Recurrent Prosthetic Mitral Valve Dehiscence due to Infective Endocarditis: Discussion of Possible Causes
A 30-year-old male patient had undergone mitral valve replacement with a No. 27 St. Jude metallic valve six years previously. He also underwent mitral valve replacement with a bioprosthetic valve one year previously due to dehiscence of the metallic valve and cardiogenic shock caused by PVE (, ). Six weeks after this second operation, the patient again was evaluated for cardiogenic shock and prosthetic valve dehiscence was noted. He underwent a third operation, and the mitral valve was replaced with a No. 27 St. Jude metallic valve. Vancomycin (2 g/day), rifampicin (600 mg/day), and gentamicin (80 mg/day) were started immediately. After the third operation, the patient received six weeks of antibiotic therapy and was discharged without sequelae. Several blood cultures were drawn, and all were negative for a causative agent. He was scheduled for outpatient follow-up monthly to adjust the warfarin dose. Fourteen months after the last operation, he was admitted to our clinic with fever for nearly two weeks. Transthoracic echocardiography showed a mobile mass on the mitral valve prosthesis. Transesophageal echocardiography (TEE) was performed, and a partially mobile mass on the prosthetic valve was revealed. The mass was on the atrial side of the medial valve within the suture line and sized 8×5 mm (). Laboratory evaluation showed an increased white blood count (13,500 mm/L), erythrocyte sedimentation rate (80 mm/hr) and C-reactive protein (161 mg/L). The international normalized ratio (INR) was 2.4. The patient was then hospitalized for PVE, and three sets of blood cultures were drawn. Vancomycin (2 g/day) and rifampicin (600 mg/day) were started immediately. Blood cultures were negative for a causative agent. On follow-up, clinical and laboratory values were improved. After six weeks of treatment, the mass was shown to regress on TEE (). By adjusting the dose of warfarin, a steady INR level between 3 and 3.5 was achieved and the patient was discharged. There was no relapse during the first six months of close follow-up.