The four heart valves perform one of the most important functions in the human circulatory system: they act as valves in the heart, determining the direction of blood flow and ensuring an even inflow and outflow of blood between the atrium and ventricle and the adjacent blood vessels.
What are the heart valves?
The heart has a total of four heart valves, which close the entrances and exits of the heart chambers. They are made up of tissue equipped with a valve function that ensures a steady flow of blood between the atria and ventricles of the heart during cardiac contraction.
Anatomy and structure
The human heart is divided into two equal halves by the cardiac septum and thus consists of a right ventricle and an associated right atrium, and a left ventricle and a left atrium. Due to their different functionality, the four heart valves are divided into two groups: the pocket valves and the leaflet valves. The pocket valves are located in the right and left halves of the heart, respectively, between the ventricle and the adjacent outflow tract. In the left half is the pulmonary valve, located between the right ventricle and the pulmonary artery, the arteriae pulmonales. In the right half between the left ventricle and the aorta is the so-called aortic valve. The valves located between the atria and the ventricles are called leaflet valves because of their characteristic appearance. The so-called mitral valve is located in the right side of the heart between the left atrium and the left ventricle, while the tricuspid valve is located in the left side of the heart, where it separates the right atrium from the right ventricle.
Function and Tasks
During systole, the blood inflow phase, blood that is deoxygenated and enriched with carbon dioxide passes through the tricuspid valve from the right atrium into the right ventricle. Here it is passed through the pulmonary valve into the pulmonary circulation, where it is enriched with oxygen and the carbon dioxide content is reduced. The “fresh” blood is now ejected from the lungs into the left atrium and subsequently passes through the mitral valve into the left ventricle. From here, the blood now passes through the aortic valve into the largest artery in the body and thus into the great circulatory system. During the entire process of systole, the heart valves function like mechanical valves, preventing backflow of blood by their respective opening or closing. As the left and right ventricles fill with blood flowing in from the two atria, they contract and the mitral and tricuspid valves close to prevent blood from flowing back into the atria. The growing pressure in the ventricles now opens the aortic and pulmonary valves, which eject blood into their respective outflow tracts. At the end of systole, the ventricles are largely empty, the pressure drops, and the aortic and pulmonary valves are closed to prevent blood from flowing back into the ventricles. At the same time, the mitral and tricuspid valves open again and fill the ventricles with blood anew. Thus, the heart valves play an irreplaceable role in the human circulatory system: they control the flow of blood through the heart, prevent a backlog of incoming blood, and thus ensure a steady supply to all organs.
Diseases
If there is calcification, narrowing or leakage in one or more of the four heart valves, this can have significant health consequences. The usually nonspecific and seemingly harmless symptoms of valvular heart disease, such as frequent weakness or dizziness, shortness of breath on light exertion, a feeling of pressure in the chest, and water retention in the legs, are often not taken seriously enough by those affected or are misinterpreted, which promotes unnoticed progression of the disease. The long-term consequence of untreated valvular heart disease is usually heart failure, often with subsequent heart failure. Valve disease should therefore be diagnosed and treated as early as possible to avoid serious damage to the heart. The most common cause of heart valve disease is the natural wear and tear of the valves due to the aging process of the body. The valves wear out, calcify or narrow. In this case, valve stenosis is present, i.e. a narrowing of the valves.In this case, the valve cannot open fully, blood backs up in front of it and the amount of blood that can be pumped through the body is reduced. In order to continue to supply the body adequately, the heart must pump at a higher rate, which leads to heart failure in the long term. Another disease of the heart valves is valvular insufficiency. In this form of defect, the valve can no longer close completely; the backflow of blood is no longer blocked sufficiently, allowing it to flow back into the ventricles. This reduces the pumping capacity, and pressure builds up on the heart and lungs. However, a heart valve defect can occur not only with increasing age, but also as a result of a bacterial infection, rheumatic fever or inflammation of the inner lining of the heart. Congenital heart valve defects, on the other hand, are very rare and occur in only about 3 percent of all people. However, if the valvular defect is diagnosed in time, an immediate and nowadays very promising therapy can be initiated, which in the case of a minor defect amounts to a mere medical treatment of the patient’s symptoms. In the case of a severe valve defect, however, where there is already a threat of damage to the heart muscle, surgery is regularly advised, which in the case of valve stenosis may consist of valve disruption by means of a cardiac catheter and in the case of valve insufficiency of valve reconstruction or valve replacement by means of an artificial heart valve. Thanks to significant advances in the field of cardiac surgery, such interventions are very promising nowadays and can even cause an already existing heart failure to regress completely.
Typical and common heart diseases
- Heart attack
- Pericarditis
- Heart failure
- Atrial fibrillation
- Heart muscle inflammation
