Synonyms: Valva aortae
The aortic valve is composed of three pouches. A distinction is made between the right, left and rear (septal) semilunar valve:
The pouches are indented towards the heart and can therefore become filled. These indentations are referred to as the aortic sinuses. As a whole, they form the aortic bulb. The right and left coronary arteries exit from the right and left sinuses. At the free end of each semilunar valve, there is a node (semilunar valvular nodule), which is bordered by a crescent-shaped valve cuticle. The structure of the pulmonary valve at the outflow of the right ventricle is similar to the aortic valve, although the aortic valve is larger and thicker because of the higher strain.
During the heartbeat, in systole, the left ventricle pumps blood into the aorta via contraction. As long as the pressure in the left ventricle exceeds the pressure in the aorta, there is no back-flow of blood into the left ventricle. When the left ventricle is relaxed during diastole, the pressure in the left ventricle falls below the aortic pressure. If the aortic valve did not close, the blood now located in the ascending aorta would flow into the left ventricle. If the valve is functioning properly, the semilunar valves are filled at the beginning of diastole and lead to a closure. The back-flow is effectively suppressed. During Auscultation, the closing of the aortic valve can best be heard on the right side of the second intercostal space as the second heart tone.
A narrowing of the aortic valve is referred to as aortic stenosis. It increases the afterload (pressure load) of the heart. An extension or loosening of the aortic valve is referred to as aortic insufficiency and increases the preload (volume overload) of the heart. The protuberance of the aortic valve in the direction of the ventricle is referred to as aortic valve prolapse.
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