With regards to chromosome 21

With regards to chromosome 21 there is an association “Catch-22”. And the CATCH is an acronym for the defects that we commonly see here. This includes the cardiac anomalies, the facial abnormalities, the thymic hypoplasia, the cleft palate and the hypocalcemia as the components that we frequently associate with aberrations on chromosome 21. The cardiac anomalies are for the most part, the cono-truncal abnormalities. So patients with tetralogy of Fallot, truncus arteriosus. Tetralogy of Fallot again being associated independent of either of these syndromes with chromosome 22 aberrations as well. We list a couple of other associations here with specific chromosomes.

Here again, as we talk about the other group of factors as etiology of congenital heart disease and think about environmental factors – teratogens, if you will – there are some specific associations of congenital heart disease with certain teratogens; fetal alcohol syndrome for example. Twenty-five to thirty percent of those babies will have ventricular septal defects, PDA’s or ASD’s. We’ll talk about, for example, transposition of great arteries, and there is an association of transposition, tetralogy of Fallot, hypoplastic left heart syndrome with anticonvulsants of the trimethadione group. Tricuspid atresia, for example, is one of the cyanotic congenital heart diseases and there is an association with maternal lithium intake with that particular form of congenital heart disease. So as we look through this list of potential teratogens we can see that there are some specific kinds of congenital heart disease that may be found in association.

As we go back to the etiologic reference here of the different types of effects; genetic can account for only 5% or less of the congenital heart diseases as we know now. But as I mentioned, this is a growing category as we are learning more about genetic factors through our molecular biologists. Environmental factors that we listed in the previous slide account for really a very small percent of congenital heart disease. Again, the majority, as we know to date, there are probably some interplay between genetic factors and environmental interactions.

Now we will talk about a case to help us focus on some of the lesions, especially the cyanotic congenital heart diseases, in terms of their presentations, the pathophysiology involved, and the treatment modalities. Particularly as it would relate to the primary care physician. Here’s a fairly common presentation of a child with potential cyanotic congenital heart disease. Here’s a well-developed, 4 kg male newborn who presents at term, uncomplicated pregnancy with Apgar scores of 8 and 8. So looking very good, other than being a little cyanotic, moderately cyanotic. As you might expect, being a little cyanotic he’s a little tachypnic as well. But really in no acute distress. His lungs are clear on auscultation. A fairly unremarkable precordium for a newborn. No signs of congestive heart failure and his peripheral perfusion and pulses are normal. Now, first to review; cyanosis in terms of this implication. Cyanosis is a bluish discoloration that we see in the skin or mucous membranes which is related to reduced or unsaturated hemoglobin in the peripheral circulation. Cyanosis can occur either based on central factors, as congenital heart disease, and pulmonary disease would present as peripheral. A lot of babies, as you know, tend to have some vasomotor instability that make them appear to be cyanotic peripherally but it’s important to look at the mucous membranes to discern central cyanosis that may represent pulmonary or cardiac disease. The other thing in assessing the cyanosis in the newborn – as we can do by x-ray – is to determine whether there is a problem of increased or decreased pulmonary blood flow.

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