Evaluation of hyaluronan and calcifications in stenotic and regurgitant aortic valves.

OBJECTIVE

Hyaluronan (HA) is a major component of the interstitium and has been observed in normal heart valves. The function of HA in heart valves is unknown but contribution to biomechanical function has been proposed. The purpose of this investigation was to study the distribution of HA in relation to calcifications in diseased human aortic valves.

METHODS

Human aortic valves were collected at aortic valve replacement, of whom nine patients had regurgitation and 13 stenotic disease. The valves were decalcified and stained for the visualisation of HA. The specimens were macroscopically evaluated for magnitude of calcification using image analysis. The microscopic amount and distribution of HA and calcifications were semiquantitatively evaluated using histochemistry.

RESULTS

The overall HA staining showed an inverse relationship against the magnitude of observed valve calcifications (p<0.001) and type of disease (p=0.014). Multiple-group comparison revealed regionally reduced HA staining in diffuse and heavy calcified regions inside the valve (both p<0.001) compared with normal-structured parts of the valve. HA was concentrated on the ventricular side of the valve (p=0.002).

CONCLUSIONS

The content of HA was reduced in calcified aortic valves and had a heterogeneous distribution, potentially contributing to poor valve function. HA may also be involved in the pathophysiological process in degenerative aortic stenosis.