Well the heart is a complex structure we think of it as one organ but
essentially it’s a muscle pump it has valves inside it has the pipes
that provide nourishment to the heart muscle and it also has a very intricate
electrical system unfortunately we don’t have any single
investigation that gives us complete answers about all aspects of
the heart, we therefore have different investigations that look at specific
aspects of heart and that’s why we have a wide variety of
different investigations and we pick and choose each
investigation based on patient symptoms and the clinical scenarios. This is sound-based examination of the heart we introduce through the
machine sound waves which are then reflected
and construct a picture of the heart. Because it is sound-based it’s
completely harmless and non-invasive it exposes you
to no radiation. To begin with we used to have echocardiogram in one plane and then
with the last 20 years we’ve been using two-dimensional echocardiogram more recently over the last few years
there has been an enormous new development of a three-dimensional echocardiography. Well palpitations is a very very common
symptom and essentially this is due to either extra heartbeats in the rhythm of
the heart or it is due to some kind of electrical
short circuiting now essentially we need to pick up the
arrhythmia as we call it and the basic, the first and foremost
investigation is going to be a simple twelve-lead ECG which is simply a snapshot of the
electrical activity of the heart at that particular moment but as you can
appreciate patients may not develop palpitations at
that time and therefore we have to have a
mechanism where we can capture the heartbeat over a prolonged period of time and that’s why we have the ability now
to record your heartbeat for 24 hours or to record it for 3, 5 or 30 days and in case of patients who have
symptoms very very occassionally we can implant little
small devices under the skin for up to a year and they keep recording
the heartbeat. The second essential investigation that a patient with palpitations will require
is the echocardiogram which is based on echocardiography
essentially sound-based examination of the heart. Now this is essential
because this simple investigation that takes 10
minutes and is completely non-invasive will give us complete information about
the size of heart chambers the function of the heart, the state of the
heart valves and several other aspects of pressures within the heart and this is the key to
finding an underlying heart problem for example palpitations with a
structurally and functionally normal heart are by far and large benign. So we’ve got no concerns about them but if the
palpitations are due to underlying heart disease then we need to pick it up and treat that
first. Well breathlessness can be multifactorial but in general people can get breathless
either due to lung disease or heart disease and if you do suspect
heart disease an echocardiogram, ultra sound-based
scan is the first starting point. It’s not
always possible to get very clear pictures from the surface echocardiogram and therefore sometimes we inject
certain agents in the arm, in the vein, which brightens
up the heart and that is called contrast echocardiography. If sometimes that again doesn’t give us enough
information we move on to the next level which is a slightly more complex
investigation call the transesophageal echocardiogram
essentially what it means is we ask the patient to swallow a small
probe and we look at the heart from behind from the food pipe and get very very
clear pictures We fortunately now, we are one of the centres in the country where we have three-dimensional transesophageal
echocardiography available in the country and that gives
us very precise information particularly about the heart valves. Every chest pain has to be taken
seriously and it is true but there are many other
causes of chest pain like simple muscle cramp but we’re always concerned in case it
is the heart because amongst all the other causes of chest
pain the most important bit and the dangerous bit is the heart. In general investigations for heart chest pain what
we call as angina which is due to lack of blood supply to
the heart muscle, they fall into two broader categories, we have anatomical tests and we have functional tests. Anatomical
tests enable us to look at the anatomy of the
heart vessels, the pipes that bring nourishment to the heart muscle it tells us how many pipes, whether they
are beginning to develop any furring, whether there’s early plot deposition those
are the anatomical tests. The functional tests evaluate the
amount of blood flow into the heart muscle and the effect of furring up of your pipes
on the function of the heart. If you suspect angina you need to look
at the pipes of the heart to see if they are either beginning to develop any furring
or they have any blockages, now to do that there are broadly speaking two
ways of achieving the same goal, one is that you perform invasive coronary angiography and the
other is you perform a CT scan based non-invasive coronary
angiography. I’m not going to touch upon the invasive
angiography because that will be covered. The non-invasive angiography
essentially requires injection of a dye in the arm and you go through a CT scanner and it is
completely non-invasive because we do not interfere with the body in any way. I think it is essential to
understand the fundamental differences between the two techniques I want to clarify that both of these
techniques expose patients to radiation however
the dose of radiation given in a non-invasive CT is less than half of that of the invasive angiography. Secondly, of course, non-invasive CT angiography does not give you any kind of risk of invasive complications. The third and important aspect is that CT scan enables you to look at
early developing atheromas or areas of furring up which cannot be seen through invasive coronary angiography so based on these factors what the
national guidelines now dictate is that people who are low-to-intermediate
risk of developing heart disease, or suspicion is low or intermediate,
should go through the non-invasive CT scan and if you suspect that someone has a
high risk of having significant disease then you should perform invasive
coronary angiography. Functional tests for angina are indeed
very important because they determine what is the final effect of furring up in the heart vessels. In general there are three kinds of tests that are used one is the good old treadmill exercise
test, one is what you call as a stress echo which I will explain in a while, and one is a nuclear perfusion scan The good old treadmill has a
sensitivity of about 67%, 70% at most, however the other two modalities which
is the stress echo, and and myocardial perfusion scan have a
sensitivity of over 90%, and it is for this reason now that most
of the national and international guidelines recommend not using the treadmill test, instead using stress echoes or nuclear perfusion scan. It’s a test where we stress the heart out one way or the other and then take
images of the heart through an ultrasound which is an echo scanner, to see what is the
performance of the heart under stress. Essentially we can either exercise the
patient on a cycle which is the bicycle exercise echo or
we can inject a medicine in the arm to a small cannula in the arm and that stimulates the heart. Now the
injection in the arm enables us to perform the test on
those people who are not able to walk or cycle, for example people
with arthritis, or other reasons for not being able to
exercise, and when we inject and we stimulate the heart we keep taking pictures through the
ultrasound scan and look at the performance of the heart. A nuclear perfusion scan is again part of the family of functional
tests of the heart. It is done on very similar principles
to a stress echo that we have to have a means of stressing the heart either by exercise or by injecting a
medicine in the arm however instead of taking pictures of
the heart through an ultrasound scanner we in fact inject some radio-isotope dye
which is taken up by the heart muscle and it is taken up by the heart muscle
in proportion to the amount of blood flow. The test is
usually performed in two settings one during a period of stress on the heart
and one without stress on the heart and we then compare the two images to
determine if there’s any element of angina. I must make it very clear that by default the preferred choice is a stress echo because that involves no exposure
to radiation. The perfusion scan is done in those
patients who are not suitable for one, reason or the other, to undergo a stress echo instead. Well heart surgery is a major operation
and therefore we want to take every care that all aspects of management are properly looked after. We want to
make sure that the patient is suitable for surgery we want to make sure the patient is
fully prepared for surgery and we want to minimise any
complications that can occur during surgery, therefore
your treating physician or surgeon would definitely require a battery of blood tests which will check that your liver and kidney functions are for example normal. We need to assess the function of
the heart we need to get the anatomy of the heart
vessels and therefore you would require an echocardiogram and
you will either require a CT based non-invasive angiogram or an invasive coronary angiogram. Apart from that your lungs have to be checked therefore
there will be some formal lung function tests and similarly we want to make sure there’s
no furring up in your blood vessels going to the brain
so that the risk of stroke is minimised. So it’s
not just one investigation there will be a battery of investigations that will be required before heart
surgery. Well it depends upon the type of heart
surgery but in general every patient will require an ultrasound echocardiogram of the heart. It is mandatory to assess the heart
function after any form of heart surgery because
the long-term survival of patients depends upon the heart function amongst
few other things. The rest of investigations will depend
upon the symptoms, if patient complains of any,
if patient complains of chest pain we may need to look at the bypass graft, we
may need to look at the native heart vessels and that can
be done through a non-invasive CT scan or invasive angiography. If patient complains of breathlessness then any form of echocardiography will be required and there are several other investigations that
we may resort to but that depends upon the patient’s clinical scenario after surgery.