Among the many dangers of a heart attack is damage to the walls of the heart. When cardiac muscle is stressed, ruptures between the usually separate left and right ventricles can cause blood to slosh back and forth between the two chambers, lowering its oxygen content. Surgery to repair the damage can be dangerous since, by definition, it's performed on a weakened heart. But doctors and patients now have a safer alternative, thanks to a new technique in which a polyester-coated metal patch is collapsed, threaded via catheter into the body and positioned in the heart to close off the tear. This can buy patients the time they need to recuperate and allow them to postpone more extensive repair surgery. In many cases, it may even help them avoid that operation altogether, since the polyester covering on the patch encourages new heart tissue to grow, helping to seal the rupture.