CASE PRESENTATION
A 78-year-old woman was referred to our institute for an elective AVR for AS. At 55 years of age, she had undergone a left hip replacement for degenerative arthropathy. She had consanguineous parents. Transthoracic echocardiography showed a thickened and calcified aortic valve with a mean transvalvular gradient and calculated aortic valve area of 57.4 mmHg and 0.63 cm2, respectively. Cardiac catheterization revealed severe AS with a transvalvular pressure gradient of 99 mmHg and no calcification or stenosis of coronary vessels. The patient underwent AVR for severe asymptomatic AS.
A cardiopulmonary bypass was performed intraoperatively using aortic and caval cannulation, and moderate hypothermia was induced. Cold antegrade crystalloid cardioplegia was performed. After an oblique aortotomy, black pigmentation of the aortic intima extending to the aortic valve leaflet was observed (Figure 1). The leaflets were heavily calcified, thickened, and covered with black patches. The black pigmentation extended to the left ventricular outflow tract and anterior leaflet of the mitral valve. AVR was performed using a 19-mm bioprosthesis (Crown PRT, LivaNova, London, UK).
Postoperatively, the patient disclosed a history of normal-colored urine on voiding, which darkened in diapers during her childhood. Her sclerae and cartilage of the pinnae were bluish black. Discoloration of collagenous tissues and a history of degenerative arthropathy and dark urine prompted the diagnosis of alkaptonuria. Increased urinary excretion of HGA confirmed this diagnosis. A histopathological examination of the excised aortic valve leaflets revealed dark-brown pigmentation in the body of the valve, which was associated with calcium nodules (Figure 2). The postoperative period was uneventful. She was discharged from the hospital without complications. She has been free from any cardiovascular system-related symptoms for 3 years. Follow-up echocardiography revealed a mean prosthetic valve gradient, calculated aortic valve area, and left ventricular ejection fraction of 9.7 mmHg, 1.53 cm2, and 72%, respectively. The difference in prosthetic valve functionality between discharge and follow-up was not significant.