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.