The Heart House
To simplify how blood flows through a normal, healthy heart, think of the heart as a house with:
- 4 Rooms (Chambers)
- 4 Doors (Valves)
- 4 Big Hallways (Vessels)
- 4 Small Hallways (Vessels)
Now that we are thinking of the heart as a house, we will explore what can go wrong with the house. A child could be born with several defects (abnormalities) involving the various parts of the heart house.
Congenital Heart Disease
Problems with the Walls
- Atrial Septal Defect (ASD). The wall between the right atrium and left atrium is called Atrial Septum. Please note that the word “septum” in Greek means “wall.” A hole between the two atriums called an Atrial Septal Defect (ASD). When the blood coming back from the lungs to the Left Atrium crosses the ASD it mixes with the blue blood coming back from the body in the Right Atrium. Doctors fix an Atrial Septal Defect (ASD) by patching the hole between the two atriums.
- Ventricular Wall Defect (VSD). The wall between the front two chambers (between the two ventricles) is called Ventricular Septum. A hole between the two ventricles is called a Ventricular Septal Defect (VSD). When the pink blood in the Left Ventricle crosses the VSD it mixes with the blue blood in the Right Ventricle. Doctors fix a Ventricular Septal Defect (VSD) by patching the hole between the two ventricles.
- Coarctation of the Aorta. If this hallway is narrowed as it makes the bend to go down to the body it is called Coarctation of the Aorta
- Pulmonary Artery Problems.
- Branch Pulmonary Artery Stenosis
- Transposition of Great Arteries. Prostaglandin, Atrial Septostomy, or Switch Operation. If the pulmonary artery is narrowed as it branches to either the right or left lung this condition is called Branch Pulmonary Artery Stenosis. When these two main hallways leading away from the heart are swapped or transposed, it is called Transposition of Great Arteries.
Problems Involving More Than One Part of the Heart
- Tetralogy of Fallot. This involves a hole between the ventricles, a narrow pulmonary hallway, an overriding aortic hallway, and enlargement and thickening of the right ventricular wall.
- Truncus Arteriosus. Part of the wall between the front large heart chamber is missing. An overriding aorta, which means the door from the left ventricle (aortic valve) originates from both front chambers.
- Common Atrioventricular Canal. This defect involves a hole between the two atriums called an Atrial Septal Defect (ASD) and a hole between the two ventricles called a Ventricular Septal Defect (VSD). There is a common opening between all the chambers of the heart. As a result, the wall that was separating the Mitral Valve and the Tricuspid Valve which usually looks like a cross is missing. Treatment can include Pulmonary Artery Band (Temporary Fix) or Operation to Fix Defect ( Permanent Fix)
- Ductus Arteriosus. Ductus Arteriosus is a passageway that normally is present in every baby before birth. It is a communication between the two major arteries coming out of the heart. The Ductus usually closes within the first few days after birth. Patent Ductus Arteriosus is a condition that exists when the Ductus does not close. Since the pressure in the Aorta is much higher than in the Pulmonary Artery lots of blood will be going to the Pulmonary Artery and it will be larger and the lungs will be getting much more blood than they really need. Treatment can include Clip Operation
Problems with the Chambers
- Hypoplastic Right Ventricle. If the right ventricle is small and weak, this condition is called Hypoplastic Right Heart or Hypoplastic Right Ventricle. It happened because the tricuspid valve guiding the blood from the right atrium to the right ventricle did not open in the very early embryonic weeks of the baby’s life, and so no blood came through to make the right ventricle grow.
- Hypoplastic Left Heart Syndrome. If the left ventricle is small and weak, this condition is called Hypoplastic Left Ventricle or Hypoplastic Left Heart Syndrome. It happened because the mitral valve guiding the blood from the left atrium to the left ventricle did not open in the very early embryonic weeks of the baby’s life, and so no blood came through to make the left ventricle grow.
Problems with the Plumbing
- Anomalous Origin of the Coronary Artery from the Pulmonary Artery. This defect happens when the main coronary artery originates from the Pulmonary Artery instead of the Aorta. The pulmonary artery carries less oxygen in its blood, so now the muscle of the heart which is working very hard instead of getting fresh oxygenated blood it is getting blood with less oxygen. The muscle of the heart does not like that and starts to become weaker and weaker, the muscle walls of the heart becomes thinner and thinner, and this predisposes to a condition called Cardiomyopathy
Problems with the Doors
- Tricuspid Valve. The Tricuspid Valve is located between the right atrium and right ventricle. If this door is not developed this condition is called Atresia (Tricuspid Valve Atresia). There is a 3-step procedure to fix this defect:
- Stage 1: Shunt Operation
- Stage 2: Glenn Operation
- Stage 3: Fontan Operation
- Since the door did not develop in the baby before birth there was no blood coming from the right atrium to the right ventricle so the right ventricle became underdeveloped (hypoplastic right ventricle). If the tricuspid door is displaced downward from it’s usual location, this will result in the right atrium becoming excessively large and the right ventricle small and underdeveloped. This condition is called Ebstein Anomaly.
- Mitral Valve. The mitral valve is the door between the left atrium and the left ventricle. If the mitral valve does not develop during the very early gestation weeks, the blood in the left atrium will not flow to the left ventricle, and therefore the left ventricle will be small and underdeveloped (Hypoplastic Left Heart Syndrome). There is a 3-step procedure to fix this defect:
- Stage 1: Norwood Operation
- Stage 2: Glenn Operation
- Stage 3: Fontan Operation
- Pulmonic Valve. The pulmonic valve is the door located between the right ventricle and the main pulmonary artery. If this door is a little bit small (depending on how small it is) we call this condition stenosis (Pulmonic Valve Stenosis). If it does not develop at all we call this condition atresia (Pulmonic Valve Atresia).
- Aortic Valve. The aortic valve is the door located between the left ventricle and the aorta. If the valve is small this condition is called stenosis (Aortic Valve Stenosis). If this valve does not develop at all this condition is called atresia (Aortic Valve Atresia).