Abstract
Calcific aortic valve stenosis affects an increasing number of elderly patients and causes considerable morbidity. The etiology of this disease is unclear. Lately, the issue has been raised that its pathogenesis may be linked to chronic inflammation caused by microorganisms. The aim of the present study was to investigate if bacteria are present in calcific stenotic aortic valves. Tissue specimens were collected from 19 patients undergoing aortic valve replacement for aortic valve stenosis and from ten patients with regurgitant aortic valves or clinically healthy valves from explanted hearts (controls). Specimens were sectioned and subjected to transmission and scanning electron microscopy, as well as to anaerobic culturing. Bacteria of various morphologies (cocci, rods, spiral and crescent forms) were detected in 16 of the 19 patients with valve stenosis. Twelve of these patients yielded positive cultures and 12 were positive assessed by electron microscopy. The bacteria were present in fibrous tissue in the thickened areas of the valve and in lacunae of calcified nodules. Bacteria seemingly undergoing cell division were observed. Macrophage digestion of bacteria was also noticed. No bacteria were detected in the valves from the control group except in one patient. Bacteria of different morphologies were observed in calcific stenotic aortic valves. It appears likely that the bacteria are implicated in the pathogenesis of acquired, calcific aortic valve stenosis.