I have had a lot of documented palpitations (PACs,PVCs, NSVT, SVT) via Holters and event recorders are they mostly correlated to postural changes (lying to sitting, standing to lying, etc.). I really believe it is tied to cardiac filling, more specifically filling of the left ventricle which is the heart's main pumping chamber. In a non-POTS person, it takes only two heart beats to bring back up the blood that is pulled down by gravity. In us however, the complex mechanism is faulty so blood pools making our heart work harder to adapt to the shift in volume. I have had bigeminy (normal sinus beat, PVC, normal sinus beat, PVC, etc.) after a vasalva-type maneuver which modifies venous return. So IMHO and in my case, I have definitely put the two together. If I do something that affects the venous return to my heart or if I don't wear my compression gear to help with pooling or if I'm dehydrated and didn't have enough salt, I will definitely get more of those. Also, I had several ECGs lying down and standing and the standing ones show my T-waves (to simplify the "electricity" in the ventricles) are flat or inverted. After founding that out, I dug a bit deeper and found that studies came across this phenomenon in POTS patients. Dr. Raj at Vanderbilt even discusses this briefly. http://www.ncbi.nlm.nih.gov/pubmed/17617070 http://www.ipej.org/0602/raj.htm I was told these are benign. They are uncomfortable at times and yes they can be weird or scary but I've learned to keep them at bay as best I could by eating salt, being hydrated and wearing all of my compression garments. I never had them before the onset of POTS; they started two months afterwards. I've had POTS for 18 months and palps for 16 and I'm still here! Hope this helps! P.S.: The palps do wax and wane like the rest of the symptoms and I have more of them when I'm more potsie.