The normal heart
The heart has four chambers. The right side (blue) receives oxygen-poor blood from the body and pumps it to the lungs through the pulmonary artery. The left side (red) receives oxygen-rich blood from the lungs and pumps it to the whole body through the aorta. Four valves keep blood flowing in one direction, and walls (septa) separate the two sides.
Atrial septal defect (ASD)
What is it? An opening in the wall between the two upper chambers, allowing blood to pass from left to right and overloading the right side of the heart.
Signs: Usually no symptoms; found because of a murmur or on echocardiography. A large hole may cause fatigue and arrhythmias in adulthood.
Treatment: Small holes sometimes close on their own. A significant "secundum" ASD is usually closed by catheter with a device at preschool age; other types require surgery.
Ventricular septal defect (VSD)
What is it? The most common heart defect: an opening in the wall between the ventricles, through which high-pressure blood passes from the left ventricle to the right and into the lungs.
Signs: Small hole – a murmur only. Large hole – fast breathing, sweating and tiring during feeds, and slow weight gain.
Treatment: Most small holes close on their own. Large ones are treated with medication and usually surgery in the first months; in selected cases – catheter closure.
Patent ductus arteriosus (PDA)
What is it? A vessel that connects the aorta and pulmonary artery before birth and normally closes in the first days of life. If it stays open, extra blood flows to the lungs. Common in premature babies.
Signs: Small PDA – no symptoms. Large PDA – breathing and feeding difficulties and slow weight gain.
Treatment: In premature babies – sometimes medication. In children, and premature babies who did not respond – catheter closure with a plug or coil; rarely surgery.
Atrioventricular septal defect (AVSD)
What is it? A large hole in the center of the heart involving the wall between the atria, the wall between the ventricles and the valves – instead of two valves there is one common valve. Common in children with Down syndrome.
Signs: Fast breathing, feeding difficulties, sweating and slow weight gain in the first weeks of life.
Treatment: Medication for heart failure followed by corrective surgery, usually at 3–6 months. Lifelong follow-up of valve function is needed.
Pulmonary valve stenosis
What is it? The valve between the right ventricle and the pulmonary artery is narrow and does not open well, so the right ventricle must work harder to pump blood to the lungs.
Signs: Mild stenosis – a murmur only. Severe stenosis in a baby – cyanosis (bluish color) and breathing difficulties.
Treatment: Mild stenosis – follow-up only. Significant stenosis is treated by balloon valvuloplasty in the cath lab, the treatment of choice, which usually solves the problem.
Coarctation of the aorta
What is it? A narrowing of the aorta, usually just after the branches to the head and arms. The left heart works harder, and less blood reaches the lower body.
Signs: In babies – breathing and feeding difficulties, sometimes an emergency. In older children – high blood pressure in the arms and weak pulses in the legs.
Treatment: Newborns and infants – surgery. Older children and adults, or re-narrowing – balloon dilation and stenting by catheter.
Tetralogy of Fallot
What is it? The most common cyanotic heart defect, made up of four parts: a large VSD, narrowing of the outflow to the pulmonary artery, an aorta that "overrides" the hole, and a thickened right ventricle. Oxygen-poor blood reaches the body.
Signs: Varying cyanosis, a murmur, and sometimes "tet spells" during crying or exertion.
Treatment: Corrective surgery, usually at 3–6 months. Later in life the pulmonary valve tends to leak, and many patients need it replaced – today often by transcatheter pulmonary valve implantation.
Transposition of the great arteries (TGA)
What is it? The aorta arises from the right ventricle and the pulmonary artery from the left ventricle, so oxygen-poor blood returns to the body and oxygen-rich blood returns to the lungs – two separate circuits.
Signs: Marked cyanosis within hours of birth. Often diagnosed on fetal echocardiography.
Treatment: Prostaglandin to keep the ductus open and sometimes an urgent balloon atrial septostomy (Rashkind). In the first weeks – the arterial switch operation.
Hypoplastic left heart syndrome (HLHS)
What is it? The left ventricle, left-sided valves and aorta are very small and cannot pump blood to the body. In the first days, blood flow to the body depends on the open ductus.
Signs: Usually detected on fetal echocardiography. After birth – cyanosis, fast breathing, and an emergency when the ductus closes.
Treatment: A series of staged operations (Norwood or a hybrid approach, Glenn and Fontan), after which the right ventricle supports the body. Diagnostic and interventional catheterizations are a regular part of the journey.
