Management of severe asymmetric pectus excavatum complicating aortic repair in a patient with Marfan's syndrome

Abstract

We describe the case of a 28-year old man with Marfan's syndrome and severe pectus excavatum who required an aortic root replacement for an ascending aortic aneurysm. There was a near-vertical angulation of the sternum that presented challenges with opening and exposure of the heart during aortic surgery. Furthermore, removal of the sternal retractor after aortic repair resulted in sudden loss of cardiac output. A Ravitch procedure was then performed to successfully close the chest without further cardiovascular compromise. We propose that patients with a severe pectus excavatum and mediastinal displacement seen on preoperative CT scanning should be considered for simultaneous, elective repair.

CASE PRESENTATION

A 28-year old patient with Marfan's syndrome was found to have progressive aortic root enlargement to 5 cm. Elective repair was recommended. His preoperative CT scan demonstrated a severe asymmetric pectus excavatum (Haller index of 11.8). His sternum was angled almost vertically due to an abnormal curvature of the anterior arc ribs on the right, with a maximum tilt of ∼75°. This resulted in significant cardiac luxation (Fig. 1).

Figure 1:

CT image demonstrating severe asymmetric pectus excavatum (Haller index 11.8) with near-vertical angulation of the sternum (>70°) and left mediastinal cardiac luxation.

The near-vertical sternal tilt resulted in technical challenges during initial sternotomy. This was managed by manually reducing the deformity with a handheld retractor, allowing the sternal saw to be used. Due to the extreme tilt in the right hemisternum, two sternal retractors were required. A smaller retractor was used for the manubrium, and a deeper thoracotomy retractor was used for the angulated lower sternum. Afterwards, a standard valve sparing aortic root replacement with a reimplantation technique was performed. Post-repair transoesophageal echocardiography demonstrated normal ventricular function with no aortic insufficiency.

However, following removal of the sternal retractor, there was sudden loss of cardiac output, resulting in near arrest. Pressure largely from the right hemisternum caused direct compression of the right heart, and subsequent reduction in preload. Cardiac output promptly recovered when the sternal pressure was relieved. A Ravitch procedure was therefore performed with constant upwards traction to relieve right ventricular compression. In brief, bilateral pectoralis muscle flaps were raised, and the costal cartilages from rib 3 to 8 were resected, taking care to preserve the perichondrial sheaths. Once the sternal depression was corrected, haemodynamic instability was no longer observed. The sternotomy was closed with steel wires, and reduction was maintained with an 8″ substernal bar (BioMet Pectus Bar, Part 01-3808, Jacksonville, FL, USA). No significant bleeding occurred either intraoperatively or postoperatively. His postoperative course was uneventful; subpectoral drains were removed on Day 3, and he was discharged on Day 6. A follow-up CT scan demonstrated satisfactory reduction in the pectus deformity with a stable aortic repair (Fig. 2).

Figure 2:

Postoperative CT demonstrating satisfactory reduction in pectus deformity, however, with persistence of the curvature of the anterior arc of ribs on the right (Haller index 3.4) and relief of mediastinal displacement.

COMMENT

Simultaneous pectus excavatum and aortic pathology is common, and the sequence of repair remains controversial in the literature. Initial pectus surgery is theoretically problematic since a substernal bar could complicate emergency exposure for dissection/rupture [1]. Alternatively, pectus repair after aortic surgery may be potentially dangerous due to postoperative mediastinal adhesions. Indeed, we would consider only the Ravitch procedure for this strategy; adhesions would be prohibitively risky for the Nuss procedure as described by Craner et al. [2].

It is becoming apparent that simultaneous repair is gaining traction in the literature. Prior concerns regarding blood loss, increased operative time and complications have not been observed in recent reports [3, 4]. While we chose to perform a Ravitch repair following separation from cardiopulmonary bypass (CPB), other groups have advocated alternate strategies of repair. Rousse et al. [3] have proposed performing first a subperichondrial resection of abnormal rib cartilages to facilitate sternotomy and to complete the Ravitch procedure with substernal bar after separation from CPB. Indeed, this strategy could have prevented the compression of the right heart after closure as seen in our case and also would have simplified our sternotomy. Ultimately, however, we had chosen to repair the sternum after CPB in order to minimize intraoperative chest wall blood loss while systemically heparinized.

Some other groups have proposed performing an ‘open’ Nuss procedure; the open chest facilitates placement of the curved bar with minimal dissection [4]. We have some reservations regarding this approach. The longer curved Nuss bar may prevent meaningful external cardiac compression in an arrest situation and may impede rapid re-exploration. In addition, constant upward pressure on the sternum and internal thoracic arteries could predispose the patient to sternal dehiscence and infection. Finally, dense adhesions may form between the pericardium, or worse, the myocardium, and this could complicate bar removal [2]. In contrast, our straight, short bar is used simply as a strut; the pectus is reduced surgically. This also simplifies removal, planned for 3 years after the operation.

In our patient, simultaneous repair was necessary due to cardiovascular collapse during attempted closure. We propose that this phenomenon was due to cardiac luxation into the left chest by the pectus excavatum deformity (Fig. 1). We hypothesize that the mediastinum was allowed to return to the midline after sternotomy and exposure for aortic repair. Therefore, when the retractor was subsequently removed, the more deformed right hemisternum directly compressed the right ventricle. This compression was relieved by the correction of the excavatum (Fig. 2). This phenomenon was also observed by Stephens et al. [5], and in their report, an unplanned, emergency Ravitch procedure was performed.

It is presently unclear as to what are the specific risk factors for haemodynamic collapse following sternotomy in a patient with severe pectus deformity. It appears that the common features between the two cases include (i) significant mediastinal shift resulting in cardiac luxation and (ii) Haller index of >10. It is possible that the presence of either of these risk factors may predict for haemodynamic compromise upon sternal closure. We suggest that patients with severe pectus excavatum undergoing cardiovascular surgery should be considered for simultaneous repair with a planned collaboration of both thoracic and cardiac surgeons.

Conflict of interest: none declared.