This x-ray is actually from a newborn

This x-ray is actually from a newborn with tetralogy of Fallot but the point to make is that it does not often show the typical boot-shaped heart that we associate with tetralogy of Fallot. This, on the other hand, is an x-ray of an older child with tetralogy of Fallot and it does show the boot-shaped heart. Because of the overall heart size, which is actually normal, there is some up-tipping of the apex with the right ventricle hypertrophy and absence of the normal pulmonary outflow here that usually forms part of the left shoulder. This is actually due in part to a right aortic arch. The electrocardiogram can be helpful usually to show right axis deviation and to show right ventricular hypertrophy, as indicated in this tracing. So in blue babies the EKG can be helpful in certain of these congenital heart diseases but not always. So in this day of medical economics when you have to choose your tests the EKG may not be very helpful in suspected tetralogy of Fallot.

The course of a patient with tetralogy of Fallot can be quite variable too. It can be very benign. The baby that, for example, you pick up in the neonatal period because of a murmur, that doesn’t look very blue and who may show progressive cyanosis over the first months of life and to the point of actually having hypercyanotic spells. We’ll come back to that a little bit later. For management of tetralogy of Fallot, especially in this newborn baby that we’ve described as our index case, the medical management might be just close follow-up. If the baby is mildly cyanotic or not cyanotic at all then we can just follow this baby very closely. If the baby, on the other hand, is very cyanotic then intervention with prostaglandin – especially if he’s showing a deteriorating course in those few hours – would be appropriate. Specifically the PGE in this case increases the pulmonary blood flow in a setting where the obstruction to pulmonary outflow is severe enough that the pulmonary vascular flow is decreased.

The surgical interventions might be indicated in the young infant in terms of a shunt, a palliative procedure, tapping from the aorta or one of its branches to effect an aorticopulmonary shunt of various names and techniques. On the other hand, in many of the even newborns we can effect a repair if the anatomy of the outflow tract is favorable. The repair often involves a patch across the outflow tract or sometimes across the anulus of the pulmonary valve. And internally the ventricle septal defect that we can see here with the overriding aorta is patched. With reaming out, often, of some of the infundibulum sub-pulmonic muscle affecting obstruction.
If this baby were tetralogy of Fallot, how might he appear to us? How might he present? Just to review. Transposition of great arteries; transposition indicating that the aorta arises here from the right ventricle, the pulmonary artery arises from the left ventricle and these are parallel circulations unless there is some mixing level. Most commonly that’s at the atrial level as a patent foramen ovale or a true atrial septal defect. These babies usually present in the newborn period with their cyanosis and the cyanosis and hypoxemia can progress as in our index case. With that progressive hypoxemia, metabolic acidemia. The physical examination usually shows a cyanosis of varying severity and that relates to how well he is mixing through that atrial communication or if there are other levels of mixing as a ventricle septal defect. Not so likely, mixing at the ductus. The ductus is good for other reasons in this setting. Other important features on physical examination; increased right ventricular impulse, a loud single heart second heart sound – because that aorta is sitting right under your stethoscope under the anterior chest. The pulmonary is more remote and not well heard. The patient may or may not have a murmur. There is nothing about transposition itself that produces turbulent flow, to produce a murmur. So the murmurs that we hear are usually associated with ductal flow or the presence of a ventricle septal defect or other anatomical problems associated with transposition. About 30% of transpositions have no murmurs at all. This is a fairly typical x-ray for a baby with transposition of great arteries, however we’d have a hard time distinguishing this x-ray from a baby with truncus arteriosus. And basically it’s that egg-on-end shape with a narrow waist, and a narrow waist because the aorta is right but almost directly anterior to the pulmonary artery, which is just a little bit left-ward. So it leaves us with a narrow cardiac waist. The pulmonary vascularity is usually normal to slightly increased.

One Response to This x-ray is actually from a newborn

  1. Dan says:

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