IN reply to danab. Hi, I had to reply to your response however, it's not in reference to the original post. On 6/28/15 I experienced being very short of breath in which, I rushed myself to the hospital and the doctor was discharging me but I prompt him to do more test even though he said everything was fine and I didn't look distressed in breathing however, the squeezing/tightness and feeling like I was running a marathon was present in my chest so he ran more test/ ct and discovered I had 3 clots in my lungs. I've clotted 5 more episodes after that lungs and legs even on clotting meds in which, i'm on enoxaparin now 80mgs 2x a day due to this unknown disorder. I had to be my own advocate with each clotting episode found and press the doctors to do more! I've been to almost every ologist that you can name and no one can find out why this left me with extreme shortness of breath, the squeezing feeling in my chest/ sharp chest pain, and tachycardia with even moving my limbs, doing small household chores, showering or even walking up stairs. I was brushing my teeth on one episode and my heart rate went up to 200 so I was hospitalized in which they gave me metoprolol but I couldn't handle that due to it lowering my blood pressure too much and not lowering my heart rate and now I've been on a heart failure pill corlanor in which, I'm suffering extremely everyday from the exact symptoms and went out on medical leave. I've been to the best hospitals in Chicago and even visit the Mayo 11/2016 for a week but they just gave me more appointments( didn't do anything different from the doctors in chicago) that I couldn't meet. I recently discussed this vegas nerve that you mentioned to my cardiologist in which, I've had a right and left side heart cath and it showed nothing and now I have a loop recorder in my chest to monitor my heart rate and rhythm but nothing! My cardiologist wants me to see someone at University Of Chicago in which, he practices in microvascular disease in which, I do have that but they said early on that microvascular coudn't contribute to all my symptoms, I'm hopeful that they can correlate this microvasular to the vegas nerve that you mentioned because sometimes it feels like it's coming from the stomach area before it hits the chest and thats when I have to been over because it feels like I've ran 5mls. Thank you and the originally poster for sharing! Just maybe this will help someone or someone can give me some insight.