We have arrived at acute myocardial infarction.
If you remember, we had discussed the two
different types of myocardial infarctions and I need
to make sure that we are clear about where
we are heading next. There were the transmural
type and you tell me if it is transmural,
entire wall has been affected and so,
therefore, you would find your obstruction
where exactly? Is it an artery or arteriole?
If you remember that functional anatomical
picture that I showed you of the left ventricular
wall and that is what we called it then the
coronary artery was on the superficial aspect
of the wall, on the surface by the pericardium.
Thus, if the coronary artery was to be affected,
then entire wall underneath was, so, therefore,
you then refer to this as being a transmural
infarct. So, as you move forward here and
when you see NSTEMI this refers to what the
actual patient is suffering from? A non-ST
elevation myocardial infarction and by that
we are referring to an ST depression. Or if
it is an ST elevation myocardial infarction
and if it is transmural of any type and I
walked you through the three major blood vessels
in our earlier discussion with left anterior
descending, with left circumflex, and also right
coronary artery, those will then result in
an ST-elevation myocardial infarction. Now
we are at a point where you need to make sure
that you put all of this together, please. As
we had discussed earlier, if the atherosclerotic
plaque becomes large enough and as you see
in the illustration here, there will be rupture.
And if there is rupture, then understand that
the central necrotic material including LDL
and such escapes into and embolizes distally
into the coronary artery, resulting in complete
occlusion, and may result in a transmural type of infarct
if it is artery. Once again, what kind of
myocardial infarction with that be if it is
transmural? ST elevation, depending on which
artery. Can I ask you a question? If it is
left circumflex, which leads are you referring
to? Lateral leads, which include please? V5,
V6, aVL and lead I. A nd these are things that
you discussed earlier in physiology and these
are things that we will continue discussing
as we move through our lecture series. Please
do not panic when you don't see certain points
on the slides. It is just the fact that we need
to discuss all this so that things come to
life and we will repeat and repeat and repeat
information until it becomes extremely familiar
to you. Now if the coronary artery
has been infarcted,
then we talk about how it would be let us
say something like acute myocardial infarction,
the death of the tissue. It is a coagulant
necrosis, isn't it? The architecture is preserved.
Why is that? Because of lactic acid production.
About 1/3 of the patients with AMI, unfortunately,
will not survive, why? Perhaps due to arrhythmia.
You completely messed up the conduction system,
may result in cardiac death.