Aortic valve: pocket valve in the left heart
The aortic valve acts as a valve between the left ventricle and the aorta. In terms of construction, it is a so-called pocket valve: it consists of three crescent-shaped “pockets”, the shape of which is reminiscent of a swallow’s nest. Due to their position and shape, they are called the posterior, right and left semilunar valves and consist of a double layer of endocardium (inner wall of the heart). Like the other valves, the aortic valve is attached to a fibrous ring of the cardiac skeleton.
Function as an outlet valve
The aortic valve opens towards the aorta when blood is pumped from the left ventricle into the aorta and thus into the large circulation during systole (ventricular contraction). As long as the pressure in the left ventricle exceeds that in the aorta (which is the case during systole), no blood can flow back into the ventricle. However, if the ventricle relaxes in the following diastole (relaxation of the ventricle) in order to absorb the blood from the left atrium, the pressure in the ventricle drops compared to that in the aorta. The blood could flow back; however, the aortic valve prevents this backflow:
The doctor can hear the closure of the aortic valve with the stethoscope as the 2nd heart sound.
Common problems with the aortic valve
Aortic valve stenosis (aortic stenosis) is the term used by doctors to describe a narrowed aortic valve. It is usually acquired, more rarely congenital. The most common cause of aortic stenosis is degenerative changes due to arteriosclerosis: calcium deposits in the heart valve impair its mobility. The blood can only be pumped out of the left ventricle with difficulty and the pressure in the ventricle increases. As a result, the ventricular wall thickens (hypertrophy).
In the case of aortic valve insufficiency, the heart valve no longer closes tightly, so that blood flows back from the aorta into the left ventricle during diastole. The now larger volume of blood puts a strain on the left ventricle (volume load), which eventually widens (dilatation). In the case of aortic insufficiency, the heart wall can also thicken.
People whose aortic valve consists of only two pockets are particularly susceptible to these diseases. This so-called bicuspid (bicuspid) aortic valve is the most common congenital heart valve defect. It occurs in around one to two percent of the population and mainly in men.
The doctor can best hear aortic valve disorders with a stethoscope to the right of the sternum, approximately between the second and third rib.
