[Pathology of infective endocarditis]

Clinico-pathological studies were made of 40 patients with infective endocarditis : 34 (22 men, 12 women ; ages, 5-71 years, mean, 40.4 years) had native valve endocarditis (NVE) and 6 (3 men, 3 women ; ages, 26-48 years, mean, 38.3 years) had prosthetic valve endocarditis (PVE). The aortic valve was involved most frequently (AV : 16, MV : 6, AV+MV : 8, TV : 3, MV+TV : 1). Thirteen patients had preexsisting heart disease (rheumatic in 4, floppy in 6, other in 3). Six of 21 "normal" valves showed myxomatous changes with connective tissue degradation, findings compatible with the histological diagnosis of floppy valve. The infecting organisms were identified by blood cultures in 26 patients. Bacteria and/or fungi were found histologically in 23 valves, even in those in which cultures of excised tissues were negative. In 2 cases, fungi were identified in the sewing ring of the prosthetic valves. This study demonstrates that : 1) floppy valve is a most important underlying heart disease in NVE ; 2) the infecting organisms are frequently identified histologically, even when cultures of excised tissues are negative ; and 3) fungi are important causes of both NVE and PVE, especially in patients given intensive antibiotic therapy.