What is TOF?
TOF is referred to as “Tetralogy of fallot “in medical parlance. It is a congenital heart defect that is present from birth. It is a combination of four anatomical or structural abnormalities.
TOF is a condition where in the blood is poorly oxygenated or there not enough oxygen present in the blood. Narrowing or thinning of the right ventricular tract, excessive growth of heart muscle is the major causes of heart dysfunction.
In TOF patients, the abnormal features prevent enough oxygen from following to the lungs as it should. As a result, a person with TOF has a lower than normal amount of oxygen in the blood. It is called blue baby syndrome. It is a combination of four related heart defects that commonly occur together.
Ventricular septal defect (VSD) :
This abnormality occurs when the muscle wall demarcating the heart into the left side and the right side does not form fully, which is basically a structural abnormality. The right portion of the heart pumps blood to the lungs to receive oxygen from them while breathing, the left side supplies the oxygenated blood to all the other parts of the body which is a vital function, VSD may allow the oxygenated blood to leak into the impure blood or the blood that is devoid of oxygen. A small VSD may not require surgery, but VSD’s or larger holes may require surgeries and long-term monitoring until the child reaches adult hood.
Signs & Symptoms :
Usually, children minor structural defects may not exhibit symptoms, but if the VSD is of a measurable size then the child may experience shortness of breath, irregular heart rhythm, getting tired easily, poor diet intake and constant fatigue.
How to detect VSD :
The basic symptom to detect VSD is irregular heart beat which can be detected by a normal stethoscope. Electrocardiogram (ECG), Pulse oximetry, cardiac catheterization, 2D or 3D echo are tests which are commonly recommended to detect the same.
Line of treatment procedures adopted :
First Line of treatment usually includes administering diuretics like Lasix, furosemide to curtail fluid accumulation in the lungs and few drugs to keep the blood circulation normal in the heart. Secondary treatment usually includes surgery aided procedures such as open heart surgery, catheter procedures or a combination of both surgery and catheterization which varies from case to case, as deemed fit by our experienced doctors at KIMS followed by a course of antibiotics to prevent infections.
Pulmonary stenosis :
Pulmonary stenosis is a structural anomaly which usually occurs when the pulmonary valve is deformed or ill-formed which disturbs the circulation of blood from the heart to the lungs and vice-versa. Usually, surgery is not the recommended option, but in severe cases surgery can be opted for when major conditions such as rheumatic fever or characinoid syndrome come out as additional complications which may cause injuries to the valves of the heart to the already pre-existing condition.
An overriding aorta :
The aorta which is located between the left and right ventricles, directly over the VSD or a hole may let the oxygen-poor blood or deoxygenated blood from the right ventricle to flow directly into the aorta instead of into the pulmonary artery which may cause further complications which are usually reversible in most cases.
Right ventricular hypertrophy :
Hardening of the muscular walls of the right ventricle, which occurs because the right ventricle is pumping at high pressure, is termed as right ventricular hypertrophy.
The pulmonary stenosis and right ventricular outflow tract obstruction seen with TOF usually limits blood flow to the lungs. When the blood flow to the lungs has subdued the combination of the ventricular septal defect and overriding aorta allows oxygen less blood that is often called as blue blood returning to the right atrium and right ventricle to be pumped out of the aorta to the body resulting in abnormalities such as discolouration.
Signs and Symptoms risk factors of TOF :
The first or basic symptom is Cyanosis. Cyanosis detected by the blue colour of the skin and mucous membranes due to lower than normal or permissible levels of oxygen in the blood. The extent of cyanosis is dependent on the amount of narrowing or trimming of the pulmonary valve and right ventricular outflow tract.
Tetralogy of fallot is most often diagnosed in the first few weeks of life due to either a loud murmur or cyanosis. Children with tetralogy of fallot usually have a patent ductus arteriosus at the time of birth that provides additional blood flow to the lungs, so severe cyanosis is almost rare early after birth.
Parents who have a child with a TOF or any another congenital defect have a somewhat greater chance of having a second child with a heart defect. A few babies will have signs of cardiac pressure accompanied by signs such as becoming tired for no reason, no proper feed.
Most commonly the baby may have few symptoms at first. But as time progresses the cyanosis increases, eventually the cyanosis becoming so severe that it interferes with normal growth development and activities. Usually, parents can notice these symptoms after giving the baby a bath or after a feed the body becomes blue.
Rapid breathing in response to low oxygen levels and reduced pulmonary blood flow can occur.
Children having a tetralogy spell will initially become extremely irritable in response to the critically low oxygen levels in the bloodstream, and may become sleepy or unresponsive if severe cyanosis persists.
A tetralogy spell can sometimes be treated by comforting the infant and flexing the knees forward and upward, however, immediate medical attention is necessary.
Causes and risk factors :
The exact cause of tetralogy of fallot among babies has not been arrived at. Some babies have heart defects on account of any changes in their genes or chromosomes. The combination of genes and other risk factors, such as any radioactive material the mother or foetus come in contact or any food items which the mother partakes during the course of her pregnancy are attributed as few causes.
Diagnosis procedures for TOF :
A diagnosis of TOF is usually made by echocardiogram (cardiac ultrasound). Other tests may be used to provide any additional information.
When a newborn with significant cyanosis is first seen he or she is often placed in supplemental oxygen. The increased oxygen improves the child’s oxygen levels in case of lung disease, but breathing extra oxygen will have little effect on the oxygen levels of a child with tetralogy of fallot which needs further attention.
Cardiologists monitor baby’s heart and lungs rhythm, feel the baby’s pulses, measure the oxygen level in the blood and make other observations that help to determine the Condition.
An echocardiogram evaluates the structure and function of the child’s heart using electronically recorded sound waves that produce a moving picture of the heart and heart valves. It may last for 30 to 60 minutes, usually under sedation. An ultrasound can also detect TOF prenatally.
EKG is used to evaluate the electrical activity of your child’s heart. An EKG is the initial or basic test for evaluating the causes of symptoms and detecting heart abnormalities. It is performed by placing electrodes on the arms, legs and chest to record the electrical activity. The test usually takes 5 minutes or even less. No pain and discomfort are felt during the course of the test.
Cardiac magnetic resonance imaging :
A cardiac MRI is a non-invasive test using 3D imaging technology to accurately determine the shape size, and function of your child’s heart. No pain is involved. It takes about an hour. Children under 10 years usually need anaesthesia
Chest X-ray :
A conventional chest X-ray will evaluate the size and spatial relationships of the heart within the child’s chest.
Cardiac catheterization :
This procedure is usually performed under sedation or anaesthesia and provides detailed information about the structural anomalies inside the heart. Blood pressure and oxygen levels are monitored in the four chambers of the heart, as well as pulmonary artery and aorta.
Treatment of TOF:
Once tetralogy of fallot is diagnosed the immediate focus is on determining whether the child’s oxygen levels are in a safe range. If oxygen levels are critically low soon after birth a prostaglandin infusion is usually initiated to keep the ductus arteriosus open which will provide additional pulmonary blood flow and increase the child’s oxygen level. These infants will usually require surgical intervention during the neonatal period. Infants with normal oxygen levels or only mild cyanosis are usually able to go home in the first week of life.
Complete repair initiation is usually done electively when children are about 6 months of age, as long as the oxygen levels remain adequate.
Commonly TOF is treated with surgery.
Babies with TOF must have open heart surgery for repair. Surgery is usually performed in the first 3to 6 months of life, or it can be performed earlier if needed. This surgery consists of closing the VSD usually using Dacron cloth to reduce the narrowing between the right ventricle and pulmonary artery.
Catheterization: Few babies may require catheterization to obtain information not available from echocardiography. A baby may benefit from interventional catheterization to widen the connection between the right ventricle and the pulmonary artery. This procedure can serve as a temporary way to increase the oxygen level in the blood to a certain extent.
The goal of the operation is to address the defect some patients develop from leakage of the pulmonary valve that requires replacement. This usually occurs in adolescence or adulthood
Adults who were treated for congenital heart disease as a child will need to be monitored by a cardiologist to avoid complications from TOF as they may be at some risk for arrhythmias, leaky valves and other heart problems.
After surgery :
The right ventricle is stiff from the previous hypertrophy. An incision is made into the muscle of the ventricle, making the muscle temporarily weaker, hence it takes time for the child to recover
Long term follows up with a cardiologist to detect recurrent or new problems as early as possible is essential. Follow-up visits in the cardiology clinic usually consist of physical examination, electrocardiogram and periodic evaluation and personalised monitoring through various tests such as MRI, ECG.
Most patients with repaired tetralogy should be regularly evaluated by a congenital heart expert. Pulmonary regurgitation can be treated with a tissue valve replacement, which is usually a low-risk procedure that can allow the heart to shrink again and improve the patient’s quality of life and life expectancy factors. These artificial pulmonary valves usually last many years in adult patients but require expert surveillance which KIMS provides. Fortunately, if these valves now fail they can be replaced using valves inserted through catheters rather than a re-operation.
Some adults with tetralogy have a genetic basis for the underlying condition. It is important that this be identified so that other manifestations of their genetic abnormality can be managed properly.
Hospitalization and caring :
After the operation, the baby is taken to the cardiac intensive care unit, where the baby’s vital signs and other factors are very closely monitored by our expert KIMS care team. Constant monitoring is done to ensure speedy recovery and early discharge with follow-up visits.
Survival rate of TOF :
Survival of children with tetralogy of fallot has improved dramatically over recent decades. Usually, the survival rate is 95% to 98% without any other underlying complications.
Team KIMS Vs TOF :
Our team in KIMS, understands how distressing a diagnosis of tetralogy of fallot can be for parents of lovely little blooming kids. We ensure the best possible care is given and each child as we know and understand a child is unique, precious and irreplaceable. We assure the blooming bud does not whither half-way on account of TOF, it continues to grow and blossom. TOF is a reversible condition which in cent percent cases and we aim at that.