Bradycardia in children is most often caused by hypoxemia but can also be caused by acidosis, elevated ICP, vagal stimulation, heart blocks or overdoses.
First degree heart block in otherwise healthy children can be caused by infectious diseases, myocarditis, rheumatic fever, Lyme disease and congenital heart disease.
Third degree heart block can be congenital, caused by maternal connective tissue disorders such as Lupus, or may result from cardiac surgery.
Any infant presenting with a third degree heart block should have an investigation for neonatal lupus.
References
Doniger S. Pediatric Dysrhythmias. Pediatric Emergency Medicine Reports. Sept 2008. Vol 13, No 9 (This was edited by a UMMS Combined EM/PEDS graduated Dr. Jim Colletti who is Associate Residency Director, Emergency Medicine, Mayo Clinic College of Medicine, Rochester, MN.)
