Anatomy of Native Heart Valves

Abstract

The valves in between the ventricles and the aorta and pulmonary artery are semilunar, swallow nest-like cusps attached to the arterial wall, separate by interleaflet triangles up to the commissure. They are located within the sinus portion and histologically consist in three layers (fibroelastic ventricularis, ground substance spongiosa, and collagen fibrosa).

The aortic valve is posterior and right sided, whereas the pulmonary valve is higher, anterior, and left sided. The coronary arteries take origin from the anterior sinuses facing the pulmonary valve. The posterior cusp of the aorta is in fibrous continuity with anterior leaflet of the mitral valve, whereas all the pulmonary cusps lie over muscle of the pulmonary infundibulum.

The valves separating the ventricles from the atria are much more complex. The apparatus indeed consists of leaflets, chordae tendineae, and papillary muscles.

Both are situated into the ventricular cavities. The main difference between the two atrioventricular (av) valves is that the tricuspid valve shows the septal leaflet attached to the ventricular septum, whereas the mitral valve is entirely attached to the free wall.

The cardiac valves can be investigated by echo transthoracic tomographic views (short axis, long axis, four chamber) allowing optimal visualization of atrioventricular and ventricular arterial connections.

The av conduction system is in close relationship with the cardiac valve. The av node is a right-sided structure of the atrial septum, just above the septal leaflets of the tricuspid valve. The course of the His bundle is located underneath the membranous septum just in correspondence of the anteroseptal commissure of the tricuspid valve.