Cardiovascular involvement in Alcaptonuria: a case report on ochronotic aortic valve

Alcaptonuria is a rare autosomal recessive metabolic disorder. It is characterized by the accumulation of homogentisic acid-derived brown and bluish-black pigments in connective tissues, a condition known as ochronosis. This occurs due to a defect in the metabolic pathways of phenylalanine and tyrosine caused by a deficiency of the enzyme homogentisate 1,2-dioxygenase. The triad of homogentisic acid accumulation in urine and its darkening upon exposure to air, blue-gray pigmentation in connective tissue and degenerative ochronotic arthropathies are the main features of alcaptonuria. The ochronotic pigments accumulated in connective tissues act as triggers for dystrophic calcifications in these tissues. In alcaptonuria, the joints, eyes, ears, skin, and genitourinary system are typically affected. Although rare, cardiovascular involvement can also be observed, including the aortic intima, coronary vessels, heart valves, and pericardium. This report presents a case of ochronosis that was observed during surgery in a patient scheduled for aortic valve replacement and coronary artery bypass grafting due to aortic valve stenosis and coronary artery disease. Despite being rare, cardiac ochronosis may be identified and diagnosed during surgery in patients who had not previously received a diagnosis. As cardiovascular surgeons, we need to be aware of it.