A rare differential diagnosis of aortic stenosis with a black aortic valve: A case report

Cardiac ochronosis, presenting as a rare manifestation of alkaptonuria, an autosomal recessive disorder, is characterised by black pigmentation of calcified cardiac valves and atherosclerotic plaques. We report an intraoperative dilemma on the discovery on the black aortic valve in a case of an old lady with degenerative calcific aortic stenosis.

A 60-year-old lady was electively admitted for valve replacement with a bioprosthetic valve for severe aortic stenosis. She was symptomatic with complaints of headache and giddiness and had a pressure gradient of 113/17mmhg across the aortic valve. Intraoperatively, she was found to have cardiac ochronosis on the discovery of pigmented aortic intima extending to the valve leaflets and underwent valve replacement with a mechanical prosthetic valve. She was post-operatively evaluated for the same and diagnosed with alkaptonuria. Though the surgery went uneventful and the patient was discharged without any complication, she was advised to be on regular follow-up to assess valve gradients, paravalvular leaks and to monitor the disease progression.

The presented case sheds light on the rare cardiac manifestation of alkaptonuria. In the absence of definitive pre-operative diagnosis, intraoperative findings played a pivotal role in guiding the surgical approach and choice of prosthetic valve. The decision to use a mechanical valve was influenced by the potential risks associated with bioprosthetic valves in the setting of ochronosis. Ongoing follow-up and monitoring are essential to assess the durability of the chosen prosthetic valve and to manage any long-term consequences of the underlying metabolic condition.