On Friday Ali MacDonald gave us a very interesting lecture about congenital heart defects. It was very interesting to learn about this as I had a few heart kiddos (as we like to call them) during my PICU rotation. Specifically they had a variety of ASD, AVSD, VSD, coarctation of the aorta and tetralogy of fallot. We covered all these cardiac conditions – and then some, and also discussed the roles of different anticoagulants in pediatrics.
Below are some amazing tidbits I learned on Friday:
- AVSD 50% incidence in Trisomy 21 pts
- With lupus you get bands of non-conducting tissues – so the kid will be born with an AV block (it won’t conduct properly)
- If by day 23 you are on isotretinoin that you can screw up the looping of the heart (because it’s very vitamin A dependent) –
- Derivatives of vitamin A, called retinoids, function in proper embryonic development. With insufficient vitamin A, embryos fail to segment and grow, blood vessels fail to form, and the embryo is ultimately lost. Retinoids are involved in the expression of Hox genes, which function in signaling pathways that regulate the patterning of embryonic structures during the fourth week of development. However, embryos exposed to excess vitamin A have higher than normal amounts of retinoids, and their Hox genesmalfunction, disrupting genetic control of body shape (axial patterning) during the embryo’s development. Such disruptions can lead to developmental defects, particularly in the embryonic spinal cord, central nervous system, and spinal cord, where retinoic acid synthesizes and where catabolic enzymes are located.
- Heart defects can be defined as cyanotic and acyanotic
- Cyanotic: neural crest cells from the primitive NS to make the connection the heart and lungs à conotruncal defects
CHF in peds:
- 2 tachys, 2 megalys
- tachypnea, tachycardiac
- cardiomegaly, hepatomegaly
- Dig may not have much benefit in flow defects since its not a matter of cardiac muscle strength
- Dig levels not studied in peds – so no utility in using them
- Metolazone- MONITOR electrolytes closely
Tetralogy of Fallot:
- Pulmonary stenosis (thickened, narrow pulm outflow tract)
- Because of the obstruction at 1 you get thickening (hypertrophy) to the R ventricle wall
- Ventricular septic defect
- Overriding aorta
Treatment of Tet Spells
- Morphine: Subcutaneous morphine should be administered to decrease the release of catecholamines. This will increase the period of right ventricular filling by decreasing the heart rate, and promote relaxation of the infundibular spasm.
- Phenylephrine (potent vasoconstriction) to inc SVR to override R to L shunting
Prevention: propranolol (to dec HR and reduce infundibular spasm)
Enoxaparin has higher doses in <2 mos – because they have not had much development of their intrinsic and extrinsic clotting factors
Berlin heart: only time you have dipyridamole
- Xa level should be done 4hrs post the second dose of enoxaparin – range is 0.5-1, the level should be done until stabilized then frequency can decrease to prn.
- Immunizations should continue regardless of having anticoags on board – just may get more bruising
- Live vaccines should be avoided when on IVIG