Aortic sinus aneurysm is a rare congenital heart disease with a higher incidence in Asian populations, and it occurs more frequently in males than in females. It results from abnormal development of the aortic sinus tissue during the embryonic period, leading to a deficiency of normal elastic fibers in the middle layer of the wall. Prolonged exposure to high-pressure blood flow causes gradual outward bulging, forming an aortic sinus aneurysm. The aneurysm typically appears as a sac-like structure measuring 0.5–3.5 cm in length and 0.5–1.2 cm in diameter, with a weak apex that can rupture, creating one or more openings. Rupture most commonly occurs in the right coronary sinus, frequently leading to the blood flow entering the right ventricular cavity. Rupture into the right atrium is less common and typically involves the non-coronary sinus. Frequently associated cardiac anomalies include ventricular septal defect and aortic valve insufficiency.
Pathophysiology
Aortic sinus aneurysms may protrude into the right ventricular outflow tract, obstructing blood flow in the right ventricle. If the aneurysm ruptures, blood from the aorta flows into the right ventricle or right atrium, creating a persistent left-to-right shunt. This increases the volume load on both the right and left ventricles and elevates pulmonary blood flow, potentially leading to heart failure and pulmonary hypertension. The severity of these effects depends on the size of the rupture and the pressure differential between the adjacent heart chambers. Rupture into the right atrium, where pressure is lower, results in more severe and rapidly progressing symptoms. Reduced diastolic aortic pressure may further cause insufficient coronary blood supply.
Clinical Manifestations
Unruptured aortic sinus aneurysms often remain asymptomatic. In rare cases, a large aneurysm may protrude into the right ventricular outflow tract and cause obstructive symptoms. Aneurysm rupture typically has a distinct history and triggering factors, such as intense physical activity or trauma. Approximately 40% of patients experience sudden symptoms such as chest pain and dyspnea, which can lead to acute right heart failure and death. Most patients exhibit insidious onset and progressive symptoms such as exertional palpitations and shortness of breath.
Physical examination may reveal different findings depending on the location of the rupture. In cases of rupture into the right ventricle, a continuous machinery-like murmur of grade III–IV intensity can be heard along the left sternal border at the 3rd–4th intercostal space, radiating toward the cardiac apex and accompanied by systolic thrill. In rupture into the right atrium, the murmur shifts toward the central or right sternal border. Peripheral vascular signs such as widened pulse pressure, water-hammer pulse, and capillary pulsations may be observed. Additionally, signs of right heart failure, including jugular vein distension, hepatomegaly, and bilateral lower extremity edema, may be present.
Ancillary Examinations
Electrocardiogram (ECG)
Findings may include left-axis deviation and evidence of left or bi-ventricular hypertrophy.
Chest X-Ray
Increased pulmonary vascular markings, enlarged cardiac silhouette, and prominent pulmonary artery segment may be noted.
Ultrasound
The affected aortic sinus may exhibit significant bulging, with the aneurysm protruding into the right ventricular outflow tract or beneath the interatrial septum during diastole. The rupture site and shunting may be directly visualized.
Diagnosis
Diagnosis can be established based on clinical history, distinctive heart murmur characteristics, and findings from ultrasound, ECG, and chest X-ray examinations. Differential diagnosis of ruptured aortic sinus aneurysm should consider patent ductus arteriosus, high ventricular septal defect with aortic valve insufficiency, coronary artery fistula, and defects between the aorta and pulmonary artery. Retrograde aortic angiography can confirm aneurysm formation in the right coronary sinus or non-coronary sinus, as well as detect early visualization of the right atrium, right ventricular outflow tract, or pulmonary artery.
Treatment
Indications for Surgery
Early surgical intervention is recommended upon diagnosis, especially in cases of ruptured aortic sinus aneurysm accompanied by uncontrolled acute heart failure, which require urgent or semi-urgent surgery. Unruptured aortic sinus aneurysms associated with ventricular septal defect, aortic valve insufficiency, or obstruction in the right ventricular outflow tract also necessitate concurrent surgical repair. Smaller unruptured aneurysms may not require surgery but should be monitored through regular follow-ups.
Surgical Techniques
Cardiopulmonary bypass is employed for direct visualization surgery within the heart. Depending on the chamber involved and any associated abnormalities, exposure of the aneurysm is achieved via incisions in the right atrium, right ventricle, or ascending aorta. The aneurysm wall is excised circumferentially at the neck of the aneurysm. Small openings at the aneurysm site can be closed directly with sutures, while larger openings require repair using artificial patch materials. Concurrently present ventricular septal defects and aortic valve insufficiency are addressed during the same procedure.