Tetralogy of Fallot is a combination of four heart defects that result in oxygen-poor blood flowing out of the heart and into the body. This can cause cyanosis — the medical term for turning blue because of deficient oxygen in the blood.
The four defects that characterize this condition include:
To understand tetralogy of Fallot, it helps to understand the healthy heart and how it functions. The heart consists of four chambers: the two upper chambers, called atria, where blood enters the heart, and the two lower chambers, called ventricles, where blood is pumped out of the heart. The flow between the chambers is controlled by a set of valves that act as one-way doors.
Normally blood is pumped from the right side of the heart through the pulmonary valve and the pulmonary artery to the lungs, where the blood is filled with oxygen. From the lungs, the blood travels back down to the left atrium and left ventricle. The newly oxygenated blood then is pumped through another big blood vessel, called the aorta, to the rest of the body.
Babies with tetralogy of Fallot are blue at birth or soon after, and have detectable heart murmurs, an extra sound in the heartbeat. Activity such as crying may exacerbate the condition and babies may be short of breath or faint. Babies may also experience a "tet spell" in which oxygen levels drop suddenly, leading to irritability and then sleepiness or unresponsiveness. Giving oxygen to a baby with tetralogy of Fallot usually doesn't improve blood oxygen levels.
A complete evaluation for tetralogy of Fallot will include:
Placing the baby in the "fetal position" — on the stomach with the knees bent — may control a tetrology spell. Newborns may be given a drug called prostaglandin to keep the ductus arteriosus, a part of the fetal circulation system that normally closes after birth, open to improve blood flow. The defects usually are corrected during a single operation performed when the baby is about six months old, unless the baby has inadequate oxygen. If the baby is too small, there may be two surgical procedures.
The first procedure connects the pulmonary arteries to the aorta or its branches by a tube called a shunt to supply blood to the lungs. Later surgery enlarges the pulmonary valve opening and closes the ventricular septal defect with a patch so that blood flows easily into the pulmonary artery and lungs. The shunt is then removed.
Reviewed by health care specialists at UCSF Children's Hospital.
Last updated
November 6, 2009
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