Experimental aortic valve stenosis in rabbits

OBJECTIVES We studied a known rabbit model of atherosclerosis to assess the effect of a hypercholesterolemic diet on aortic valve morphology and function. We also evaluated the effects of the combination of this diet with vitamin D supplements on the development of the disease and the occurrence of valve calcification. BACKGROUND Aortic valve stenosis (AVS) is the most common valvular heart disease. Recent observations have suggested a link between atherosclerosis and the development of AVS. However, until now, there has been no solid direct proof of this potential link. METHODS Rabbits were divided in three groups: 1) no treatment; 2) cholesterol-enriched diet (0.5% cholesterol); and 3) cholesterol-enriched diet plus vitamin D-2 (50,000 IU/day). Echocardiographic assessment of the aortic valve was done at baseline and after 12 weeks of treatment. The aortic valve area (AVA) and maximal and mean transvalvular gradients were recorded and compared over time. RESULTS Control animals displayed no abnormalities of the aortic valve. Despite important increases in blood total cholesterol levels, animals in group 2 did not develop any significant functional aortic valve abnormality over 12 weeks. However, eight of 10 of the animals in group 3 developed a significant decrease in AVA (p = 0.004) and significant increases in transvalvular gradients (p = 0.003). CONCLUSIONS This study supports a potential link between atherosclerosis and the development of AVS. The differences noted between hypercholesterolemic animals with or without vitamin D, supplementation imply a significant role of calcium in the development of AVS, meriting further attention.