Hello, Mary Lou.
It sounds like your friend has all the symptoms of posttraumatic stress, which is not uncommon following a scary cardiac event. (It doesn't matter if it turned out to be not such a serious health problem - it's the terrified helplessness at the time of the situation that activates those pesky, survival-driven, neurohormone soaked, alarm systems. And when that biochemistry doesn't go back into balance but stays in hyper-gear for months - that's PTS.
Believe it or not, there's a high correlation between digestive issues and all manner of functional pain conditions and PTS. It's not really 'psychosomatic' - in fact that term may no longer be meaningful, given what we've come to understand these days. More likely, it's about trapped, accrued, pain-generating kinens in the muscle tissue and joints, from all the cascading alarm biochemicals and alternating sedating biochemicals that occur with PTS and don't get rinsed out, as the body seeks balance. (If you want a more complete explanation, you can check out Chapter 5, The Physical Effects of Trauma, in my book Invisible Heroes. But that's the bottom line for what you're asking.)
And of course, hypervigilance and anxiety are part of the very definition of PTS - no mystery there.
So I'd suggest your friend start out with some simple self-regulation tools first. This could be guided imagery, like our Relaxation and Wellness; or Andy Weil's Breathwork exercises; or something like Sacred Pause or AM and PM Meditations - any meditative exercise that teaches her how to calm herself down at will - or re-regulate her biochemistry by going on 'manual' if you will.
Once she gets used to that - maybe after 2 or 3 weeks - she can move on to the Healing Trauma imagery; or to a tapping therapy, such as Mary Sise's Thought Field Therapy video exercises.
But don't overload her with too much stuff at once - you'll just overwhelm her and she won't do any of it. Instead, just get her one item and see how she responds to it.
And if she's a cerebral type, get her the book (please link) so she can see why any of this stuff makes good sense for her to do (and the explanation of what PTS is and how it's activated could be very reassuring to her. Because it's likely she thinks she's going nuts. And she isn't. She has PTS.)
You're a good friend to go to the trouble of asking for her.
Best of luck to you both,