Decreased stroke volume. The change in the value of the IOC occurs in two ways. Determination of cardiac output

Stroke volume (SV)

The amount of blood ejected from the ventricle of the heart in one heart contraction, is called stroke volume (SV). At rest, the stroke volume in an adult is 50-90 ml and depends on body weight, the volume of the chambers of the heart and the force of contraction of the heart muscle. The reserve volume is the part of the blood that remains in the ventricle at rest after contraction, but during exercise and in stressful situations ejected from the stomach.

It is the value of the reserve blood volume that largely contributes to an increase in the stroke volume of the blood during exercise. The increase in SV during physical exertion is also facilitated by an increase in venous return of blood to the heart. During the transition from rest to exercise, the stroke volume of blood increases. The increase in the value of SV goes until its maximum is reached, which is determined by the volume of the ventricle. With a very intense load, the stroke volume of blood may decrease, because due to a sharp shortening of the duration of diastole, the ventricles of the heart do not have time to completely fill with blood.

During the transition from a state of rest to a load, the SV increases rapidly and reaches a stable level during intense rhythmic work lasting 5-10 minutes, for example, during physical training.

The maximum value of stroke volume is observed at a heart rate of 130 beats/min. Further, with increasing load, the rate of increase in stroke volume of blood decreases sharply and at a work power exceeding 1000 kgm/min, it is only 2-3 ml of blood for every 100 kgm/min increase in load. With prolonged and increasing loads, the stroke volume no longer increases, but even decreases somewhat. Maintaining the required level of blood circulation is provided by a higher heart rate. Cardiac output increases mainly due to more complete emptying of the ventricles, that is, by using the reserve volume of blood.

The minute volume of blood (MBV) measures how much blood is ejected from the ventricles of the heart in one minute. The value of the minute volume of blood is calculated according to the following formula:

Minute volume of blood (MOV) \u003d VV x HR.

Since in healthy adults the stroke volume of blood (hereinafter, when comparing the parameters of untrained people and athletes, see Table 1) is 50-90 ml at rest, and the heart rate is in the range of 60-90 beats / min, the value of the minute blood volume at rest is in the range of 3.5-5 l / min.

Table 1. Differences in the reserve capabilities of the body in an untrained person and an athlete (according to N.V. Muravov).

In athletes, the value of the minute volume of blood at rest is the same, since the value of the stroke volume is slightly higher (70-100 ml), and the heart rate is lower (45-65 beats / min). When performing physical activity, the minute volume of blood increases due to an increase in the magnitude of the stroke volume of the blood and the heart rate. As the magnitude of the exercise performed increases, the stroke volume of the blood reaches its maximum and then remains at this level with a further increase in the load. The increase in the minute volume of blood in such conditions occurs due to a further increase in the heart rate. After the cessation of physical activity, the values ​​of central hemodynamic parameters (IOC, VR and HR) begin to decrease and after a certain time reach the initial level.

In healthy untrained people, the value of the minute volume of blood during exercise can increase to 15-20 l / min. The same value of the IOC during physical activity is observed in athletes who develop coordination, strength or speed.

For representatives of team sports (football, basketball, hockey, etc.) and martial arts (wrestling, boxing, fencing, etc.), the IOC value under load is in the range of 25-30 l / min, and for athletes of the elite level reaches maximum values(35-38 l/min) due to the large stroke volume (150-190 ml) and high heart rate (180-200 beats/min).

During physical activity of moderate intensity in the sitting and standing positions, the IOC is approximately 2 l / min less than when performing the same exercise in the supine position. This is explained by the accumulation of blood in the vessels of the lower extremities due to the action of gravity.

With intense exercise, the minute volume can increase 6 times compared to the state of rest, the oxygen utilization factor - 3 times. As a result, the delivery of O 2 to the tissues increases approximately 18 times, which makes it possible to achieve an increase in metabolism by 15–20 times compared with the level of basal metabolism during intensive loads in trained individuals.

In an increase in the minute volume of blood during exercise important role plays the so-called muscle pump mechanism. Muscle contraction is accompanied by compression of the veins in them, which immediately leads to an increase in outflow venous blood from the muscles of the lower extremities. Postcapillary vessels (mainly veins) of the systemic vascular bed (liver, spleen, etc.) also act as part of the general reserve system, and contraction of their walls increases the outflow of venous blood. All this contributes to increased blood flow to the right ventricle and the rapid filling of the heart.

When performing physical work, the IOC gradually increases to a stable level, which depends on the intensity of the load and provides the necessary level of oxygen consumption. After the termination of the load, the IOC gradually decreases. Only with light physical exertion, an increase in the minute volume of blood circulation occurs due to an increase in stroke volume and heart rate. During heavy physical exertion, it is provided mainly by increasing the heart rate.

IOC also depends on the type of physical activity. For example, with maximum arm work, the IOC is only 80% of the values ​​obtained with maximum leg work in a sitting position.

Adaptation of the body of healthy people to physical activity occurs optimal way by increasing both stroke volume and heart rate. Athletes use the most optimal variant of adaptation to the load, since due to the presence of a large reserve volume of blood during exercise, a more significant increase in stroke volume occurs. In cardiac patients, when adapting to physical activity, a non-optimal option is noted, because due to the lack of a reserve blood volume, adaptation occurs only by increasing the heart rate, which causes the appearance of clinical symptoms: palpitations, shortness of breath, pain in the heart, etc.

To assess the adaptive capacity of the myocardium in functional diagnostics the functional reserve indicator (FR) is used. The indicator of myocardial functional reserve indicates how many times the minute volume of blood during exercise exceeds the level of rest.

If the patient has the highest minute blood volume during exercise is 28 l / min, and at rest it is 4 l / min, then his myocardial functional reserve is seven. This value of the functional reserve of the myocardium indicates that when performing physical activity, the myocardium of the subject is able to increase its performance by 7 times.

Long-term sports contribute to an increase in the functional reserve of the myocardium. The greatest functional reserve of the myocardium is observed in representatives of sports for the development of endurance (8-10 times). Somewhat less (6-8 times) the functional reserve of the myocardium in athletes of team sports and martial arts representatives. In athletes developing strength and speed, the functional reserve of the myocardium (4-6 times) differs little from that in healthy untrained individuals. A decrease in myocardial functional reserve less than four times indicates a decrease in the pumping function of the heart during exercise, which may indicate the development of overload, overtraining, or heart disease. In cardiac patients, a decrease in the functional reserve of the myocardium is due to the lack of a reserve blood volume, which does not allow an increase in the stroke volume of blood during exercise, and a decrease in contractility myocardium, limiting the pumping function of the heart.

Therefore, one of the indicators functional state heart is the value of minute and shock (systolic) volumes. The study of the value of minute volume is of practical importance and is used in the physiology of sports, clinical medicine and professional hygiene.

The amount of blood ejected by the heart per minute is called the minute volume of blood (MBV). The amount of blood ejected by the heart in one contraction is called the stroke (systolic) blood volume (SV).

The minute volume of blood in a person in a state of relative rest is 4.5-5 liters. It is the same for the right and left ventricles. Stroke volume can be easily calculated by dividing the IOC by the number of heartbeats.

Of great importance in changing the magnitude of the minute and stroke volumes blood has exercise. When performing the same work in a trained person, the value of systolic and minute volumes heart with a slight increase in the number of heartbeats; in an untrained person, on the contrary, the heart rate increases significantly and the systolic blood volume hardly changes.

SVR increases with increased blood flow to the heart. As the systolic volume increases, so does the IOC.

Stroke volume of the heart

An important characteristic of the pumping function of the heart gives stroke volume, also called systolic volume.

Stroke volume (SV) - the amount of blood ejected by the ventricle of the heart in arterial system for one systole (sometimes the name systolic ejection is used).

Since the systemic and pulmonary circulations are connected in series, in a stable hemodynamic regime, the stroke volumes of the left and right ventricles are usually equal. Only on a short time during the period abrupt change the work of the heart and hemodynamics between them there may be a slight difference. The value of the SV of an adult at rest is ml, and during exercise it can increase up to 120 ml (for athletes up to 200 ml).

Starr formula (systolic volume):

where CO - systolic volume, ml; PD - pulse pressure, mm Hg. Art.; DD - diastolic pressure, mm Hg. Art.; B - age, years.

Normal CO at rest is -ml, and under load -ml.

End diastolic volume

End-diastolic volume (EDV) is the amount of blood in the ventricle at the end of diastole (at rest, about ml, but depending on gender, age, it can vary within ml). It is formed by three volumes of blood: remaining in the ventricle after the previous systole, flowing from venous system during general diastole and pumped into the ventricle during atrial systole.

Table. End-diastolic blood volume and its components

End-systolic volume of blood remaining in the cavity of the ventricles by the end of systole

End-Dastal Blood Volume (EDV)

Venous return - the volume of blood flowing into the cavity of the ventricles from the veins during diastole (at rest approx.)

Additional volume of blood entering the ventricles during atrial systole (at rest, about 10% of the EDV or up to 15 ml)

End systolic volume

End-systolic volume (ESV) is the amount of blood remaining in the ventricle immediately after systole. At rest, it is less than 50% of the value of the end-diastolic volume or ml. Part of this blood volume is a reserve volume that can be expelled with an increase in the strength of heart contractions (for example, during exercise, an increase in the tone of the centers of the sympathetic nervous system, the action of adrenaline, thyroid hormones on the heart).

A number of quantitative indicators, currently measured by ultrasound or by probing the cavities of the heart, are used to assess the contractility of the heart muscle. These include indicators of the ejection fraction, the rate of blood ejection in the rapid ejection phase, the rate of pressure increase in the ventricle during the stress period (measured by ventricular probing) and a number of cardiac indices.

Ejection fraction (EF) - expressed as a percentage of the ratio of stroke volume to the end-diastolic volume of the ventricle. ejection fraction healthy person at rest is 50-75%, and during exercise it can reach 80%.

The rate of expulsion of blood is measured by the Doppler method with ultrasound of the heart.

The rate of pressure increase in the cavities of the ventricles is considered one of the most reliable indicators of myocardial contractility. For the left ventricle, the value of this indicator is normally mm Hg. st./s.

A decrease in the ejection fraction below 50%, a decrease in the rate of blood ejection, and the rate of pressure increase indicate a decrease in myocardial contractility and the possibility of developing insufficiency in the pumping function of the heart.

Minute volume of blood flow

Minute volume of blood flow (MOV) is an indicator of the pumping function of the heart, equal to the volume of blood expelled by the ventricle into the vascular system in 1 minute (also called minute output).

Since the SV and HR of the left and right ventricles are equal, their IOC is also the same. Thus, the same volume of blood flows through the small and large circles of blood circulation in the same period of time. In mowing, the IOC is 4-6 liters, with physical exertion it can reach, and for athletes - 30 liters or more.

Methods for determining the minute volume of blood circulation

Direct methods: catheterization of the heart cavities with the introduction of sensors - flowmeters.

where IOC is the minute volume of blood circulation, ml/min; VO 2 - oxygen consumption for 1 min, ml/min; CaO 2 - oxygen content in 100 ml arterial blood; CvO 2 - oxygen content in 100 ml of venous blood

where J is the amount of the injected substance, mg; C is the average concentration of the substance calculated from the dilution curve, mg/l; T-duration of the first wave of circulation, s

• Ultrasonic flowmetry
• Tetrapolar thoracic rheography

Cardiac index

Cardiac index (SI) - the ratio of the minute volume of blood flow to the body surface area (S):

where IOC - minute volume of blood circulation, l / min; S - body surface area, m 2.

Normally, SI \u003d 3-4 l / min / m 2.

The work of the heart ensures the movement of blood through the system blood vessels. Even in conditions of life without physical exertion, the heart pumps up to 10 tons of blood per day. The useful work of the heart is spent on creating blood pressure and giving it acceleration.

To give acceleration to portions of ejected blood, the ventricles spend about 1% of common work and energy costs of the heart. Therefore, this value can be neglected in calculations. Almost all the useful work of the heart is spent on creating pressure - the driving force of blood flow. Work (A) performed by the left ventricle of the heart during one cardiac cycle, is equal to the product of the mean pressure (P) in the aorta and the stroke volume (SV):

At rest, in one systole, the left ventricle performs work of about 1 N / m (1 N \u003d 0.1 kg), and the right ventricle is approximately 7 times less. This is due to the low resistance of the vessels of the pulmonary circulation, as a result of which the blood flow in the pulmonary vessels is provided at an average pressure of mm Hg. Art., while in big circle circulatory mean pressure is mm Hg. Art. Thus, the left ventricle needs to expend about 7 times more work than the right ventricle to expel the blood ultraviolet. This leads to the development of more muscle mass left ventricle compared to the right.

Performing work requires energy costs. They go beyond providing useful work, but also to maintain basic life processes, ion transport, renewal cell structures, synthesis of organic substances. Coefficient useful action heart muscle is in the range of 15-40%.

The energy of ATP, necessary for the vital activity of the heart, is obtained mainly in the course of oxidative phosphorylation, carried out with the obligatory consumption of oxygen. At the same time, various substances can be oxidized in the mitochondria of cardiomyocytes: glucose, free fatty acid, amino acids, lactic acid, ketone bodies. In this regard, the myocardium (as opposed to nervous tissue, which uses glucose for energy) is an "omnivorous organ". To ensure energy needs hearts at rest in 1 min require ml of oxygen, which is about 10% of the total oxygen consumption by an adult human body for the same time. Up to 80% of oxygen is extracted from the blood flowing through the capillaries of the heart. In other organs, this figure is much less. Oxygen delivery is the weakest link in the mechanisms that supply the heart with energy. This is due to the peculiarities of cardiac blood flow. Insufficiency of oxygen delivery to the myocardium, associated with impaired coronary blood flow, is the most common pathology leading to the development of myocardial infarction.

Ejection fraction

where CO - systolic volume, ml; EDV - end diastolic volume, ml.

The ejection fraction at rest is %.

Blood flow rate

According to the laws of hydrodynamics, the amount of liquid (Q) flowing through any pipe is directly proportional to the pressure difference at the beginning (P 1) and at the end (P 2) of the pipe and inversely proportional to the resistance (R) to the fluid flow:

If we apply this equation to vascular system, then it should be borne in mind that the pressure at the end of this system, i.e. at the confluence of the hollow veins in the heart, close to zero. In this case, the equation can be written as:

where Q is the amount of blood expelled by the heart per minute; P - the value of the average pressure in the aorta; R is the value of vascular resistance.

It follows from this equation that P = Q*R, i.e. pressure (P) at the mouth of the aorta is directly proportional to the volume of blood ejected by the heart in the arteries per minute (Q), and the value of peripheral resistance (R). Aortic pressure (P) and minute volume (Q) can be measured directly. Knowing these values, peripheral resistance is calculated - the most important indicator of the state of the vascular system.

The peripheral resistance of the vascular system is the sum of many individual resistances of each vessel. Any of these vessels can be likened to a tube, the resistance of which is determined by the Poiseuille formula:

where L is the length of the tube; η is the viscosity of the liquid flowing in it; Π is the ratio of the circumference to the diameter; r is the radius of the tube.

The difference in blood pressure, which determines the speed of blood movement through the vessels, is large in humans. In an adult, the maximum pressure in the aorta is 150 mm Hg. Art., and in large arteries-mm Hg Art. In smaller arteries, the blood encounters greater resistance and the pressure here drops significantly - domme. rt st. The sharpest decrease in pressure is observed in arterioles and capillaries: in arterioles it is mm Hg. Art., and in the capillaries -mm Hg. Art. In the veins, the pressure decreases to 3-8 mm Hg. Art., in the hollow veins, the pressure is negative: -2-4 mm Hg. Art., i.e. at 2-4 mm Hg. Art. below atmospheric. This is due to the pressure change in chest cavity. During inhalation, when the pressure in the chest cavity decreases significantly, it decreases and blood pressure in hollow veins.

From the above data, it can be seen that blood pressure in different areas bloodstream is not the same, and it decreases from the arterial end of the vascular system to the venous. In large and medium arteries, it decreases slightly, by approximately 10%, and in arterioles and capillaries - by 85%. This indicates that 10% of the energy developed by the heart during contraction is spent on the movement of blood in large arteries, and 85% is spent on its movement through the arterioles and capillaries (Fig. 1).

Rice. 1. Change in pressure, resistance and lumen of blood vessels in different parts of the vascular system

The main resistance to blood flow occurs in the arterioles. The system of arteries and arterioles is called resistance vessels or resistive vessels.

Arterioles are vessels of small diameter - microns. Their wall contains a thick layer of circularly located smooth muscle cells, with the reduction of which the lumen of the vessel can significantly decrease. At the same time, the resistance of arterioles sharply increases, which makes it difficult for blood to flow out of the arteries, and the pressure in them rises.

A decrease in the tone of arterioles increases the outflow of blood from the arteries, which leads to a decrease in blood pressure(HELL). Among all parts of the vascular system, it is the arterioles that have the greatest resistance, so the change in their lumen is the main regulator of the level of total arterial pressure. Arterioles - "faucets circulatory system". The opening of these "faucets" increases the outflow of blood into the capillaries of the corresponding area, improving local blood circulation, and the closure sharply worsens the blood circulation of this vascular zone.

Thus, arterioles play a dual role:

• participate in maintaining the level of general arterial pressure necessary for the body;
• participate in the regulation of the magnitude of local blood flow through a particular organ or tissue.

The value of organ blood flow corresponds to the organ's need for oxygen and nutrients, determined by the level of organ activity.

In a working organ, the tone of the arterioles decreases, which ensures an increase in blood flow. So that the total blood pressure does not decrease in other (non-functioning) organs, the tone of the arterioles increases. The total value of the total peripheral resistance and general level BP remains approximately constant, despite the continuous redistribution of blood between working and non-working organs.

Volumetric and linear velocity of blood movement

The volumetric velocity of blood movement is the amount of blood flowing per unit time through the sum of the cross sections of the vessels of a given section of the vascular bed. The same volume of blood flows through the aorta, pulmonary arteries, vena cava and capillaries in one minute. Therefore, the same amount of blood always returns to the heart as it was thrown into the vessels during systole.

The volumetric velocity in various organs may vary depending on the work of the organ and the size of its vasculature. In a working organ, the lumen of the vessels can increase and, together with it, the volumetric velocity of blood movement.

The linear velocity of blood movement is called the path traveled by blood per unit of time. The linear velocity (V) reflects the speed of movement of blood particles along the vessel and is equal to the volumetric velocity (Q) divided by the cross-sectional area of ​​the blood vessel:

Its value depends on the lumen of the vessels: the linear velocity is inversely proportional to the cross-sectional area of ​​the vessel. The wider the total lumen of the vessels, the slower the movement of blood, and the narrower it is, the greater the speed of blood movement (Fig. 2). As the arteries branch, the speed of movement in them decreases, since the total lumen of the branches of the vessels is greater than the lumen of the original trunk. In an adult, the lumen of the aorta is approximately 8 cm 2, and the sum of the lumens of the capillaries is much larger - cm 2. Consequently, the linear velocity of blood in the aorta is many times greater than 500 mm/s, and in the capillaries it is only 0.5 mm/s.

Rice. 2. Signs of blood pressure (A) and linear blood flow velocity (B) in various parts of the vascular system

Indicators of the work of the heart. Stroke and minute volume of the heart

The cardiovascular system. Part 6

In this part we are talking about the main work of the heart, about one of the indicators of the functional state of the heart - the magnitude of the minute and systolic volumes.

Systolic and minute volumes of the heart. The work of the heart.

Heart exercising contractile activity, during systole throws a certain amount of blood into the vessels. This is the main function of the heart. Therefore, one of the indicators of the functional state of the heart is the value of minute and systolic volumes. The study of the value of minute volume is of practical importance and is used in the physiology of sports, clinical medicine and professional hygiene.

Minute and systolic volume of the heart.

The amount of blood ejected by the heart into the vessels per minute is called the cardiac output. The amount of blood ejected by the heart in one contraction is called the systolic volume of the heart.

The minute volume of the heart in a person in a state of relative rest is 4.5-5 liters. It is the same for the right and left ventricles. Systolic volume can be easily calculated by dividing the minute volume by the number of heartbeats.

The value of minute and systolic volumes is subject to large individual fluctuations and depends on various conditions: the functional state of the body, body temperature, body position in space, etc. It changes significantly under the influence of physical activity. With great muscular work, the value of the minute volume increases by 3-4 and even 6 times and can be 37.5 liters at 180 heartbeats per minute.

Training is of great importance in changing the magnitude of the minute and systolic volumes of the heart. When performing the same work in a trained person, the value of systolic and minute volumes of the heart increases significantly with a slight increase in the number of heartbeats. In an untrained person, on the contrary, the heart rate increases significantly and the systolic volume of the heart hardly changes.

The work of the heart.

The blood pressure in the pulmonary arteries is approximately 5 times less than in the aorta, so the right ventricle performs the same amount of less work.

The work performed by the heart is calculated by the formula: W \u003d Vp + mv 2 / 2g,

where V is the volume of blood ejected by the heart (minute or systolic), p is the blood pressure in the aorta (resistance), m is the mass of ejected blood, v is the speed at which blood is ejected, g is the acceleration of a freely falling body.

According to this formula, the work of the heart is composed of work aimed at overcoming the resistance of the vascular system (this reflects the first term) and work aimed at giving speed (the second term). Under normal conditions of the heart, the second term is very small compared to the first (1%) and therefore it is neglected. Then the work of the heart can be calculated by the formula: W=Vp, i.e. all of it is aimed at overcoming resistance in the vascular system. On average, the heart performs work of about kgf m per day. The work of the heart is the greater, the greater the blood flow.

The work of the heart also increases if the resistance in the vascular system increases (for example, blood pressure in the arteries increases due to capillary constriction). At the same time, at first, the force of contractions of the heart is not enough to throw out all the blood against the increased resistance. Within a few contractions, a certain amount of blood remains in the heart, which helps to stretch the fibers of the heart muscle. As a result, there comes a moment when the force of contraction of the heart increases and all the blood is ejected, i.e. the systolic volume of the heart increases, and consequently, the systolic work also increases. The maximum amount by which the volume of the heart increases during diastole is called the reserve or reserve forces of the heart. This value increases in the process of training the heart.

Stroke and minute volume of the heart / blood: the essence, what they depend on, calculation

The heart is one of the main "workers" of our body. Not stopping for a minute during life, it pumps a huge amount of blood, providing nutrition to all organs and tissues of the body. The most important characteristics of the efficiency of blood flow are the minute and stroke volume of the heart, the values ​​of which are determined by many factors both from the side of the heart itself and from the systems that regulate its work.

Minute blood volume (MBV) is a value that characterizes the amount of blood that the myocardium sends to the circulatory system within a minute. It is measured in liters per minute and equals approximately 4-6 liters at rest when horizontal position body. This means that all the blood contained in the vessels of the body, the heart is able to pump in a minute.

Stroke volume of the heart

Stroke volume (SV) is the volume of blood that the heart pushes into the vessels in one contraction. At rest in the average person, it is approx. This indicator is directly related to the state of the heart muscle and its ability to contract with sufficient force. An increase in stroke volume occurs with an increase in pulse (up to 90 ml or more). In athletes, this figure is much higher than in untrained individuals, even if the heart rate is approximately the same.

The volume of blood that the myocardium can eject into the great vessels is not constant. It is determined by the requests of the authorities in specific conditions. So, during intense physical activity, excitement, in a state of sleep, the organs consume different amount blood. The effects on myocardial contractility from the nervous and endocrine systems also differ.

With an increase in the frequency of heart contractions, the force with which the myocardium pushes out blood increases, and the volume of fluid entering the vessels increases due to the significant functional reserve of the organ. The reserve capacity of the heart is quite high: in untrained people during exercise cardiac output per minute reaches 400%, that is, the minute volume of blood ejected by the heart increases up to 4 times, for athletes this figure is even higher, their minute volume increases by 5-7 times and reaches 40 liters per minute.

Physiological features of heart contractions

The volume of blood pumped by the heart per minute (MOC) is determined by several components:

• stroke volume of the heart;
• The frequency of contractions per minute;
• The volume of blood returned through the veins (venous return).

By the end of the period of relaxation of the myocardium (diastole), a certain amount of fluid accumulates in the cavities of the heart, but not all of it then enters the systemic circulation. Only a part of it goes into the vessels and makes up the stroke volume, which in quantity does not exceed half of all the blood that entered the heart chamber during its relaxation.

The blood remaining in the cavity of the heart (about half or 2/3) is the reserve volume required by the organ in cases where blood needs increase (during physical exertion, emotional stress), as well as a small amount residual blood. Due to the reserve volume, with an increase in the heart rate, the IOC also increases.

The blood present in the heart after systole (contraction) is called the end-diastolic volume, but even it cannot be completely evacuated. After the release of the reserve volume of blood in the cavity of the heart, there will still be some amount of fluid that will not be pushed out from there even with the maximum work of the myocardium - the residual volume of the heart.

cardiac cycle; stroke, end systolic and end diastolic volumes of the heart

Thus, during contraction, the heart does not throw all the blood into the systemic circulation. First, the stroke volume is pushed out of it, if necessary, a reserve volume, and after that the residual volume remains. The ratio of these indicators indicates the intensity of the work of the heart muscle, the strength of contractions and the efficiency of systole, as well as the ability of the heart to provide hemodynamics in specific conditions.

IOC and sports

The main reason for the change in the minute volume of blood circulation in healthy body consider physical activity. It could be classes in gym, jogging, fast walk etc. Another condition for the physiological increase in minute volume can be considered excitement and emotions, especially in those who acutely perceive any life situation, reacting to it with an increase in heart rate.

When performing intensive sports exercises stroke volume increases, but not to infinity. When the load has reached approximately half of the maximum possible, the stroke volume stabilizes and takes on a relatively constant value. Such a change in the output of the heart is associated with the fact that when the pulse accelerates, the diastole is shortened, which means that the chambers of the heart will not be filled with the maximum possible amount of blood, so the stroke volume indicator will sooner or later stop increasing.

On the other hand, working muscles consume a large amount of blood that does not return to the heart during sports activities, thus reducing venous return and the degree of filling of the chambers of the heart with blood.

The main mechanism that determines the rate of stroke volume is the extensibility of the ventricular myocardium. The more the ventricle is stretched, the more blood will enter him and the higher will be the force with which he will send it to the main vessels. With an increase in the intensity of the load, the level of stroke volume, to a greater extent than extensibility, is affected by the contractility of cardiomyocytes - the second mechanism that regulates the value of stroke volume. Without good contractility, even the most filled ventricle will not be able to increase its stroke volume.

It should be noted that in myocardial pathology, the mechanisms regulating the IOC acquire a slightly different meaning. For example, hyperextension of the heart walls in conditions of decompensated heart failure, myocardial dystrophy, myocarditis and other diseases will not cause an increase in stroke and minute volumes, since the myocardium does not have sufficient strength for this, as a result, systolic function will decrease.

Increased blood volume with physical work helps to provide nutrition to the myocardium that is in great need of it, to deliver blood to working muscles, and also skin for proper thermoregulation.

As the load increases, blood delivery to the coronary arteries Therefore, before starting endurance training, you should warm up and warm up the muscles. In healthy people, neglect of this moment can go unnoticed, and with pathology of the heart muscle, ischemic changes are possible, accompanied by pain in the heart and characteristic electrocardiographic signs (depression of the ST segment).

How to determine the indicators of systolic function of the heart?

The values ​​of the systolic function of the myocardium are calculated according to various formulas, with the help of which the specialist judges the work of the heart, taking into account the frequency of its contractions.

ejection fraction of the heart

The systolic volume of the heart divided by body surface area (m²) will constitute the cardiac index. The surface area of ​​the body is calculated using special tables or a formula. In addition to cardiac index, cardiac output and stroke volume, the most important characteristic myocardial work is considered ejection fraction, which shows what percentage of end-diastolic blood leaves the heart during systole. It is calculated by dividing the stroke volume by the end-diastolic volume and multiplying by 100%.

When calculating these characteristics, the doctor must take into account all the factors that can change each indicator.

The end-diastolic volume and filling of the heart with blood is influenced by:

1. The amount of circulating blood;
2. The amount of blood entering right atrium from the veins of the large circle;
3. The frequency of contractions of the atria and ventricles and the synchronism of their work;
4. The duration of the period of relaxation of the myocardium (diastole).

An increase in minute and stroke volume is facilitated by:

• An increase in the amount of circulating blood with water and sodium retention (not provoked by cardiac pathology);
• The horizontal position of the body, when the venous return to the right parts of the heart naturally increases;
• Psycho-emotional stress, stress, strong excitement (due to increased heart rate and increased contractility of venous vessels).

A decrease in cardiac output accompanies:

1. Blood loss, shocks, dehydration;
2. Vertical position of the body;
3. Increased pressure in the chest cavity (obstructive pulmonary disease, pneumothorax, severe dry cough) or heart sac (pericarditis, fluid accumulation);
4. Hypodynamia;
5. Fainting, collapse, taking drugs that cause sharp drop pressure and varicose veins;
6. Some types of arrhythmias, when the chambers of the heart do not contract synchronously and are not sufficiently filled with blood in diastole (atrial fibrillation), severe tachycardia, when the heart does not have time to fill with the necessary volume of blood;
7. Myocardial pathology (cardiosclerosis, heart attack, inflammatory changes, myocardial dystrophy, dilated cardiomyopathy, etc.).

The index of the stroke volume of the left ventricle is influenced by the tone of the autonomic nervous system, the pulse rate, the state of the heart muscle. Such frequent pathological conditions as myocardial infarction, cardiosclerosis, dilatation of the heart muscle in decompensated organ failure contribute to a decrease in the contractility of cardiomyocytes, so cardiac output will naturally decrease.

Reception medicines also determines the performance of the heart. Adrenaline, norepinephrine, cardiac glycosides increase myocardial contractility and increase the IOC, while beta-blockers, barbiturates, some antiarrhythmic drugs reduce cardiac output.

Thus, the parameters of the minute and SV are influenced by many factors, ranging from the position of the body in space, physical activity, emotions and ending with a variety of pathologies of the heart and blood vessels. When assessing systolic function, the doctor relies on the general condition, age, gender of the subject, the presence or absence of structural changes in the myocardium, arrhythmias, etc. Only A complex approach can help to correctly assess the efficiency of the heart and create conditions under which it will contract in the optimal mode.

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9. Systolic and minute volume of the heart.

The heart, carrying out contractile activity, during systole throws a certain amount of blood into the vessels - this is the main function of the heart. Therefore, one of the indicators of the functional state of the heart is the value of minute and systolic volumes.

The amount of blood ejected by the heart into the vessels per minute is the minute volume of the heart. The amount of blood ejected by the heart in one contraction is the systolic volume of the heart.

The minute volume of the heart in a person in a state of relative rest is 4.5-5 liters. It is the same for the right and left ventricles.

The value of minute and systolic volumes is subject to large individual fluctuations and depends on various conditions: the functional state of the body, body temperature, body position in space, etc.

Training is of great importance in changing the magnitude of the minute and systolic volumes of the heart.

Systolic volume increases as blood flow to the heart increases. With an increase in systolic volume, the minute volume of blood also increases.

The minute volume of a healthy person and under physiological conditions depends on a number of factors. Muscular work increases it by 4-5 times, in extreme cases for a short time 10 times. Approximately 1 hour after a meal, the minute volume becomes 30-40% more than it was before, and only after about 3 hours does it reach its original value. Fear, fright, excitement - due to the development a large number adrenaline - increase minute volume. At low temperatures, cardiac activity is more economical than at higher temperatures. high temperature. Temperature fluctuations of 26 ° C do not have a significant effect on the minute volume. At temperatures up to 40 ° C, it increases slowly, and above 40 ° C - very quickly. The position of the body also affects the minute volume. At lying position it decreases, and in standing it increases.

The main work of the heart is to pump blood into the vessels against the resistance (pressure) that develops in them. The atria and ventricles perform various work. The atria contract to pump blood into the relaxed ventricles. This work does not require their great tension, since the blood pressure in the ventricles increases gradually as blood enters them from the atria.

Much more work is done by the ventricles, especially the left one. From the left ventricle, blood is pushed into the aorta, where blood pressure is high. In this case, the ventricle must contract with such force to overcome this resistance, for which the blood pressure in it must become higher than in the aorta. Only in this case, all the blood in it will be thrown into the vessels.

The work of the heart also increases if the resistance in the vascular system increases (for example, blood pressure in the arteries increases due to capillary constriction). At the same time, at first, the force of contractions of the heart is not enough to throw out all the blood against the increased resistance. Within a few contractions, a certain amount of blood remains in the heart, which helps to stretch the fibers of the heart muscle. As a result, there comes a moment when the force of contraction of the heart increases and all the blood is ejected, i.e. the systolic volume of the heart increases, and consequently, the systolic work also increases. The maximum amount by which the volume of the heart increases during diastole is called the reserve or reserve forces of the heart. This value increases in the process of training the heart._______________________________________________

The amount of blood ejected by the ventricle of the heart with each contraction is called the systolic volume (CO), or shock. On average, it is ml of blood. The amount of blood ejected by the right and left ventricles is the same.

Knowing the heart rate and systolic volume, you can determine the minute volume of blood circulation (MOV), or cardiac output:

IOC = SD heart rate. - formula

At rest in an adult, the minute volume of blood flow averages 5 liters. With physical exertion, systolic volume can double, and cardiac output can reach liters.

Systolic volume and cardiac output characterize the pumping function of the heart.

If the volume of blood entering the chambers of the heart increases, then the force of its contraction increases accordingly. The increase in the strength of heart contractions depends on the stretching of the heart muscle. The more it stretches, the more it contracts.

Physiologist Starling established the “Law of the Heart” (Frank-Starling law): with an increase in the filling of the heart with blood during diastole and, accordingly, with an increase in the stretching of the heart muscle, the force of heart contractions increases.

For some beginner runners, the question arises, “how healthy is it to run long and often in the upper heart rate zones?”. And here we again run into the question of the fitness of the cardiovascular system, muscles and the new phrase "stroke volume of the heart" (SV). The stroke volume of the heart is the portion of blood ejected by the left ventricle in 1 contraction.

AT the first part of the article I showed. In second part consider the stroke volume of the heart, the work of the heart at an increased heart rate.

With each contraction of the heart in an adult (at rest), 50-70 ml of blood is ejected into the aorta and pulmonary trunk, 4-5 liters per minute. With great physical stress, the minute volume can reach 30-40 liters. In other words, the athlete's heart is stretched to such a size that it can pump more than 200 ml of blood in one contraction. For example, the heart of a professional athlete when working for a minute at a pulse of 180 bpm. can pump 36 liters. blood. These are 4 buckets of 10 liters each!

For each person, VR is individual, depends on hereditary data and fitness. In women, for example, SV is 10-15% less than in men.

A person with an athletic heart (having a higher VR) has a higher endurance index, especially for prolonged physical exertion (marathon, cycling, long-distance swimming).

What effect does exercise have on the heart?

1. An increase in heart rate (HR)
2. Increased stroke volume (SV)
3. An increase in systolic pressure
4. Decreased diastolic pressure and peripheral vascular resistance
5. The respiratory rate increases
6. Increased coronary blood flow
7. There is a redistribution of blood (blood will be in the working muscle)

The effect of aerobic exercise (long-term)

1. Athletic heart (increase in size and strength of contraction)
2. Decreased heart rate
3. Increase in the number of capillaries in the muscles

Stroke volume during exercise.

The stroke volume of the heart increases with the growth of the pulse until and until the intensity of physical activity reaches the level of 40-60% of the maximum possible. After that, the UO is leveled. That is, when running at a pulse of 120-150 beats per minute, the heart is ergonomically stretched and contracted, optimally ensuring the exchange of oxygen and nutrients in the muscles, freeing itself from CO2 and enriching itself with O2 again. Therefore, in order to “stretch” the heart and increase VR, it is recommended to run for 2-3 hours a day, for 6 months!

Surely some noticed that you run and run for 20-30 minutes, the pulse is high, and after that from 150-155 bpm. it drops to 135 bpm. at the same intensity. This is an indicator that the heart has reached the norm of its MR, the vessels and capillaries of the body have started to work.

With prolonged physical activity of 40-60% of the maximum (or 120-150 bpm when running), the chamber of the left / right ventricle is stretched, as it enters maximum amount blood in this manner. If the chamber of the ventricle is stretched (diastole phase), then, accordingly, it should further contract as much as possible (systole phase) in order to expel blood.

The work of the heart with increased heart rate.

In the case when the load increases, when working in the 4th-5th pulse zone(PZ), then the heartbeat increases, the pulse too. The phase of systole and diastole (contraction and relaxation) becomes more frequent. Why can't we run at a heart rate of 170-180 bpm for as long as we can at a heart rate of 150 bpm? The thing is the following...

On the increased heart rate the blood does not have time to be fully enriched with oxygen, and also the ventricular chamber does not have time to fully stretch, as on a pulse of 140 beats per minute, and also fully, contract as much as possible to push out the blood. It turns out that the blood is not completely enriched and the heart also begins to “rush” and passes smaller portions of blood through the ventricle with rapid relaxation and rapid contraction.

SV with increased heart rate will decrease, oxygen exchange between muscle tissues (upper / lower limbs), which will limit the performance of the work.

Accordingly, in this mode (anaerobic glycolysis), the athlete will not be able to show high results for a long time. With a decrease in nutrients and oxygen supplied to the muscles, as we know, the body in an anaerobic mode begins to use glucose, muscle glycogen, while releasing pyruvate, lactate, which goes into the blood. Together with lactate, the amount of hydrogen ions (H+) increases. And now an excess of H + destroys protein and myofibrils. In a small amount, it helps to increase strength, and in excess, with strong acidification, it only harms the body. If there is a lot of H + and they are in the blood for a long time, then this also reduces the aerobic capacity of the athlete, endurance, as it destroys mitochondria.

But the good news is that with the help of competent interval training, tempo training, we can increase the buffering capacity of the body, increasing the VO2 max and pushing back the TAN.

Interval training, especially among professional athletes and even amateurs who work for the result, is associated with large intervals of 1000 m and above, and these workouts are very exhausting not only physical state, but also nervous system. If they are done often, then this can lead to overtraining, inflammation, disease, injury. In my opinion, depending on the period of preparation of the athlete and the level of the athlete, 1-2 diverse interval training sessions per week or even 1 time in 2 weeks is enough.

The more often the heart rate, the more biochemistry shifts towards anaerobic metabolism, the less time we can perform this or that work. The higher the heart rate, the more oxygen and energy the muscles need to consume. As a result, the heart muscle will receive less nutrition, which will lead to ischemia (impaired cardiac circulation) of the heart.

In order to increase endurance, it is not enough just to increase the stroke volume of the heart (SV). The condition of the muscles, capillaryization and the development of the circulatory system also matter here. These qualities develop in the process of training.

Interval training is also different: short intense and long (not at full strength). The first can last 10-20 minutes, and the second 40-60 minutes or more. The more intense the interval, the higher the heart rate (pulse), the stronger the heart muscle pumps up, the elasticity decreases.

You need to understand that interval training at maximum heart rate is acceptable if you are a professional athlete and are preparing for competitions. Prolonged exercise in this mode is undesirable for health, as it leads to acidification of not only the muscles, but also the heart.

Exercising at too high a heart rate leads to hypertrophy of the heart muscle and a decrease in stroke volume, and as a result can lead to heart failure and even lethal outcome. Therefore, a competent preparation of a training plan and an understanding of the specifics of training exercises allows you to consistently and evenly develop body functions without harm to health.

What threatens the health of an athlete for a long run on high heart rate Or how does the body protect us from the sad consequences?

1) First, fatigue of the body appears, then the working muscles (arms, legs) become clogged, they become wadded.

2) Vomiting reflex, nausea, as a reaction to acidification of the body.

3) Shutdown of the central nervous system, loss of consciousness.

4) Cardiac arrest.

We are now smart and we will not bring ourselves to the state of the 4th point.

Cardiac output, or cardiac output, is the amount of blood that the heart pumps per minute (measured in liters per minute). It measures how efficiently the heart delivers oxygen and nutrients to the body and how well it functions compared to the rest of the cardiovascular system. To determine cardiac output, it is necessary to determine the stroke volume and heartbeat. This can only be done by a doctor using an echocardiogram.

Steps

Determination of heart rate

Take a stopwatch or watch. Heart rate is the number of heartbeats per unit of time. It is usually measured in one minute. This is very easy to do, but you will need a device that accurately counts seconds.

• You can try to count the beats and seconds mentally, but this will be inaccurate, as you will be focused on the pulse, and not on the internal sense of time.
• It's better to set a timer so you can only focus on counting the hits. The timer is in your smartphone.

1. Find a pulse. Although there are many points on the body where you can feel the pulse, the easiest way to find it is on the inside of the wrist. Another place is on the side of the throat, where the jugular vein is located. When you find the pulse and clearly feel its beats, put the index and middle fingers of the other hand on the place of the beat.

   • The pulse is usually best felt with inside wrist, on a line mentally drawn from index finger across the wrist and about 5 cm above the first crease on it.
   • You may need to move your fingers back and forth a little to find where the pulse is heard most clearly.
   • You can lightly press your fingers on your wrist to feel for a pulse. However, if you have to push too hard, you have chosen the wrong place. Try moving your fingers to a different point.

2. Start counting the number of beats. When you find a pulse, turn on the stopwatch or look at the clock with a second hand, wait until it reaches 12 and start counting the beats. Count the number of beats in one minute (until the second hand returns to 12). This number is your heart rate.

   • If you find it difficult to count beats for a full minute, you can count 30 seconds (until the second hand is at 6), and then multiply the result by two.
   • You can also count the beats in 15 seconds and multiply by 4.

   Stroke volume determination

   1. Get an echocardiogram. Heart rate is simply the number of times the heart beats per minute, and stroke volume is the volume of blood pumped from the left ventricle of the heart with each beat. It is measured in milliliters, and it is much more difficult to determine it. For this, it is carried out special study called echocardiography (echo).

      Calculate the area of ​​the left ventricular outlet (LVOT). The left ventricular outlet is the area of ​​the heart through which blood enters the arteries. To calculate stroke volume, you need to know the left ventricular outflow tract area (LVOT) and the integral of the left ventricular outflow tract flow velocity (LVOT).

      Determine the integral of the blood flow velocity. The integral of blood flow velocity is the integral of the rate at which blood flows through a vessel or through a valve in a given time. To calculate VOLV IS, the specialist will measure the flow using Doppler echocardiography. To do this, he uses a special function of the echocardiograph.

      • To determine the IS VOLZH, calculate the area under the curve of the aorta on pulsed wave Doppler. The specialist can take multiple measurements to make a conclusion about the efficiency of your heart.

   2. Calculate stroke volume. To determine the stroke volume, subtract the volume of blood in the ventricle before the stroke (end-diastolic volume, EDV) from the volume of blood in the ventricle at the end of the stroke (end-systolic volume, ESV). Stroke volume \u003d BDO - KSO. As a rule, stroke volume is associated with the left ventricle, but it can also apply to the right. Usually the stroke volume of both ventricles is the same.

      Determine cardiac output. Finally, to calculate cardiac output, multiply the heart rate by the stroke volume. This is a fairly simple calculation that will tell you how much blood your heart pumps in one minute. The formula is: Heart rate x Stroke volume = Cardiac output. For example, if the heart rate is 60 beats per minute and the stroke volume is 70 ml, you get:

   Factors affecting cardiac output

   Understand what heart rate means. You will better understand what cardiac output is if you know what influences it. The most immediate factor is the heart rate (pulse), that is, the number of heartbeats per minute. The faster the pulse, the more blood is pumped throughout the body. The normal heart rate is 60-100 beats per minute. If the heart beats too slowly, it is called bradycardia, a condition in which the heart pumps too little blood into the circulation.

The invention relates to medicine, in particular physiology, cardiology. The age and sex of the patient are taken into account when determining the stroke volume of the heart according to the Starr formula. The presence or absence of heart defects is also taken into account. The value of the stroke volume of the heart, obtained by the Starr formula, is multiplied by different coefficients. The method is reliable when BPs=105-155 mm Hg, BPd=55-95 mm Hg. Art., heart rate = 60-90 min -1. The method allows to increase the accuracy of determining the indicators of central hemodynamics, which makes it possible to timely establish violations of the functioning of the circulatory system and prevent their further development. 1 z.p. f-ly, 2 tab.

The invention relates to medicine and can be used in its various branches, such as anesthesiology, intensive care, cardiology. The search for publicly available informative non-invasive methods for determining the stroke volume of the heart (SV) continues to be topical issue. The need for control this indicator is obvious, since it characterizes the immediate pumping function of the heart and determines the delivery of oxygen to tissues (Zhiznevsky Ya. A. Fundamentals of infusion therapy. Minsk, 1994). In addition, the determination of UOS makes it possible to calculate other hemodynamic parameters (minute volume of the heart, total peripheral vascular resistance, pulmonary vascular resistance, etc.), reflecting more complete picture functioning of the circulatory system. Effective pharmacological effects on preload, afterload and contractility is also impossible without measuring the SV (Morgan Jr. J.E., Magid S.M. Clinical anesthesiology. Moscow, St. Petersburg, 1998). Currently, there are many ways to determine the stroke volume of the heart. 1. Calculation method for determining the minute volume of the heart using the Starr formula. In 1954, Starr based on experimental material and clinical observations proposed a calculation method for determining the stroke volume of the heart according to the formula: SV = 90.97 + 0.54PD-0.57ADd-0.61V, where SV is the stroke volume of the heart, PD is the pulse pressure, ADD is the diastolic pressure, B is the age in years (Stair I. Clinical tests of the simple method of estimating cardiac stroke volume from blood pressure and age. Circulation, 1954, 93, P/ 664-681). 2. Fick's method. The essence of the method is as follows. Oxygen from the exhaled air is absorbed by the blood flowing through the pulmonary capillaries. By the concentration of oxygen in the arterial and venous blood, it is possible to establish the arteriovenous difference in oxygen. By calculating the content of oxygen absorbed within 1 minute, you can calculate the volume of blood flowing through the lungs for the same period of time, or the minute volume of the heart (Petrosyan Yu. S. Catheterization of the heart cavities and great vessels. - In the book: Guide to cardiology. Under the editorship of Academician E. I. Chazov, Moscow, 1982). Therefore: MOC=Oxygen Consumption: Arteriovenous Oxygen Difference. Knowing the heart rate, determine the stroke volume of the heart. All variants of the indicator dye dilution technique that allow measuring cardiac output are based on the Fick principle. Disadvantages: The results obtained using the Starr formula were repeatedly compared with those established by other research methods (Grolman, Fick methods). It was noted that although there is a high correlation between the indicators determined by this method with those found by other methods, the hemodynamic parameters differed from each other in absolute values ​​(Sazonov K.N. On the issue of determining shock and minute volumes in patients with defects hearts subjected to surgical treatment. Wedge. Medicine, 1959; Mikirtumova E.V. Comparative evaluation some clinical methods for determining the minute volume of blood. Ter. Archive, 1960; Mizerovsky V.V. To the method for determining systolic volume and mean dynamic arterial pressure during anesthesia. Bulletin of Surgery. Grekova, 1968). Fick's method has time limits abdominal surgery due to the redistribution of blood circulation occurring during the operation and anesthesia, changes in the gas exchange system, arteriovenous shunt, changes in the relative position internal organs and accumulation of fluid (blood) in the cavities. As a prototype, the thermodilution method was chosen, which is the "gold standard" for determining minute and stroke volumes of the heart (H. Metzler. Non-invasive and reasonable invasive monitoring of the circulatory system. - In the book: Refreshing lecture course. Arkhangelsk, 1997). The method consists in catheterization pulmonary artery and introducing through it into the right atrium a certain amount of solution (2.5; 5 or 10 ml), the temperature of which less temperature patient's body (usually room temperature or icy). In this case, there is a change in the temperature of the blood in contact with the thermistor in the pulmonary artery. The degree of change is inversely proportional to the cardiac output. The graphic representation of temperature changes versus time is a thermodilution curve. Minute volume of the heart is determined using a computer program that integrates the area under the curve. Knowing the heart rate, the stroke volume of the heart is calculated. Determining the stroke volume of the heart using the thermodilution method can be accompanied by quite serious complications, such as rupture of the pulmonary artery, catheter-associated sepsis, thrombophlebitis, vein thrombosis, pulmonary infarction, parietal thrombosis, endocarditis, etc. In addition, the use this method requires specialized expensive equipment. Therefore, the use of the thermodilution method is limited, first of all, to cardiac surgery, as well as critical conditions blood circulation (H. Metzler. Non-invasive and reasonable invasive monitoring of the circulatory system. - In the book: Refreshing lecture course. Arkhangelsk, 1997; Morgan Jr. J. E., Magid S. M. Clinical anesthesiology. Moscow, St. Petersburg, 1998). The goal is to increase the accuracy of stroke volume indicators of the heart, obtained by the Starr calculation method for monitoring hemodynamics. Objectives: 1. Reducing trauma in determining the stroke volume of the heart. 2. Reducing labor costs and costs in the implementation of the method. 3. Reducing the study time. The essence of the invention lies in the fact that the age period of the patient is taken into account and when determining the stroke volume of the heart according to the Starr formula in patients of the I period of adulthood with heart defects, the value is divided by a factor of 1.33, in patients of the II period of adulthood - divided by a factor of 1.44 , and in elderly patients - divided by a factor of 1.50; and in the absence of heart defects in patients of the I period of mature age, the values ​​of the stroke volume of the heart obtained by the Starr formula are multiplied by a factor of 1.25, in patients of the II period of mature age they are multiplied by a factor of 1.55, and in elderly patients they are multiplied by coefficient 1.70. The first period of adulthood includes women from 20 to 35 years old, men - from 21 to 35 years old, to the second period of adulthood - from 36 to 55 years old and from 36 to 60 years old, respectively, to old age - over 55 and 60 years old, moreover, the method is reliable when BPs= 105-155 mm Hg, BPd=55-95 mm Hg, heart rate=60-90 min -1 . The conducted patent study showed that the proposed method for determining the stroke volume of the heart has not been described and has not been used so far. Publications and patents in domestic and foreign sources were not found. The inventive step is confirmed by non-obviousness. The reproducibility of the method is not in doubt, since known equipment and a process accessible to medical personnel were used. The method is carried out as follows. The patient produces precise measurement blood pressure (systolic and diastolic) by one of the non-invasive methods (for example, auscultatory, Doppler, oscillometric, using plethysmography or arterial tonometry). The stroke volume of the heart in patients without heart defects is calculated by the formula: SV=(90.97+0.54PD-0.57ADd-0.61V)k. In patients with heart defects, the stroke volume is determined as follows: SV = (90.97 + 0.54PD-0.57ADd-0.61B):k, where SV is the stroke volume of the heart, PP is pulse pressure, BPd is diastolic pressure, B - age in years, k - entered coefficient depending on the patient's age. To level individual fluctuations in stroke volume of the heart associated with differences in body weight, it is preferable to use stroke index indicators, which are calculated as follows:
where UI - shock index, S - body area. To determine the area of ​​​​the body, there are many calculation formulas, one of which is:
S=(4P+7)/(90+P),
where P is the weight of the patient. To determine k (the correction factor introduced into the Starr formula), a comparative and correlation analysis of the impact index indicators obtained using the Starr calculation method was carried out with the indicators obtained by the thermodilution method. The study was conducted in cardiac surgery patients operated on for coronary disease and heart defects. Assuming that in patients with heart defects there are significant changes in hemodynamics ("regurgitation" of blood, a decrease in myocardial contractility, etc.), the indicators obtained before the elimination of the defect were included in a separate group. The study included only those indicators of CI that were calculated by blood pressure, which is within the limits: systolic blood pressure - 105-155 mm Hg, diastolic blood pressure - 55-95 mm Hg, heart rate ranged from 60 to 90 min -1 . The measurements were made in three age groups Oh:
1. in persons of the I period of mature age (men 21-35 years old, women 20-35 years old);
2. in persons of the II period of mature age (men 36-60 years old, women 36-55 years old);
3. in the elderly (men over 60 years old, women over 55 years old). All patients underwent simultaneous recording of SV and BP by invasive methods: the cardiac output was determined by thermodilution, after which the stroke volume of the heart was calculated by dividing the value of the cardiac output by the heart rate and the stroke index, which is the ratio of SV to the body surface area; BP was determined by direct method using an intra-arterial catheter inserted into the radial artery. In parallel, the determination of SVR and SI was carried out by the Starr calculation method based on non-invasively measured blood pressure (Korotkov method). The results were compared by the method of variation statistics and correlation analysis was carried out. In the group of patients operated on for coronary heart disease and heart defects after their elimination, the following results were found (table 1). When analyzing data obtained by invasive and non-invasive methods, a significant (p<0,05) сильная (r>0.7) a direct correlation between the impact index indicators obtained invasively and determined by the Starr calculation method. However, despite the strong correlation between invasive and non-invasive SI, there is a difference in absolute values. At the same time, in persons of the I period of mature age, the SI, determined by the thermodilution method, exceeded the SI, determined by the Starr method, by 1.25, in persons of the II period of mature age, by 1.55, and in the elderly, by 1.7. Thus, taking into account the high parallelism between the calculated and measured invasive stroke index, as well as the difference in the results obtained, it is proposed to introduce an additional coefficient k into the Starr formula, which reflects the difference in the values ​​of the stroke index determined invasively and non-invasively, and is calculated by dividing the average values ​​of SI , obtained invasively, on the average values ​​of SI determined by calculation. Therefore, Starr's formula should look like this:
UOS=(90.97+(0.54PD)-(0.57ADd)-0.61B)k,
where PP - pulse pressure, BPd - diastolic blood pressure, B - age in years, k - coefficient depending on the age of patients. In the group of patients operated on for heart defects before their elimination, we obtained the following results (table 1). When analyzing data obtained by invasive and non-invasive methods, a significant (p<0,05) сильная и средняя (r>0.7) a direct correlation between the impact index indicators obtained invasively and determined by the Starr calculation method. However, despite the strong correlation between invasive and non-invasive SI, there is a difference in absolute values. At the same time, in persons of the I period of mature age, the SI determined by the Starr method exceeded the SI determined by the thermodilution method by 1.33, in persons of the II period of mature age - by 1.44, and in the elderly - by 1.5. Thus, Starr's formula should look like this:
UOS \u003d (90.97 + (0.54PD) - (0.57ADd) -0.61V) / k,
where PP is pulse pressure, BPd is diastolic blood pressure, B is age in years, k is a coefficient depending on the age of patients. The input coefficient k reflects the difference in stroke index values ​​determined invasively and non-invasively, and is calculated by dividing the mean SI values ​​obtained by calculation by the average SI values ​​determined invasively. Example 1 Case history 755/77. Patient Kozintseva S.Yu., aged 20, weight - 58 kg, body S - 1.61 m 2 . Diagnosis - defect mitral valve with predominance of stenosis. The patient's cardiac output was determined by thermodilution, after which the stroke volume of the heart was calculated by dividing the value of the cardiac output by the heart rate and the stroke index, which is the ratio of the SV values ​​to the body surface area. In this case, the AI ​​before the defect was eliminated was 28 ml/m 2 . In parallel, the determination of SOS and SI was carried out by the Starr calculation method with the correction factor k introduced into it (for this case k=1.33 -1) in terms of blood pressure measured non-invasively (by the Korotkov method): SVR= (90.97+0.5442-0.5767-0.6120): 1.33= 48 ml, SI=48 /1.61=30 ml/m2. As can be seen from the proposed example, the SI values ​​determined by the thermodilution method correspond to the SI values ​​obtained using the modified Starr method. In this example, the value of the AI ​​indicates a violation of the contractile function of the heart (normally, the AI, according to various authors, is 33-60 ml/m 2) and requires medical correction. Example 2 Case history 6100/537. Patient Sergienko E.V., aged 21, weight - 64 kg, body S - 1.71 m 2 . Diagnosis - defect of the mitral valve with a predominance of stenosis. UI determined by thermodilution method was 32 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.33 -1) UI: YOC = (90.97 + 0.5447-0.5764-0.6121): 1.33 \u003d 50 ml , UI \u003d 50 / 1.71 \u003d 30 ml / m 2. As in the previous example, the patient's SI is outside the lower limit of normal, which requires cardiotropic therapy. Example 3 Case history 705/60. Patient Chikhanov O.V., aged 35, weight - 65 kg, body S - 1.72 m 2 . Diagnosis - combined defect of the mitral valve. UI determined by thermodilution method was 23 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.33 -1) UI: UOS \u003d (90.97 + 0.5450-0.5788-0.6135): 1.33 \u003d 35 ml , UI=35/1.72=20 ml/m 2 . In this example, the obtained SI values ​​indicate significant reduction contractile function of the heart and require urgent medical correction. Example 4 Case history 3846/414. Patient Dondenko O.K., 36 years old, weight - 67 kg, body S - 1.75 m 2 . Diagnosis - combined defect of the mitral valve. UI determined by the thermodilution method was 15 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k \u003d 1.44 -1) UI: UOS \u003d (90.97 + 0.5448-0.5795-0.6136): 1.44 \u003d 28 ml , UI \u003d 28 / 1.75 \u003d 6 ml / m 2. The SI values ​​in this example are significantly reduced compared to normal values. Measures aimed at increasing myocardial contractility should be taken immediately. Example 5 Case history 1247/125. Patient Guleva VN, aged 55, weight - 75 kg, body S - 1.86 m 2 . Diagnosis - defect of the mitral valve with a predominance of stenosis. UI determined by the thermodilution method was 15 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k \u003d 1.44 -1) UI: UOS \u003d (90.97 + 0.5457-0.5792-0.6155): 1.44 \u003d 25 ml , UI \u003d 25 / 1.86 \u003d 13 ml / m 2. As in the previous example, SI values ​​are well below normal values ​​and immediate cardiotropic therapy is required. Example 6 Case history 138/1. Patient Shuev B.L., aged 60, weight - 81 kg, body S - 1.94 m 2 . Diagnosis - defect aortic valve with a predominance of insufficiency. UI determined by the thermodilution method was 12 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.44 -1) UI: UOS = (90.97 + 0.5453-0.5785-0.6160): 1.44 \u003d 24 ml , UI \u003d 24 / 1.94 \u003d 12 ml / m 2. Both invasively and non-invasively determined SI value is far beyond the lower limit of normal and requires medical correction. Example 7 Case history 350/33. Patient Nemchinova L.D., aged 56, weight - 71 kg, body S - 1.81 m 2 . Diagnosis - combined defect of the mitral valve. UI determined by the thermodilution method was 14 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k \u003d 1.5 -1) UI: UOS \u003d (90.97 + 0.5444-0.5781-0.6156): 1.5 \u003d 23 ml , UI \u003d 23 / 1.81 \u003d 13 ml / m 2. The obtained values ​​of SI indicate a significant violation of the contractile function of the heart and medical measures should be aimed at increasing it. Example 8 Case history 5243/459. Patient Kriushin N.I., 61 years old, weight - 69 kg, body S - 1.78 m 2 . Diagnosis - combined defect of the mitral valve. UI determined by thermodilution method was 11 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k \u003d 1.5 -1) UI: YOC \u003d (90.97 + 0.5442-0.5784-0.6161): 1.5 \u003d 19 ml , UI \u003d 19 / 1.78 \u003d 11 ml / m 2. The values ​​obtained in this example are three times less than the lower limit of normal. Therefore, an immediate drug effect on the contractile function of the heart is required. Example 9 Case history 186/3. Patient Bratova A.V., aged 20, weight - 57 kg, body S - 1.60 m 2 . Diagnosis - defect of the mitral valve with a predominance of stenosis. In the study of hemodynamics by thermodilution during anesthesia after the elimination of the defect UI= 63 ml/m 2 . In parallel, using the Starr formula with the correction factor k introduced into it (for this case, k = 1.25), we calculated SI: SOC = (90.97+0.5466-0.5767-0.6120)1.25 = 95 ml, UI= 95/1.60= 60 ml/m2. The SI values, determined invasively and by calculation, are indicative of the patient's normal impact ejection. Example 10 Case history 2932/283. Patient Omnchenko N.V., 21 years old, weight - 63 kg, body S - 1.69 m 2 . Diagnosis - defect of the mitral valve with a predominance of stenosis. UI after elimination of the defect, determined by the thermodilution method, amounted to 40 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.25) SI: SV = (90.97 + 0.5446-0.5778-0.6121) 1.25 = 73 ml, SI = 73 / 1.69 \u003d 43 ml / m 2. In this example, the AI, determined in two ways, is within the normal range and does not require medical interventions. Example 11 Case history 707/61. Patient Gichyan LN, 35 years old, weight - 71 kg, body S - 1.81 m 2 . Diagnosis - ischemic heart disease. UI determined by thermodilution method was 34 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.25) SI: SV = (90.97 + 0.5439-0.5777-0.6135) 1.25 = 59 ml, SI = 59 / 1.81 \u003d 32 ml / m 2. The UI values ​​are on lower border normal and further monitoring of the contractile function of the heart is required to avoid its further decline. Example 12 Case history 2874/276. Patient Bobryshev VV, aged 36, weight - 84 kg, body S - 1.97 m 2 . Diagnosis - ischemic heart disease. UI determined by thermodilution method was 47 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.55) SI: SV = (90.97 + 0.5458-0.5776-0.6136) 1.55 = 88 ml, UI = 88 / 1.97 \u003d 45 ml / m 2. The AI ​​values ​​are within the normal range and do not require medical correction. Example 13 Case history 4776/404. Patient Zavada A.A., aged 55, weight - 75 kg, body S - 1.86 m 2 . Diagnosis - ischemic heart disease. UI determined by thermodilution method was 32 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.55) SI: SV = (90.97 + 0.5458-0.5787-0.6155) 1.55 = 61 ml, SI = 61 / 1.86 \u003d 33 ml / m 2. The AI ​​values ​​are at the lower limit of the norm and further monitoring of the contractile function of the heart is required in order to avoid its further decrease. Example 14 Case history 1278/129. Patient Vasilevsky, 60 years old, weight - 69 kg, body S - 1.78 m 2 . Diagnosis - ischemic heart disease. UI determined by thermodilution method was 25 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.55) SI: SV = (90.97 + 0.5444-0.5782-0.6160) 1.55 = 49 ml, SI = 49 / 1.78 \u003d 27 ml / m 2. The AI ​​values ​​are outside the lower limit of the norm, indicating a decrease in the contractile function of the heart. In this example, the patient requires cardiotropic therapy. Example 15 Case history 2460/255. Patient Norova L.Kh., aged 56, weight - 72 kg, body S - 1.82 m 2 . Diagnosis - ischemic heart disease. UI determined by the thermodilution method was 33 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.7) UI: SV = (90.97 + 0.5439-0.5774-0.6156) 1.7 = 61 ml, UI = 61 / 1.82 \u003d 33 ml / m 2. The AI ​​values ​​are at the lower limit of the norm and further monitoring of the contractile function of the heart is required in order to avoid its further decrease. Example 16 Case history 2097/219. Patient Kazarin IN, 61 years old, weight - 79 kg, body S - 1.91 m 2 . Diagnosis - ischemic heart disease. UI determined by the thermodilution method was 22 ml/m 2 . According to the Starr formula with the correction factor k introduced into it (for this case, k = 1.7) UI: SV = (90.97 + 0.5452-0.5795-0.6161) 1.7 = 47 ml, UI = 43 / 1.91 \u003d 24 ml / m 2. In this example, the obtained SI values ​​indicate a significant decrease in the contractile function of the heart and require urgent medical correction. Thus, the identified indicators of UI correspond to those, but determined invasively. Knowledge of the UI allows you to prevent and prevent violations of the contractility of the heart. The medico-social effect is to increase the accuracy of determining indicators of central hemodynamics, which makes it possible to timely establish violations of the functioning of the circulatory system and prevent their further development.