Open arterial( botall) duct
The arterial duct is a vessel that connects the aorta and the pulmonary trunk in the intrauterine period.
Open of the bottles is a vessel that has retained its function after the expiration of its closure. Open-water bottles are more common in preterm infants - in 3-37% of cases, although in the future they are often spontaneously closed.
The open arterial duct has within a few months of life 50% of children born with a body weight of less than 1700 g. 20% remain uncovered for 1-2 years. The duct in newborns with a syndrome of acute respiratory disorders is practically not closed, which considerably increases the burden of the underlying disease and sometimes causes urgent surgical intervention. The duct can be long, narrow and tortuous or short and wide. Its diameter is 10-15 mm. Often there are accompanying abnormalities of the development of the gastrointestinal tract, genitourinary system, etc.
During fetal development, the majority of the blood from the fetus from the right ventricle enters through the arterial duct to the aorta. After birth with the first inhalation, pulmonary resistance drops, and at the same time, the pressure in the aorta rises, which promotes the appearance of a reverse discharge of blood( from the aorta into the pulmonary artery).High blood saturation with oxygen after the inclusion of pulmonary respiration causes a spasm of the duct. Noise when listening to the activity of the heart disappears within 15-20 hours after the birth of the child( functional closure).The final obliteration( infection) and the transformation of the duct into a ligament occur between 2 and 10 weeks of life. Arterial duct is considered an anomaly, if according to clinical data it functions after 1-2 weeks after birth. Closure of the duct begins at the point of its departure from the pulmonary artery, where there are many muscle cells. Perhaps the failure of the arterial duct is associated with deficiency or underdevelopment of muscle cells or elastic fibers in its wall. Increased oxygen saturation of the blood is the main stimulus for contraction of muscle cells.
When the arterial duct is open, the oxygen-enriched blood is discharged from the aorta into the pulmonary artery. The discharge of blood from the aorta occurs both during systole and during diastole, since in both these phases the pressure in the aorta exceeds that in the pulmonary artery.
The severity of the defect is determined by the following moments:
1) duct size;
2) the angle of its withdrawal( it is more favorable if it departs from the aorta at an acute angle, worse - if under blunt, as this contributes to a greater discharge of blood);
3) the value of resistance in the vessels of the lungs.
With a large duct, a significant amount of blood enters the pulmonary artery, then into the left heart, causing them to be overloaded with an increased volume of blood. In addition, the pressure in the aorta is transmitted directly through the duct to the pulmonary artery, which causes early development of pulmonary hypertension. Disorders of blood flow in the open arterial duct cause the enlargement of the predominantly left heart, but with the development of pulmonary hypertension, especially in its sclerotic stage( see above), the expansion of the right ventricle predominates.
An open arterial duct is more common in girls than in boys. The sex ratio is 2: 1 -3: 1. Family cases of vice are described. When it is combined with cataracts and a decrease in the size of the brain, the child has congenital rubella syndrome. The course of the disease can be different: from asymptomatic to extremely severe forms. Pay attention to such factors as rubella, borne by the mother during pregnancy, prematurity of the child, repeated pneumonia. Often the first year of life develops a deficiency of body weight, which is typical for children with severe heart failure. An extremely serious condition is typical for premature babies. Children born before the age of 30 weeks have a marked discharge of blood from the aorta into the pulmonary artery. Botallov duct they do not shrink and long remains large.
Children with an open arterial duct are lagging behind in development. Complain of rapid fatigue, shortness of breath with a slight load. Usually they are inactive. More adults can complain about palpitations, irregularities in the heart. Often there are pneumonia. In children with an open arterial duct, attention is drawn to the development of the heart hump. Exceptions are cases with a small size of the duct. When you feel the area of the heart is determined by a rough jitter. By the end of the first week of life there is a characteristic noise when listening to a phonendoscope. For the open arterial duct, a high, rapid pulse is characteristic. In this case, a slightly increased systolic( "upper") and low diastolic( "lower"), up to 30-40 mm Hg, is determined. Art.(up to zero), pressure. Sign of a large discharge of blood from the aorta into the pulmonary artery through the duct is a heart failure, which manifests a rapid heartbeat and breathing, an increase in the size of the liver and spleen.
One of the possible complications with the open arterial duct is bacterial endocarditis( bacterial damage of the inner shell of the heart), which occurs in 2% of cases, more often with a small duct. Another complication may be the development of an aneurysm( saccular protrusion of the wall) of the duct and its rupture. In some cases this is combined with bacterial endocarditis.
The diagnosis of the open arterial duct is established on the basis of the examination:
1) the borders of the heart are widened, a rough systolic-diastolic noise characteristic for this disease is heard at auscultation, the so-called "engine" noise;
2) on the electrocardiogram there are no changes that cause an open arterial duct to be suspected;
3) echocardiography reveals the presence of a characteristic blood flow in a typical place between the aorta and the pulmonary artery in the direction from the aorta to the pulmonary artery;
4) on lung X-rays, judge the degree of changes in lung tissue.
Additional methods of examining the child are: FGK( graphic recording of heart sounds), chest radiograph, ultrasound of the heart. In doubtful cases, the heart is probed.
In cases of severe flow of the open arterial duct, cardiac glycosides( digoxin) and diuretics are used. In premature infants, oxygen deficiency contributes to non-closure of the duct, which can be due to anemia. This condition requires urgent treatment. The total amount of fluid administered to such children should not exceed 70-100 ml per kg of body weight per day. To maintain the hemoglobin content at a normal level, blood transfusion is performed. Oxygen therapy also helps maintain the optimal oxygen level in the blood of the newborn to close the duct.
In 75% of prematurees, the duct closes spontaneously in the first 4-5 months of life and later. The possibility of such an outcome for the term after the 3rd month of life does not exceed 10%.The average life expectancy with the open arterial duct is 39 ± 4 years, and only a small number of people survive to 50-60 years. Consequently, an open arterial duct, even of small size, leads to premature death.
Indications for surgical treatment of the defect at an early age are circulatory insufficiency, which can not be treated with medications, body weight deficiency, and progression of pulmonary hypertension( increased pulmonary artery pressure).In preterm infants with an open arterial duct and respiratory disorders, urgent surgical intervention is performed with a stable heart failure.
Children who have an open arterial duct accompanied by pulmonary hypertension deserve special attention. Uncertainty of the method of treatment in such cases is associated with high lethality during the operation, as well as in the postoperative period. Mortality in these children is 25%.With bacterial endocarditis, surgical correction is performed, since without it complete recovery from endocarditis is impossible. Before the operation, a course of drug treatment is conducted.
The operation consists in ligation of the open arterial duct. The long-term results of surgical correction of the defect are good, the lethality after surgery is minimal.