I am 4 months post-op for an Aortic Valve repalacement at the Cleveland Clinic. I have been doing fine and am back to my normal routines. The only meds I am taking is 25 mg. of Lopressor twice a day. In the past few days, I have experienced brief periods of very rapid heart beats (300 bpm). It only lasts for 15 to 30 seconds and occurs in the middle of the night. Last night it happened about 4 or 5 times around 4 AM. Has anyone experienced this sensation? Does anyone know anything about this type of fibrilation? I will be seeing my Cardiologist soon to get his opinions.