The heart is separated into four chambers. Deoxygenated blood enters into the right chambers of the heart and continues through the<unk> <unk> es to be oxygenated in the lungs. Oxygenated blood returns into the left side of the heart and out to the rest of the body, known as the systemic circulation. In congenital heart defects such as ventricular septal defects (VSD) and Atrioventricular septal defects (AVSD), there may be one or multiple holes in the walls separating adjacent chambers. This causes left-to-right shunting of blood as oxygenated blood can flow back to the right side of the heart, resulting in a mixture of oxygenated and deoxygenated blood. Increased amounts of blood on the right side of the heart cause an excess of blood flow into the lungs<unk>  circulation) and increased<unk>  resistance due to the buildup of pressure.
Pulmonary artery banding
Arterial switch operation
Blalock–Taussig shunt
Atrial septostomy
Atriocaval shunt
Percutaneous pulmonary valve implantation
Aortic valvuloplasty
Aortopexy