86: Congenital Anomalies of the Sinuses of Valsalva and Aortico–Left Ventricular Tunnel

Congenital Anomalies of the Sinuses of Valsalva

Initially described in 1839,¹ sinus of Valsalva (SoV) aneurysm is a rare condition incidentally found in 0.15 to 1 percent of patients undergoing cardiopulmonary bypass (CPB)^2,3 and five times more frequently in Asians.⁴ In 1956, Morrow and Lillehei, using inflow inclusion and a membrane oxygenator, separately reported successful SoV aneurysm repair.^5,6 Since then, surgical repair has been established as the accepted standard of care.

Although acquired SoV aneurysms can occur in the setting of infection or trauma, they are most commonly congenital in origin and associated with many different connective tissue disorders, including rheumatoid arthritis, Ehlers–Danhlos syndrome, Marfan syndrome, Klippel–Feil syndrome, Turners syndrome, trisomies 13 and 15, Loeys–Dietz syndrome, arachnodactyly, and osteogenesis imperfecta. SoV aneurysms are frequently associated with other cardiac abnormalities, including ventricular septal defect (VSD) and aortic valve regurgitation.

SoV aneurysms most commonly originate from the right coronary sinus (RCS), followed by the noncoronary sinus (NCS),⁷ reflecting the embryologic origin of the RCS and NCS from fusion of the bulbar septum and truncal ridges. Incomplete fusion of the bulbar septum can in fact result in aneurysm formation when the septum is subjected to long-standing systemic arterial pressure.⁸ Aneurysms of the left coronary sinus are exceedingly rare and are usually an acquired phenomenon, as the left coronary cusp does not arise from the bulbar septum.

Morphology

On histopathology, SoV aneurysms are characterized by separation of the sinus aortic media adjacent to the hinge point of the aortic valve cusp.⁸ Normally, the sinuses are thinner than the tubular portion of the aorta and are limited inferiorly by the semicircular hinge point of the corresponding aortic valve cusp. In patients with SoV aneurysms, this otherwise normal characteristic is accentuated, and thinning of the aortic wall with disconnection of the media increases over time, resulting in aneurysm formation.⁹

The anatomic relationship between aortic root and adjacent cardiac structures predicts the clinical findings associated with gradual dilation and rupture of SoV aneurysms (Fig. 86-1). Aneurysms arising from the RCS most commonly involve the right atrium (RA) or right ventricular outflow tract (RVOT), while NCS aneurysms decompress either into the right or left atrium. Rare aneurysmal dilation of the left aortic sinus can eventually rupture into the left atrium. Although aortic root involvement is usually limited to a single sinus, enlargement of two sinuses or the entire aortic root occurs in rare cases. A concomitant VSD is found in up to 50 percent of congenital cases.^10,11