My first episode occurred during the night. The swishing sound woke me several nights in a row and I actually went outside at 2am to check the irrigation system and on another night to check the water level in the swimming pool. The sound soon changed to constant loud rapid thumping and continued for a year before I was able to consult my cardiologist. It was maddening and kept me from sleeping. I eventually was prescribed Losartan and Metropolol for high blood pressure. Now, another year has gone by and my heart beat has slowed and so has the thumping, which I rarely notice during the day. It does thump at night. I think my problem was caused because I stopped daily aspirin after 30 years. None of my physicians comment on this supposition, however. The thumping did start shortly after I quit taking the aspirin. Trying to decide next step. Thank you for your comments.