Hereditary diseases of the cardiovascular system
The heart is the central organ of the cardiovascular system of any living organism. It is a muscular organ that consists of two atria and two ventricles( right and left).The atria are located above the ventricles and are separated by an interatrial septum consisting of muscle tissue. The ventricles of the heart are located under the atrium and separated from each other by the interventricular septum, which consists of muscle tissue. This septum has two parts: the upper part - membranous( membranous), the lower part( large) - muscular. The atria are separated from the ventricles by means of valves. Between the right atrium and the ventricle is a tricuspid( tricuspid) valve, and between the left - bivalve( mitral).The heart wall consists of three layers: the inner - endocardium, the middle - the myocardium( formed by the muscle tissue) and the outer - the epicardium. The heart is located in the chest cavity and is enclosed in a connective tissue bag - a pericardial bag( pericardium), which performs a protective function. A person has two circles of circulation: large and small. On a large scale, blood flows to all organs and tissues of the body, enriching them with oxygen and nutrients and taking away various metabolic products from them. In a small circle of blood circulation, blood flows rich in metabolic products. It passes through the lungs, enriched there with oxygen, and then again sent to a large circle. A large circle of circulation begins in the left ventricle. Its muscular wall is intensively contracted and expels blood to the aorta through the aortic aperture, which, like the openings between the atria and ventricles, is covered by a valve.
The process of contraction of the ventricles is called systole. From the aorta, which is the largest vessel of the body, the blood is carried along the arteries to all organs and tissues. Then the organs collect blood from the organs into the veins. All veins combine into the two largest: the upper and lower hollow veins. The upper vena cava collects blood from the head, neck and upper body. The lower vena cava collects blood from the lower part of the trunk. Both hollow veins end in the right atrium, bringing here the "spent" blood from the entire body. The blood from the right atrium falls into the right ventricle, from which the small circle of circulation originates. From the right ventricle there is a pulmonary trunk, which is divided into the right and left pulmonary arteries. On the right pulmonary artery, the blood is delivered to the right lung, on the left - to the left. In the lungs, the blood is enriched with oxygen, and then along the four pulmonary veins goes to the left atrium, where the small circle of blood flow ends. From there, the blood, rich in oxygen, enters the left ventricle. Heart work consists of three phases: atrial contraction - atrial systole, ventricular contraction - ventricular systole, general pause - diastole. When systole atrial blood enters the ventricles, with systole ventricles - expelled into the vessels. After this, there comes a pause in the work of the heart, during which the heart muscle "rests."According to the duration of the phase, the systoles and diastoles are equal, that is, half of all life the heart is at rest.
In a child developing in the mother's body, blood circulation occurs in a slightly different way. The fetus has only one circle of blood circulation - large, but it has its own characteristics. Blood to the fetus comes from the placenta through the umbilical vein, which passes through the umbilical cord. In the child's body, the umbilical vein is divided into two vessels. One of them goes to the liver, and the other runs into the lower vena cava. Since the umbilical vein from the placenta receives blood that is rich in oxygen and nutrients in the fetus's organism, and the "spent" blood flows in the inferior vena cava, then the last vessel contains mixed blood that enters the right atrium. From there, a very small part of the blood is sent "in the usual way", as it happens in adults, that is, it flows into the right ventricle. However, most of the blood from the right atrium falls into the left atrium. It would seem, how can this happen if the atria are separated by an interatrial septum? However, the fetus in this septum has a hole, due to which this unusual movement of blood is carried out. This hole in the interatrial septum is called oval.
In the fetus, just like in an adult, the upper vena cava collects blood from the head, neck and upper body. Through this vein, the blood enters the right atrium, and from there into the right ventricle. After that, the blood, as usual, should occur, enters the pulmonary trunk, that is, into the small circle of blood circulation. But in a child in the prenatal period, the lung vessels are undeveloped. In this connection, the blood from the pulmonary trunk flows into the aorta. Again, the question arises: how does this happen? It turns out that there is also a message between the pulmonary trunk and the aorta - the arterial( botall) duct.
After the birth of the child, when the umbilical cord is cut, the supply of blood enriched with oxygen is stopped by the umbilical vein. This leads to a deficiency of oxygen in the body of the newborn baby, which causes the activation of special structures in the brain that are responsible for the first breath. After the first inhalation, the lungs and their vessels spread out, which is accompanied by the beginning of the functioning of the small circle of blood circulation. At the same time there is a reflex narrowing of the arterial( botallova) duct, which completely overgrows 1.5-2 months after birth. The oval aperture at this time narrows down to the size of the gap and completely overgrows to 5-6 months of life.
Due to the influence of various causes, first of all, of course, genetic, there are various deviations in the development of the heart and the closure of the communication available in the prenatal period for such unusual movement of blood, which leads to the occurrence of congenital heart defects.
The frequency of occurrence of cardiovascular pathologies is 1% of all cases of live births. In modern medicine, early diagnosis of anomalies of the cardiovascular system does not cause difficulties, as a result, most children can be saved with the help of medical or surgical treatment. In most cases, congenital heart defects occur in newborn males.
Congenital pathology of the cardiovascular system is usually the result of abnormal development of the heart during pregnancy. The developmental flaws are the result of the impact of a whole range of surrounding and genetic factors. Only in 1% of cases it becomes possible to identify any one immediate cause that led to the onset of pathology. Mutation of genes can cause hereditary forms of the reverse location of all internal organs( mirror image), prolapse of the left atrial-ventricular( mitral) valve, atrial and ventricular septal defect, etc. However, gene mutations cause less than 10% of all congenital heart defects. The birth of a child with congenital heart disease suggests a low risk of having a second child with a similar deviation. This fact, as well as the continuous development of methods for the treatment of congenital heart diseases and their continuously increasing effectiveness, allow us to recommend to parents to positively solve the issue of the birth of a second child. The risk of having a sick child is significantly increased if two or more family members have heart disease. The risk of the birth of a child with a defect in repeated pregnancies can be predicted fairly accurately if it can be established that the inheritance of the blemish is dominant or recessive in accordance with Mendel's law.
Currently, due to the availability of an effective effective rubella vaccine, the risk of congenital heart disease has been significantly reduced. In connection with the possibility of pathological effects on the fetus, none of the medications should not be taken during pregnancy without first consulting a doctor.