HM, I had an open heart surgery in Dec. 2002, a single by-pass. I think it's safe to say, You're not going to want to take any risks (that includes avoiding Rifle Recoil) for awhile anyway,
your Surgeon/Doctors are probably going to explain all the activities you should avoid, they won't even want you to drive a vehicle for a period of time as well because,
if you get into an accident an the air bag deploys your chest wont be able to handle the impact, even wearing a seatbelt isn't going to feel very comfortable on you.
I'm sorry to have to say it but it's better to accept that you may have to miss a year of hunts in order to be totally ready for the following year.
With todays medical advancements I would tell you to NOT worry at all,,,, it sounds a lot more dangerous than it statistically is now a days and I'm sure your surgeon will point that out to you as well.
Of course all surgeries have risks but I think you'll be comforted to find out there's a very high success rate with heart valve replacements...
Democracy is two wolves and a lamb voting on what to have for lunch.
Liberty is a well-armed lamb contesting the outcome of the vote.