What is tetralogy of Fallot?
Tetralogy of Fallot
Tetralogy of Fallot is a rare, complex congenital (present at birth) heart defect. Named after the physician who first described this condition in 1888, tetralogy of Fallot is the name for a cluster of four heart defects:
A large ventricular septal defect: The ventricles are the heart’s two lower chambers, and the septum is the wall that separates the left and right chambers. A ventricular septal defect is a hole in the septum that allows oxygen-rich blood to flow from the left ventricle back into the right ventricle and mix with the oxygen-poor blood there, instead of flowing to the aorta and out to the rest of the body.
Alternatively, oxygen-poor blood can flow across the defect at times (right to left), bypassing the lungs and leading to cyanosis (low oxygen levels in the systemic circulation).
Pulmonary stenosis: Blood normally flows from the right ventricle through a valve or flap into the pulmonary artery in the lungs where it gets loaded with oxygen. Pulmonary stenosis is a narrowing of the valve between the right ventricle and the pulmonary artery, or the muscle growth immediately below the valve (subpulmonic stenosis). Often, the narrowing not only involves the valve, but also the muscle directly below it. The constriction of the passageway causes the heart to pump harder to push the blood through and reduces the amount of blood flowing through the valve.
Right ventricular hypertrophy: The extra pumping required by the pulmonary stenosis causes the right ventricle to thicken (hypertrophy).
Overriding aorta: The aorta is the main artery that carries oxygen-rich blood from the heart to the rest of the body. Normally the aorta is connected to the left ventricle, and oxygenated blood flows out of the ventricle into the aorta. In tetralogy of Fallot, the aorta is positioned between the left and right ventricles, above the ventricular septal defect. This location allows the aorta to receive blood from both sides of the heart, so that oxygen-poor blood from the right ventricle mixes with oxygenated blood from the left ventricle.
How common is tetralogy of Fallot and what causes it?
Tetralogy of Fallot is relatively rare, occurring in about 5 of every 10,000 births. Although this heart defect has been recognized for 120 years, the exact cause is still unknown. The defect occurs during the heart’s development before birth. About 15 percent of people with tetralogy of Fallot have a specific genetic abnormality that is also linked with other birth defects such as cleft palate.
How is tetralogy of Fallot diagnosed?
This complex set of defects means that the body is in an oxygen crisis. Not enough blood can flow to the pulmonary artery to pick up oxygen, and blood flowing through the aorta to the body is oxygen-poor.
In most cases, the defect is severe enough at birth that lack of oxygen causes a bluish tint (cyanosis) to develop in a baby’s skin, lips and fingernails. Cyanosis usually gets progressively worse over the first few weeks of life, and tetralogy of Fallot usually is diagnosed quite early, although it can go undiagnosed for a few months or even up to several years.
What are the treatment options for tetralogy of Fallot?
There is no medical treatment for tetralogy of Fallot. The structural abnormalities in the heart require surgical correction. In most cases, infants undergo the operation within the first year of life.
The first step in children may be palliative surgery to correct the blood flow to the lungs without directly repairing the structural defects. Palliative surgery usually involves some type of shunt to increase blood flow to the lungs. These techniques can relieve symptoms for a number of years, well into adulthood until more definitive repair surgery can be performed.
What type of ongoing care is necessary for an adult who has had surgical repair of tetralogy of Fallot?
Specialists in adult congenital heart disease recommend that an adult who has had palliative surgery for tetralogy of Fallot as a child periodically undergo a thorough cardiac evaluation. The shunts used in the palliation are associated with problems such as narrowing (stenosis), high blood pressure in the pulmonary artery or causing excess volume load on the left side of the heart. Definitive surgery often results in significant leaking of the pulmonary valve and the size and function of the right side of the heart needs to be monitored closely.
Some patients may also develop large aortopulmonary collateral vessels as a way of getting extra blood flow to the lungs. These need to be closed prior to definitive surgical repair.
The presence of any of these problems or worsening of symptoms, such as cyanosis or fatigue, are reasons for an adult to undergo a complete repair surgery.
Occasionally, an individual reaches adulthood without having had any surgical repair, although this is not common. Specialists recommend that these individuals consider undergoing a complete surgical repair to prevent future complications or sudden death.
How is tetralogy of Fallot surgically repaired in an adult?
Surgical repair for tetralogy of Fallot is complex, delicate and highly technical, and should be performed by a surgeon who specializes in adult congenital heart disease. The operation will involve a combination of techniques to fix all four defects.
To perform a complete repair, the surgeon closes the ventricular septal defect with a patch. The passageway out of the right ventricle is opened, and the pulmonary valve is repaired or replaced. The pulmonary arteries to both lungs are enlarged, and sometimes a tube is placed between the right ventricle and the pulmonary artery to improve blood flow.
How successful is the surgery in adults?
When performed by an experienced congenital heart disease surgeon, surgical repair of the defect in adults has a very high success rate. In one long-term study, the 36-year survival rate for adults who underwent surgical repair for tetralogy of Fallot was 86 percent.
Are there any potential problems or complications associated with the surgery?
Although the surgical treatment of tetralogy of Fallot is very effective in correcting the structural defects and blood flow through the heart, it can cause some ongoing abnormalities in the heart’s function. If these problems develop, they can be treated with additional surgery. Many adults who undergo repair for tetralogy of Fallot do not need further surgical treatment. In a study reported by the Canadian Adult Congenital Heart Network, 10 to 15 percent of people required a reoperation over a 20-year period.
The potential complications associated with surgical repair for tetralogy of Fallot include:
- Electrical disturbances: Putting a patch on the ventricular septal defect can block the ability of the atria to transmit electrical signals to the ventricles. This can be corrected by a pacemaker.
- Rhythm disturbances (arrhythmias): Atrial fibrillation – when the heart’s upper chambers contract irregularly and often too quickly - is a common complication following heart surgery. This can be treated with medication or a non-surgical procedure. A rarer but more serious arrhythmia is ventricular tachycardia. This is a life-threatening, overly-rapid heartbeat in the lower heart chambers. The congenital heart disease specialist will determine if an individual is at risk for this postoperatively.
- Leaking valves: Heart valves are designed to allow blood to flow in one direction. When a valve leaks, blood can flow back into the chamber. Patients with tetralogy of Fallot are also at risk for developing aneurysms of the ascending aorta. The most common valve problem after tetralogy of Fallot repair is a leaking pulmonary valve, but the aortic and tricuspid heart valves can leak also. Leaky valves are generally repaired surgically, but newer ways of implanting valves without surgery are currently being explored.
- Residual ventricular septal defect: Sometimes the ventricular septal defect does not seal completely and there is some leaking around the patch. If the leak is large or causes major symptoms, it can be repaired surgically.
- Aneurysm: The patches placed on the ventricle to repair it can cause weak sections of the ventricle to bulge out, forming an aneurysm. There is also an increased risk for developing aneurysms of the ascending aorta. An aneurysm that becomes large requires surgical repair.
What follow up care is needed after surgery?
Adults who have had a tetralogy of Fallot repaired need to have regular cardiac checkups with an adult congenital heart disease specialist. Various tests of cardiac function such as an echocardiogram, a Holter monitor, electrocardiogram or an exercise stress test may be required periodically to ensure that the heart is functioning adequately. People with repaired tetralogy of Fallot typically have some restrictions on certain strenuous activities, such as competitive sports.
Is pregnancy safe for women who have had the defect repaired?
Women who have undergone surgical repair for tetralogy of Fallot and are considering pregnancy should consult an adult congenital heart disease specialist and an obstetrician who specializes in caring for women with special medical conditions. With proper prenatal care and careful monitoring, most women with repaired tetralogy of Fallot are able to carry a pregnancy safely to term. The obstetrician, in consultation with an adult congenital heart disease specialist, can help determine an individual’s risk profile related to pregnancy.
Where can I learn more about tetralogy of Fallot?
For more information or to make an appointment with a Cleveland Clinic congenital heart disease specialist, please call the Heart and Vascular Institute Resource and Information Line at 216.445.9288 or toll-free 866.289.6911.
How to find a doctor if you have adult congenital heart disease
Doctors vary in quality due to differences in training and experience; hospitals differ in the number of services available. The more complex your medical problem, the greater these differences in quality become and the more they matter.
Clearly, the doctor and hospital that you choose for complex, specialized medical care will have a direct impact on how well you do. To help you make this choice, read more about our Sydell and Arnold Miller Family Heart & Vascular Institute outcomes. See: About Us to learn more about the Miller Family Heart & Vascular Institute at Cleveland Clinic.
The Center for Adult Congenital Heart Disease in the Sydell and Arnold Miller Family Heart & Vascular Institute is a specialized center involving a multi-disciplinary group of specialists, including cardiologists, cardiac surgeons and nurses from Cardiovascular Medicine, Pediatric Cardiology, Pediatric and Congenital Heart Surgery, Cardiothoracic Surgery, Diagnostic Radiology, Pulmonary, Allergy and Critical Care Medicine, and Transplantation Center, who provide a comprehensive approach to diagnosing and treating adult congenital heart disease.
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