Defect of the interventricular septum of the heart - Causes, symptoms and treatment. MF.
Interventricular septal defect( VSD) is a congenital heart disease characterized by a defect in the muscular septum between the right and left ventricles of the heart. VSD is the most common congenital heart disease in newborns, its frequency is approximately 30-40% of all cases of congenital heart disease. This vice was first described in 1874 by PF Tolochinov and in 1879 by H. L. Roger.
According to anatomical division of the interventricular septum into 3 parts( upper - membranous, or membranous, middle - muscular, lower - trabecular), give names and defects of interventricular septum. Approximately 85% of cases of VSD are located in the so-called prelocated part of it, that is, right under the right coronary and non-coronary valves of the aortic valve( when viewed from the left ventricle of the heart) and at the site of the transition of the anterior valve of the tricuspid valve to its septum( if viewed fromside of the right ventricle).In 2% of cases, the defect is located in the muscular part of the septum, and several pathological openings are possible. A combination of muscular and other localizations of VSD is rare.
The dimensions of defects of the interventricular septum can be from 1 mm to 3.0 cm and even more. Depending on the size, large defects are distinguished, the size of which is similar or exceeds the diameter of the aorta, the average defects having diameters from ¼ to ½ of the diameter of the aorta, and small defects. Defects of the membranous part, as a rule, have a round or oval shape and reach 3 cm, defects in the muscular part of the interventricular septum are often round and small.
Quite often, approximately 2/3 of cases, VSD can be combined with another concomitant anomaly: atrial septal defect( 20%), open arterial duct( 20%), aortic coarctation( 12%), congenital mitral valve insufficiency( 2%)., stasis of the aorta( 5%) and pulmonary artery.
Schematic representation of an interventricular septal defect.
Causes of VSD
Violations of the formation of the interventricular septum are found to occur during the first three months of pregnancy. The interventricular septum of the fetus is formed from three constituent parts, which during this period should be compared and adequately connected to each other. Violation of this process leads to the fact that there is a defect in the interventricular septum.
Mechanism of development of hemodynamic disorders( blood flow)
The fetus located in the mother's uterus circulates through the so-called placental circle( placental circulation) and has its own peculiarities. However, soon after birth, a normal blood flow is established in the newborn for large and small circles of blood circulation, which is accompanied by the appearance of a significant difference between blood pressure in the left( pressure is higher) and right( pressure is less) ventricles. At the same time, the existing VSW leads to the fact that blood from the left ventricle is injected not only into the aorta( where it should be normal), but also through the DMZHP - into the right ventricle, which should not normally be. Thus, with each cardiac contraction( systole), a pathological discharge of blood from the left ventricle of the heart to the right occurs. This leads to an increase in the load on the right ventricle of the heart, as it produces unnecessary work to pump additional volume of blood back to the lungs and left parts of the heart.
The volume of this abnormal discharge depends on the size and location of the VSD: in the case of a small defect, the latter hardly affects the functioning of the heart. On the opposite side of the defect in the wall of the right ventricle, and in some cases also on the tricuspid valve, a cicatricial thickening can develop, which is a consequence of the reaction to trauma from a pathological ejection of blood flowing through the defect.
In addition, due to pathological discharge, the additional volume of blood entering the vessels of the lungs( a small circle of blood circulation) leads to the formation of pulmonary hypertension( increased blood pressure in the vessels of the small circle of blood circulation).Over time, compensatory mechanisms are included in the body: an increase in the muscle mass of the ventricles of the heart, a gradual adaptation of the lung vessels, which first absorb the incoming excessive volume of blood, and then pathologically change - thickens the arteries and arterioles, which makes them less elastic and denser. Increase in blood pressure in the right ventricle and pulmonary arteries occurs until finally, there is an equalization of pressure in the right and left ventricle in all phases of the cardiac cycle, after which the pathological discharge from the left ventricle of the heart to the right stops. If, over time, the blood pressure in the right ventricle is higher than in the left ventricle, there is a so-called "back discharge", in which venous blood from the right ventricle of the heart through the same VSD enters the left ventricle.
Symptoms of
The timing of the appearance of the first signs of VSD depends on the size of the defect itself, as well as the magnitude and direction of the pathological discharge of blood.
Small defects of in the lower parts of the interventricular septum in the overwhelming majority of cases do not have a significant effect on the development of children. Such children feel satisfactory. Already in the first few days after birth, there appears an average intensity of the heart murmur of a rough, scraping tone that the doctor listens to in systole( during cardiac contraction).This noise is better heard in the fourth to fifth intercostal space and is not carried to other places, its intensity in standing position may decrease. Since this noise is often the only manifestation of a small VSD that does not have a significant impact on the well-being and development of the child, such a situation in the medical literature has received a figurative name "a lot of noise from nothing".
In some cases, in the third to fourth intercostal space, at the left edge of the sternum, you can feel the trembling at the time of cardiac contraction - systolic trembling, or systolic "cat-purring".
With large defects of the membranous segment of the interventricular septum, the symptoms of this congenital heart disease usually appear not immediately after the birth of the child, but in 12 months. Parents begin to notice difficulties in feeding the child: he has shortness of breath, he is forced to take pauses and breaths, because of what can remain hungry, there is anxiety.
Born with a normal mass, such children begin to lag behind in their physical development, which is explained by malnutrition and a decrease in the volume of blood circulating through the large circle of blood( due to a pathological discharge into the right ventricle of the heart).There is a pronounced sweating, pallor, marbling of the skin, a slight cyanosis of the terminal parts of the hands and feet( peripheral cyanosis).
Characteristically rapid breathing with the involvement of an auxiliary respiratory musculature, a paroxysmal cough that occurs when the body position changes. Developing recurring pneumonia( pneumonia), which are difficult to treat. To the left of the sternum there is a deformation of the chest - a heart hump is formed. The apical impulse shifts to the left and down. A systolic jitter is felt in the third-fourth intercostal space near the left edge of the sternum. When auscultation( listening), the heart is determined by severe systolic noise in the third-fourth intercostal space. In children of the older age group, the main clinical signs of the defect persist, they have complaints of soreness in the heart and heart palpitations, children continue to lag behind in their physical development. With age, the well-being and condition of many children improves.
Complications of VSW:
Aortic regurgitation of occurs in patients with VSD about 5% of the time. It develops if the defect is located in such a way that it also causes the sagging of one of the valves of the aortic valve, which leads to a combination of this defect with aortic valve insufficiency, the attachment of which significantly complicates the course of the disease due to a significant increase in the load on the left ventricle of the heart. Among clinical manifestations, pronounced dyspnea prevails, sometimes acute left ventricular failure develops. With auscultation of the heart, not only the above-described systolic murmur is heard, but also the diastolic( in the phase of cardiac relaxation) noise at the left edge of the sternum.
Infundibular stenosis of is observed in patients with VSD also in about 5% of cases. It develops if the defect is located in the back of the interventricular septum under the so-called septum tricuspid valve( tricuspid) valve below the supraventricular ridge, which causes the passage of a large amount of blood through the defect and traumatization of the supraventricular ridge, which consequently increases in size and cicatrices. As a consequence, narrowing of the infundibular part of the right ventricle and formation of subvalvular stenosis of the pulmonary artery occur. This leads to a decrease in pathological discharge through the VSW from the left ventricle of the heart to the right and unloading of the small circle of blood circulation, but there is also a sharp increase in the load on the right ventricle. Blood pressure in the right ventricle begins to increase significantly, which gradually leads to a pathological discharge of blood from the right ventricle into the left ventricle. With pronounced infundibular stenosis, the patient develops cyanosis( cyanosis of the skin).
Infectious( bacterial) endocarditis - affection of the endocardium( inner shell of the heart) and heart valves caused by infection( most often bacterial).In patients with VSD, the risk of developing infectious endocarditis is approximately 0.2% per year. It usually occurs in children of the older age group and adults;more often with small dimensions of the VSD, which is caused by trauma to the endocardium at a high velocity jet of pathological blood discharge. Endocarditis can be provoked by dental procedures, purulent skin lesions. Inflammation first arises in the wall of the right ventricle, located on the opposite side of the defect or around the edges of the defect itself, and then the aortic and tricuspid valves spread.
Pulmonary hypertension - increased blood pressure in the vessels of the small circle of blood circulation. In the case of this congenital heart disease, it develops as a result of the entry into the vessels of the lungs of an additional volume of blood caused by a pathological discharge through the VSW from the left ventricle of the heart to the right. Over time, pulmonary hypertension worsens due to the development of compensatory mechanisms - the formation of a thickening of the walls of the arteries and arterioles.
Eisenmenger syndrome is a subordinal location of the interventricular septal defect in combination with sclerotic changes in the pulmonary vessels, expansion of the pulmonary artery and the increase in muscle mass and size( hypertrophy) of the predominantly right ventricle of the heart.
Repeated pneumonia - is caused by stagnation of blood in a small circle of circulation.
Heart rate disturbances.
Heart failure.
Thromboembolism - Acute clotting of a blood vessel by a blood clot that detached from the place of its formation on the wall of the heart and got into the circulating blood.
Instrumental diagnosis of VSD
1. Electrocardiography( ECG): In the case of small dimensions of VSD, significant changes in the electrocardiogram may not be detected. As a rule, the normal position of the electrical axis of the heart is characteristic, but in some cases it can deviate to the left or to the right. If the defect is large, this is more significant in electrocardiography. At the expressed pathological discharge of blood through the defect from the left ventricle of the heart to the right without pulmonary hypertension on the electrocardiogram signs of an overload and increase in the muscular mass of the left ventricle are revealed. In the case of the development of significant pulmonary hypertension, there are symptoms of congestion of the right ventricle of the heart and the right atrium. Heart rhythm disturbances are infrequent, as a rule, in adult patients in the form of extrasystole, atrial fibrillation.
2. The phonocardiography of ( recording of vibrations and sound signals emitted during the activity of the heart and blood vessels) allows the instrumental recording of pathological noises and altered heart tones due to the presence of VSD.
3. Echocardiography ( ultrasound examination of the heart) allows not only to detect a direct symptom of a congenital defect - echo break in the interventricular septum, but also to accurately determine the location, number and size of defects, and to determine the presence of indirect signs of this defect( enlargement of the ventricles of the heartand left atrium, an increase in the thickness of the wall of the right ventricle, and others).Doppler echocardiography reveals another direct symptom of the defect - a pathological flow of blood through the VSW in systole. In addition, it is possible to assess the blood pressure in the pulmonary artery, the magnitude and direction of the pathological discharge of blood.
4. Radiography of chest organs ( hearts and lungs).At small sizes of VSD, pathological changes are not detected. If the size of the defect is significant, with a marked discharge of blood from the left ventricle of the heart to the right, an increase in the size of the left ventricle and the left atrium, and then of the right ventricle, and an increase in the vascular pattern of the lungs are determined. As the development of pulmonary hypertension is determined by the expansion of the roots of the lungs and swelling of the pulmonary artery.
5. Cardiac catheterization is performed to measure pressure in the pulmonary artery and in the right ventricle, as well as determine the level of oxygen saturation of the blood. Characterized by a higher degree of oxygen saturation of the blood( oxygenation) in the right ventricle than in the right atrium.
6. Angiocardiography - the introduction of a contrast agent in the heart cavity through special catheters. When contrast is introduced into the right ventricle or pulmonary artery, a second contrast is observed, which is explained by the return to the right ventricle of contrast with abnormal discharge of blood from the left ventricle through the VSW after passing through a small circle of blood circulation. When water-soluble contrast is introduced into the left ventricle, the contrast from the left ventricle of the heart to the right through the DMZHP is determined.
Treatment of VSD
With small dimensions of VSD, absence of signs of pulmonary hypertension and heart failure, normal physical development in the hope of spontaneous closure of the defect, it is possible to refrain from performing a surgical intervention.
In children of early preschool age, the indication for surgery is the early progression of pulmonary hypertension, persistent heart failure, recurring pneumonia, severe physical retardation and weight loss.
Indications for surgical treatment in adults and children aged 3 years are: fatigue, frequent ARI, leading to the development of pneumonia, heart failure and a typical clinical picture of the disease with a pathological discharge of more than 40%.
The surgical intervention is reduced to the plastic of the DMF.The operation is performed using the apparatus of artificial circulation. With a defect diameter of up to 5 mm, it is closed by suturing with U-shaped seams. With a defect diameter of more than 5 mm, it is closed with a patch made of synthetic or specially processed biological material, which is covered for a short time with its own tissues.
In those cases when an open radical operation is not immediately possible because of the high risk of performing an operative intervention with artificial circulation in children of the first months of life with large sizes of VSD, insufficient weight, with unapparable correction of severe heart failure, surgical treatment is performed in twostage. First, the pulmonary artery is superimposed above its valves of a special cuff, which increases the resistance to ejection from the right ventricle, thereby leading to equalization of blood pressure in the right and left ventricles of the heart, thereby reducing the volume of pathological discharge through the VSW.A few months later, the second stage is carried out: the removal of the previously placed cuff from the pulmonary artery and the closure of the DMF.
Prognosis for VSW
The duration and quality of life in the defect of the interventricular septum are depending on the size of the defect, the state of the vessels of the small circle of blood circulation, the severity of developing heart failure.
Defects of the interventricular septum of small sizes do not significantly affect the life expectancy of patients, however, up to 1-2% increase the risk of infectious endocarditis. If the small defect is located in the muscular part of the interventricular septum, it can self-close up to the age of 4 years in 30-50% of such patients.
In case of an average defect size, heart failure develops already in early childhood. Over time, an improvement in the condition is possible, due to a certain decrease in the size of the defect, and in 14% of such patients self-closure of the defect is observed. At an older age, pulmonary hypertension develops.
In the case of a large size of the VSW, the prognosis is serious. Such children already at an early age develops severe heart failure, often there are and repeated pneumonia. Approximately 10-15% of these patients are formed Eisenmenger syndrome. Most patients with large ventricular septal defects without surgery are killed already in childhood or adolescence from progressive heart failure more often in combination with pneumonia or infective endocarditis, pulmonary artery thrombosis or rupture of its aneurysm, paradoxical embolism in the vessels of the brain.
The average life expectancy of patients without surgery in the natural course of VSD( without treatment) is approximately 23-27 years, and in patients with small defect sizes - up to 60 years.
Doctor surgeon Kletkin ME