Non-ruptured sinus valsalva aneurysm mimicking obstructive cardiac mass

A 91-year-old male presented at the emergency department with shortness of breath, elevated arterial blood pressure (184/85 mmHg), elevated D-Dimer (2.76 mg/L), AV-block I, frequent ventricular extrasystoles and bigeminal pattern. CT pulmonary angiography (CTPA) was performed to rule out pulmonary artery embolism (PAE), followed by echocardiography and cardiac MRI.

CTPA (Fig.1) was negative for PAE but showed a 6.0cm×4.5cm hypodense structure between the left ventricular (LV) outflow-tract and the right ventricle (RV). Cardiology was consulted and echocardiography was performed.

Echocardiography showed the structure without signal in Doppler sonography suggestive of a pericardial cyst with suspicion for RV outflow-tract obstruction. The patient was referred to cardiac MRI for further evaluation of the suspected cardiac mass.

Comprehensive cardiac MRI was performed according to current recommendations for evaluation of cardiac masses [1]. Cine-realtime and single-shot imaging was used to compensate for patient’s irregular heart rhythm and inability to breath-holding. In T2-weighted bright-blood imaging (Fig.2) the structure was hyperintense compared to the RV and LV cavity. Unlike in cysts - which are characterized by extremely high native T1 and T2 values [2] - relaxation times in the structure were in the range of blood (Fig.2) indicating its vascular nature. First-pass rest perfusion showed avid enhancement of the structure (Fig.3) establishing the diagnosis of a large non-ruptured sinus of Valsalva aneurysm (SOVA). Late enhancement imaging excluded the presence of thrombi in the aneurysm (Fig.4).

Background

SOVA is a rare finding with an estimated incidence of 0.09% of the general population [3,4]. SOVAs are located between the aortic valve annulus and the sinotubular junction and originate more frequently from the right or the noncoronary than the left coronary sinus [5,6]. They are more frequently observed in males with the highest incidence in the Asian population [6,7].

SOVAs may be congenital or acquired. Congenital SOVAs are typically associated with connective tissue disorders (Marfan’s syndrome, Loeys–Dietz syndrome, Ehlers-Danlos syndrome) or bicuspid aortic valve [4,8]. Causes for acquired SOVAs are infectious diseases (endocarditis, syphilis, tuberculosis), degenerative (atherosclerosis, cystic medial necrosis) and chest trauma injuries [6,8].  

Clinical Perspective

Non-ruptured SOVAs are usually asymptomatic [6-8] but can lead to arrhythmia, AV block, and atrial fibrillation. During expansion compression of adjacent structures can cause RV outflow-tract obstruction, symptoms of acute coronary syndrome and aortic valve regurgitation [9]. According to guidelines surgical repair of non-ruptured SOVAs should be considered in aneurysms > 5.5 cm and growth rates > 0.5 cm/year [10]. Even though various studies highlight strengths and limitations of non-invasive imaging in the management of SOVA, guidelines for optimal assessment, monitoring, and management of SOVAs are lacking [11].

Imaging Perspective

The case represents the common situation of SOVA incidentally detected during clinical workup. ECG-gated contrast-enhanced CT angiography of the thoracic aorta represents the standard technique for SOVA evaluation [11,12], CTPA can misinterpret unenhanced aortic lesions. Echocardiography represents the established first screening modality for detecting SOVA [13] but - as in the present case - might misclassify SOVA due to eccentric inflow, which explains the absence of the Doppler signal.

Cardiac MRI offers various tools for morphological and functional assessment of the heart and surrounding structures [1,14]. As shown in the present case it also allows the diagnosis of SOVA, even in patients with arrhythmic heartbeat and inability to hold the breath by using single-shot and cine (compressed-sensing) realtime imaging techniques.

Outcome

After diagnosis was established the patient was referred to cardiothoracic surgery for further clinical management. Due to the advanced age of the patient a conservative therapeutic approach was decided.

Conclusion

Fast and correct diagnosis of SOVA might be challenging, requires awareness of this rare condition and appropriate use of cardiac imaging techniques. If patients with SOVA are referred to cardiac MRI, first-pass perfusion technique represents a highly valuable method for visualization and analysis of complex dynamic cardiac and cardiovascular configurations, especially when imaging planes are oriented through and along suspicious structures.