Abstract
Bacterial endocarditis has been reported to occur in 5 to 9 percent of patients with hyper trophic obstructive cardiomyopathy (HOCM), but in only a few cases has the heart been examined either during operation or at necropsy. Recently we experienced a case of bacterial endocarditis, which primarily demonstrated manifestations of HOCM, and subsequently the diagnosis was confirmed during the operation (i. e. mitral valve replacement and ventriculomyotomy).
This case was a 33 year old man who was admitted to our hospital because of high fever and dyspnea. He had been well until 2 months prior to admission, when he began to complain of general fatigue. During those 10 days prior to admission, he experienced high fever, chills and nocturnal dyspnea. His cousin and aunt were diagnosed as hyper-trophic cardiomyopathy in the past. During the physical examination a grade 4 systolic murmur was audible at the apex radiating to the axillary area. The third heart sound and the forth heart sound were present. The echocardiogram showed specific signs of HOCM (i. e. asymmetric septal hypertrophy, systolic anterior motion of the mitral valve and mid-systolic closure of the aortic valve). Vegetations were observed on the anterior leaflet of the mitral valve and the chordae tendinae. The patient was started on intravenous me-thicillin and intramusuclar gentamiciri. After all six blood cultures grew streptococcus viridans, these antibiotics were replaced by intravenous penicillin G and intramuscular streptomycin daily. After the antibiotics therapy his condition improved and his temperature became normal. On the 10th day his temperature rose to 39°C and he developed left side heart failure. On the 11th day a Swan-Ganz catheter was inserted. The “v” wave of the pulmonary capillary wedge pressure was 55 mmHg. The results showed the presence of severe mitral regurgitation. An emergency operation was performed on the same day. The concluding results were that left ventricle had typical appearance of HOCM and multiple vegetations were attached to the anterior mitral leaflet and chordae tendinae. The anterior mitral leaflet was severely deformed. After a mitral valve replacement and the ventriculomyotomy, the intraventricular pressure gradient fell from 70mmHg to 15mmHg and the left atrial pressure was also reduced. His postoperative condition was uneventful and infection was well controlled.
It is postulated that the pathogenesis of the bacterial endocarditis in patients with HOCM is a chronic mechanical endocardial trauma, which is induced by systolic anterior motion of the mitral valve and by midsystoric jet of the blood passing through the aortic valve at high velocity. The aortic valve, the mitral valve and the outflow tract of the left ventricle may be affected. Bacterial endocarditis is not a rare complication of HOCM, paticularly of the hemodynamically severe form of the disease. This case report is presented to reemphasize the fact that a patient with HOCM has a high risk of developing bacterial endocarditis. We would like to stress the need for adequate prophylactic antibiotics in patients who undergo manipulations which may produce bacteremia.
