tricuspid valve repair

9 years ago I had my Mitral and Aortic valves replaced  and things were great  up until  18 months ago it took my doctors a year  to believe  I was having difficulty walking etc, etc  now after tests at the hospital  I have been told my tricuspid valve was not working at full capacity  only at  a quarter , and I am due to have the valve repaired by stitching it , am just a little ,well a lot scared at undergoing a second  op ,having read articules on the side effects of the heart /lung machine.  thanks for reading