Hi and welcome to the Chiari forum.
When you have reflux it can affect the vagus nerve which could in turn affect the BP.
If you, like me have reflux due to your Chiari and related conditions PPI like Prilosec may not be the best med for you.....I was on it for years and it really didn't help in fact at one point it got worse....and I found it was due to the fact a PPI(proton pump inhibitor) causes all the proton pumps to stop working producing acids....BUT we do need those acids to digest food...and once you miss a pill those pumps turn back on and over produce acids....which is known as rebound effect....so it can become a vicious cycle.
So to get back to the Chiari side of reflux is many of us over produce histamines...so the right med for our reflux would be a H2blocker...there was research done by Dr Dianna Driscoll and she proved the theory about those with Chiari, and related EDS that we over produce histamines....
I used to get heart palps and all sorts of issues which are all gone now.....and I do see a huge difference since changing meds.
I am not suggesting you change meds, but do look into related conditions and the best course of action once you get those answers.