Врожденный порок сердца: Дефект атриовентрикулярного септа (AVSD)

Atrioventricular septal defect (AVSD) or atrioventricular canal defect (AVCD), also known as "common atrioventricular canal" or "endocardial cushion defect" (ECD), is characterized by a deficiency of the atrioventricular septum of the heart that creates connections between all four of its chambers. It is a very specific combination of 3 defects:

1) Atrial Septal Defect (ASD), a hole in the wall between the right and left atria;

2) Ventricular Septal Defect (VSD), a hole in the wall between the right and left ventricles; and

3) Abnormalities of the mitral and/or tricuspid valves. AVCD is caused by an abnormal or inadequate fusion of the superior and inferior endocardial cushions with the mid portion of the atrial septum and the muscular portion of the ventricular septum. Unlike some heart defects, the condition will not resolve over time and most infants must undergo open heart surgery. The surgery to correct this defect is usually successful and most babies do very well post op. An infant will begin to show signs of congestive heart failure, which can include rapid breathing, feeding problems, slow weight gain, low energy, and cold, clammy sweating. Symptoms often appear between 1 2 months of age but can occur earlier in some newborns.

Down syndrome is often associated with AVCD. Other risk factors include: having a parent with a congenital heart defect, alcohol use while pregnant, uncontrolled diabetes treatment during pregnancy and some medications during pregnancy. 45% of children with Down syndrome have congenital heart disease. Of these, 35–40% have AV septal defects. Approximately 40 50% of fetuses diagnosed with AVCD have Down syndrome, and a further 15 20% are associated with other chromosomal abnormalities and syndromes, such as DiGeorge syndrome. The remaining 30 40% of cases are not linked to a syndrome, with AVCD observed without other major defects. AVCD is also linked with Noonan syndrome.

Defective embryonic formation of the heart results in multiple holes between the heart chambers. In AVSD, all four chambers are connected, but the exact characteristics of holes and malformations may vary between patients. Even within the categories of "complete" and "partial" AVSD, multiple morphologies exist, with varying clinical consequences. Clinical and physiological manifestations of disease may also change over time, in response to continued stress.

AVSDs can be detected by cardiac auscultation; they cause atypical murmurs and loud heart tones. Confirmation of findings from cardiac auscultation can be obtained with a cardiac ultrasound (echocardiography less invasive) and cardiac catheterization (more invasive). It is also possible to diagnose AVSD in utero via routine fetal ultrasounds or, more conclusively, fetal echocardiograms. Infants born with AVSD are generally in sufficient health to not require immediate corrective surgery. If surgery is not required immediately after birth, the newborn will be closely monitored for the next several months, and the operation held off until the first signs of lung distress or heart failure. This gives the infant time to grow, increasing the size of, and thereby the ease of operation on, the heart, as well as the ease of recovery. Infants will generally require surgery within three to six months, however, they may be able to go up to two years before the operation becomes necessary, depending on the severity of the defect.