Why would a CRNA not be allowed to do hearts,OB, Cardio?

job protection for anesthesiologists? liability insurance costs for hospital?

Surgeon preference.

In the hospital where I just did my OB/L&D rotation, they have a CRNA who spezializes only in L&D, he did all the epidurals, spinals, ..... during the 6 days I did my clinicals there. I've never even seen an anesthesiologist there on the floor.

My guess too would be liability issues. Myabe the hosp admins feel that there is less risk if the CRNA is totally focused just on that. Just my quess.

In some areas, due to cost of liability to the facilities, various practitioners find that they have limitations on their work.

One should raise the obvious question of whether or not the hospital houses a large anesthesiology residency program. I suspect that any institution that runs 2:1 is, in fact, an academic and not private practice, otherwise this is a really poor model for making any real money for the group.

I agree with all the above and will add there MAY have been complications that occurred in those noted cases. Not to ruffle any feathers, but I could if I wanted to, press a case against a horrible CRNA myself.

politics, 99% of the time it's politics

I think you nailed it here. It would be a financial disincentive for an attending to go 2:1 except for the teaching rules--that fortunately did not change this year.

But, yes there are politics too. When I was in San Antonio, there were NO CRNAs except in government (military & VA) hospitals.

I don't think there has ever been a difference in liability...'cept an MDA telling the surgeon "ya know if you don't have an ologist on the case, the bad stuff will fall on you. You really need me in the room to protect you."