[4] Symptoms may include difficulty breathing (dyspnea) and bluish discoloration on skin, fingernails, and lips (cyanosis).

[5] 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.

Consequently, arterial blood supplies become less oxygenated than normal, causing ischemia and cyanosis in distal tissues.

[3] To compensate, the heart must pump a larger volume of blood to deliver enough oxygen, leading to cardiac enlargement and hypertrophy.

[3] Like other congenital heart defects, major associations have been found between AVCD and genes regulating embryonic cell cilia.

[10] These human cell cilia normally contain receptors for signal molecules that regulate the healthy and organized tissue.

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.

Certain complications such as tetralogy of Fallot or highly unbalanced flow across the common AV valve can increase risk significantly.

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.