NCLEX Tetralogy Of Fallot

NCLEX Tetralogy Of Fallot

Tetralogy of Fallot (TOF) is a congenital heart defect which is classically understood to involve four anatomical abnormalities of the heart (although only three of them are always present). It is the most common cyanotic heart defect and the most common cause of blue baby syndrome.  TOF is usually a right-to-left shunt, in which higher resistance to right ventricular outflow results in more severe cyanosis symptoms.

These defects, which affect the structure of the heart, cause oxygen-poor blood to flow out of the heart and to the rest of the body. Infants and children with tetralogy of Fallot usually have blue-tinged skin because their blood doesn’t carry enough oxygen.

With early diagnosis followed by appropriate surgical treatment, most children who have tetralogy of Fallot live relatively normal lives, though they’ll need regular medical care and might have restrictions on exercise.

Signs and Symptoms

Tetralogy of Fallot symptoms vary, depending on the extent of obstruction of blood flow out of the right ventricle and into the lungs. Signs and symptoms may include:

• A bluish coloration of the skin caused by blood low in oxygen (cyanosis)
• Shortness of breath and rapid breathing, especially during feeding or exercise
• Loss of consciousness (fainting)
• Clubbing of fingers and toes — an abnormal, rounded shape of the nail bed
• Poor weight gain
• Tiring easily during play or exercise
• Irritability
• Prolonged crying
• A heart murmur

Tet spells

Sometimes, babies who have tetralogy of Fallot will suddenly develop deep blue skin, nails and lips after crying or feeding, or when agitated.  These episodes are called tet spells and are caused by a rapid drop in the amount of oxygen in the blood. Tet spells are most common in young infants, around 2 to 4 months old. Toddlers or older children might instinctively squat when they’re short of breath. Squatting increases blood flow to the lungs.

Causes

Tetralogy of Fallot occurs during fetal growth, when the baby’s heart is developing. While factors such as poor maternal nutrition, viral illness or genetic disorders might increase the risk of this condition, in most cases the cause of tetralogy of Fallot is unknown.

The four abnormalities that make up the tetralogy of Fallot include:

• Pulmonary valve stenosis. Pulmonary valve stenosis is a narrowing of the pulmonary valve — the valve that separates the lower right chamber of the heart (right ventricle) from the main blood vessel leading to the lungs (pulmonary artery).Narrowing (constriction) of the pulmonary valve reduces blood flow to the lungs. The narrowing might also affect the muscle beneath the pulmonary valve.
• Ventricular septal defect. A ventricular septal defect is a hole in the wall that separates the two lower chambers of the heart — the left and right ventricle. The hole allows deoxygenated blood in the right ventricle — blood that has circulated through the body and is returning to the lungs to replenish its oxygen supply — to flow into the left ventricle and mix with oxygenated blood fresh from the lungs. Blood from the left ventricle also flows back to the right ventricle in an inefficient manner. This ability for blood to flow through the ventricular septal defect reduces the supply of oxygenated blood to the body and eventually can weaken the heart.
• Overriding aorta. Normally the aorta — the main artery leading out to the body — branches off the left ventricle. In tetralogy of Fallot, the aorta is shifted slightly to the right and lies directly above the ventricular septal defect. In this position the aorta receives blood from both the right and left ventricles, mixing the oxygen-poor blood from the right ventricle with the oxygen-rich blood from the left ventricle.
• Right ventricular hypertrophy. When the heart’s pumping action is overworked, it causes the muscular wall of the right ventricle to thicken. Over time this might cause the heart to stiffen, become weak and eventually fail.

Some babies who have tetralogy of Fallot may have other heart defects, such as a hole between their heart’s upper chambers (atrial septal defect).

Risk Factors

While the exact cause of tetralogy of Fallot is unknown, various factors might increase the risk of a baby being born with this condition. These risk factors include:

• A viral illness during pregnancy, such as rubella (German measles)
• Alcoholism during pregnancy
• Poor nutrition during pregnancy
• A mother older than age 40
• A parent who has tetralogy of Fallot
• The presence of Down syndrome or DiGeorge syndrome

Diagnosis

Tests may include:

• Echocardiography – Echocardiograms use high-pitched sound waves to produce an image of the heart. Sound waves bounce off your baby’s heart and produce moving images that can be viewed on a video screen. This test is generally used to diagnose tetralogy of Fallot. It allows your baby’s doctor to determine if there is a ventricular septal defect and where it’s located, if the structure of the pulmonary valve and pulmonary artery is normal, if the right ventricle is functioning properly, and if the aorta is positioned properly. This test can also help your baby’s doctors to plan treatment for your baby’s condition.
• Electrocardiogram – An electrocardiogram records the electrical activity in the heart each time it contracts. During this procedure, patches with wires (electrodes) are placed on your baby’s chest, wrists and ankles. The electrodes measure electrical activity, which is recorded on paper.This test helps determine if your baby’s right ventricle is enlarged (right ventricular hypertrophy), if your baby’s right atrium is enlarged and if the heart rhythm is regular.
• Chest X-ray – A chest X-ray can show the structure of your baby’s heart and lungs. A common sign of tetralogy of Fallot on an X-ray is a “boot-shaped” heart, because the right ventricle is enlarged.
• Oxygen level measurement (pulse oximetry) – This test uses a small sensor that can be placed on a finger or toe to measure the amount of oxygen in your baby’s blood.
• Cardiac catheterization – Doctors may use this test to evaluate the structure of the heart and plan surgical treatment. During this procedure, your baby’s doctor inserts a thin, flexible tube (catheter) into an artery or vein in your baby’s arm, groin or neck and threads it up to his or her heart. Your baby’s doctor injects a dye through the catheter to make your baby’s heart structures visible on X-ray pictures. Cardiac catheterization also measures pressure and oxygen levels in the chambers of the heart and in the blood vessels.

Treatments

Surgery is the only effective treatment for tetralogy of Fallot. Surgical options include intracardiac repair or a temporary procedure that uses a shunt. However, most babies and older children have intracardiac repair.