Sinus of Valsalva Aneurysm in a Preschooler With Schuurs-Hoeijmakers Syndrome

Abstract

Severe right ventricular outflow tract (RVOT) obstruction developed in a 4-year-old boy with Schuurs-Hoeijmakers syndrome and history of double-outlet right ventricle, tetralogy of Fallot type, status post repair with transannular patch augmentation of the RVOT. Echocardiography and computed tomography defined the presence of a 1 × 1-cm sinus of Valsalva aneurysm protruding into the RVOT, causing obstruction. Resection and repair of the aneurysm by a 2-patch technique as well as resection of RVOT muscle bundles and revision of the transannular patch were performed. The postoperative course was uneventful, with no evidence of persistent RVOT obstruction.

Sinus of Valsalva aneurysm (SOVA) is an abnormal dilation of the aortic root located between the aortic valve annulus and the sinotubular junction. It is the result of weakness in the elastic lamina at the junction of the aortic media and the fibrous aortic annulus.¹ SOVAs are commonly congenital but can also be acquired. Congenital forms are due to pressure forces on the aortic root leading to formation of a blind diverticulum. Acquired forms may be secondary to connective tissue disease, infection, or chronic changes to the arterial wall.¹ It is estimated that the rate of SOVA is approximately 0.09% of the general population, and it composes up to 3.5% of all congenital heart defects.^1,2 SOVAs most commonly affect the right coronary sinus, are associated with other cardiac defects, and are repaired primarily or with a patch.³

Schuurs-Hoeijmakers syndrome (SHMS) is a rare autosomal dominant disease caused by mutations in the PACS1 gene. The affected protein, phosphofurin acid cluster sorting 1 (PACS-1), is a multifunctional membrane traffic regulator.⁴ The most relevant clinical characteristics of those with SHMS are neurodevelopmental delay, seizures, and recognizable facial phenotype. In this report, we describe SOVA contributing to right ventricular outflow tract (RVOT) obstruction within several years of double-outlet right ventricle repair in a preschool-aged patient with SHMS.

Progressive postoperative RVOT obstruction developed in a 4-year-old boy with a history of SHMS and double-outlet right ventricle with subaortic ventricular septal defect and pulmonary stenosis. His history is notable for double-outlet right ventricle repair at 24 days of age, which consisted of baffle closure of the ventricular septal defect, pulmonary transannular patch augmentation with monocusp valve creation, and atrial septal defect closure.

During a period of several years, imaging demonstrated progressive, severe multilevel RVOT obstruction as well as dilation of the aortic root (absolute dimension, 27 mm; z score, +7.68) and ascending aorta (absolute dimension, 23 mm; z score, +5.85). Echocardiography and computed tomography demonstrated a 1 × 1-cm nonruptured SOVA emanating from the right coronary sinus adjacent to the right-left commissure, compressing the posterior wall of the RVOT (Figure 1). Residual RVOT muscle bundles and fixed monocusp valve also contributed to this multilevel RVOT obstruction. Because of this constellation of findings, the patient was referred for operative intervention.

Figure 1.

Computed tomography angiography images demonstrating sinus of Valsalva aneurysm and its relationship to the right ventricular outflow tract.

In the operating room, transesophageal echocardiography demonstrated severe RVOT narrowing due to posterior compression by the SOVA at the same level as anterior narrowing caused by the fixed monocusp valve (Figure 2). After median sternotomy, bicaval cannulation was achieved and cardiopulmonary bypass was instituted; the heart was completely decompressed with placement of a left ventricular vent. There was a left superior vena cava to the coronary sinus, but it was not cannulated. The RVOT was opened, and the SOVA was visualized as an unruptured aneurysm almost completely filling the RVOT. A purse-string stitch was placed in the distal ascending aorta for cardioplegia and then a cross-clamp was applied. Cardioplegia was administered and was seen to fill the aneurysm. A transverse aortotomy was performed. A transition was seen from normal aorta to aneurysmal tissue, and the aneurysmal tissue was noted to be thin. The aneurysm was repaired first with a patch of Hemashield graft (Getinge) sewn inside the aorta with a 4-0 Prolene suture and running technique. Next, the aneurysmal wall invading the main pulmonary artery (MPA) was resected, and a second patch was placed on the MPA side. Great care was taken that the inserted patches did not compromise either the aortic valve or the right coronary ostia. The aorta was reconstructed and the cross-clamp was removed. RVOT obstruction was further addressed with resection of infundibular muscle bundles; the RVOT was sized with a Hegar dilator, and then a transannular patch extending across the entirety of the MPA was placed. Insufficiency of the tricuspid valve was noted to be due to prolapse of the anterior leaflet on the septal leaflet, so 2 horizontal mattress 6-0 Prolene stitches were placed as an edge-to-edge repair. The atriotomy was then closed. Cardiopulmonary bypass time was 111 minutes and cross-clamp time was 48 minutes. Postoperative imaging did not demonstrate any residual RVOT obstruction, and there was no evidence of aortic stenosis or insufficiency. The postoperative course was unremarkable, and the patient was discharged in 6 days.

Figure 2.

(A, B) Preoperative transesophageal echocardiography demonstrating multilevel right ventricular outflow tract (RVOT) obstruction. Primary region of obstruction secondary to sinus of Valsalva aneurysm (SOVA) posteriorly and fixed monocusp valve anteriorly. Additional right ventricular muscle bundles proximally. (MPA, main pulmonary artery.)

Comment

In this report, we describe SOVA causing RVOT obstruction in a preschool-aged child. SHMS is a rare genetic syndrome with fewer than 100 reported cases. The cause of SOVA formation in this complex patient was likely to be multifactorial.

Congenital SOVA is thought to be caused by incomplete fusion of the bulbar septum, separating the aortic and pulmonary valves in the primitive bulbus cordis, leading to a weaker vascular wall in the sinus of Valsalva.² SHMS is caused by a pathogenic variant in the PACS1 gene, which is essential for neural crest migration.⁴ The PACS1 gene regulates the transport of proteins between endosomes and the Golgi apparatus as well as serving as a calcium flux regulator.⁴ We postulate that given the PACS1 gene is essential for neural crest migration and that neural crest migration is key in the proper fusion of the bulbar septum, abnormalities of the PACS1 gene may lead to incomplete formation of the bulbus cordis and a weaker vessel wall, predisposing to SOVAs.

Aortic root dilation is frequently identified in patients with conotruncal abnormalities, a finding that has often been attributed to an associated shunt or size discrepancy of the semilunar valves. Importantly, varying degrees of histologic degeneration of the aortic media have been identified in patients with congenital heart disease, and this degeneration tends to be advanced in those with conotruncal abnormalities.⁵ Specifically, studies have demonstrated histologic changes ranging from fibrosis, cystic medial necrosis, and elastic fragmentation to elastic lamellae disruption, features that may predispose to SOVA. We therefore speculate that SOVA formation in this case was related to a combination of genetic, histologic, and hemodynamic abnormalities yielding vulnerability of the aortic root.

Asymptomatic survival of patients with SOVAs to old age is not unusual, provided there is not rupture or structural impingement. Indications for repair of nonruptured SOVA are controversial and reports are limited. An aggressive approach is justified when there are complications such as arrhythmias, larger SOVAs, or evidence of RVOT obstruction, as in this case.⁶ Complications such as thrombus formation, bacterial colonization, and rupture can be avoided with early intervention.⁷