hi guys and today I thought I'd do a little video on
some of the tests that cardiologists organize
to try and work out wether the chest pain that you are getting
is coming from the heart or not. Broadly speaking
the tests that are done can be divided into two
the first set of tests
give anatomical information so they basically look at the heart arteries
and try and work out if there's any flaring up the heart arteries because the
way
heart disease occurs angina occurs and ultimately heart attacks occur
is because of flaring of the heart arteries so the first set of tests are
anatomical tests they actually directly visualize
the flaring up of the heart artery, the second set of tests are functional tests
and basically these work by assessing the functional importance
of any narrowings ie they don't tell you whether there
is any furring up but they will tell you if there is significant furring up such
that the furring up is actually stopping the flow of blood
or restricting the flow of blood so in simplistic terms
if you imagine an old house and someone said maybe there's a problem
with the
waterworks one option is simply to turn on the tap
and see if water flows out, that's a functional
test you know you're assessing the function, who cares whether there's some
furring up in the pipes
all the water is coming out when you need it, the other
solution is to actually go in and look inside the pipes and try and work out
whether
the pipes have any areas of furring up at all
so they give different information
and both sets of information are useful, and now
the anatomical tests include CT coronary angiography
all invasive coronary angiography OK
CT coronary angiography is a test where you can
have a look at the heart arteries non-invasively so basically what happens
is you go
they give you a little bit, they pop a little cannula on the back of the
hand
and they slow the heart down, the reason they have to slow the heart
down by giving patients beta blockers is
because the heart is a moving structure and when you're trying to image the
heart you need it to be still otherwise you get a blurred picture
and therefore in CT coronary angiography what they do is they slow
the heart down and then try
and acquire all the images necessary within one heart beat
and therefore by slowing the heart down your making the heartbeat as long as
possible
so CT coronary angiography
is a very good test but its only very good
if your heart arteries are normal,
because what happens is when the heart arteries start getting diseased
you develop calcium in them and the calcium can reflect
the rays and therefore obscure further
imaging of the heart artery so if you don't have any calcium then you could
be
pretty happy that you're getting a good picture and you would be able to
tell that there is no significant narrowing
if there is a lot of calcium than you can't tell beyond the fact that
all you can say is that's calcium ok
whether this furring up to the extent that it would be obstructing flow
but all you can say is that there's a lot of calcium and
further test is necessary
the problem with CT coronary angiography is two-fold one
it does involve some exposure to radiation albeit
only a small amount and the second is that you require some dye and if you
have bad kidneys
then that dye can affect the kidneys and make the kidney function
worse
the second test is the gold standard test and that is invasive coronary
angiography and invasive coronary angiography what happens is
you actually go in and someone will feel an artery
either in your wrist or in your groin they will give you some anesthetic
round it
and then they will pass a needle into the artery
and through the needle they pass a wire which goes all the way up to the heart
the wire screened under x-ray guidance and once
the wire reaches the heart they slide a tube over the wire
and then they take the wire out and then through this tube you can inject dye
and as the dye is injected you can take pictures with an x-ray
and the dye will delineate the heart arteries and that's a very
reliable way of looking at the heart arteries
and working out whether the heart arteries are narrowed or not
the problem with invasive coronary angiography is
firstly it is an invasive procedure therefore it carries with it some degree
of risk because
people are actually, you know doctors are actually
putting things in your body so there is a risk
that you could damage the blood vessel through which the
catheter passes,
by itself cause a heart rhythm disturbance and there's also a risk of
heart attack, stroke or even a risk
to one's life. the risks are in the order of about one in a thousand cases
and therefore I don't think everyone is suitable for coronary angiography
but generally the cardiologists will decide what your risks are
and depending on that risk they may decide to do the coronary angiogram but
the coronary angiogram is the gold standard way of trying to work out wether their is a
problem or not
CT coronary angiography is a very good test particularly if
you're just worried but with the risks
your risks are low and the symptoms are not absolutely typical
in which case if you want the reassurance, you have the CT coronary
angiogram
that is clear, then you can go about your own day-to-day business
however if you have a lot of risk factors, if your diabetic, you have high blood
pressure, if you've been a smoker, if you've
had previous heart attacks, if your old then
the chances are that if you end up having a CT coronary angiogram
there will be a lot of calcium there and therefore
your doctor will be none the wiser really and therefore in your
case
if those things apply to you then a coronary angiography would be preferable
test
so these are the anatomical tests, then there are the functional tests now
functional tests essentially are putting the heart under some kind of stress
and seeing how the heart copes with that stress so the easiest functional test
is a treadmill tests and
that is perhaps one of the commonest tests we're using
these days, now essentially what happens is that
someone does an ECG at rest they then put you on the treadmill
and you exercise for as long and as hard as you can
and that peak heart rate which is
which is essentially 220 minus your age
If your heart copes fine, if you're not experiencing chest discomfort
and if you're ECG's don't show any significant changes
then that suggests that your heart is coping
it doesn't tell you whether you have any narrowings all it tells you is that you don't
have any significant narrowings
there are a few caveats though exercise testing is so
cheap and cheerful it's easily available however it's not very good in women and
we didn't quite know why but in women and treadmill test can often throw up
false positives so can suggest that there may be a problem
when in reality there is not and therefore treadmill testing is not
really recommended in women
but in men its very good and the other thing to say is the treadmill is
absolutely normal and you do a good exercise time
then it's highly unlikely that you have a problem
The second test I'd like to talk about another functional test is the stress
echocardiogram
and this is something I do this is my specialty
and in stress echocardiology what happens is you have an
echocardiogram which is a heart scan
only using ultrasound waves this is not dissimilar to
at the scans that pregnant women have when they have their babies looked at
completely harmless and so someone will scan your heart
see that it's moving okay and then put you on the treadmill
or give you some medications to speed your heart up
once your heart is beating at its maximum predicted
level you can come off the treadmill or the medication will stop and someone
will scan you again
and the idea is that if an area of the heart isn't getting as much blood as
it should
than that area of the heart should show less movement so if you see
good movement all over at rest and everything improves on exercise then you
could conclude
and that there is no significant narrowing in the heart
arteries, on the other hand if you see that there is this
area which isn't moving as well at stress but was normally moving at rest
then you could conclude that possibly that
the blood supply to that area has been compromised during exercise
and then that would then necessitate an invasive coronary angiogram to
need to be absolutely certain
The other test that is commonly used is something called a myocardial perfusion
scan
and in a myocardial perfusion scan what happens is
that you get given some dye
through a small cannula on the back of the hand, the dye is
essentially
radio labeled
you are then
put through a scanner
and the dye lights up
on the scan so essentially you expect the whole of the heart to be bathed
in the dye
so you take one picture then you then
stress the heart again either by going on a treadmill or by being given
medication if you struggle with the treadmill
and the medication will speed your heart up and at your maximum predicted
level you're given some more dye
and then rapidly taken to the scanner where your scanned again and again
you get another picture
so you get two pictures one at rest one at peak stressed
and basically it's a case of trying to look to see if there are any differences
if the heart is bathed in dye at rest and the heart is bathed in dye
at stress then you can conclude that there are no significant narrowing
if there is an area however at
stress which is not covered in dye
where as it was at rest then you could see it concluded that the likelihood is
that there is an obstruction to the blood flow
to the heart at times of stress
finally they may be the possibility that you get an area
at rest which is not, which does not show any dye
and does not change at all
at stress and a you can concluded that may well be a scar either a previous
or probable previous heart attack
has happened and therefore that area is scarred and therfore it's not taking any
dye at rest
nor any die at stress so those are the basic investigations
that need to be done
in an ideal world everyone would have a coronary angiogram
if it weren't for the risks associated with it because it
certainly answers the question so it really depends I think that
the idea is that if your cardiologists thinks that your
symptoms are very suggestive and you have risk factors
then in all likelihood they would want to do a coronary angiogram
if on the other hand your symptoms are a typical not
typically cardiac then one would probably want to do a non-invasive test
a functional test
or even a CT coronary angiography because its non-invasive
so that's about it for today and I
would like to thank you for listening to this
the I hope you found it useful known
if you have any questions please don't hesitate to visit my web site
where you'll find more tips on how to deal with the heart
and if you have any questions
email my website or give me a ring
so I'd like to wish you goodnight and thank you very much