A stopped heart

A stopped heart.  Photo from www.sciencephoto.com

Interior of a modern operating today is unimaginable without cardiopulmonary bypass — AIC. Appearing at the end of 50th years, it has become firmly established in the practice of cardiac surgery. On those few hours that lasts operation, the heart and lungs of a patient given the power of this clever machine.

Congenital and acquired heart diseases today are more and more often. Therapeutic treatments often powerless to help, so the palm belongs to the surgery.

What is a heart defect? Summarizing, we can reply that this disturbance of heart structure, which leads to a change in the strict blood flow path inside. Usually this scheme strictly "performed" in a healthy person, and the slightest of disturbance affecting the whole body. As is known, the heart is composed of four interconnected cavities: two atria and two ventricles. Between the atria as well as between the ventricles of the heart, there septum. In a healthy heart, they prevent blood from flowing out of the left atrium and right ventricle, respectively. But if there are defects in these webs, of the blood begins to flow into the right ventricle. This reduces the pressure of the blood, which left ventricle ejects into the aorta (from there it spreads throughout the body). As a result of deteriorating blood supply. In right ventricular pressure rises, thereby increasing its volume, the muscle layer thickening its wall.

All this inevitably leads to chronic heart failure and the effect on other organs. Change and pulmonary vasculature: constantly resisting pressure increase, they become stiff, lose elasticity. Broken and blood oxygen saturation. The person has shortness of breath, swelling of the legs or torso, bluish skin or mucous membranes (cyanosis). All this — the consequence of a defect in the septum of the heart.

This can be avoided if the time to carry out the operation, restoring cardiac septum. But for heart surgery is necessary to stop the time: after all, beating and throwing out the blood vessels in the heart can not handle. First tried to solve this problem with the help of artificial cooling of the patient to 30 degrees Celsius. This allows for a very short time, turn off the heart from the circulation, as a decrease in body temperature to 30 degrees the body's need for oxygen is reduced by nearly half, and so it can move short — on15-20 minutes — heart failure. This time is quite enough when you need to put a few stitches for a minor heart defect.

Before the operation the patient is under anesthesia, are beginning to cool — his body draped with bags of crushed ice. Temperature sensors and pressure sensors monitor his condition, at the same time are monitored basic physiological parameters. When the body temperature drops to 32 degrees, the ice is removed, but the temperature of inertia continues to decline up to 29 degrees. Within 20 minutes, has not come yet anoxia can perform surgery on the heart wall. At the end of the operation with the help of drugs stimulate the heart and warm the body of the patient flow of warm air.

Operate in this way, for example, at the Novosibirsk Institute of Circulation Pathology, who for many years headed by Academician E.N.Meshalkin. The surgeons were able to achieve a significant reduction in the body's need for oxygen, which increased the duration of the operation to 60 minutes! However, despite the fact that this method is relatively inexpensive and can achieve good results, he has a serious problem — too limited a time frame, do not allow to carry out complex operations.

Completely solve the problem could using cardiopulmonary bypass and the creation of the AIC. In our country, the development of artificial blood circulation is due primarily to the names S.S.Bryuhonenko and S.I.Chechulina. They are still in 1924, created the prototype of the modern heart-lung machine, which they called "avtozhektor." Today's AIC is significantly different from their predecessors of the first, because since medicine has leaped forward.

Any AIC consists of two units: a physiological and mechanical. The first includes all the parts are in contact with blood. The main part of it — oxygenator, acting as "artificial" light ", and the arterial pump, taking on the task of" artificial heart. " Today it is — a sterile, single-use device, for each individual patient. Mechanical unit is a set of pumps and equipment for electronic control and continuous monitoring of the parameters of cardiopulmonary bypass.

To take blood in the tubing AIC to solve some problems. First, blood should not clot. This patient is administered a substance that prevents blood from clotting, — heparin or its analogs. Secondly, necessary to saturate the blood with oxygen. For this and serve artificial light AIC. In the first stage of the operation tube physiological unit AIC inserted into receptacles patient so thatsome time there is a parallel circulation, One of the blood passes through the AIC, and the other — a heart. Then ribbons vessels tightly pressed to the tubes, and from that moment blood has been going only through AIC. Venous blood, poor oxygen from the patient enters the oxygenator, where it is oxygenated, free from excess carbon dioxide continue to pump blood is injected into the blood vessels.

Before re-enter into the circulatory system of surgical and blood passes through a heat exchanger — a device to maintain the desired temperature of the blood, as well as via an arterial filter trap, preventing the introduction into theblood Air bubbles and foreign particles.

Thus, circulation by AIC is around the heart. This allows the surgeon to operate in the "dry" heart, devoid of the main flow of blood, as much time as is necessary for the correction of the defect. Heart continued to decline during the operation. It is not entirely exsanguinated, as part of the blood passes through the heart and blood vessels nourishing the heart muscle itself.

In recent decades the methods that also protect the heart from oxygen deprivation during the AIC. This is the so-called cold cardioplegia at which the kind of "conservation" of the heart. Before the surgery, the patient is administered directly into the aorta cardioplegic solution: a specially selected electrolyte composition with a high content of potassium, cooled to four degrees. It causes rapid heart failure for 20-25 minutes. Due solution protected from oxygen heart failure, it remains stationary, which creates conditions for a more rapid and accurate operation surgeon. The solution protects and preserves the energy reserves of the heart, even during long and complicated operations. All this has given an opportunity to correct surgically such heart defects that were previously considered hopeless.

As you can see, it is difficult to overestimate the importance of the method of artificial circulation. With it managed to restore health to millions of patients around the world.

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