instruction: hi doctor last night during sleep I was awoken by a violent diaphragm convulsion I felt a sensation of being drawn down into a cold dark blackness it was very much disturbing and I felt like I was going to die I had benign arrhythmias with follow up hotter monitor and stress test revealed no signs of heart disease it occurred thrice in the last 18 months please help
output: hello revert back with the answers to a cardiologist online