Medical video/animation source?

[Mark Suszko]

Many of those Turbosquid models come pre-animated as well; found one for just 25 bucks… YMMV

[Joseph W. bourke]

Pond5 seems to have a fair amount of stuff:

https://www.pond5.com/stock-video-footage/1/heart.html#3

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com