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ISCHEMIA.pptx
1. ACPAcademy Cardiology
STEMI, N-STEMI, and
everything else
Ada County Paramedics
Section 5
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linical Education
April 2008
5. Measuring ST Changes
ACPAcademy Section 5: Advanced Clinical Education Cardiology
• Baseline is correctly determined by finding the T-P to T-P
segment. (If TP not measureable, then preceeding P-R interval
can be used.)
• ST changes are measured 0.08 sec after the “J-point”.
• Changes must be present in 2 or more leads of a “lead group”
to be significant.
• ST elevation or depression of 1 mm or greater in frontal plane
leads is considered significant.
• ST elevation or depression of 2mm or greater in precordial
leads is considered significant.
• ST elevation of 0.5mm or greater in R precordial leads is
considered significant.
6. T-wave Changes in Ischemia
ACPAcademy Section 5: Advanced Clinical Education Cardiology
• Appear within seconds of onset of AMI
• Appear over zone of ischemia
• May be tall and or deeply inverted depending
on location of ischemia
• Symmetry is important finding in ischemia
• Are associated with prolonged QT interval
• Often associated with ST depression
9. T-Wave Changes In Ischemia
Tall, symmetrical T-Waves With ST Elevation
Section 5: Advanced Clinical Education Card
ACPAcademy iology
10. ST Depression in Ischemia
ACPAcademy Section 5: Advanced Clinical Education Cardiology
• ST depression is a sign of myocardial
ischemia and can appear in setting of
ischemia from any cause.
• Onset is usually within first hour of AMI, or
more rapidly in other causes of ischemia.
• Often associated with T-wave changes
• Can resolved rapidly with reversal of
ischemia.
• May persist in setting of AMI.
• Mimics include: Coronary artery spasm, acute
pericarditis, ventricular aneurysm.
11. Types of ST Depression
ACPAcademy Section 5: Advanced Clinical Education Cardiology
12. ST Elevation in AMI
ACPAcademy Section 5: Advanced Clinical Education Cardiology
• Abnormal ST elevation is an ECG sign of
myocardial injury.
• Usually occur within 20-40minutes following onset of
infarction.
• ST Elevation mimics: pericarditis, early
repolarization, LVH with strain pattern.
13. Reciprocal Changes?
• Reciprocal ST segment
depression: In the setting of STE
AMI, ST segment depression located
in leads distant from the infarction is
termed reciprocal change or
reciprocal ST segment depression.
• Reciprocal change is useful
– diagnostically— its presence strongly
suggests AMI
– prognostically— patients with such a
finding have larger infarcts, lower
resultant ejection fractions, and
higher rates of death.
ACPAcademy Section 5: Advanced Clinical Education Cardiology
14. S-T changes and their location?
ACPAcademy Section 5: Advanced Clinical Education Cardiology
15. Cardiac Anatomy in Relation to
Coronary Artery
Right
coronary
artery
Septal wall
ACP Academy V1-V2
Anterior wall
V3-V4
Left main
coronary
artery
Circumflex
artery
Left anterior
descending artery
Lateral wall
I, aVL, V5-V6
Section 5: Advanced Clinical Education Cardiology
20. ACPAcademy Cardiology
NOTE 1: Inferior wall
supplied by either the right
(85% to 90% of people) or
left coronary artery.
NOTE 2: If there is acute
injury in inferior leads
(II, III, aVF), unknown
whether left or right
coronary artery is blocked.
NOTE 3: KEY — you
must obtain a RIGHT-
SIDED ECG at once.
Posterior View of the Heart
HOW TO GET
RIGHT-SIDED ECG?
Leads II, III, aVF
Lateral wall
Inferior wall
Right coronary
artery
Posterior
descending
Section 5: Advance
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Posterior
wall
Circumflex
artery
(from left
coronary
artery)
21. Right Ventricular Infarction
• Inferior lead changes ➨ RV infarction?
–Use lead V4R (ST elevation >1 mm)
• Clinical significance:
–Increased mortality
–Preload dependence
• Vasodilators (Nitrates, MSO4) may cause severe
hypotension
• What is management of RV infarction?
–Increase PRELOAD!! (FLUIDS)
ACPAcademy Section 5: Advanced Clinical Education Cardiology
24. ACUTE CORONARY SYNDROMES
ST elevation
Unstable NSTEMI
angina
STEMI
Spectrum of CAD
No ST elevation
Stable
angina
CAD = coronary artery disease; NSTEMI = non-ST-segment elevation myocardial infarction;
STEMI = ST-segment-elevation myocardial infarction.
Source (Photos): Davies MJ. Heart. 2000;83:361-366.
ACPAcademy Section 5: Advanced Clinical Education Cardiology
25. STEMI Mimics
ACPAcademy Section 5: Advanced Clinical Education Cardiology
• Things that make you go … HMMMM
• Things that look (at first glance) Like a
STEMI or other MI pattern, but are NOT.
– Increase “false positive rates”
• Still may be deadly serious conditions
26. The basics of doing the 12
lead
ACPAcademy Section 5: Advanced Clinical Education Cardiology
27. The Basic 12 Lead
ACPAcademy Section 5: Advanced Clinical Education Cardiology
28. Lead Placement for a
Right-sided ECG
ACPAcademy Section 5: Advanced Clinical Education Cardiology
29. The importance of serial 12 leads
ACPAcademy Section 5: Advanced Clinical Education Cardiology
33. Most common causes of STEMI
mistakes
ACPAcademy Section 5: Advanced Clinical Education Cardiology
• RBBB/LBBB
• Pericarditis
• LVH
• Electrolyte Imbalances
• Drug Effects
34. Bundle Branch/Fascicular
Blocks
ACPAcademy Section 5: Advanced Clinical Education Cardiology
• LBBB always indicates cardiac disease or injury.
• Just not always ACUTE injury
• Just not always MI, other “Mimics” can also cause BBB
• “Making the diagnosis of acute infarction
in the presence of left bundle-branch block
can be problematic…”
– PROBLEM: Patients with (suspected new)
LBBB tend to be REALLY BAD MI’s.
35. Bundle Branch/Fascicular Blocks
Right Bundle Branch Block
• Do not rely on presence of “rabbit ears”
for diagnosis of RBBB. Will miss many
RBBBs.
ACPAcademy Section 5: Advanced Clinical Education Cardiology
36. AMI with BB?
ACPAcademy Section 5: Advanced Clinical Education Cardiology
• AMI should be no problem
• RBBB does not change S-T segment
alterations
• LBBB can make things more interesting
37. Again with the serial ECGs???
• Even though the
LBBB makes initial
ST evaluation difficult,
the serial changes
noted make this
diagnostic for MI.
ACPAcademy Section 5: Advanced Clinical Education Cardiology
40. STEMI Mimics
ACPAcademy Section 5: Advanced Clinical Education Cardiology
• Pericarditis
1. No reciprocal changes. There will only be
S-T elevation, no depression.
2. The myocardium is not involved. No
changes will be noted to the QRS complex.
3. Changes isolated to the S-T-T waves
