Mediastinal hematoma: A rare complication of Bentall-Bono surgery

A 74-year-old male with a medical history of atrial fibrillation and Bentall-Bono surgery five months ago presented to the emergency room with four-day general malaise and anterior chest pain.

Chest radiograph showed mediastinal widening not visible on early postoperative X-ray (Figures 1A, 1B).

A CT angiography of the aorta was performed.

The study without contrast showed a voluminous mediastinal hematoma (11 x 10 x 11 cm) of heterogeneous density adjacent to the root of the aorta and its ascending segment (Figure 2).

A sac formation compatible with a periprosthetic pseudoaneurysm was identified in the arterial phase (Figure 3) and originated caudal to the aortic valve prosthesis. It was accompanied by extensive circumferential extravasation of contrast due to its rupture. The mediastinal hematoma caused a slight mass effect on the superior vena cava and the brachiocephalic trunk. The venous phase showed a slight wall enhancement of the hematoma (Figures 4A, 4B).

The set of findings was compatible with a broken pseudoaneurysm with signs of infection.

Bentall-Bono surgery is indicated in patients with aortic root dilatation with aortic valve pathology associated [1, 2]. The aortic root and ascending aorta are replaced with a single composite graft that contains an aortic valve prosthesis into which the coronary arteries are anastomosed. Postoperative complications are anastomosis dehiscence, pseudoaneurysms, paravalvular leaks, valve insufficiency and infection [3]. It’s important to differentiate those aforeheads mentioned from normal imaging findings as perigraft fluid, soft-tissue stranding and mediastinal air.

Symptoms of a complication after a Bentall-Bono procedure are nonspecific. The patients use to refer chest pain in the last few days. At the emergency room, they may present hypotension, anemia and leukocytosis. The first imaging key finding is the mediastinal widening visible on the X-ray and, taking into account the history of cardiovascular surgery in the previous months, an angio-CT gives the final diagnosis.

Multiphasic CT is a very sensitive technique for detecting postoperative complications [4]. Unenhanced acquisitions are useful to distinguish between surgical material and contrast extravasation [2, 3]. To reach the diagnosis, the time since surgery was performed and possible associated complications are taken into account. The presence of extraluminal contrast and pseudoaneurysmal formations is consistent with the dehiscence of the graft composite and infection is suspected because of the hematoma's well-defined borders and wall enhancement [2, 3, 5].

Pseudoaneurysms may be surgically repaired depending on several factors including patients’ clinical symptoms [5]. The patients undergo urgent surgery where surgeons can appreciate profuse arterial bleeding due to a ruptured pseudoaneurysm. Prosthetic endocarditis may cause disinsertion of the aortic graft, which must be replaced.

It is important to know the spectrum of findings after an open surgery of the thoracic aorta [5]. Hematoma secondary to pseudoaneurysm rupture is a very rare complication, but it should be considered in patients undergoing Bentall-Bono surgery. To facilitate reparative surgery, the location of the pseudoaneurysm must be established with respect to the valve, coronary arteries, and the rest of the cardiovascular structures.

All patient data have been completely anonymized throughout the entire manuscript and related files.