I have history of a asd repair as a child, large amount of scar tissue on my heart . last few month retaining fluids in my legs/ abdomen, notice low bp but increase pulse . what could be wrong?

Echo/CTscan help: Increasing fluid buildup w relative low BP might suggest right sided heart pressures elevated (unlikely due to ASD particularly if successful repair as a child). Need to rule out calcification and thickening of the pericardium (constrictive pericarditis) which can sometimes occur decades after surgery when there is a " large amount of scar tissue on heart". A cardiac ct and careful echo doppler.

See cardiologist: If you are not already seeing a cardiologist i would immediately. These are signs of potential congestive failure.

Cardiologist : You need evaluation with a cardiologist as your symptoms are concerning. They will check an ekg & order an echocardiogram likely.

Many Things: Many complications can arise in adults who had heart surgery as children. Abnormal heart rhythms, decreased heart function, fluid around the heart, and residual heart anatomy problems are just a few. The only way to determine them is to be seen, examined, and possibly have tests done. I strongly encourage you to see an cardiologist trained in adult congenital heart disease.