hi let's talk about your coronary arteries your coronary arteries are the arteries that serve
your heart and especially that metabolically active myocardium now this is a fairly unusual
view of the heart and what you're looking at here is a superoposterior that means a little above
and a little behind view of the heart with the atria removed and so this is anterior this is
posterior this is left and this is right and we can see a couple of valves here so here's
your tricuspid valve and your bicuspid valve and here is the semilunar a aortic valve and
there is the semilunar pulmonary valve and what I want to draw your attention to are the origins of
these coronary arteries so there's the origin of the right coronary artery known as the RCA
for short and here is the origin of the left coronary artery or the LCA for short and what
we have a pristine view of is the coronary sulcus so that is the groove that these coronary arteries
are riding in and it's what separates the atria from the ventricles and so when most people here
coronary they think of oh that relates to the heart well actually coronary is in reference to
a coronal or a frontal section which is basically what you're looking at from this view with the
coronary sulcus so cardiac is how we refer to the heart and so we're really talking about cardiac
circulation and that's driven by the coronary arteries so here we can see an illustration
of the heart from the anterior as well as the great vessels and the coronary arteries both
the right coronary artery or the RCA and the left coronary artery or the LCA now there are typical
branches or patterns of distribution from each of these coronary arteries so for instance the
right coronary artery comes off of the ascending aorta and it spawns the SA nodal branch sine ooh
atrial nodal branch it also then descends in the coronary sulcus to give rise to the right
marginal branch that right marginal branch is supplying the myocardium of the right ventricle
and then it continues along posterior Li and we can't see this just yet - typically supply the
crux of the heart which is giving rise to the AV nodal branch and posterior interventricular branch
supplying the AV node and the posterior aspect of the interventricular septum respectively the
LCA also arises from the ascending aorta and it travels between the pulmonary trunk and
the left auricle of the atrium and gives rise to two branches there's the anterior
interventricular branch also known as the left anterior descending or el-ad that rides down the
anterior interventricular sulcus to supply the anterior portion of the interventricular septum
we also have the circumflex branch riding in the coronary sulcus that wraps around a little to the
posterior aspect of the heart that gives off the left marginal artery there so when we're looking
at the anterior aspect of the heart there are really three major arteries that we care about
the anterior interventricular branch the left marginal branch and the right marginal branch
now when we discuss the RCA and the LCA keep in mind that there's going to be some variation
so you'll notice that there are these asterisks next to some of these vessels and these asterisks
are meant to indicate that these are typically branches of the RCA so for instance about 60%
of the time that sa nodal branch is going to come from the RCA which means about 40% of the time it
will originate from the LCA likewise about 67% of the time the RCA is going to supply the crux
of the heart which is going to supply both the AV nodal and the posterior interventricular branch
and what that means is about 33% of the time the crux of the heart is going to be supplied by the
LCA so here posteriorly we can see some of the the continuation of the RCA and the LCA more
of the RCA than the LCA but we can see the LCA coming down as the circumflex in that coronary
sulcus we can also see the RCA wrapping around in that coronary sulcus to give rise to the AV nodal
as well as the posterior interventricular branch so this would be the most common pattern of blood
distribution we could also see this on a cadaveric specimen and I really like to show these
views because they're a little more true to life and a little more relatable than the illustration
so here we can see the ascending aorta here is the right oracle there's the origin of the RCA
and here we have the SA nodal branch and then the RCA is going to continue down we can also see the
right marginal branch following the inferior margin of the heart there a little more of a
right lateral view we can see that RCA diving down giving rise to the right Mar no branch and
then the continuation of the RCA in the coronary sulcus for the inferior surface of the heart here
we can see an inferior view or the diaphragmatic surface of the heart we can see there's where the
inferior vena cava drops in here's the apex of the heart so this would be the posterior portion
of the heart here's the RCA wrapping around we can see that right marginal branch going off
that way the RCA continues and this area here is called the the crux of the heart and that's where
we have our AV nodal branch dive deep into the fiber skeleton the heart to supply the AV node
and the posterior interventricular branch riding down that posterior interventricular sulcus to
help supply the interventricular septum here's a superior view of a cadaveric heart there's
the origin of the LCA and we can see the anterior interventricular branch heading down and supplying
the myocardium of the heart there sometimes this anterior interventricular branch is known as the
left anterior descending artery or the el-ad by clinicians the other branch of the LCA they're
coming around is the circumflex branch and that's giving rise to your left marginal artery and
then the circumflex branch continues on to the posterior aspect of the heart so here we can see
a lateral view here's the circumflex branch coming down there's our left marginal artery of the heart
the the last thing that i would like to discuss with you is the phenomenon of heart dominance
heart dominance is defined many different ways by many different people but it most correctly
describes the vasculature of the crock of the heart now we talked a little bit about
how variable vasculature may be we talked about how typically that posterior interventricular
and AV nodal branch are supplied by the RCA and this is a condition known as right dominance it
doesn't always have to be that way sometimes the circumflex branch comes down to supply the crux
of the heart and gives rise to the AV nodal and the posterior interventricular branch and
that's known as left dominance when it's the LCA supplying those we also have a condition known as
codominance where both the RCA and the LCA supply the crux of the heart now why dominance matters
is that with left dominance you would have the LCA responsible for both the anterior interventricular
sulcus and the posterior interventricular sulcus so the LCA is supplying the entirety
of the interventricular septum with blood and any occlusion of that LCA is going to most certainly
lead to a massive coronary infarction and the death of the interventricular septum now all is
not lost if there happens to be an occlusion of a coronary artery so when atherosclerosis
builds up in the walls of a coronary artery that something known as CAD or coronary artery disease
which we can see here and this plaque here is starting to narrow the lumen of the coronary
artery sometimes it may completely occlude the lumen or it may break off and embolize and then
clog up the artery more distally here we can see some of the more common locations for occlusions
so the most common location is for the anterior interventricular branch or the led the second most
is for the origin of the RCA the third most is for the circumflex and the fourth most is for the
origin of the LCA and so for an individual with a left dominant heart if they have an occlusion
of the LCA or an occlusion of both the anterior interventricular branch and the circumflex branch
then they're losing the entirety of blood flow to the heart one of the solutions to coronary artery
disease is a coronary artery bypass graft called a cabbage for short CABG and the gist of this
is that you take a healthy vessel this could be from a donor or it could be from an individual's
own vasculature which is vastly preferred because there are no issues of autoimmunity
so for instance they may harvest if there's good collateral circulation of the arm the radial
artery from the forearm and then they would take a piece of that radial artery and they would suture
it to an area where there is good strong blood flow such as the ascending aorta and then they
may continue that beyond the site of occlusion so this would be an example of a cabbage where
the RCA is occluded fairly high up in its origin so if the occlusion is there this cabbage allows
the continuation of blood flow past the sight of that occlusion so we've talked about the right
and the left coronary arteries their branches their distributions the tissues that they serve
how they might be in terms of variation and what clinicians might do when things go wrong thank you