Yes a graft, I believe it is Dacron as you say (they showed it to me before and it is a fabric like graft), I get an echocardiogram every year to mainly monitor my valve function but they also look at the graft. I also get a full body MRI (groin, abdomen, chest and head) every 4-5 years to ensure no new aneurysms are appearing (there is a propensity in my family, I also had a brain aneurysm which was repaired too). I find my cardiologist to be incredibly thorough and knowledgeable, the man is an expert in aortic diseases and aneurysms in general, and also a geneticist so he had my family enrolled in a genetic study to see if we have an unknown marker for aneurysms (he had both of my kids checked, heart and brain) that is why I say it makes such a difference to have a cardiologist that specializes in the subject, I feel lucky to have him