general structure

Last reviewed 01/2018

The general structure of heart valves is dependent on the valve:

• tricuspid and mitral valves:
• each leaflet is a flat sheet
• the margin of each leaflet has serrations where the chordae tendineae attach
• the chordae tendineae are attached to papillary muscles which contract during systole; the increased tension within the chordae and muscles acts to:
• prevent eversion of the valve
• limit ventricular distention as the left ventricular pressure rises
• therefore, tricuspid and mitral valve competence depends on the active process of papillary muscle contraction
• during diastole, the valve leaflets merge at their free margins and overlap each other centrally

• aortic and pulmonary valves:
• each leaflet is ballooned into a cup-shaped concavity when viewed from the aorta
• during diastole, the column of blood superior to the vessel forces out the leaflets from above, filling their concavities and forcing the aortic valve leaflets together
• therefore, closure of the aortic and pulmonary valves is a passive process
• there is no attachment to chorae tendineae
• a sinus - a dilation of the outflow vessel - exists superior to each valve leaflet:
• vortices, circular currents of blood, develop within the sinus during systole
• they prevent the individual leaflets from adhering to the wall of the outflow vessel, so rendering the valve incompetent
• each leaflet has a fibrous nodule at its centre which is a thickening of its lamina fibrosa