Tetralogy of fallot TOF repair, causes, symptoms & pathology


if you’ve ever played Tetris you probably know that you used pieces made of groups of four squares tetralogy of flow or tof is a congenital heart condition where patients have four heart abnormalities here’s the normal heart with upper chambers the left in the right atria and lower chambers the left in the right ventricles as well as the aorta and the pulmonary artery instead of using this anatomical heart though I’m gonna actually use this simplified version of the heart instead okay so now let’s go through these four findings in tof one by one the first abnormality is stenosis or narrowing of the right ventricular outflow tract into the pulmonary artery and this could either be narrowing of the valve itself or narrowing of the infundibulum the area right below the valve either way this makes it harder for deoxygenated blood to get to the pulmonary circulation in response and this also happens to be the second feature the myocardium of the right ventricle hypertrophy or gets really thick in order to contract harder and push blood passed the stenosis this causes their heart to look boot-shaped on an x-ray the third features that patients have a large ventricular septal defect this gap between the ventricles that allows shunting of blood between them now in a patient with an isolated ventricular septal defect meaning those that don’t have tof oxygenated blood is shunted from the left side to the right side because the pressure on the left is higher than the pressure on the right for patients with TOF though the right ventricular outflow obstruction might block the normal blood flow so much that the pressure in the right ventricle has to be really high to get past it well the high right-sided pressure means that the left side of the heart actually becomes the path of least resistance and deoxygenated blood shunts from the right side to the left side the fourth and final feature is that the aorta overrides the ventricular septal defect and this one’s super variable sometimes the aorta is way over here sitting on top of the septal defect and sometimes it’s more on the left ventricular side either way if deoxygenated blood shunted from right to left then it flows over to the left ventricle and immediately out to the body when you think about it the critical feature of these four is the degree of right ventricular outflow obstruction with less obstruction oxygenated blood might be shunted from left to right and get into the pulmonary circulation where it essentially takes another run through the lungs with more obstruction deoxygenated blood is shunted from right to left and enters the systemic circulation and more deoxygenated blood going to the body essentially means less oxygenation of the tissues right in fact shunting can be severe enough to let the oxygen saturation fall below 80 percent at which point patients skin takes on a bluish or purple discoloration called cyanosis tetralogy of flow is actually the most common cause of cyanotic congenital heart defects accounting for about 50 to 70 percents as well as about 10% of all congenital heart defects in general now it’s not quite clear why some babies developed UF but it’s associated with chromosome 22 deletions and DiGeorge syndrome babies with TOF often have cyanosis around their lips and fingernail beds at birth and can have clubbing of their fingers and toes within a few months on the other hand if a baby doesn’t have severe right ventricular outflow obstruction the baby might not be cyanotic nevertheless having any decrease in the normal oxygenation of blood can affect the baby in a lot of ways and those born with TOF can have a range of symptoms including feeding difficulty and failure to gain weight and develop normally babies with TOF will often experience symptoms in cyanosis in spells which is referred to as Tet spells so say the babies cruising around and therefore increasing their oxygen demand their heart I’ll try to pump more blood leading to a sudden decrease in oxygen saturation which causes them to be cyanotic when this happens they’ll squat down to reduce cyanosis why does this help though well squatting down or getting into a knee chest position slightly kinks the femoral arteries in the legs which increases vascular resistance in the peripheral artery and therefore increases pressure in the systemic circulation which increases pressure in the left ventricle enough such that the pressure on the left side is now greater than the right side and that shunt temporarily reverses forcing blood to take the paths of the lungs to be oxygenated therefore reducing cyanosis when patients do have a serious hypercyanotic episode or Tet spell they can be treated by keeping them calm and giving them oxygen and IV fluids along with medications that are ultimately aimed at improving pulmonary blood flow a diagnosis of tof is usually made with echocardiography which can even be done prenatally most patients with TOF will have cardiac repair surgery in the first year of life where the ventricular septal defect is closed with a patch and the right ventricular outflow tract is enlarged fixing these two defects resolves problems caused by the other two defects when the right ventricle no longer has to work so hard to pump blood to the lungs it can return to a normal thickness and fixing the ventricular septal defect means that only oxygen-rich blood will flow out of the left ventricle into the aorta thanks for watching you can help support us by donating on patreon or subscribing to our channel or telling your friends about us on social media you

4 Replies to “Tetralogy of fallot TOF repair, causes, symptoms & pathology”

  1. This video is missing some point. In fallot tetralogy, right and left ventricular pressures are equal. There is a no right to left shunt. The severity of cyanosis is determined by the percentage of pulmonary circulatory in TOF. Pulmonary circulatory is determined by the degree of pulmonary stenosis.

Leave a Reply

Your email address will not be published. Required fields are marked *