Katyjoy, have you experienced tachycardia before? I suffered it all my life but had it fixed after my first diagnosis back in 2011 so about 2013 I had it fixed as radiation aggravated it further. Its not actually a problem within the heart but the nerve pathways across the heart that throw it into this incredibly fast rhythm. I landed in hospital 2012 with possible heart muscle damage yikes! I had it fixed with an ablation, which they cautorize the nerve pathways. When my heart now goes to go into that crazy rhythm it stops itself. I know through chemo, especially I was very short of breath and yes my heart felt funny also. Melinda xo