What do you mean by "barium stress test?" There is a nuclear stress test for heart. and there is a barium swallow to take pictures of your stomach to view reflux or abnormal swallowing happening.
There is a very real connection between the esophagus and stomach to the heart, via the vagus nerve. I get tachycardia (very rapid heart rate) when I eat "trigger foods" that cause gastric reflux. It starts out feeling like a bubble in the stomach, then the heart rate jumps way over 100BPM. The phenomenon is called cardio-esophageal reflex (not reflux!), aka variant angina. It works both directions. For some people the heart problem feeds forward to affect the esophagus.
One thing you can do, since you are uninsured and the docs probably have never heard of this problem, is to try to find out if you have trigger foods. Keep a really good food log, including all spices and condiments, everything you eat or drink. Record any symtoms that occur within an hour or two. Occasionally it could take up to 2 days for a food to react, but for food triggers causing stomach and heart reactions I think it will be within a couple of hours.
Then if you discover food triggers you have to do "challenge testing." It's safest done under supervision of an allergist, but I did it on my own - carefully. Eat a teaspoon or maybe a tablespoon if you think it takes at least that much, then wait 20 minutes. Then eat 2 spoonsful and wait, then 4 then 8 and finish with 16.
I ended up with a long list of seemingly unrelated foods: maple syrup, gelatin, anything made from corn, but not fresh or frozen corn, most condiments, large delicious bagels, especially with nuts, bottled lemon juice, and lots more. I googled a whole bunch and found my triggers/allergens/sensitivities all had SULFITE. You could have something completely different, but the testing is at least free.
By eliminating sulfites from my diet I was able to mostly control the heart rate. Heart medications didn't help at all, made me feel miserable. Most docs don't have any experience with this problem, but there are several research papers written on the subject.