<s>[INST] i lay down or sit down for a long time, and then when i stand up i get a rush of blood to the head, and my heart beats HARD not FAST but slow and hard i had an ekg and stress test done all normal  i also get PVCs when exercising at times what do you make of this [/INST] ur feelings are normal. but it is not blood rushing to head but to your legs when u get up. fast hr trying to restore low bp in a few seconds. u don't need any cardiac testing if u do these will be normal. pvcs during exercise are abnormal but ur tests are normal. if frequent may get Holter monitor. </s>