SVA is a rare cardiac abnormality that is caused by weakening of the elastic lamina and muscular tissue in the aortic wall behind the sinus of Valsalva. 2,3 Most cases are congenital and secondary to connective tissue disease, including Marfan’s syndrome and many other conditions. However, acquired SVA is generally due to IE, atherosclerosis, trauma, drug or alcohol abuse, cystic medial necrosis, or degenerative disease.4 Both our patients had IE confirmed intraoperatively and by histopathology. Infection may lead to dilatation of the sinus of Valsalva and deformation of the aortic valve cusps, culminating in rupture of the SVA and dissection of the IVS. Progression of the SVA may also increase the risk of endocarditis.5 Diagnosis of endocarditis relies mainly on the finding of vegetation and a positive blood culture. The positive blood culture rate ranges between 50% and 90% depending on the timing and quantity of blood collection, whether or not antibiotic therapy has been started. In our two cases, multiple blood cultures were negative. Positive blood cultures can help with the clinical selection of antibiotics, but negative results cannot easily rule out a diagnosis of endocarditis.
Most SVAs originate from the right coronary sinus, followed by the non-coronary sinus, and the left coronary sinus is least common.6 SVA is generally asymptomatic. However, an enlarged coronary sinus may protrude into the adjacent cardiac structure, lead to neighboring cavity obstructions, cause myocardial infarction or ischemia by compression of the coronary arteries, or, in extremely rare cases, dissect into the IVS. Strenuous activity, emotional excitement, infection, trauma, and iatrogenicity (cardiac catheterization) can induce rupture of an SVA. The majority of right SVAs rupture into the right ventricular outflow tract, followed by the right ventricle and right atrium. SVA dissecting into the IVS, as in our second case, always originates from the right coronary sinus and is usually associated with conduction abnormalities and aortic regurgitation. According to its dissecting nature, an SVA can cause congestive heart failure if it ruptures into the ventricular cavity. Less ruptured noncoronary sinus aneurysms rupture into the right atrium, right ventricle, or pericardial cavity. Left SVA typically ruptures into the LV, left atrium, or pericardial cavity, as in our first case, and is the rarest type.
The clinical features and symptoms of SVA are inextricably linked to progression of the aneurysm and the site of rupture. An unruptured aneurysm is generally clinically silent until it increases in size and compresses nearby structures or develops thromboembolic complications.7 SVA rupture is an urgent and serious situation that can manifest as sudden hemodynamic collapse, acute coronary syndrome, acute heart failure, cardiac tamponade, and even sudden death, depending on the size of the ruptured orifice, the acuity of the rupture, and the receiving chamber.8,9 As in our two cases, embolic events associated with endocarditis should be taken seriously. Coronary angiography is the gold standard for diagnosis of SVA, but was not required in our cases. Echocardiography is generally the preferred initial examination tool and can detect the location and size of the dissecting aneurysm, its relationship with adjacent structures, vegetations, and any cardiac abnormality. Vortex flow in the dissecting cavity, aortic regurgitation, and communication between the dissecting cavity and the left or right ventricle can be easily shown by color Doppler. Collapse of the aneurysm during systole, filling of the aneurysm with blood during diastole, and continuous flow in systole and diastole are useful findings in a patient with a ruptured SVA. These features were demonstrated by echocardiography in our two patients.
The differential diagnosis of SVA should include subaortic aneurysm, ventricular septal defect, coronary arteriovenous malformation, fistula, and abscess. The crucial distinction is that SVA involves structural anomalies in one or more sinuses of Valsalva in the aortic root. Echocardiographic findings are crucial for correct diagnosis of SVA, and early surgical intervention is the optimum treatment to prevent further rupture and exacerbation of symptoms. In the opinion of the authors, the prognosis of the two patients in this report may have been better and the operation simpler if it had been performed in the absence of endocarditis.