Diagnostic Medical Sonography News May 2019

What is Tetralogy Fallot? The heart is a very complex organ, especially when it comes to congenital heart defects, which are abnormalities that a person can be born with. Heart defects can range from minor to major complications and can continue into adulthood if the defects have no signs or symptoms, such as tetralogy of Fallot (TOF.) Tetralogy of Fallot is a rare cluster of four congenital heart defects: ventricular septal defect, pulmonary stenosis, ventricular hypertrophy and an overriding aorta, all of which affect the normal blood flow of the heart. About five out of 10,000 babies are born with this heart defect. According to Dr. Gosta Pettersson, from Cleveland Clinic, there has been a handful of adults with tetralogy of Fallot who have not been previously diagnosed or were not fully diagnosed during infancy. Untreated TOF can lead to disability, irreversible cardiac damage or death in early adulthood. Some of the symptoms in children and adults are shortness of breath, cyanosis, fainting, fast heart rate and deformity of the nails. In a normal heart, the right ventricle pumps out oxygen-poor blood, and the left ventricle pumps out oxygen-rich blood, with a septum in between to keep the blood separated. In TOF, this is not true. Instead, there is a hole in the septum between the ventricles called a ventricular septal defect. This causes the deoxygenated and oxygenated blood to mix, reducing the supply of oxygen to the body. This mixture of blood causes the heart to work harder because of back flow and the larger blood volume in the right ventricle, which leads to the next defect: ventricular hypertrophy. Ventricular hypertrophy is when the heart is overworked from higher blood volume, causing the muscular walls in the right main chamber to thicken. The ventricle muscle thickens because the cells in that area increase in size, losing elasticity. The heart can become weak, stiffen and fail if this is not fixed over time. Not only is this fatal, but the higher blood volume from the mixture of deoxygenated and oxygenated blood will be pumped into the lungs. This volume overload can cause high blood pressure in the pulmonary valve, leading to narrowing, or even destroying the pulmonary valve and artery. This is called pulmonary stenosis. Pulmonary stenosis is the narrowing of the pulmonary valve, reducing blood flow to the lungs. A normal pulmonary valve has three thin leaflets and will open with ease when blood is pushed through. In pulmonary stenosis, the leaflets are thickened and fused together, making them less flexible. This obstruction, along with the higher blood volume, contributes to the right ventricle becoming thicker because of the back flow and vice versa. The major long-term complication for TOF repair is pulmonary valve insufficiency, or a leaky valve, which leads to right-side heart failure. Although there is narrowing and obstruction to this valve, there still can be excess fluid flowing into the lungs, which would result in difficulty breathing and having to take a diuretic for edema. The last of the four TOF heart defects is an overriding aorta. This is when the aorta is enlarged and placed over the ventricular septal defect. In a normal heart, the aorta should be directly placed into the left ventricle only, so the oxygenated blood can be successfully pumped out into the body. In TOF, the oxygen-poor blood from the right ventricle is pumped partially into the aorta instead of directly into the pulmonary valve. This mixture of blood into the aorta can cause a condition called cyanosis, a blue or purplish discoloration of the skin from the lack of oxygen to the body. The discoloration would first appear in the hands, feet or lips. The cause for tetralogy of Fallot is still unknown, but according to an article from Cleveland Clinic Journal of Medicine, 2010, in the past 40 years, the chance of a child surviving into adulthood with this heart defect is at least 90%. The corrective surgery for TOF is usually done within the first year of life. The timing of the surgery is usually dependent on how narrow the pulmonary valve is. This defect can involve several repairs and additional surgeries. Follow-up visits usually consist of a physical exam, electrocardiogram and echocardiography. The outlook for children with TOF is much higher than in the past, and although they will need long-term care to stay healthy, these children with TOF can survive long into adulthood. References: https://www.google.com/amp/s/consultqd. clevelandclinic.org/tetralogy-of-fallot-in-adults- what-to-do-when-the-diagnosis-is-and-is-not-a- surprise/amp/ https://surgery.ucsf.edu/conditions-- procedures/tetralogy-of-fallot.aspx (picture) https://my.clevelandclinic.org/health/ diseases/17546-tetralogy-of-fallot-in-adults About the author: This topic is very important to me, since my son had tetralogy of Fallot. He experienced all the symptoms of TOF, especially cyanosis, which led him to the hospital a few times. He received open heart surgery at the age of six months and will need a pulmonary stent later in life, since the valve is still narrow and could cause issues in adulthood. Only needing an echocardiogram every six months, he now lives a very active and happy life at the age of 16 months, and his chest scar is almost completely gone. Brittany Bidwell Program Intern Diagnostic Medical Sonography

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