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

Clinical Features

SoV aneurysms produce symptoms by compression or direct rupture into an adjacent chamber and are often found incidentally. Onset of symptoms is gradual in 50 to 70 percent of patients and occurs most commonly between 20 and 30 years of age but ranges in reported series from infancy to the seventh decade.^12–15 Aortic root rupture into either a neighboring cardiac chamber or within the pericardial cavity is rare in the first two decades of life.^16–18 Although clinical presentation is most commonly indolent, it can be acute depending on aneurysmal size, site of rupture (adjacent chamber versus pericardial sac), and the concomitant presence of a VSD or aortic insufficiency. In case of intracardiac rupture or fistulization, the most common presenting symptom is dyspnea, with nearly all patients exhibiting a continuous systolic–diastolic “machinery-like” murmur.¹⁹ Numerous electrocardiographic findings have been described, including ST-segment depression, onset of Q waves, atrioventricular block, atrial fibrillation, and sudden death. Intrapericardial rupture typically presents with acute hemodynamic collapse and cardiac tamponade. A minority of patients (less than 20 percent) will present with evidence of sepsis associated with bacterial endocarditis.²⁰

Surgical Therapy

Urgent operative intervention is clearly indicated for symptomatic patients with rupture or compressive fistulas. SoV aneurysms that are asymptomatic but discovered at the time of CPB should be repaired because of the high likelihood of progressive increase in size, possibility of rupture, or symptom progression. Smaller, asymptomatic SoV aneurysms discovered incidentally during routine echocardiography can be safely followed over time unless progressive enlargement is noted or the patient develops symptoms. Surgical repair may be indicated earlier in patients with significant connective tissue disorder or family history of dissection or rupture.

After induction of general anesthesia, transesophageal echocardiography is routinely performed to confirm the preoperative findings, assess valvular competence, and rule out associated septation defects and endocarditic vegetations. Transesophageal echocardiography is also crucial in defining the course of the fistulous tract in case of intracardiac rupture. The surgical treatment of three-sinus enlargement of the aortic root is detailed elsewhere in this volume and entails either valve-sparing replacement^21,22 of the root or replacement with mechanical or biological prostheses.

Aortotomy is performed to assess the aortic root anatomy and an additional right atriotomy is performed to expose the distal site of rupture or protrusion, especially the “windsock” aneurysmal sac that projects toward the right-sided chambers. A transventricular approach can be utilized alternatively to expose a concomitant VSD. The aortic aspect of the defect is repaired with prosthetic material (Fig. 86-2) to prevent the high risk of aortic valve distortion and recurrence of primary closure. In case of diverticular extension into the RA or right ventricle (RV) (via a VSD), the distal aspect of the SoV aneurysm is corrected with similar technique.