children s health issues
Overview of Heart Defects
Types of Heart Defects
The ways that heart defects cause changes in the normal blood flow to the lungs and body are Shunting the flow of blood (blood flows through openings that are not part of the normal circulation) Re-routing the flow of blood (blood flows through vessels that are arranged differently from the normal circulation) Blocking the flow of blood, as occurs when a heart valve or blood vessel is defective Shunting is usually classified as Right-to-left Left-to-right involves mixing of the oxygen-poor blood from the right side of the heart with the oxygen-rich blood in the left side of the heart that is pumped to the body tissues. The more oxygen-poor blood (which is blue) that flows to the body, the bluer the body appears, particularly the lips, tongue, skin, and nail beds. Many heart defects are characterized by a bluish discoloration of the skin (called cyanosis). Cyanosis indicates that not enough oxygen-rich blood is reaching the tissues where it is needed. Many different types of birth defects of the heart can cause right-to-left shunting and thus cyanosis, but one of the most common is Tetralogy of Fallot . involves oxygen-rich blood, which is pumped under high pressures from the left side of the heart, mixing with oxygen-poor blood being pumped from the right side of the heart through the pulmonary artery to the lungs. Left-to-right shunting makes the circulation inefficient and increases the amount of blood flowing to the lungs, which sometimes also causes high pressure in the pulmonary artery. Over time, high flow and high pressure can damage the blood vessels of the lungs and overwork both the left and right sides of the heart, causing the heart muscle to become weak and not function (heart failure—see figure Heart Failure: Pumping and Filling Problems ). Examples of disorders in which left-to-right shunting occurs are In Transposition of the Great Arteries , the normal connections of the aorta and the pulmonary artery to the heart are reversed. The aorta, which supplies the body, connects to the right ventricle instead of the left ventricle, and the pulmonary artery, which supplies the lungs, connects to the left ventricle instead of the right ventricle. As a result, oxygen-poor blood is circulated to the body, and oxygen-rich blood is circulated between the lungs and the heart and not the rest of the body. The body does not get enough oxygen, and severe cyanosis occurs within minutes of birth. Blockages may develop in the valves of the heart or in the blood vessels leading away from the heart. Blood may be impeded from flowing To the lungs because of narrowing of the pulmonic valve ( Pulmonary Valve Stenosis in Children ) or narrowing within the pulmonary artery itself (pulmonary artery stenosis) Through the aorta to the body because of narrowing of the aortic valve ( Aortic Valve Stenosis in Children ) or blockage within the aorta itself ( Into the heart because of narrowing of the tricuspid valve (on the right side of the heart) or the mitral valve (on the left side of the heart) Blockage of blood flow can lead to heart failure. Heart failure does not mean that the heart has stopped beating and is not the same as a heart attack. Heart failure means that the heart is unable to pump blood normally. As a result, blood from the left side of the heart may back up into the lungs and blood from the right side may back up into the body causing enlargement of the liver or swelling of the legs. Heart failure can also develop when the heart pumps too weakly (for example, when a baby is born with a weak heart muscle). 