The involvement of subaortic structures in the aortic valve endocarditis appears more common than previously recognized. The most common location of the subaortic complications is mitral-aortic intervalvular fibrosa(MAIVF) and the complications may be presented as abscess or pseudoaneurysm. We describe a case of infectious pseudoaneurysm of mitral-aortic intervalvular fibrosa mimicking abscess. In our case, complete AV block was revealed on ECG after aortic valve replacement (AVR). Several days after the first operation, re-do AVR and reconstruction of the MAIVF was performed because of complete AV block and dual fistula complicated by pseudoaneurysm in MAIVF.