An abscess of mitral aortic intervalvular fibrosa mimicking an intracardiac mass.

BACKGROUND

Abscess of the mitral-aortic intervalvular fibrosa (MAIVF) is a rare occurrence, with its most frequently described causative associations being active or prior endocarditis, prosthetic valves, or native valves with anomalies. We report a case of infective endocarditis (IE) complicated by an abscess of the MAIVF without valvular involvement. This case highlights the importance of this rare clinical entity and of the multimodality imaging approach in reaching an accurate diagnosis and differential diagnosis.

METHODS AND RESULTS

A 35-year-old male presented with fatigue and intermittent high-grade fever for a 2-week duration. IE was suspected based on a clinical exam. Transthoracic echocardiography (TTE) demonstrated heterogeneous mass with a size of about 2.9 cm × 2.3 cm coming from the MAIVF, mimicking an intracardiac mass. Color Doppler flow Imaging showed the mass without communication with the surrounding cardiovascular cavities. Cardiac computed tomography angiography (CCTA) revealed a large low-density mass without any enhancement, which was situated adjacent to the left ventricular tract with a severely compressed left atrial chamber. The patient underwent cardiac mass removal under extracorporeal circulation. During the procedure, a large abscess was found to be located in MAIVF. The postoperative course was uneventful.

DISCUSSION

The abscess of MAIVF is a rare entity with a high risk of developing the pseudoaneurysm of MAIVF (p-MAIVF). The periaortic spread of the abscess is a dynamic process in which the inflammation of the deep tissue causes, in the first stage, a MAIVF thickening, which eventually progresses with the formation of an abscess, and subsequently, a pseudoaneurysm. Complications of p-MAIVF include rupture into the left atrium, aorta, or pericardial space leading to hemopericardium, tamponade, and death. The major differential diagnosis for abscess of MAIVF includes p-MAIVF an intracardiac mass. TTE plays a key role in the diagnosis and differential diagnosis of abscesses of MAIVF. CCTA can be a useful adjunct to further characterize abscess spread, three-dimensional spatial relationships with other cardiac structures for preoperative planning, as well as in the evaluation of potential complications such as coronary artery compromise and communication with the aorta, left atrium, or pericardial space. Surgical management is recommended in complicated, symptomatic patients to prevent further expansion of abscesses or pseudoaneurysms.

CONCLUSION

The abscess of MAIVF is a rare complication of endocarditis and surgical trauma in the MAIVF area, TTE remains a first-line imaging modality for clinically suspected periaortic abscess or other IE complications. CCTA has a complementary role to echocardiography in identification, characterization, and preoperative planning.