The MAIVF is a thin membranous structure between the half of the noncoronary cusp, a third of the left coronary cusp of the aortic valve, and the AML [2]. The MAIVF is composed of the pericardium, while its ventricular side forms by the LVOT [2]. Since the MAIVF is relatively avascular with offering little resistance to infection, infection of this area may result in the formation of abscesses or pseudoaneurysms, or a direct communication from the LVOT to the left atrium [1]. These damages can contribute to the P-MAIVF associated with fatal complications [2]. Furthermore, the P-MAIVF is a rare condition that has been reported as a sequela of infective endocarditis (IE) and surgical trauma [4]. Şahan et al. reported that 40% of patients with the P-MAIVF had active endocarditis and that 18% had a history of previous endocarditis in 166 cases of their literature review [2]. Sudhakar et al. reported that 72% of patients with the P-MAIVF who had histories of active or prior endocarditis in 89 cases of their literature review [4]. In addition, they reported that prosthetic aortic valves and histories of endocarditis were at high risk for developing the P-MAIVF [4].

Although the P-MAIVF often remains asymptomatic in absence of complications, the most frequent presentation was symptoms and/or signs of infection from active endocarditis, followed by dyspnea and heart failure [2, 4]. If the P-MAIVF progressively enlarges and compresses around structures, the patient presents with a variety of symptoms. Compression of the coronary arteries leads to angina or myocardial infarction. The left circumflex coronary artery is often compressed because of its anatomical relationship with its position [4]. Compression of the mitral valve causes mitral valve deformity and mitral regurgitation [5]. Rupture into the pericardial may cause pericardial tamponade [6]. As in our case, perforation or rupture of the P-MAIVF can lead to regurgitation from the LVOT to the left atrium. Echocardiographics revealed an eccentric jet mimicking mitral regurgitation (Figs. 2, 4).

Differential diagnoses include aortic valve annulus abscess, mitral regurgitation, anterior mitral valve aneurysm, and ruptured aneurysm of Valsalva [2, 7]. Initially, our patient was suspected to have an anterior mitral valve aneurysm. However, intraoperative findings showed P-MAIVF.

Echocardiography is useful for the diagnosis of P-MAIVF. TEE is superior to TTE in detecting cavity lesions in MAIVF. Afridi et al. reported that the diagnostic sensitivity of TEE was higher than that of TTE (43% vs. 90%, respectively; P < 0.01) [8]. An important echocardiographic finding for diagnosis of P-MAIVF is a pulsatile echo-free sac that expands in systole and collapses in diastole [2]. This finding provides clues about presence of P-MAIVF [6].

The patient had asymptomatic moderate AR with eccentric regurgitant jet for approximately five years previously. He had been evaluated by TTE for AR without significant changes. He had no previous history of cardiovascular intervention. His clinical records suggested episodes of IE, such as a recent history of fever of unknown origin and current ICH of unknown etiology. Therefore, we suspected that the patient may have presented with IE. However, bacterial and laboratory examinations, intraoperative findings, and histological findings didn’t indicate any current infection.

We considered that AR and endocarditis contributed to ruptured P-MAIVF. We hypothesized that a mechanism of ruptured P-MAIVF was as follows. We suspected that he was the IE by clinical course. Because the infection was spread to the MAIVF, these tissues was destroyed and weakened. The continuous eccentric AR jet hit these weaken area and added a physical load. As a result, the pseudoaneurysm and perforation was formed in short-term. Aortic regurgitation is a contributing factor by adding further insult to the already compromised MAIVF region by the regurgitant jet blood flow as well as by helping establish a secondary infected site in this region [9]. Transthoracic echocardiography and TEE showed the blood flow of the AR jet directly crashing into the P-MAIVF in Figs. 2 and 3, respectively. Because of the rapid formation of P-MAIVF after admission, it is plausible that the fragile P-MAIVF by the continuous blood flow of the AR jet may have become infected and brittle, and then ruptured owing to the additional mechanical stress caused by the AR jet. Postoperative pathological findings showed no obvious active infectious findings such as infiltration of inflammatory cells. Microbiological findings of the resected tissues and blood culture results were negative. Therefore, the patient was considered to have recovered from IE.

The natural course of uncomplicated P-MAIVF remains unclear. In addition, it is well known that left ventricular pseudoaneurysms are prone to rupture. [10] Therefore, surgical repair is currently the recommended treatment to prevent further enlargement and complications [4]. Aortic valve replacement was performed in most patients in conjunction with some type of pseudoaneurysm repair, simple closure of the aneurysmal mouth, patch closure using a pericardial or synthetic graft, and aortic root replacement [2, 4, 11]. The patient was underwent AVR and mitral valve repair with P-MAIVF repair. We approached via transseptal which provide a good visual field. We resected P-MAIVF and patch reconstruction with bovine pericardial patch (Edwards Lifescience, CA., USA) through transseptal approach to prevent re-rupture because tissues of P-MAIVF was weakened. The bovine pericardial patch was made to fit the resection area with 3 mm extra margin for suture. Carpentier et al. said that associated aortic valve involvement requires a combined technique of valve replacement and annular reconstruction [12]. Therefore, we performed MAP for reinforcement of mitral valve annulus. The patch did not affect the procedure of MAP (Fig. 5). We selected a bioprosthetic valve for AVR because of a history of ICH.

Although the patient had volume overload from left ventricular to left atrial, similar to MR, there was no sign of heart failure. Therefore, according to the guidelines [3, 13, 14], the patient underwent surgical repair more than four weeks after the onset of ICH, whereas the clinical course following the surgical procedure was uneventful.