CircusSquirrel

I am scheduled for a cardiac ct scan soon. I am a 31 year old female with anxiety problems and I've had left arm/jaw pressure on and off for about, oh, 7 years or more. I've been to the ER, had EKGs while the pressure was there, had blood drawn to see if there was any acute heart attack or damage happening, nothing. In the last three months I've had a stress test (base model), echocardiogram, about 3 resting EKGs, and blood work. They were all ok. My cardiologist says that he feels I'm fine, but to "put this issue to bed" he's ordering a cardiac ct. They recently got one at the hospital I go to and they love using it. I am on a beta-blocker because I have spells of tachycardia (those have been checked out multiple times, too---just sinus tachycardia). My worry is this: For the cardiac CT scan, the heart rate has to be low (at least under 75, but preferably 50-60) so nearly every patient is given a beta-blocker even if they don't usually take one. OK, the problem being: each time I've had a CT with contrast (I have had them to follow different abdominal issues, and to check for a pulmonary embolism) while I've been on a beta-blocker, I've felt as if my heart rate dropped a lot and I became nervous and shaky. It passed after like 15 minutes or so. I sat up on my gurney and never fainted right after each scan (this was 3 different times), though I don't faint easily, I've never fainted, actually. I've had two CTs without being on beta-blockers and did not have those strange heart slowing and shaky symptoms at all. I'm a nervous person, so I don't know if I'm just overreacting, but I find it suspicious. I mean, if I truly had a bad reaction with those 3 CTs I would have passed out or gotten sicker or something, right? But I have read that beta-blockers increase the chances of reactions to contrast dye, and sometimes people can have "vasovagal responses" to contrast, which means their heart rate and blood pressure drop. I think that's what happened to me, but back then my heart rate was much higher (my resting heart rate was in the 80s even on beta-blockers, now it is in the 50s on beta-blockers). So I'm thinking, well, if my heart rate dropped back then, it still would have been beating at a relatively normal speed, but if it drops now, it will be going dangerously slow. I can't get hold of anyone in the radiology dept. who can really answer my questions. I'm really scared of this and wondering if I should just ask for an alternate test like a thallium stress test (even though my resting heart rate is low, I'm on a very low dose of beta-blocker and I can exercise to my target heart rate). I'm so afraid to go in there and they'll inject me with that contrast and my heart rate will plummet, then they'll have to give me more scary medications. Am I being ridiculous here (I won't take offense if anyone says I am, seriously!) or do I have a valid concern? Being an anxious person, it is sometimes hard to tell. I just don't want to show up for the test and have a technician totally dismiss my concerns only to have a bad outcome.