Based on what you've shared, it's probably too soon to tell just what's going on with you. Your doctor is conducting a number of tests to get to the bottom of it, so hang in there for an accurate diagnosis.   As far as the "catheterization" you refer to, I'm assuming you mean a heart catheterization. If so, please see:   Cardiac Catheterization: A Patient Guide http://www.healthcentral.com/heart-disease/patient-guide-44528-6.html   Regarding your symptoms, being "tired all the time" (fatigue and weakness) is common to heart trouble, among other conditions. Again, I'd say it's best to continue following your doctor's lead to get true answers.   Best regards, Maria