Atrioventricular Septal Defect

Definition

Definition of Atrioventricular Septal Defect
Atrioventricular septal defect (AVSD) or atrioventricular canal defect (AVCD), previously known as "common atrioventricular canal" (CAVC) or "endocardial cushion defect", is characterized by a deficiency of the atrioventricular septum of the heart. It 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.

Symptoms

Symptoms of Atrioventricular Septal Defect
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 1-2 months of life.

The doctor will usually hear a loud 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.

Causes

Causes of Atrioventricular Septal Defect
Consult with your doctor.

Diagnosis

Diagnosis of Atrioventricular Septal Defect
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).

Tentative diagnosis can also be made in utero via fetal echocardiogram. An AVSD diagnosis made before birth is a marker for Down syndrome, although other signs and further testing are required before any definitive confirmation of either can be made.

Treatment

Treatment of Atrioventricular Septal Defect
Treatment is surgical and involves closure of the atrial and ventricular septal defects and restoration of a competent left AV valve as far as is possible. Open surgical procedures require a heart-lung machine and are done with a median sternotomy. Surgical mortality for uncomplicated ostium primum defects in experienced centers is 2%; for uncomplicated cases of complete atrioventricular canal, 4% or less. Certain complications such as tetralogy of Fallot or highly unbalanced flow across the common AV valve can increase risk significantly.

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.

Prognosis

Prognosis of Atrioventricular Septal Defect
Consult with your doctor.

Prevention

Prevention of Atrioventricular Septal Defect
Consult with your doctor.