A little bit more about me......my wife and I have been preparing for possible things that can or may go bad in our country/world. If you wish to call me a prepper, then so be it. So that entails food, water. alternative energy, ham radio, etc. I have a huge concern - receiving a mechanical valve and if SHTF. I assume you know what that acronym means. Right now I have a years supply of my medicines put away in case this country goes over the financial cliff, etc. My worry is not having access to coumadin if society breaks down. Another concern is, although a remote one, and that is if there is a huge solar flare (CME-coronal mass ejection) i.e. such as the Carrington Event in 1859 or an EMP (electrical magnetic pulse). If one of those happened, pacemakers and implantable cardioverter-defibrillators (ICD) would/most likely be rendered toast. I am more concerned about access to coumadin. Now before you deem me paranoid, I can assure you I am not. I just like to plan for possible emergencies that could spring up. We once had a power outage that lasted three days during a blizzard. I had enough wood cut and split whereby I stayed very warm throughout. But anyway, those factors have been on my mind on the tissue vs. mechanical valve option. I'm sure I can discuss this with my surgeon, but if they get in there and find something unplanned, all bets are off the table what I will wake up with (I did say wake up).