Question:
My husbands blood pressure is normally low, and heart rate is normally
low, BUT when he has a stress test evaluation, his starting pulse and
blood pressure is just about at max. rate almost, from nervousness.
Normally his bp is 110/65 and hr is 50-60 bpm.
Before the test, bp is 145/90 and hr is ca. 110.
Why cant they still do the test?? I mean is it not the same, whether or
not the stress comes from physical or psychological stress, the max. hr
and bp is reached and they can check the ekg???
Answer:
You haven't explained yourself well. I think that you are implying that
your husband's test was cancelled because he had anxiety which elevated his
vital statistics and threatened to confound the test.
The concept of a 'stress test' is that it detects exercise-induced cardiac
ischemia.
The change in circulation produced by anxiety is not entirely the same as
the change induced by exercise. Nevertheless, the test would be invalid.
Everyone will become ischaemic if the heart goes fast enough - because there
isn't enough time for the coronary arteries to carry blood in between
contractions of the heart. There's no point detecting ischemia under
conditions that don't happen in the real world. There are protocols for
stress-testing people, and while I don't know them off my head, I don't
doubt that having a heart rate twice the usual rate at rest is enough to
abort the test.
Just driving to the hospital would create stress so that one's BP
would be higher than "normal"; sometimes, being a passenger in a
car could create more stress than if one was doing the driving....
No, it's the relative tachycardia which would abort the test. That's
probably too high for the test to be meaningful. Every heart will become
relatively ischemic with higher heart rates. At some point it will show up
Ok, then if the tachycardia was caused simply by anxiety about having the
test, presumably, the person would never be able to have an exercise stress
test again, since the same thing would likely happen every time. If that's
the case, wouldn't they just give the person a lorazepam or something, and
get on with it?
Wouldn't the stress test-induced faster heart rate be self-limiting anyway.
By that, I mean, (1) they always want you to achieve a certain heart rate,
and if it's passed, the test usually stops shortly thereafter, (2) what does
it matter how the heart rate gets there (whether by exercise only or by
combination of emotional and exercise stress?, and (3) if a person starts
out with an elevated heart rate due to anxiety (and 110 isn't
dramatically-high), wouldn't the maximun heart rate achieve by exercise be
the same anyway?
I don't pretend to be an expert, but it still seems to me that the doctor
doing the test must have decided against it for a reason other than, or in
addition to slightly elevated heart rate due to anxiety - otherwise, they
would be cancelling an awful lot of stress tests every day.
