At age of around 57 I worked in a potato field and got very hot late in afternoon. I drank some very cold Gator-aid and my heart started to race and felt like it was flip flopping in my chest. Doctor said it was the cold fluid acting against my Vegus nerve. After two more times I stopped drinking anything cold and problem has not returned other than the discovery of a severe Myocardial Bridge of the LAD artery 20 years later.