DIAGNOSTICS OF
Acute Coronary Syndromes
At the end of this self study the participant will:
• Verbalize meanings of specific ECG changes:
– ST Elevation
– ST Depression
• Describe common tests used for patients with
suspected Acute Coronary Syndromes
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Abbreviations:
• ACS = Acute Coronary Syndrome
• STEMI = ST Elevation Myocardial Infarction
• AMI = Acute Myocardial Infarction
• PCI = Percutaneous Coronary Intervention (e.g.,
angioplasty, stents)
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Time is Still Muscle!
4 D’s of Timely Reperfusion
•
•
•
•
Door to Data (ECG)
Door to Decision
Door to Drug
Door to Dilatation
Goal < 10 min.
Goal < 20 min.
Goal < 30 min.
Goal < 90 min.
• Door can be time of patient arrival, or time the
patient tells nursing staff of possible ACS signs
and symptoms
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Door to Data: 10 minutes
• INITIAL DIAGNOSIS
– 12-LEAD ECG
• ST Elevation
– ST elevation MI (STEMI) – All High
Risk
• No ST elevation
– Acute Coronary Syndrome OR Non ST
elevation MI (Non STEMI)
» High, Intermediate or Low Risk
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Lead
Placement to
obtain a 12lead.
V lead
(chest lead)
placement
must be
exact.
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Normal 12 Lead EKG Configurations
In order to more easily recognize abnormalities in
the 12 lead ECG one must first be able to recognize
the normal 12 lead ECG
Look for:
•Flat baseline
•Little to no
artifact
(waveforms are
clear)
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12-lead changes seen in ACS
~ 2.0 MM patients admitted
to CCU or telemetry annually
ST Elevation
0.6 MM
ST-elevation MI
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ST depression
1.4 MM
Non-ST elevation ACS
T wave inversion
Ischemia
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Injury
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ECG Progression
in AMI
ST-segment elevation may occur
within the first few hours of
infarction.
ST-segment elevation is indicative of
injury that is leading to infarction.
When ST-segment elevation is seen,
time is limited and the healthcare
provider must act quickly to initiate a
reperfusion strategy in order to
salvage the most myocardium.
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From Garcia, et.al. (2001). 12 Lead ECG. The Art of interpretation, pg. 408. Used by permission.
Non-diagnostic ECGs
• According to the National Registry of Myocardial
Infarction, only 39% of Acute MI patients have
STEMI on admit
• Subsequent STEMI occurs within 12 hrs of symptoms
• Acute MI patients who present & maintain normal or
nonspecific ECGs have lower mortality rates;
Increased mortality risk associated with development
of STEMI
Fesmire, FM, et al. Ann Emerg Med. 1998: 31: 3-11.
Littrell, KA, et al. JACC. 2001: 37 Suppl A p. 1282-101.
French, WJ, et al. NRMI 4 Special Report, June 2001
Welch, RD, et al. JAMA, 2001: 286: 1977-1984.
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Door to decision: 20 minutes
• Based on ECG and patient presentation
• Does not require lab data nor advanced assessments
such as angiography (cardiac catheterization)
• If decision is AMI, treatment planned
– Door to Drug 30 minutes
– Door to Dilatation (PCI) 90 minutes
• If decision is not AMI, further evaluation is required
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ACS
DIAGNOSIS
• CARDIAC
ENZYMES
– Negative
• Unstable
Angina
• Non-cardiac?
– Positive
• MI
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Serum Enzyme Changes
Onset
Peak Time
CPK-MB
4-6 hours
12-24 hours 2-3 days
Troponin-I
4-6 hours
Myoglobin
1-2 hours
12-24 hours Up to 10
days
4-6 hours
24 hours
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Duration
Diagnostic Tests
Echocardiogram evaluates:
• Wall motion and valve function
• Ejection fraction (EF)
– % of blood pumped out of
ventricle with each beat
– normal = 60-70%;
– failure = < 40%
– The greater the damage,
the greater the muscle loss, the lower the EF
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Diagnostic Tests
Stress Testing: only performed if
enzymes are negative.
• ECG
• Perfusion Studies (indicate capillary
perfusion = better predictor)
– Exercise Thallium
– Dobutamine Stress Echo
– Adenosine Thallium
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Cardiac Catheterization
(Angiography)
• Access: radial, brachial or
femoral arteries
If we can upload from YouTube,
there’s a terrific video (no audio)
of a cath
http://www.youtube.com/watch?
v=yzxSrLa1d0g
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Photo under fluoroscopy
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Possible Post-Cath Complications
•
•
•
•
•
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Hypotension
Active Bleeding
Limb Ischemia
Recurrent Ischemia/MI
Arrhythmias:
Ventricular and
Bradycardia
• Contrast Reaction
• Contrast Nephropathy
• Congestive Heart
Failure
• Neuro Deficits
Post Cath Care
Sheaths are used with all PCI’s
– Assess for bleeding at site, and under the site;
outline ecchymotic areas
– Note any perfusion changes around site
– Palpate abdomen for firmness or distention
– Be alert to changes in oxygenation assessment and
hemodynamic status
• If bleeding is seen at site, place immediate manual
pressure
• Monitor peripheral pulses
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Next: ACS Treatments
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