Windkessel function is a process by which the arteries reduce the pressure difference between systole and diastole of the heart. The effect helps maintain blood pressure and reduces cardiac stress. Atherosclerosis can make it difficult for the arteries to perform their windkessel function or even take it away.
What is the Windkessel function?
Windkessel function is a process by which arteries reduce the pressure difference between systole and diastole of the heart. Arteries are elastic. This is especially true of the aorta. Because of their elasticity, arteries have what is known as the windkessel function. The rhythmic contractions of the heart create a pulsating blood flow. This pulsating blood flow is converted into a steady stream of volume within the arteries. This windkessel effect has consequences for the fluid mechanics within the human body and reduces the pressure difference between diastole and systole of the heart. The fact that there is talk of a wind boiler effect in this context has to do with the different pump designs of the wind boiler. Pressure surges were absorbed into the rigid vessels via compression of an air bubble. The result was a steady release of fluid. The same principle underlies all arteries near the heart, which explains the name.
Function and purpose
Arteries near the heart carry a particularly high density of elastic fibers in their vessel walls. These elastic fibers allow the arteries to stretch in a passive manner within the initial vessel segment. Blood volume can be stored in these areas for a short time. Potential energy is generated in the process. The retraction efforts of the vessel walls convert this energy into mechanical energy. In this context, medicine understands retraction as the tendency to contract. With the conversion of potential energy into mechanical energy, the continued transport of blood through the vessel is ensured. The dilation and subsequent retraction of all subsequent sections of the artery are repeated as the blood is transported onward. In this way, a uniformly continuous flow of blood is created. Arteries are able to equalize pressure based on their elasticity because of this windkessel effect. The aorta in particular benefits from the wind kettle effect. There is a large pressure difference between the contraction-induced blood ejection phase of the heart and the relaxation phase of the heart muscle. This pressure difference between systole and diastole can be significantly minimized by the aorta in particular due to the wind boiler effect. The volume of the aortic arch increases during this experiment. At the same time, the tension of the vessel walls increases by increasing their diameter. Through these processes, the aorta stores a certain amount of energy from the work of the heart. After the aortic valve closes, the stored energy works against the resistance of the vessel as it flows out of the aortic arch and ends up being transformed into kinetic energy. In consequence, blood flow and pulse strength harmonize after blood is stored for a short time. So, originally there is pressure near the heart, but this pressure is relieved to a certain extent by the wind kettle effect. This allows the capillaries to cope with the residual pressure and the blood flow exhibits an approximately constant flow. The heart of the wind kettle effect is thus the intermediate storage of blood. A young adult temporarily stores approximately 40 milliliters, or about half of his or her physiological stroke volume. It is only through this process of intermediate storage that blood pressure can be maintained. As a fluid-mechanical consequence of the wind-jet effect, the maximum volume flow rate decreases. The minimum flow rate increases at the same time. This results in a decrease in the maximum pressure difference and, at the same time, an increase relative to the minimum pressure difference.
Diseases and complaints
In an age-physiological way, the Windkessel function of the arteries decreases with age. One reason for this is the remodeling work that takes place in the arterial wall as we age. The elastic fibers are gradually replaced by collagen fibers and the vessel walls lose elasticity. In addition, arteriosclerotic deposits appear on the walls of the vessels with age.The more the arteries lose their windkessel function, the higher the column of blood fluid that the left heart has to accelerate. For this reason, the heart is exposed to higher stresses in old age. Since deposits in the vessels play a significant role in the decrease of the windkessel effect, heart diseases are sometimes associated with diseases such as arteriosclerosis. In atherosclerosis, fat, thrombi, connective tissue components and calcium deposits within the blood vessels. In most cases, the disease is completely asymptomatic for many years. During the first years, arteriosclerotic plaques form in the area of the vessel walls. This plaque formation narrows the lumina of the individual vessels bit by bit until even occlusions occur. Symptomatic functional impairment or even infarction results from these occlusions. Because of the increase in mechanical stress, atherosclerosis may also cause rupture of the vessel walls, which may be associated with hemorrhage and thrombus formation. Thrombi can be washed into other tissues and cause occlusions that promote hypoxia or tissue death. Elderly people over the age of 80 usually always suffer from atherosclerosis. However, an unhealthy lifestyle can cause arteriosclerosis to set in early. Since the arteries lose their windkessel function bit by bit as a result of the disease and a high heart load results from this, the heart attack is one of the most relevant secondary diseases along with the stroke. Those who banish the risk factors for arteriosclerosis from their lives thus ultimately also prevent an early heart attack due to a lost windkessel function of the arteries.
