The morphology and physiology of the circulatory system is a very subtle mechanism that supports life in a person. Any disturbances associated with the heart valves or blood vessels will ultimately lead to numerous problems throughout the hemodynamic system.
Compensatory mechanisms for a while help restore balance, but not for long. If there is no appropriate treatment, the resulting stagnation of blood in a large circle of blood circulation and breathing problems will immediately appear. Everyone should know how his heart functions and take care of his normal, trouble-free operation.
What is hemodynamics of the heart?
Everyone knows that the heart serves as a "motor" for pumping blood in the body. Small and large circles of blood circulation are studied in a school biology course. Blood flows from the lungs to the right half of the heart, and through the inner septum from the right to the left ventricle; and from there to the aorta.
The constant movement of blood from areas of high pressure to areas of low is called hemodynamics in physiology. Consider in very detail the hemodynamics of the heart, the general characteristics of the indicators and common disorders.
If the vessels are not damaged, the blood moves freely, and there are no abnormalities in the anatomy of the heart, then the doctors say that the hemodynamic parameters are normal. But what is the norm?
With normal hemodynamics, the volumetric blood flow velocity does not go beyond a certain framework. Heart rate also without a reason does not particularly increase. Cardiodynamics is studied using conventional echocardiography. But violations can be suspected during auscultation at a reception with a regular therapist.
Blood should not be thickened for its normal movement through the vessels. And the pressure - both arterial and venous - should also be within normal limits. In general, there are a lot of indicators. But consider the most important nuances for the normal functioning of the heart.
Hemodynamic indicators
Let’s analyze the hemodynamics of the heart for parts. The main indicator of hemodynamics is the volume of blood that flows through the veins or arteries in 1 minute. This volume of blood per unit time should be the same - both in the aorta, the largest artery, and in small branching vessels. This is due to the closure of the circulatory system.
The second important indicator is vascular resistance. Blood, like any liquid, passing through the vessels, due to friction against the walls, experiences some resistance. Moreover, the farther the vessels are from the aorta, the greater the resistance to overcoming the blood flow.
The next indicator is the linear velocity of blood, that is, the movement of blood particles along the vessel. Measured in cm for 1 s. The value is inversely proportional to the cross-sectional area of the bloodstream and is directly proportional to the volumetric velocity of the blood. In the capillaries, the speed is very low, while in the main arteries it is higher and the highest in the aorta. In this main highway, the linear speed reaches 50 cm per minute.
Pressure in the vessels. Pressure is created by alternating systole, the phase of contraction of the heart muscle, and diastole, the phase of relaxation. Pressure standards are known to everyone: it is 120 by 80 mm Hg. pillar ideally. However, a deviation in either direction of 10-15 mm Hg is permissible. Art.
Such is the hemodynamics of the heart. The physiology of all abnormal processes in the heart is very interesting and requires special consideration.
Types of hemodynamics
How do doctors navigate indicators? What is considered normal and what is a deviation? Three main types of hemodynamics of the heart are distinguished, which display a deviation from the general norm of cardiac output of 2.5-4.2 l / min / m 2 and vascular resistance of 1500-2000 dyne / sec / cm 5 .
- Eukinetic type of hemodynamics - when the indicators are normal.
- Hypokinetic type - both values are lower than set.
- Hyperkinetic - indicators are higher.
Hemodynamics is interconnected with the nervous system and lungs. Disorders in heart defects greatly change hemodynamics. How exactly, be sure to consider.
Hemodynamic management
You need to know that doctors are able to manage all hemodynamic parameters. The work of the heart is a physical process that is entirely subject to physical laws that can be influenced indirectly. Hemodynamics depend on cardiac output and total vascular resistance.
Normal indicators of cardiac output are from 5 to 7 l / min. Cardiac output (or CB) has a correlation with the volume of blood that fills the heart chambers.
With hypovolemia (that is, with a decrease in the entire volume of blood circulating in the vessels), it is necessary to increase the tone of the veins and prescribe infusion therapy. This is a procedure in which a patient is injected with intravenous fluid to normalize the water-electrolyte balance.
If the filling of the heart chambers is excessive, and as a result, pulmonary edema is observed, then infusion therapy should not be prescribed.
Blood viscosity and hemodynamics
Increasing the viscosity of the blood slows down its flow through the vessels. The current is linear and turbulent.
A turbulent flow is characteristic of those areas where there are bifurcations (bifurcations) - the aortic region and large main vessels. In other areas, this process has an extremely adverse effect on all hemodynamics, because it increases the load on the heart. Therefore, excessive blood viscosity must be controlled.
The rate of blood flow through the vessels, the human body temperature, the diameter of the lumen in the vessels, and the daily diet have a significant effect on this indicator. Fans of fatty foods have, as usual, increased viscosity. A normal indicator is a value from 3 to 4 units.
Viscosity increases with a high level of fibrinogen in the blood and with an excessive content of hemoglobin. This value decreases with a vegetarian diet. If the blood viscosity is not increased, there are no particular valve defects, then there is nothing to worry about, and the hemodynamics of the heart are normal.
Cardiomyopathy and hemodynamics
The function of the heart is to pump blood filled with oxygen. This is the first. And secondly - control of the water-electrolyte balance in the body. In the case of cardiomyopathy, the heart grows in volume, its walls thicken, and the cardiac output becomes less than normal. If the operation is not performed on time, the person may suddenly die.
With cardiomyopathy in humans, the hemodynamics of the heart is significantly impaired. Physiology of the heart is a harmonious system, if blood flow decreases or increases, a person already feels bad.
This can be caused by many problems in the cardiovascular system. Whether it is an infection, or an autoimmune disease. The doctor will have to figure out what exactly is the reason.
In case of hemodynamic disturbance due to cardiomyopathy, the patient has all the symptoms of heart failure - this is shortness of breath, fatigue, broken heart rate.
What is the ejection fraction?
Hemodynamic disturbances reflect such an indicator as the ejection fraction. This is an index that reflects the ratio of two values. The first is the volume of blood entering the aorta, and the second is the diastolic volume of blood, that is, the filling of the ventricles during diastole - relaxation of the heart muscle.
The fact is that with a low ejection fraction (this is below 45% of the norm), all organs suffer greatly from a lack of oxygen. When the indicator falls below 35%, already irreversible changes in the work of the heart muscle begin, which provoke the patient's quick death. You can examine the heart by undergoing an ultrasound or echocardiogram.
Mitral valve insufficiency
The value of the valvular apparatus of the heart for hemodynamics is invaluable. Any functional or organic disorders of the mitral valve lead to a change in the functioning of the entire cardiovascular system.
The mitral valve is located between the left atrium and the left ventricle. When it does not close completely, blood can flow in the opposite direction - again into the atrium. And it should be directed from the left ventricle to the aorta, starting a new large circle of blood circulation. This phenomenon is called blood regurgitation. There is overload of the left ventricle with an unexpectedly large volume of blood, which threatens with dilatation and hypertrophy of the left ventricle.
Hypertrophy is an increase in the heart muscle. In this case, there is little free space in the chamber of the heart. Blood is not pumped well, and therefore, a person will experience respiratory failure.
Against this background, there is pulmonary edema, increased heart rate and occasionally hemoptysis. Doctors understand that functional valve failure is not a heart defect; such a diagnosis cannot be made. But health problems will be the same as with severe valve stenosis.
During listening, the doctor may notice abnormal noises in the heartbeat. This noise occurs when the blood flows back into the ventricle, and it is called systolic.
Violations of the aortic valve. Effects
The most common heart problems are aortic stenosis and aortic insufficiency. Blood from the aorta with normal valve physiology fills the bloodstream and nourishes all organs. With valve insufficiency, that is, when it does not completely close due to any defects, significant hemodynamic disturbances are observed.
If aortic heart defects are detected, hemodynamics changes as follows:
- Violation of blood filling the arterial bed.
- Impaired perfusion.
- Cardiac decompensation.
- Left ventricular hypertrophy due to increased pressure in the left side of the heart.
Also, changes occur with valve stenosis. Stenosis of the aortic orifice leads to an increase in systole and an increase in pressure inside the left ventricle.
What causes the failure? Deficiency sometimes occurs as a result of infectious endocarditis, but in 70% of cases due to rheumatism. A very rare cause is systemic lupus erythematosus.
Special signs for a long time may not be observed. But with increased overload, the signs of stenosis appear more and more.
What are the signs of aortic stenosis? These are frequent dizziness and possibly fainting. A person begins to feel specific pains in the chest. Further changes can affect not only the heart, but also the liver and lungs.
Tricuspid valve and hemodynamics
The tricuscupidal valve passes portioned blood from the right atrium to the right ventricle. Violations of his work are extremely rare, usually when the mitral and aortic valves are already broken, the left ventricle is significantly hypertrophied and the hemodynamics of the heart are already upset.
If a person suffers from rheumatism or systemic lupus, valve flaps often thicken and the gap between them narrows. This process is called stenosis.
With stenosis of the tricuspid valve, hypertrophy of the right atrium is observed. Fatigue, respiratory failure are characteristic of such a patient. And if stenosis is combined with mitral valve insufficiency, a person begins severe tachycardia - an increase in the number of heart contractions per minute.
Surgery for heart stenosis
With stenosis, you need to constantly do heart research and monitor its condition. In severe cases, it is important to do the operation on time. Serious cardiac abnormalities, such as coronary disease or a stroke in the recent past, preclude the possibility of surgery.
But if in general the patient’s health is considered satisfactory, the operation is carried out quickly and without problems, because in modern medicine minimally invasive methods of surgery are used. After valve replacement, all traces of aortic heart disease pass. Hemodynamics is fully restored. But in the postoperative period, the patient needs special care.
Compensatory reactions
Always with heart failure accompanying defects, there are some compensatory reactions that help the heart cope with increased stress.
- The sympathetic nervous system is activated and adrenaline secretion increases. At the same time, the frequency of contractions increases to keep the cardiac output at a normal level.
- Ventricular hypertrophy - the mass of the myocardium increases in response to increased pressure inside the chambers.
- Increase in preload. When the heart can no longer cope with venous return, such an adaptive reaction as increasing the size of the ventricle begins.
Even if this does not help, stagnation of blood in large and small circles increases. The hemodynamics of the heart is gradually disturbed, indicators differ significantly from normal. Then extracardiac compensation mechanisms cease to help, chest pains begin, a beat rhythm, dizziness and decreased performance are observed.
Congenital and acquired heart defects
Other heart defects can be detected by ultrasound during pregnancy. If a baby is born with already broken valves in the heart - this is called a congenital heart disease. Hemodynamics in such cases is very quickly unbalanced. For example, a lot of childhood problems are associated with defects in the atrial or interventricular septum.
Hemodynamics of the heart, morphology and physiology of the entire apparatus supplying blood to the body will deteriorate rapidly, faster than in the case of acquired defect. And earlier, children with this diagnosis did not live long. However, now any defect can be fixed thanks to valve prosthetics.
Acquired defects develop due to normal aging of the body, especially in middle and old age, the heart "gets tired" very quickly. Many after 60 years of age have any hemodynamic impairment, even if there are no particular defects.
Types of congenital heart defects. Hemodynamics
In cardiac surgery, there are 3 main types of defects, each of which in its own way affects hemodynamics. We will see.
- Defects of a pale type with an arteriovenous shunt. These include: open ductus arteriosus and atrial septal defects.
- Vices of the blue type. These are the Fallot triad, the transposition of the great vessels and others similar in type.
- CHD without discharge of blood, but with barriers to blood flow. This type includes stenosis of the aorta or pulmonary tracts of varying severity.
With defects associated with an increase in blood flow in a small circle, hypertension will be observed, with poor blood flow - hypoxemia. If a defect of a pale type is detected, severe hypovolemia is observed.
One of the most common defects is aortic valve failure. What is it? In newborns who, in the prenatal period of development, do not breathe completely lungs, there is a duct between the aortic and venous vessels. It should grow with the first breath. But if this does not happen, the child will have a severe congenital malformation. With such a physiological defect, the newborn quickly weakens, sometimes turns blue and suffocates, because the organs, especially the brain, lack oxygen.
In many cases, the gaps in the heart muscle overgrow themselves over time. But most often the newborn is undergoing surgery. The child should be closely monitored at this time.
Heart disease prevention
How to prevent the development of heart defects in old age? To do this, you need to take care of heart health at a young age, to get rid of such a bad habit as smoking. You need to start hardening and jogging in the morning. It has long been known that physical training strengthens the heart muscle and allows you to extend the health of this organ.
Some infections can lead to inflammation - endocarditis. Therefore, diseases such as tonsillitis, pneumonia, should be treated immediately, until they lead to heart complications.
conclusions
What is a hemodynamic disorder in heart defects? This is a change in key indicators, such as cardiac output, blood pressure and blood speed. When, for some reason, it becomes difficult for the heart to perform its functions, it triggers compensatory mechanisms, such as increased heart rate (heart rate) and thickening of the walls of the myocardium.
If a child is born with aortic defect, then with a high degree of probability without surgical intervention he will not live a year without an operation, since all indicators of cardiac dynamics sharply worsen. The hemodynamics of heart defects in children can recover if the aortic duct or other opening in the heart grows on its own. Then you don’t have to operate and put the child at risk. However, do not let the situation drift. Important constant monitoring of the heart in such cases.