Babies with congestive heart failure breathe fast and hard, often sweat and / or tire out while feeding, and grow slowly or sometimes even lose weight. These symptoms usually develop gradually over the first one to two months of life.
The doctor will usually hear a heart murmur when this type of defect is present. The murmur is caused by the blood passing from the left ventricle to the right ventricle and out the pulmonary artery.
A small number of infants with a complete atrioventricular septal defect will not develop congestive heart failure. This occurs because in some cases, the muscle cells that line the small arteries to the lungs get bigger and constrict to try to protect the lungs from the extra flow and high pressure caused by the atrioventricular septal defect.
Called increased pulmonary vascular resistance (PVR), or pulmonary vascular disease, this condition is more common in infants with Down syndrome.
The increase in pulmonary vascular resistance is very effective in preventing the signs and symptoms of congestive heart failure by minimizing the amount of left-to-right shunt, and may even cause blood with low oxygen to go from the right ventricle to the left ventricle and out to the body without picking up oxygen.
This causes cyanosis, which is a bluish discoloration of the skin, fingernails and mouth and it may also cause the murmur to be softer.
While infants with a complete atrioventricular septal defect and elevated pulmonary vascular resistance often grow better and appear healthier than those with low pulmonary vascular resistance and congestive heart failure, the occurrence of increased pulmonary vascular resistance may prompt early surgical correction of the defect.
Repair of the atrioventricular septal defect lowers the pressure in the pulmonary artery and allows these muscles to relax before they become permanently constricted.
Infants with the partial or transitional forms of atrioventricular septal defects have more subtle signs and symptoms. Like children with a complete atrioventricular septal defect, they have an increased volume of blood passing through the pulmonary artery.
The main difference between a left-to-right shunt that occurs primarily between the atria rather than the ventricles is that the pressure in the pulmonary artery usually remains low despite the increase in flow.
This causes less work for the heart and lungs and results in fewer breathing and growth problems. It also lessens the possibility that the pulmonary vascular resistance will increase.
Nevertheless, there is an increased workload on the heart and growth may occur more slowly than infants and children with normal hearts. There is usually a heart murmur present, but it is softer than that which occurs with a complete atrioventricular septal defect.
These types of defects may not come to medical attention until the child is several months or even years old because of the subtlety of the signs and symptoms that may be associated with them.
Significant congestive heart failure, growth failure or a very loud murmur in a child with a partial atrioventricular septal defect can occur when the defect in the mitral valve leaflet causes this valve to be very leaky.