<s>[INST] I had triple bypass 10 weeks ago.  2 days after surgery I started to experience an increased heart rate which I was given medication for.  At the same time my heart started beating really hard.  So hard that I could not even lean back or lie in my bed.  I am 10 weeks in and the heart beat is still thudding in my back, stomach and head.  What is causing this and when will it stop. [/INST] Thanks for your question on Chat Doctor. I can understand your concern. Since you recently had triple bypass surgery, we should first rule out arrhythmia as a cause four your increased heart rate. So consult your doctor and get done ECG, 2d echo and Holder monitoring (24 hours continuous recording of ECG). If all these are normal then no need to worry about arrhythmia or other heart diseases. Sometimes stress and anxiety related to surgery is also caused similar symptoms. So consult psychiatrist and get done counselling sessions. Try to identify stressor in your life and start working on its solution. You may need anxiolytic Chat Doctor.  Don't worry, you will be alright. But first rule out arrhythmia. Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks. </s>