Ambulance UK April 2024

FEATURE
FEATURE
DISCUSSION: Discussion: WHERE Where IS Is the THE Occlusion? OCCLUSION?
Jerry W. Jones, MD FACEP FAAEM
Jerry W. Jones, MD FACEP FAAEM
Figure 1
Figure 1 (repeated)
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I received
some excellent,
some
well-thought
excellent,
responses
well-thought
and I was
responses
artery – you’re
and
right!
I
But
was
you still
very
haven’t
impressed
answered completely.
with
A
the
very impressed with the degree of advanced skill that many of
superdominant right coronary artery can also produce ST elevation
degree of advanced skill that many of you demonstrated.
you demonstrated.
subtle. All three coronary arteries can create ST elevations in
more than one vascular area on the 12-lead ECG.
There is ST elevation in the inferior (II, III, aVF) leads and ST elevation in all the precordial
other. Apparently, the ST elevation in Lead III was greater than in Lead
Intermediate leads, though Level the ST elevation in Lead V6 is quite aVL because subtle. Lead All III has three retained coronary some STE while arteries the STE in Lead can aVL
has been totally neutralized.
create ST elevations in more than one vascular area on the 12-lead ECG.
OK… we’ve noted inferior ST elevation and anterior ST elevation.
in the inferior leads and ALL the precordial leads. However, the ST
elevation tends to be maximal in Lead V1 and diminishes as we follow
the leads leftward (not the case here). Also, an occlusion of the RCA is
Introductory Level
not going to result in ST elevation of Leads I and aVL. Again, that is not
Obviously,
Introductory
there is a lot of ST
Level
elevation on this ECG! We need to try to the situation here because we have ST elevation in both Leads I and
make sense of it. One reader suggested acute pericarditis. Pericarditis aVL. You don’t see the ST elevation in Lead aVL? That’s because you
is Obviously, characterized by there ST elevation is a that lot is of not ST restricted elevation to a particular on (or this ECG! need advanced We need level skills to to try see to it. make sense of it. One
single)
reader
vascular
suggested
area on the ECG.
acute
While
pericarditis.
that finding is true,
Pericarditis
it is not as
is characterized by ST elevation that is not
specific as we would like. Acute ischemia can frequently involve
restricted
more than one
to
vascular
a particular
region. If you
(or
look in
single)
Lead V6 you
vascular
will see a
area
Advanced
on the ECG.
Level
While that finding is true, it is
gradual not as downsloping specific of the as TP we segment. would That like. is called Acute Spodick’s ischemia Sign You should can have frequently noted that, although involve there is ST more elevation than in the one
and it is said to be characteristic of acute pericarditis. The problem is: inferior leads, Lead III has much less STE than Leads II and aVF. You
vascular region. If you look in Lead V6 you will see a gradual downsloping of the TP
this isn’t acute pericarditis! Thus, Spodick’s Sign is not always reliable also should have noted that there is ST elevation in Lead I which should
as segment. a sign of acute That pericarditis. is Look called at those Spodick’s “tombstones” (massive Sign and be accompanied it is said by STE to in be Lead characteristic aVL – but there doesn’t of appear acute to be
ST elevations) in Leads V2 – V4; you will never see ST elevation of that
pericarditis. The problem is: this isn’t acute pericarditis!
any in that lead.
Thus,
So we have
Spodick’s
two unexpected,
Sign
unexplained
is not
findings:
always
magnitude in acute pericarditis – never!
less STE in Lead III than in Leads II and aVF and essentially no STE
reliable as a sign of acute pericarditis. Look at those
in Lead aVL
“tombstones”
while ST elevation is present
(massive
in Lead
ST
I. Could
elevations)
there be a
There
in Leads
is ST elevation
V2 –
in
V4;
the inferior
you
(II,
will
III, aVF)
never
leads and
see
ST elevation
ST elevation connection? of that Yes! magnitude And that connection in is acute the fact that pericarditis Leads III and aVL –
in all the precordial leads, though the ST elevation in Lead V6 is quite are reciprocal to each other. Both have ST elevation but their systolic
never!
currents of injury are traveling in opposite directions (Lead III: down
and to the right, Lead aVL: up and to the left) and thus cancel each
Which vessel can cause ST elevation of BOTH those vascular areas? Let’s say two leads are reciprocal to each other, like Leads III
If you answered a type 3 (“wraparound”) left anterior descending and aVL…
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Intermediate Level
If one lead has acute ischemia with ST elevation and the other
remains nonischemic, the nonischemic lead will act reciprocally
and manifest the reciprocal changes of ST depression.
However, if BOTH leads manifest acute ischemia with ST elevation, supports (but doesn’t prove) an occlusion proximal to D1 and distal to
anterior
then based on
descending
their relative locations
artery
to each
–
other,
you’re
the ST
right!
elevations
But
S1.
you
If haven’t
still haven’t
noticed it, look
answered
again before continuing.
completely. A
will cancel each other and it is possible that both leads will have
3 (“wraparound”) LAD. Most people – between 75% to 80% – have
and infarctions.
located in the inferior wall caused by the occlusion of the LAD. So
maybe it is and maybe it isn’t proximal to S1.
OK… we’ve noted inferior ST elevation and anterior ST elevation. Which vessel can cause
As advanced ECG nerds, you should have noticed something that
ST elevation of BOTH those vascular areas? If you answered a type 3 (“wraparound”) left
superdominant right coronary artery can also produce ST elevation in the inferior leads and
normal-appearing ST segments!
The first septal perforator supplies blood to the right bundle branch.
ALL the precordial leads. However, the ST elevation Occlusions tends proximal to to S1 be will often maximal result in acute in Lead RBBB – a V1 very and
Which artery is occluded and at which level is the
ominous sign during an occlusion of the LAD. There is no RBBB
diminishes as we follow the leads leftward (not the case here). Also, an occlusion of the
occlusion located?
present on this ECG. While that adds to the likelihood that the
RCA is not going to result in ST elevation of Leads I and aVL. Again, that is not the situation
occlusion is distal to S1 and proximal to D1, it unfortunately doesn’t
The
here
infarct
because
related artery
we
(IRA)
have
– often
ST
referred
elevation
to as the “culprit”
in both
artery
Leads
prove
I
it.
and aVL. You don’t see the ST elevation
is the left anterior descending artery (LAD). In this case, it is a Type
in Lead aVL? That’s because you need advanced level skills to see it.
There is another issue with occlusions of a Type 3 (“wraparound”)
a Type 3 LAD. It is by far the most common type of LAD and, when LAD: the ischemia causing the ST elevation in Leads I and aVL can
occluded, can result in very complex, difficult-to-see acute ischemias – at times – perfectly cancel the ST elevation in Leads II, III and aVF!
Advanced Level
This will leave you with signs of acute ischemia only in the precordial
leads. Now, the ischemic changes in the precordial leads of this ECG
So, can we tell where the level of the infarction is located? We can are extremely impressive – but in other ECGs they may not be. In fact,
definitely You should say that it have is proximal noted to the that, first diagonal although branch there (D1) is ST the precordial elevation leads in may the show inferior nothing more leads, than hyperacute Lead III T waves has
because of the ST elevation that involves Leads V2 to V5, and the which could be missed by someone not as astute and skilled as you.
much less STE than Leads II and aVF. You also should have noted that there is ST elevation
ST elevation in Lead I (and presumably, Lead aVL). We used to think So, a proximal occlusion of a Type 3 (“wraparound”) LAD may appear
that in Lead if ST elevation I which were present should in Lead be V1, accompanied then the occlusion was by STE like in a Lead minor, distal aVL occlusion – but when there – in doesn’t fact – it is quite appear large! to be
automatically any in that proximal lead. to the So first we septal have perforator two branch unexpected, (S1). While unexplained findings: less STE in Lead III than
that is often, if not usually the case, it still doesn’t represent 100% And remember: most people have a Type 3 (“wraparound”) LAD.
in Leads II and aVF and essentially no STE in Lead aVL while ST elevation is present in Lead
assurance of a proximal location. We normally confirm an occlusion Exactly the kind of comforting thought that keeps you on your toes,
proximal I. Could to S1 there by presence be a connection? of ST depression in the Yes! inferior And leads, that isn’t connection it? The next time is you the see fact a patient that with Leads ACS type III chest and pain aVL –
but we don’t have that opportunity here because of the acute ischemia but the ECG appears normal – remember this!
are reciprocal to each other. Both have ST elevation but their systolic currents of injury are
traveling in opposite directions (Lead III: down and to the right, Lead aVL: up and to the left)
and thus cancel each other. For further Apparently, recruitment vacancies the ST visit: elevation www.ambulanceukonline.com
Lead III was greater than in Lead
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