Porcine bioprosthetic aortic valve endocarditis with ring abscess and aortic stenosis.

Porcine bioprosthetic valve endocarditis is an infrequent but serious complication of valve replacement surgery. Ring (or annular) abscess is a frequent finding in mechanical valve endocarditis. In contrast, porcine valve endocarditis most often involves the cusps, and annular infection is uncommon. Porcine valvular dysfunction secondary to endocarditis usually takes the form of incompetence, whereas stenosis is less frequent. We report a case of a 76-year-old female who developed endocarditis with Staphylococcus epidermidis nine months after placement of a Carpenter-Edwards porcine aortic valve. Her initial presentation included complete heart block and moderate aortic stenosis. Transesophageal echocardiography aided the diagnosis by demonstrating large vegetations, while transthoracic echocardiography showed only slight thickening of the valve leaflets. At operation, there was a circumferential abscess around the sewing ring causing valve dehiscence and virtual discontinuity of the aorta from left ventricle. Valve degeneration and organisms within the cusps were observed on microscopy. This case illustrates two infrequent complications of porcine aortic valve endocarditis, namely massive annular abscess with invasion of the conducting system and aortic stenosis. It also demonstrates the utility and limitations of transesophageal echocardiography in the diagnosis of this disorder.