I had my mitral vavle replaced 4 yrs ago. I have since accomplished 100+ dives. I did have to jump thru some hoops to get my Dr signature, including the stress test to 13mets. I have had no issues diving, Its actually better than before surgery, no more dizziness. I have a mechanical valve and I am a little more careful than before...mostly because of the anticoagulants. I am more cautious on the boats, more conservative with my depths. I don't hang to close to the side of the boat waiting to get back in for fear of getting my head bumped. i don't do the swim-thru were I may get scratched up, I traded in my fullfit fins for those with booties. I have given up cold water diving. I been on a live a board in the Maldives and now getting ready for 3 weeks in Palau and Yap