I too have had open heart surgery, and I must say, we have some of the best heart specialists in the country around here, and they do very good work. That said, I have done lots of traveling, and though I might point out that while traveling in a car one is often more than 5 minutes from medical care, I do think that restricted work travel (especially by air) would have been a very reasonable restriction for a certain period of time after my surgery. Thankfully, I did not have to go back into the work world quickly after surgery. But I did find the drill of travel, particularly air travel a bit daunting for a while.
For a while, though I was considered fully recovered and released by my doctor, I felt just a bit.....fragile. And in cardiac rehab, I was repeatedly warned about trying to do too much too soon. There is a bit more danger involved in that first few months after surgery. I was told the same type thing. We don't have to push that type of mentality that we're going to soldier through, be back at work and in tip-top shape and able to do everything we did before right away. We as a nation already are working ourselves to pieces anyway.
Since my surgery, (that one at least) though I haven't been traveling for work reasons, I have done quite a bit of air travel. And sometimes, I've had to make accommodations for myself. And sometimes I just haven't been up to it. Especially that first bit of time after the heart surgery. Sometimes when traveling by air, you find yourself really hurrying, really rushed and stressed, and let's face it folks, having to really hustle, carry weight (your luggage and paraphernalia) and change plans and time zones very quickly.
Especially since, as a member of a traveling work group, you'd certainly be less inclined to request such accommodation as a wheelchair when you were really tired or a longer lay-over so you could have less of a walk(or run) through a crowded airport, I think the no air travel for some period of time restriction would be appropriate. At least if you were driving, you could more set your own pace, plan a rest or check with a medical facility if you felt you needed to.