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Tetralogy of Fallot
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tetralogy of Fallot as cause p. 304
Tetralogy of Fallot p. 304
Tetralogy of Fallot p. 304
20q10 syndromes p. 306
cyanosis caused by p. 728
fetal alcohol syndrome p. 306
lab findings in p. 721
outflow tract formation p. 287
thymic aplasia p. 114
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.
This causes their heart to look “boot-shaped” on an x-ray.
The third feature is 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 pressures 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. This one is super variable, sometimes the aorta’s 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 is shunted from right-to-left, then it flows over to the left ventricle and immediately out to the body.
Tetralogy of Fallot, or TOF, is a congenital disorder characterized by four heart abnormalities. There is stenosis in the right ventricular outflow tract, right ventricular hypertrophy, ventricular septal defect, and aortic override of the septal defect. These four defects cause oxygen-poor blood to flow from the right ventricle into the aorta, rather than being pumped to the lungs, which results in cyanosis. TOF is diagnosed with patient examination and health ultrasound, and treatment involves cardiac surgical repair, usually in the first year of life.
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