Standardization & Interpretation of
ECG
Dr Frijo Jose A
Normal QRS Duration
• ↑with ↑ heart size
•
•
•
•
•
Wider - precordial > limb leads
Age- and gender-dependent
Children <4 yrs -QRS ≥90 ms prolonged
4 -16 yrs –QRS ≥ 100 ms prolonged
Adult males – N-QRS up to 110 ms
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Mean Frontal Plane Axis
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Shifts to the left with increasing age
Complete RBBB
QRS ≥120 ms (>16 yrs), >100 ms (4-16 yrs), >90
ms (<4 yrs)
rsr’, rsR’, or Rsr’ - V1 or V2. R’/r’ - Usually wider
>R
S duration > R or >40 ms (I&V6)
Normal R peak time (V5 & V6) but >50 ms (V1)
• First 3 should be present to make ∆
o V1- pure dominant R wave ± notch → Criterion 4
should be satisfied
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Incomplete RBBB
• QRS duration
110 -120 ms (adults), 90 - 100 ms (8 -16 yrs),
86 - 90 ms (<8 yrs)
• Other criteria - Same as for complete RBBB.
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Complete LBBB
1. QRS ≥120 ms (Adults),>100 ms (4-16), >90 ms ( <4)
2. Broad notched /slurred R wave - I, aVL, V5, V6
3. Absent q waves - I, V5, V6 (±q Avl)
4. R peak time > 60 ms in V5 & V6 but N in V1, V2,& V3
(when r+)
5. ST & T - Usually opposite in direction to QRS
6. + T wave with upright QRS may be N (+ concordance)
7. ↓ST and/or −T with −QRS (- concordance) -ABN
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Criteria for infarction in the presence of complete
left bundle-branch block(GUSTO)
•
•
•
•
ST↑≥0.1 mV in leads with +QRS (concordant ST)
ST ↑≥ 0.5 mV in leads with −QRS (discordant ST)
ST ↓≥ 0.1 mV in V1-V3 (concordant ST)
Concordant ST changes -↑specificity but ↓
sensitivity
• Discordant ST changes - ↓↓ specificity ↓↓
sensitivity
• LBBB + concordant ST > 30-d mortality > LBBB +
enzyme -- concordant ST changes
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Incomplete LBBB
• 1. QRS 110 -120ms (adults),90 - 100ms(8 -16),
80 - 90ms (<8)
• 2. Presence of LVH pattern
• 3. R peak time >60 ms in leads V4, V5, and V6
• 4. Absent q in I, V5, V6
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Nonspecific/Unspecified
Intraventricular Conduction Disturbance
• QRS >110ms (adults), >90ms (8 -16), >80ms
(<8) without criteria for RBBB or LBBB
Also
• RBBB criteria in precordial leads and LBBB
criteria in limb leads, and vice versa
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Left Anterior Fascicular Block
•
•
•
•
1. Frontal plane axis -45°to -90°
2. qR pattern in aVL
3. R-peak time in aVL of ≥45 ms
4. QRS duration <120 ms
These criteria do not apply to patients with CHD
in whom LAD is present in infancy
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Left Posterior Fascicular Block
•
•
•
•
1. Frontal plane axis +90°to 180° (adults)
2. rS pattern in I and aVL
3. qR pattern in III and aVF
4. QRS <120 ms
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Preexcitation of WPW Type
Whether preexcitation is full or not cannot be
determined from surface ECG, but following
criteria are suggestive of full preexcitation:
• 1. PR interval <120 ms during SR (adults) and
<90 ms (children)
• 2. Delta wave
• 3. QRS >120 ms (adults) and > 90 ms (children)
• 4. Secondary ST and T wave changes
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Terms Not Recommended
• Mahaim-type preexcitation -because ∆ cannot
be made with certainty with surface ECG
• Atypical LBBB, bilateral bundle-branch block,
bifascicular block, and trifascicular block because of great variation in anatomy and
pathology producing such patterns
• Recommends that each conduction defect be
described separately in terms of the structure
or structures involved
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Peri-infarction block
• abnormal Q wave generated by a MI in Inf/lat
leads, terminal portion of QRS- wide and
directed opposite to Q wave
(i.e., a QR complex in the inferior or lateral
leads)
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Peri-ischemic block
• transient ↑ in QRS duration accompanies the
ST-segment deviation seen with acute injury
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Primary Repolarization Abnormalities
Abn in ST & T, without changes in depolarization
Localized or diffuse
• ischemia, myocarditis, drugs, toxins,
electrolyte abn-esp Ca & K
• Abrupt HR change, hyperventilation, body
position, catecholamines, sympath stimulation
or ablation of stellate ganglion, temp changes
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Secondary Repolarization Abnormalities
Abn in ST & T →direct result of changes in sequence
and/or duration of ventri depolarization
• manifested as changes in QRS shape and/or
duration
• due to voltage gradients that are normally largely
cancelled but become manifest when the
changes in the sequence of depolarization alter
the repolarization sequence
• BBBs, preexcitation, ectopics, paced V- complexes
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Displacement of ST
• usually measured at “J point,” and, in exercise
testing 80 ms after the J point
•
J. Am. Coll. Cardiol. 2009;53;976-981;
T-Wave Abnormalities
T wave in I, II, aVL, and V2 - V6
• Inverted −0.1 to − 0.5 Mv
• Deep negative − 0.5 to − 1.0 mV
• Giant negative <− 1.0 Mv
Low -amplitude <10% of R-wave in same lead
Flat - +0.1 to − 0.1 mV in leads I, II, aVL (with an
R wave taller than 0.3 mV), and V4 to V6
•
J. Am. Coll. Cardiol. 2009;53;976-981;
• Virtually impossible to develop a causespecific classification for minor T-wave abn
• Classification as slight or indeterminate Twave abnormality
• Overreader -analysis
– other features
– clinical condition
– prior ECGs
•
J. Am. Coll. Cardiol. 2009;53;976-981;
T-Wave Alternans
• T-wave amplitude variations that alternate
every 2nd beat
• Typically microvolt T-wave alternans
rarely,more pronounced
• Latent instability of repolarization predictive
of malign arrhythmias
• Generally not present at the resting state even
in high-risk patients
• Stress test, requiring special equipment &
analysis software- needed to provoke it
•
J. Am. Coll. Cardiol. 2009;53;976-981;
The U Wave
• The U wave is a mechanoelectric pheno
• Frequently absent in limb leads & is most
evident in V2 & V3 (0.33 mv or 11% of T wave)
• HR dependent
• Rarely present at rates >95 bpm
• Bradycardia enhances U-wave amplitude &
present in 90% at HR< 65 bpm
•
J. Am. Coll. Cardiol. 2009;53;976-981;
• ↑ in U, usually in asso with ↓ST & a ↓in Twave, may be due to quinidine-like effects &
↓K+ and that with more ↑ hypokalemia
(<2.7), U may >T in same lead
• More recent information
– may be due to fusion of U with T rather than to an
↑U. Fusion of U with T also occurs in asso with an
↑ in sympath tone & in presence of a markedly ↑
QT as in LQTS
• ↓U(V2 - V5)→ abn(a/c ischemia/hypertension)
•
J. Am. Coll. Cardiol. 2009;53;976-981;
The QT Interval
• QRS onset to end of T wave
• Onset of QRS -occur up to 20 ms earlier in V2,
V3 than limb leads
• Some regard differences 50 ms up to 65 ms in
QT measured in various leads being normal
• This value is reported to be less in women
than in men
•
J. Am. Coll. Cardiol. 2009;53;976-981;
• When QT is measured in individual leads, lead
showing ↑QT should be used (usually V2/V3)
• If T & U are superimposed/cannot be
separated→
– QT be measured in leads not showing U (aVR and
aVL) or
– Downslope of T be extended by drawing a tangent
to the steepest proportion of downslope until it
crosses TP segment
– Might underestimate the QT interval
•
J. Am. Coll. Cardiol. 2009;53;976-981;
QT Correction for Rate
• Linear regression functions rather than Bazett’s
formula be used for QT-rate correction and
method used for rate correction be identified in
ECG analysis reports
• Rate correction of QT interval should not be
attempted when RR interval variability is large,
as with AF, or when identification of the end of
the T wave is unreliable
•
J. Am. Coll. Cardiol. 2009;53;976-981;
• Prolonged QT: women ≥460 ms; men ≥450 ms
• Short QT (women & men) ≤390 ms
• In ventricular conduction defects- JT interval
(QT duration– QRS duration)
• QT dispersion not be included in routine ECG
reports
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Threshold Values for ST-Segment Changes
• For men ≥40 - abn J-point ↑ → 0.2 mV in V2 & V3 and
0.1 mV in others
• For men <40 - abn J-point ↑ → 0.25 mV in V2 & V3
• For women - abn J-point ↑ → 0.15 mV in V2 & V3 and
0.1 mV in others
• For men & women - abn J-point ↑ → 0.05 mV in V3R &
V4R, except for males <30 →0.1
• For men & women - abn J-point ↑ → 0.05 mV in V7-V9
• For men & women of all ages - abn J-point ↓ → 0.05
mV in V2 & V3 and 0.1 mV in all others
•
J. Am. Coll. Cardiol. 2009;53;976-981;
Criteria for Acute Myocardial Infarction
Any one of the following criteria
• Detection of ↑and/or ↓ of markers (trop) with at
least 1 value above 99th percentile of URL +
evidence of myo ischaemia with at least 1 of the
following:
– • Symptoms of ischaemia;
– • ECG changes indicative of new ischaemia (new ST-T
changes or new LBBB)
– • Development of pathological Q waves in ECG
– • Imaging evidence of new loss of viable myo or new
RWMA
J. Am. Coll. Cardiol. 2007;50;2173-2195
• Sudden, unexpected cardiac death, involving
cardiac arrest, often with symptoms
suggestive of myo isch, and accompanied by
– new ST ↑ or new LBBB,
– and/or evidence of fresh thrombus by CAG and/or
at autopsy, but death occurring at a time before
appearance of cardiac biomarkers
J. Am. Coll. Cardiol. 2007;50;2173-2195
• For PCI in pts with N baseline trop, ↑of markers >99th
percentile URL - peri-procedural M necrosis . By
convention, ↑ of markers >3×99th percentile URL PCI-related MI
• For CABG in pts with N baseline trop, ↑ of markers
>99th percentile URL - peri-procedural M necrosis. By
convention, ↑ of markers >5×99th percentile URL plus
either new path Q waves or new LBBB, or
angiographically documented new graft or native CA
occlusion, or imaging evidence of new loss of viable
myocardium - CABG-related MI
• Patho findings of an a/c MI
J. Am. Coll. Cardiol. 2007;50;2173-2195
Criteria for Prior Myocardial Infarction
Any one of the following criteria :
• New patho Q waves ± symptoms
• Imaging evidence of a region of loss of viable
myo that is thinned & fails to contract, in
absence of a non-ischaemic cause
• Patho findings of a healed/healing MI
J. Am. Coll. Cardiol. 2007;50;2173-2195
J. Am. Coll. Cardiol. 2007;50;2173-2195
J. Am. Coll. Cardiol. 2007;50;2173-2195