Isolated infective endocarditis of the pulmonary valve: an autopsy analysis of nine cases

Abstract

Infective endocarditis (IE) of the pulmonary valve is uncommon and usually occurs in conjunction with tricuspid and/or left-sided valvular endocarditis. There have been only sporadic reports of isolated pulmonary valvular infective endocarditis (PVIE). This report documents the pathological features of nine such cases at autopsy. Among 155 cases of IE encountered in a 14-year period, we selected nine cases that had isolated PVIE for analysis. The clinical records were reviewed for the patient demographics, presence or absence of underlying cardiac disease or other predisposing factors, and modes of presentation; these were correlated with the relevant investigations. A detailed study of the heart was done in all with special attention to the pulmonary valve morphology. The nine cases of isolated PVIE formed 5.8% of the IE cases, seen in six males and three females, largely adults. Seven patients (77.8%) had admissions for about 24 h. Hospital admission was sought for mainly progressive shortness of breath (66.7%) and fever (44.4%). Congenital heart disease was seen in seven (77.8%); two (an infant and an adult) had normal hearts. A single blood sample for blood culture in two patients was negative. Two-dimensional echocardiography, performed in eight, revealed vegetations on the pulmonary valve in four. The pulmonary valve was tricuspid in six cases, bicuspid in two, and unicuspid in one. The vegetations (active in three, active and healing in two, healed in four) were accompanied by concomitant thickening, shortening, perforations, or complete destruction of the cusps. Involvement of the right ventricular outflow tract or the main pulmonary artery was identified in five hearts. Five patients (55.6%) developed pulmonary complications, related to the endocarditis. Detection of PVIE, especially the isolated type, may be underdiagnosed. This condition should be kept in mind during evaluation of patients especially with cardiac anomalies, who present with fever, prominent respiratory symptoms, and negative blood cultures.