Defect of interventricular septum
Jun 12, 2018
Defect of the interventricular septum is one of the most common congenital heart defects. It was first described by P. Tolochinov in 1874 and Roger in 1879.
There are two main variants of the defect of the interatrial septum: in the membranous and muscular part. The size of the defect can vary from 1 to 30 mm, the defect can have a different shape( round, ellipsoidal).Depending on the size, two variants of the defect are distinguished: large - its size is comparable with the diameter of the aorta, and small or medium size - less than the diameter of the aorta.
The defect of the interventricular septum causes a change in normal blood flow. In the prenatal period, this defect does not affect blood circulation. After birth, the direction of blood flow is determined by the size of the defect and the ratio of pressure in the right and left ventricles. In the first days of life, the discharge of blood can be cross, that is, it occurs from right to left( from the right ventricle to the left), and vice versa. However, the structure of the pulmonary vessels changes soon, pulmonary resistance decreases, as a result of which the pressure in the great circle of the circulation much exceeds that in the small one. Arterial blood from the left ventricle is discharged into the right ventricle, then into the pulmonary artery, from where it returns to the left heart. In response to the discharge of blood into the pulmonary artery, in 25-50% of children with such a heart disease there is an increase in pressure in it( pulmonary hypertension), which passes through three phases.
Hypervolaemic phase. This phase is the result of discrepancy in the volume of the vascular bed of the small circle of blood circulation to the volume of blood flowing through it. This phase occurs in children in the first months of life. In this case, the vessels of the lungs are full of blood, but there is no protective reflex in the form of spasm, which explains the serious course of the disease in this period of time. The pressure in the pulmonary artery can be normal or moderately elevated.
Mixed phase. In this phase, there is a spasm of pulmonary vessels in response to a blood overflow( protective reflex), which leads to an increase in pulmonary artery pressure. In addition, pulmonary resistance increases, which helps to reduce the discharge of blood from the left ventricle to the right.
Sclerotic phase. In this phase irreversible sclerotic changes occur in the vessels of the lungs. The reason for such changes are a prolonged spasm of blood vessels and their blood overflow.
It is believed that this phase may occur immediately after birth as a consequence of delayed fetal development( anomaly) of the lung vessels retaining the intrauterine structure.
The time of appearance of the first signs of a defect is determined by the magnitude of the discharge of blood from left to right, which depends on the difference in pressure between the right and left ventricles. As a rule, the disease manifests itself not immediately after birth, but after 1-2 months. Parents pay attention to difficulties in feeding: dyspnea appears, the child pauses, inhales, as a result of which remains hungry, becomes restless. Children with a defect of the interventricular septum are born more often with normal body weight, but soon begin to lag behind in mass and growth. The causes of malnutrition are constant malnutrition and circulatory disorders. Characteristic manifestations are pronounced sweating, pallor, marbling of the skin with a slight cyanotic skin of the fingertips, the tip of the nose and ears.
One of the leading symptoms of the disease is shortness of breath with increased respiration and the involvement of ancillary musculature. At the same time, during breathing, the child's nose wings swell, ribs rise high. Often there is an obsessive cough, which is worse when the position of the body changes. An interventricular septal defect with a large discharge of blood from left to right can be accompanied by repeated, difficult to treat pneumonia, which does not allow timely surgery to repair the defect.
Upon careful examination of such a child, an early developing heart hump attracts attention, which is a prominent outward protrusion of the chest in the sternum. Sometimes such protrusion( hump) reaches considerable dimensions( Davis' breast).It is formed as a result of blood overflow of the right heart, which, with its contraction, "pushes" outward the bones of the chest, and they are still soft and easily deformed in a small child. If you put your palm on the heart, you can feel the trembling that occurs when the heart is contracted. Such tremor is called systolic. It occurs when swirling blood passing from the left ventricle to the right through a small hole of the defect. This tremor is localized to the right of the sternum in the region of attachment to it of the III-IV ribs, which indicates the discharge of blood into the right ventricle. The absence of jitter in the defect of the interventricular septum is a sign of a reduced discharge due to increased pressure in the pulmonary artery. The boundaries of the heart, which only the doctor can determine, turn out to be extended in both directions, but especially to the left.
The doctor receives great information on this defect when listening to the work of the heart with a phonendoscope. This method of investigation is designated as auscultation. Thus the doctor can hear characteristic noises which arise at wrong movement of a blood through an aperture in an interventricular septum. In addition, with different heart defects, the noise differs in its characteristics and place of best listening. In case of an interventricular septal defect, the noise is best heard in III-IV intercostal space on the left, ie, the place of the best audibility corresponds to the projection of the defect on the front wall of the chest of the child.
In most cases, from the first days or months of life, the child has signs of total heart failure. These signs include: an increase in the size of the liver and spleen, shortness of breath, palpitations, the appearance of edema, stagnant moist wheezing in the lungs. Chryps are especially long on the left side of the back.
The manifestations described above are most typical for medium and large defects of the membranous part of the interventricular septum in young children. At an older age, the main manifestations of the defect persist, but children begin to complain of pain in the heart, palpitations and still lag behind in physical development. The condition and well-being of many children improve with age, which is associated with a decrease in the size of the defect in relation to the increased total volume of the heart. Insufficiency of blood circulation( heart failure) in older age is less common than in newborns and children of the first years of life.
If there is a defect in the muscular part of the interventricular septum( Tolochinov-Roger disease), there are no manifestations of malformation. A defect is revealed only when listening to the work of the heart, when the doctor determines the characteristic noise. If this part of the interventricular septum is defective, there is a tendency to spontaneously close it.
When the child is examined, ECG, FKG( fixes heart sounds), ultrasound of the heart. At a roentgenography of organs of a thorax at children with the small sizes of defect of an interventricular septum of deviations or rejections it is not revealed. With a significant discharge of blood from left to right, the physician determines the intensification of the pulmonary pattern, which is the result of overflow of the blood vessels of the lungs with an excess of blood. The shape of the heart also changes.
Introduction of a catheter in the heart cavity and filling the vessels with a contrast agent followed by X-ray examination is performed for children with a defect of the interventricular septum if they develop heart failure and( or) signs of increased pulmonary artery pressure( pulmonary hypertension).If the catheter can be guided into the aorta by probing the right divisions, then the diagnosis of the defect becomes indisputable, as it penetrates into the vessel through a defect in the interventricular septum.
The following variants of outcome of an interventricular septal defect in children can be identified.
1. Spontaneous closure of a defect, that occurs in 45% of cases. Small defects are closed, as a rule, to 5-6 years.
2. Development of the Eisenmenger syndrome .This syndrome has long been described as an independent congenital heart disease in the form of an interventricular septal defect with the opposite location of the aorta( right) and increased pressure in the pulmonary artery. Currently, Eisenmenger syndrome is considered as a complication of an interventricular septal defect with the development of a sclerotic, irreversible phase of pulmonary hypertension. As a result of high pressure in the right ventricle, a discharge of blood from the right to the left occurs. Since the right parts of the heart contain "spent" blood, it begins to flow into the large circle of blood circulation. The child has a pathological staining of the skin of the cheeks, lips, fingertips, at first a crimson shade( a sign of a moderate lack of oxygen in the blood), then a cyanotic and violet. Gradually, the fingers become a kind of "drumsticks", and the nails are a kind of "watch glass".At the same time, the fingers are thin, and the tips are enlarged, the nails are flattened. There may be nasal bleeding, palpitations, pain in the heart. The picture of noises in the heart also changes. At the same time, the heart decreases in size, as does the liver. Often children cease to suffer from pneumonia. Such dynamics( reduction of noise, signs of heart failure, heart borders, crimson cheeks) introduces pediatricians and parents into deception: all this is regarded as an improvement in the condition. In reality, the child becomes inoperable, that is, it becomes impossible to perform a surgical correction of the defect due to the development of a large number of complications.
3. Transition of the defect of the interventricular septum into the "pale form" of the tetralogy of Fallot .In connection with the vortex of blood flow, when it is discharged through a defect in the interventricular septum, a narrowing( stenosis) of the pulmonary artery occurs, resulting in the formation of the "acquired" form of the tetralogy of Fallot. This changes all manifestations of the defect. Children cease to suffer from pneumonia, cyanosis of the skin appears( at first only when crying, then at rest), the size of the heart and signs of heart failure decrease, and a second noise joins. On the roentgenogram, the heart changes its configuration. There are changes on the ECG.
The average life expectancy without treatment is 23-27 years.
The greatest lethality with significant defects occurs in early childhood: more than 50% of children die before the age of one, of which 30% - up to 6 months. In this critical age, the child needs close attention and intensive treatment. In surviving children, there is often an improvement in the condition. In the case of a defect with no serious circulatory disturbances, without signs of heart failure and increased pulmonary artery pressure, and with normal physical development, one can refrain from surgical intervention at an early age. Indications for surgical correction in children of the first years of life are the early development of pulmonary hypertension, the development of heart failure, repeated pneumonia, a pronounced body mass deficit. At present, early and radical intervention in the form of a defect plastic in the conditions of artificial circulation is performed here in our country and abroad. Children who have been operated before the age of 2 years have better results than older children. In severe condition and the impossibility of radical correction of the blemish, an operation is performed to artificially narrow the lumen of the pulmonary artery( artificial stenosis).After 2-3 years, such children need a second stage of surgical treatment.