominal aorta causing atresia of the celiac and superior mesenteric artery origins and ostial stenosis of her bilateral renal arteries. In 1979, she underwent a supraceliac to aortoiliac bifurcation bypass using a 24-mm Dacron graft, in addition to bilateral renal artery bypasses from her native aorta using saphenous vein conduits. Her mesenteric flow was solely relying on an ectatic inferior mesenteric artery (IMA). She was subsequently lost to follow-up until 2010, when she presented with a ruptured pseudoaneurysm at the distal anastomosis. She underwent emergent repair with placement of a 24-mm interposition Dacron graft extending from the prior aortic graft to a more distal segment of the native aorta through a redo laparotomy. Owing to hemodynamic instability, the operation required cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest via median sternotomy.

Upon presentation to our institution in 2023, surveillance imaging showed recurrence of an enlarging pseudoaneurysm at the distal aortic anastomosis (Fig 1). She had coronary artery disease, a 40 pack-year smoking history, stage II chronic kidney disease (creatinine of 0.96 and estimated glomerular filtration rate of 70), hypertension, and hyperlipidemia. Apart from her vascular surgical history, she had open ventral hernia repair with composite mesh placement in 2013.

Fig 1.

Preoperative illustration demonstrating a recurrent and enlarging pseudoaneurysm of the distal anastomosis of a 24-mm aorto-aortic Dacron bypass graft done for aortic coarctation.

Preoperative evaluation included computed tomography angiography (CTA) of the abdomen and pelvis, which demonstrated a patent descending thoracic aorta, absent origins of the celiac artery and superior mesenteric artery, a patent supraceliac to aortoiliac bypass graft, stable ectasia of the bilateral renal artery saphenous vein conduits, an ectatic IMA, patent bilateral iliac arteries, and an 8.0-cm pseudoaneurysm at the distal aortic anastomosis, representing an interval increase of more than 3 cm over a 1-year period. Positron emission tomography computed tomography was negative for infectious or inflammatory changes. Echocardiogram showed an ejection fraction of 68% without any regional wall motion abnormalities, and a coronary angiogram performed at an outside hospital demonstrated a left anterior descending (LAD) artery occlusion with distal reconstitution. The patient agreed to undergo open surgical repair of her anastomotic pseudoaneurysm.

Given the patient’s history of multiple prior laparotomies, open abdomen, and mesh placement for abdominal closure, a multidisciplinary staged surgical approach was elected. On the first operative day, the general surgery team performed abdominal exploration with extensive lysis of adhesions, explantation of the ventral hernia mesh (Fig 2), and temporary abdominal closure. The following day, the vascular surgery team performed re-entry into the abdomen with exposure and control of the aorto-aortic bypass graft, pseudoaneurysm, IMA, and bilateral common iliac arteries. Simultaneously, the cardiac surgery team performed a redo sternotomy, initiated CPB, and proceeded with a one-vessel coronary artery bypass grafting from the left internal mammary artery to the LAD artery. While on CPB, the vascular surgery team proceeded by placing hypogastric clamps on the bilateral common iliac arteries and a bulldog clamp on the IMA. An aortic cross-clamp was subsequently placed on the aorto-aortic Dacron graft above the pseudoaneurysm level. The pseudoaneurysm cavity was entered, revealing complete disruption of the anterolateral aspect of the distal anastomosis, with the Prolene sutures detached from the native aortic tissue (Fig 3). The devitalized tissue was debrided and excised, and the luminal openings of the patient’s native distal aorta, the right common iliac artery (RCIA) as well as the left common iliac artery (LCIA) were identified. The proximal LCIA was noted to be friable and devoid of adventitia, rendering it unsuitable for suturing, whereas the distal abdominal aorta and RCIA demonstrated adequate tissue integrity and satisfactory suture-holding capacity. The existing 24-mm interposition Dacron graft was beveled and sewn in an end-to-end fashion to the healthy distal abdominal aorta and RCIA origin. The LCIA was trimmed back to healthy tissue, after which an 8-mm Dacron was sewn to the LCIA in an end-to-end fashion and to the existing 24-mm Dacron aortic graft in an end-to-side fashion (Fig 4). Intraoperative Doppler signals were found in the IMA, bilateral renal grafts, and feet. The patient was successfully weaned from CPB, and the retroperitoneum, sternum, and abdomen were closed primarily.

Fig 2.

Intraoperative picture of the ventral hernia mesh that was excised during initial abdominal exploration.

Fig 3.

Pseudoaneurysm cavity showing complete disruption of the anterolateral aspect of the distal anastomosis, with the Prolene sutures detached from the native aortic tissue.

Fig 4.

Postoperative illustration demonstrating a new end-to-end anastomosis performed between the old interposition Dacron graft and the distal abdominal aorta and right common iliac artery origin. The left common iliac artery was trimmed back and reimplanted into the 24-mm aortic graft using an 8-mm Dacron graft.

Postoperatively, the patient developed ventilator-associated pneumonia complicated by respiratory failure, necessitating initiation of veno-venous extracorporeal membrane oxygenation on postoperative day (POD) 5 and tracheostomy on POD 8. Her hospital course was further complicated by acute kidney injury requiring intermittent hemodialysis beginning on POD 8. The patient was successfully decannulated from veno-venous extracorporeal membrane oxygenation on POD 16 and from the tracheostomy on POD 35. She was subsequently discharged home on POD 37 without the need for ongoing hemodialysis. Two years postoperatively, the patient is doing well with improved functional status at home and kidney function (creatinine of 0.87; estimated glomerular filtration rate of 73). A 2-year follow-up CTA showed a patent aortic graft and reconstruction without any significant stenosis or recurrence of the pseudoaneurysm (Fig 5).

Fig 5.

Three-dimensional reconstruction of a follow-up computed tomography scan showing a patent aortic graft and reconstruction without any significant stenosis or recurrence of the pseudoaneurysm.

Discussion

MAS is a rare clinical entity that typically presents in children and young adults and accounts for approximately 0.5% to 2% of all aortic stenosis cases.^1,7,8 The majority of cases involve the abdominal aorta, often with varying degrees of renal and visceral branch vessel involvement.^1,2 Refractory hypertension is among the most common and clinically significant manifestations, with the severity of hypertension and/or renal dysfunction representing the primary indications for surgical intervention.^4,5,9, 10, 11 Open revascularization remains the gold standard for treatment and includes aorto-aortic bypass grafting, the most commonly performed procedure, as well as patch angioplasty, interposition graft replacement, and renal autotransplantation.^1,3, 4, 5 Endovascular interventions, such as angioplasty and/or stenting, are generally reserved as temporizing adjuncts to medical therapy until definitive surgical repair can be undertaken.³

A pseudoaneurysm is a rare but life-threatening complication of aorto-aortic bypass grafting.⁶ In this case report, we describe the case of a medically and surgically complex 55-year-old female who presented with progressive enlargement of a recurring pseudoaneurysm involving the distal anastomosis of a prior aorto-aortic graft performed for MAS. She was successfully treated with open resection of the pseudoaneurysm, and reconstruction of the distal aorta and bilateral iliac arteries after multidisciplinary discussion determined that an endovascular approach was not technically feasible, as it would not achieve durable exclusion of the pseudoaneurysm while preserving perfusion to the native aorta, IMA, and bilateral renal arteries.

Pseudoaneurysm formation following aorto-aortic bypass grafting may arise from several etiologies, including blunt or penetrating trauma, infection, atherosclerotic degeneration, and anastomotic dehiscence.¹² In our patient, there was no history of traumatic injury, and preoperative positron emission tomography-computed tomography and CTA of the abdomen and pelvis did not show any evidence of infection or significant atherosclerotic disease. We suspect that progressive weakening of the distal aortic anastomosis created during the emergent repair of the ruptured pseudoaneurysm in 2010 contributed to the recurrence, likely because the sutures along the anterolateral wall were not incorporated through the full thickness of the native aortic wall. To mitigate this, we meticulously dissected the distal native aorta free from the spine and iliac veins to allow direct visualization and placement of sutures through all layers of the aortic wall.

We elected to perform the aortic repair under CPB given the hostile reoperative field and the anticipated difficulty in obtaining proximal control of the native abdominal aorta and bilateral renal saphenous vein conduits. CPB helped minimize blood loss from the uncontrolled distal native aorta and provided pressure offloading while performing the anastomotic repair. In addition, CPB allowed immediate availability of perfusion cannulas for the IMA and/or renal saphenous veins should prolonged visceral or renal ischemia have occurred. Moreover, the cardiac surgery team elected to perform a single-vessel coronary artery bypass grafting to bypass the occluded LAD because of the patient’s high risk for progression of coronary artery disease and to potentially avoid the need for a future third-time redo sternotomy.

Given the patient’s history of multiple redo laparotomies, open abdomen, and mesh placement for ventral hernia repair, a prolonged and technically challenging abdominal exploration with extensive lysis of adhesions was anticipated, prompting a staged operative approach. Staging the operation allowed safe abdominal entry and meticulous adhesiolysis during the initial procedure while limiting operative duration and physiologic stress before the definitive vascular reconstruction. Multidisciplinary collaboration among the general surgery, cardiac surgery, vascular surgery, and intensive care teams was essential for comprehensive perioperative planning and optimal surgical and postoperative management. In carefully selected patients with hostile abdominal anatomy undergoing complex aortic reconstruction, a staged approach may facilitate operative planning, reduce procedural complexity, and help mitigate the physiologic burden associated with extensive reoperative abdominal surgery.

Conclusions

To the best of our knowledge, this is the first reported case describing the surgical management of a recurrent enlarging anastomotic pseudoaneurysm following prior aorto-aortic bypass grafting for MAS in a surgically complex patient. This case highlights the feasibility and durability of open reconstructive repair in the reoperative setting and underscores the importance of a multidisciplinary staged operative strategy in achieving favorable outcomes in medically and surgically challenging patients.

Funding

None.

Disclosures

None.