Dear Linkquest,
There are very few cases in the medical literature where myocardial rupture is felt to have occurred in association with cardiopulmonary resuscitation. In the
case reports that I could find, 3 were adults,
and one was a 4 year-old child. As best as I can tell, this is most likely due to perforation from a fractured rib during CPR. It also may be due to weakening of the heart muscle from an underlying disease, such as myocarditis, a viral infection of the heart muscle.