Pseudoaneurysm of the mitral-aortic intervalvular fibrosa with fistulous communication to the left atrium causing congestive heart failure.

Pseudoaneurysms of the mitral-aortic intervalvular fibrosa can rupture and form fistulous communications between the left ventricle and left atrium. Pulmonary venous systolic flow reversal in such cases reflects elevated left atrial pressure due to shunting. This finding, particularly in the setting of endocarditis, is not specific for severe mitral regurgitation.