"Burmese pythons like a meal they can really get their fangs around, especially since the snakes are known to go half a year or more between meals. That gustatory pause is merely one of pythons' more remarkable adaptations.

New research shows that when the reptiles swallow whole rats, birds, and other prey, the pythons' hearts temporarily grow bigger."

http://news.nationalgeographic.com/news/2005/03/0302_050302_python.html