"Flap valve phenomenon" limiting aortic regurgitation in prosthetic valve dehiscence

The authors describe the case of a 52-year-old man with a history of supra-annular mechanical aortic valve replacement who presented with fever and abdominal pain. He was found to have an abdominal wall abscess. Subsequent transesophageal echocardiography revealed dehiscence of his mechanical aortic valve, supporting a diagnosis of prosthetic valve endocarditis. Transesophageal echocardiography demonstrated that the dehisced aortic valve rocked on a hinge point, mimicking the motion of a flap valve. As the prosthetic valve rose with systole, it permitted flow into the aorta and, falling back in diastole, formed enough of a seal against the wall of the aortic annulus to limit aortic insufficiency. This "flap valve phenomenon" resulted in minimal perivalvular regurgitation, and the patient remained hemodynamically stable without heart failure before valve replacement.