Coarctation of the Aorta (CoA): An area of localized narrowing of the large artery called the aorta.

Balloon Atrial Septostomy: A procedure used to stabilize a patient suffering from TGA by trans-catheter method. This helps a patient to withstand the more invasive procedure needed for total correction. A catheter is threaded through the groin to the heart. Through this catheter, a special device that resembles a balloon is passed into the heart. The wall between the right and left atrium is punctured and the catheter device pushed through the small hole created. The balloon is then inflated, and the catheter is pulled back through the small hole, tearing it and making it larger. The purpose is to create a large enough opening between the two atria, so that blood can freely mix across it, and improve oxygen supply.

Congestive Heart Failure (CHF): Congestive heart failure is a problem in which the heart does not pump as well as it should. Fluid backs up in the lungs or the legs because the flow of blood is slowed down.

Pulmonary Stenosis (PS): A narrowing of the pulmonary valve that guards the opening to the pulmonary artery, causing a strain on the right ventricle with harmful effects.

Right Ventricular Hypertrophy (RV Hypertrophy): A thickening of the wall of the right ventricle. This causes blood to be pumped more forcibly.

Tetralogy of Fallot (ToF): A complex congenital heart defect with four major defects. They include Ventricular Septal Defect, Pulmonary Stenosis, Right Ventricular Hypertrophy, and an over-riding aorta. An over-riding aorta arises partly from the right ventricle, rather than the normal position of the left ventricle. The other defects are explained on this page.

Transposition of the Great Arteries (TGA): The aorta and the pulmonary arteries arise from the "wrong" ventricles. They are "transposed", resulting in a mixing of pure and impure blood with harmful effects.

Ventricular Septal Defect (VSD): A "hole" in the wall between the two lower chambers of the heart - the ventricles. This hole may be small, medium-sized or large, and may be single or multiple. It may occur in different parts of the wall, and may sometimes be found along with other heart defects. In Bryn’s case, the hole was large.