I Had An Ultrasound Of The Neck That Showed Pulsatile

I had an ultrasound of the neck that showed pulsatile veins (veins, not arteries). got an echo at the recommendation of the radiologist and it was normal. met with the cardiologist who said my heart is extremely healthy and he didnt know why my veins are pulsatile. every other doc I've brought it up with had no answers. I'm a 35 year old female with a rather unremarkable medical history. any ideas where to go from here?