A Case of Infantile Infective Endocarditis Presenting Acute Mitral Regurgitation due to Valvular Destruction without Fever

Abstract

We present a case of a healthy 7-month-old female infant who developed sudden left heart failure due to acute mitral regurgitation (MR). She was rushed to our hospital on the day of onset and underwent semiemergency surgery the next day. Antimicrobial treatment was initiated upon admission, and pyrexia occurred 8 h later. At surgery, the anatomical findings included the destruction of both the anterior and posterior leaflets of the mitral valve, posterior mitral valve leaflet perforation, an undetected rupture of the chordae tendineae, and no vegetation on the mitral valve. Mitral valve replacement was performed because of the difficulty of mitral valve annuloplasty. A culture test of blood and resected anterior mitral valve demonstrated no bacterial or fungal infection, but histopathological analysis revealed polymorphonuclear cell infiltration of the resected mitral valve leaflet. The patient was diagnosed with infective endocarditis (IE) based on these findings; however, we were unable to determine the cause of infection or pathogenic bacteria. Acute MR in infants can be caused by IE and acute rupture of the chordae tendineae of the mitral valve (RCTMV). The current case of infantile IE started with acute MR due to significant valvular destruction, followed by pyrexia, and progressed quickly, similar to RCTMV in infants. Because the treatment and complications of acute MR in healthy infants are dependent on the cause, we must take special care to ascertain the cause along with histopathological analysis.