Transcript ECG Changes - Calgary Emergency Medicine

ECG Rounds: Pulmonary
Embolism
Todd Ring
Jan 08/04
Case
• 72 yo male with CLL
• Unwell for 4-5 days with fatigue
• SOB x’s 2 days, abrupt onset, progressively
worse
• Denies CP
• Mild respiratory distress
• HR 113 RR 34 BP 135/60 SaO2 85 % RA
Case
• CVS: pulse reg, S1 S2 (wide split) II/VI
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SEM
Chest: Clear
Ext: tender L popliteal fossa
TNT: 2.8
D-Dimer: 4.79
Background
• The initial electrocardiographic finding of PE first
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reported in 1935 was the traditional S1Q3T3
21 different ECG manifestations of PE
ECG changes are best seen in those patients with
massive or submassive embolization
Studies have shown that 15% to 27% of ECG
were normal
The most common abnormalities are nonspecific
ST segment-T wave changes with sinus
tachycardia
Pathophysiology
• Clinical and ECG changes related to the response
of the right ventricle to the PE
• Majority of findings result from the right-sided
heart strain pattern
the increase in right-sided heart pressures creates an increased right
ventricular afterload
increased right-sided myocardial wall tension
rapidly dilates, with an increase in chamber size and eventual
contractile dysfunction
reduction in right heart cardiac output (ie, a reduction the preload
for the left ventricle) which ultimately produces a decrease in left
heart cardiac output
as right-sided ventricular dysfunction worsens, right ventricular
infarction and circulatory collapse may occur
ECG Changes
• Arrhythmia (sinus tach, atrial tach, atrial fib, atrial
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flutter, PAC)
Nonspecific ST segment/T wave changes
T wave inversions in the right precordial leads
Rightward QRS complex axis shift and other axis
changes
S1Q3 or S1Q3T3 pattern
RBBB
Acute cor pulomnale defined by S1Q3T3 pattern,
right axis deviation, and RBBB
“Normal ECG”
• Sinus rhythm between 60 and 100 beats/min
• Normal conduction, axis, and P wave, QRS
complex, and ST segment/T wave
morphologies
• An entirely normal ECG has been found in
approximately 10% to 25% of PE patients
• a number of such patients will continue to
manifest a normal ECG during hospitalization
Sinus Tachycardia
• Sinus tachycardia is the most frequent rhythm
encountered on presentation to the ED in the
patient with PE
• The rate is usually between 100 to 125 beats/min
• Likely related to the physiologic demand to
increase cardiac output
• as left-sided stroke volume decreases, heart rate must
increase to maintain cardiac output.
Sinus Tachycardia
Atrial Tachyarrhythmia
• Primarily atrial fibrillation and atrial flutter,
also PAC’s
• Likely results from atrial enlargement
Atrial Fibrillation
RBBB
• Variable incidence reported 6 – 67 % (25 % often
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citied)
Transient and often resolves with the restoration of
normal right-sided hemodynamic parameters
May persist ultimately resolving 3 months to 3
years after the index
New RBBB is suggestive of PE but still
nonspecific and therefore not diagnostic
May also be associated with ST segment elevation
and prominent, upright T waves in lead V1 and/or
V2, potentially mimicking anterior or posterior
infarct pattern
RBBB
QRS Axis Deviation
• Right, left, and indeterminant QRS axis changes n
reported in acute PE
• Although right axis deviation (RAD) is described
as the classic axis change associated with PE, left
axis deviation (LAD) actually occurs more often
• may be secondary to pre-existing axis deviation
• in the Urokinase-Pulmonary Embolism Trial (UPET),
the investigators report that LAD occurred more
frequently than RAD in the PE study population
however when those individuals with pre-existing
cardiopulmonary disease were excluded, the incidence
of LAD and RAD was equivalent
P-Pulmonale
• Increase in the P wave amplitude greater
than 2.5 mV in lead II
• Classically associated with PE, likely
resulting from right atrial hypertrophy or
enlargement associated with acute
obstruction from clot
• Reported in 2% to 30% of PE patients
P-Pulmonale
S1Q3T3
• Characterized by an S wave in lead I, a Q wave in
lead III, and shallow T wave inversions in one or
more of the inferior leads
• ST segments may be slightly elevated in the
inferior leads
• Although this finding is consistent with right-sided
cardiac changes, it remains unclear if this finding
actually predicts PE
• The S1Q3T3 pattern is usually short-lived,
resolving within 2 weeks after PE
S1Q3T3
• Mistakenly considered pathognomonic for acute
PE by many clinicians
• 15% to 25% of patients ultimately diagnosed with
PE have this pattern
• The UPET reveals that approximately 12% of
patients with angiographically documented acute
PE initially had the electrocardiographic S1Q3T3
• Often considered strongly suggestive for PE when,
in fact, poor specificity—approximately 50%—for
the diagnosis of PE
S1Q3T3
S Wave Changes
• S wave in lead I greater than 1.5 mm and/or
an R wave-S wave ratio greater than 1 in
leads I and aVl was noted in 73% of
patients diagnosed with PE
• A more subtle finding is a slurred S wave in
leads V1 and/or V2.
S Wave in V1
ST Segments
• May be either depressed or elevated
• Minimal ST segment depression is a common
finding
• More pronounced depression may also be
encountered in the anterior, inferior, and lateral
distributions
• likely represents myocardial ischemia resulting from
the physiologic strain of the PE itself
• The S1Q3T3 pattern may be associated with ST
segment elevation in the inferior leads. The RBBB
pattern may present with ST segment elevation in
the right precordial leads
ST Depression V2-V6
ST Elevation V2-V5
T Wave Inversion
• Anterior subepicardial ischemia caused by PE
manifests as inverted T waves in the right to mid
precordial leads (leads V1 to V3)
• Early studies attributed this pattern to coronary
insufficiency
• More recent studies suggest either
cathecholamine- or histamine-induced ischemia
• Diffuse T wave inversion rarely is diagnostic for
PE
T Wave Inversion V1-V4
Evidence?
• Nielsen et al. found 82% of cases of documented
had electrocardiographic changes suggestive of
acute right ventricular strain. These findings
included:
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Incomplete right bundle branch block;
S1Q3T3 pattern;
Q wave in lead III;
Inverted T waves in leads III, V2 and V3; and/or
Increase in the frontal QRS axis of >20 degrees.
Nielsen et al: Changing electrocardiographic findings in pulmonary embolism
in relation to vascular obstruction. Cardiol 1989;76:274-284
Evidence?
• Sreeram suggests that PE should be considered
when 3 or more of the following
electrocardiographic changes are encountered:
• Incomplete or complete RBBB;
• Large S waves in leads I and a VL;
• A shift in the transition zone in the precordial leads to
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V5
Q waves in leads III and aVF (not lead II);
Right-axis deviation;
A low voltage QRS complex in limb leads; and/or
T wave inversion in inferior and anterior leads
Sreeram et al.: Value of the 12-lead electrocardiogram at hospital admission
in the diagnosis of pulmonary embolism. Am Cardiol 1994; 73:298-303
Evidence?
• Petruzzeli et al. studied 21 electrocardiographic
abnormalities in 245 patients with suspected PE—
60% of patients ultimately had PE. Those patients
diagnosed with PE were found to manifest the
following patterns more commonly:
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PR segment displacement;
Delayed R wave (lead aVr);
Slurred S wave (leads V1 or V2);
S1Q3T3 pattern;
T wave inversion (leads V1 or V2); and/or
Diffuse T wave inversions
Petruzzelli et al.: Routine electrocardiography in screening for pulmonary
embolism. Resp 1986; 50:233-43
Evidence?
• Nazeyrolas studied 70 patients with
suspected PE and found only an S wave in
lead I and Q wave in lead III significantly
more common among those with confirmed
PE
Panos et al. The electrocardiographic manifestations of pulmonary embolism.
Emerg Med 1988; 6:301-7
Canadian Evidence?
• Rodger et al. studied the ECGs of 246 patients
with suspected PE (49 with PE) comparing the
frequency of 28 different ECG findings of PE
• only found sinus tachycardia and incomplete RBBB
significantly more common in PE patients
• Sreeram's guide of 3 or more findings on the ECG had
only a 26.7% sensitivity and 57.1% positive predictive
value for PE
• the S1Q3T3 pattern was equally prevalent among those
with and without PE
Rodger et al. Diagnostic value of the electrocardiogram in suspected
pulmonary embolism. Am Cardiol 2000; 86:807-9
Fig. 7.