AV Canal Repair - Nicholas Mark on Tuesday Jan.4th.

AV Canal repair is also known as atrioventricular canal defects or endocardial cushion defects, they account for about 5 percent of all congenital heart disease, and are most common in infants with Down syndrome. (About 15 percent to 20 percent of newborns with Down syndrome have an atrioventricular septal defects).

The primary defect is the failure of formation of the part of the heart that arises from an embryonic structure called the endocardial cushions. The endocardial cushions are responsible for separating the central parts of the heart near the tricuspid and mitral valves (AV valves), which separate the atria from the ventricles.

The structures that develop from the endocardial cushions include the lower part of the atrial septum (wall that divides the right atrium from the left atrium) and the ventricular septum (wall that divides the right ventricle from the left ventricle) just below the tricuspid and mitral valves.

The endocardial cushions also complete the separation of the mitral and tricuspid valves by dividing the single valve between the embryonic atria and ventricles. An atrioventricular septal defect may involve failure of formation of any or all of these structures.

Problems With AVSD

The specific type of defect strongly influences the symptoms that may develop and the timing and details of surgical repair.

A complete atrioventricular septal defect allows oxygenated blood that has returned from the lungs to the left atrium and ventricle to cross either the atrial or ventricular septum and go back out the pulmonary artery to the lungs.

This re-circulation of blood to the lungs, called a left-to-right shunt, is inefficient because the left ventricle must pump a volume of already oxygenated blood back to the lungs while trying to meet the body's usual demand for its own oxygenated blood.

The amount of extra blood pumped by the left ventricle is often an additional 2-3 times that required of a left ventricle in an anatomically normal heart.

Because there is a large hole in the ventricular septum, the high pressure normally generated by the left ventricle to propel blood throughout the body is also transmitted to the lungs. Under normal circumstances, the lungs have a blood pressure much lower than that in the rest of the body.

The presence of a large left-to-right shunt and the associated increased workload on the left ventricle and high pulmonary artery pressure cause the lungs to become engorged with blood, and causes fluid to leak from the bloodstream into the air spaces of the lungs.

This condition is called pulmonary edema and makes it harder for a baby with this condition to move his or her lungs and breathe comfortably. The combination of increased heart and lung work uses large amounts of calories and results in the constellation of symptoms referred to as congestive heart failure (CHF).

Repair of the atrioventricular septal defect lowers the pressure in the pulmonary artery and allows these muscles to relax before they become permanently constricted.

Treatment for AVSD

Symptomatic infants with atrioventricular septal defects may improve with medicine, but in all cases corrective heart surgery will be necessary.

Medicines commonly used to treat congestive heart failure from left-to-right shunts in infants include diuretics such as lasix (furosimide), angiotensin converting enzyme (ACE) inhibitors such as captopril, and digoxin.

These type of defects will never close on their own and will always require corrective surgery for treatment.

Medical treatment of infants with atrioventricular septal defects is usually used to relieve symptoms and allow the baby to get big enough to undergo surgical repair with lower risks.

This usually occurs at 3-6 months for infants with a complete atrioventricular septal defect and 6-18 months for infants with a partial atrioventricular septal defect.

Atrioventricular Septal Sefects Treatment Outcomes

The usual recovery period following repair of a partial atrioventricular septal defect is relatively brief. Most patients are out of the Intensive Care Unit (ICU) in 1-2 days and home in 4-5 days following surgery.

Reported surgical survival is greater than 97 percent but is probably close to 100 percent in the current era.

If you would like to read more click: AV Canal

Nicholas Mark's surgery is schedule for Tuesday January 4th first thing in the morning. Your prayers are appreciated. You know we love ya, Don