Ochronosis of the aortic valve

Abstract

Ochronosis is the bluish-black discolouration of connective tissue, including heart valves, joints, kidney and the skin. It is due to the deposition of homogentisic acid (HGA) commonly found in alkaptonuria. Ochronosis in the aortic valve is a rare occurrence and there is limited data available on the most appropriate choice of valve prosthesis in these patients. This case involves a 72-year-old male with symptomatic aortic stenosis and on echocardiogram a severe calcific trileaflet aortic stenosis with normal ejection fraction. Intraoperative aortic cannulation was routine and uncomplicated, and bluish-black discolouration of aortic valve was noted. Thorough decalcification was undertaken and a bioprosthetic valve was chosen in accordance with patient's age and preference. There were no complications post-operatively and the patient reported being well. Ochronosis affecting the aortic valve is a rare condition and there is limited data on the recurrence rate as well as the natural history of the disease. This case reports aims to provide data to facilitate further research to better understand the natural history of aortic valve ochronosis and rates of recurrence following bioprosthetic aortic valve replacement (AVR).

A black heart: Aortic valve ochronosis secondary to alkaptonuria causing aortic stenosis

“…It can also affect the aorta, pericardium, endocardium and coronary arteries. Ochronosis‐related valvular disease usually presents in the fifth decade of life—allowing time for accumulation of HGA on valvular tissue 2 . The aortic valve has the highest incidence followed by the mitral and pulmonary valves.…”

“…Ochronosis-related valvular disease usually presents in the fifth decade of life-allowing time for accumulation of HGA on valvular tissue. 2 The aortic valve has the highest incidence followed by the mitral and pulmonary valves. Multiple valves may also be involved simultaneously.…”

“…Alkaptonuria is a rare autosomal recessive genetic disorder due to mutations on the chromosome 3q21‐23 that codes for the enzyme homogentisate 1,2‐dioxygenase—an enzyme that breaks down the amino acids phenylalanine and tyrosine by converting homogentisate to 4‐maleylacetoacetate. This results in the accumulation of homogentisic acid (HGA) in the tissues, leading to ochronosis—a term used for the resulting pathological dark pigmentation from excess HGA 1,2 . Aortic valve ochronosis is a rare cardiac manifestation of alkaptonuria and is thought to stimulate progressive dystrophic calcification and fibrosis, leading to stenosis 3–5 .…”

“…This results in the accumulation of homogentisic acid (HGA) in the tissues, leading to ochronosis-a term used for the resulting pathological dark pigmentation from excess HGA. 1,2 Aortic valve ochronosis is a rare cardiac manifestation of alkaptonuria and is thought to stimulate progressive dystrophic calcification and fibrosis, leading to stenosis. [3][4][5] We present a rare case of aortic valve stenosis secondary to alkaptonuria that required surgical intervention.…”

Black Aortic Valve: Incidental Finding of Alkaptonuria

“…A mutation in chromosome 3q21–23 causes a deficiency in the homogentisic acid oxidase enzyme and results in accumulation of homogentisic acid in extracellular tissues, leading to pathologic pigmentation termed ochronosis. 1 …”