Heart issues making sex short

My husband and I are in our early twenties. He has a heart issue that causes his heartbeat to go way up during periods of stress, making any sort of exercise super difficult. He used to be a long distance runner but has had to stop in recent years because of this.

This is making sex shorter and shorter. Even when we have the libido and the sexual stamina, his heart will make him need to stop just as it starts to get good. I can’t even touch him. It’s a _serious_ mood killer.

Anyway, has anybody else had this issue, and if so, what did you do? If you haven’t had this issue, any tips on how to make it a little better? I just wanna have good sex with my partner, dang it!