Download ECG2

by Dr.Doaa Kamal
ECG Interpretation
ECG
► View of the heart from each of the 12 leads:
From what angle does each lead overlook the heart?
So leads:
 II, III, aVF = inferior wall.
 I, aVL + V1,2 = anterior wall (right ventricle).
+ V3,4 = antero-septal (septum).
+ V5,6 = antero-lateral wall (left ventricle).
► Speed of the paper in the machine: most commonly 25 mm/sec.
► Standardization mark: most commonly 1 mV= 2 large squares.
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by Dr.Doaa Kamal
ECG Interpretation
► Normal values of waves and intervals:
N.B. 1 small square = 0.04 sec = 40 millisecond.
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(A) Waves:
P wave: Width < 3mm, Height < 2.5mm. [Atrial depolarization].
QRS complex: Width < 3mm (120 ms) [Ventricular depolarization].
Q wave: Width < 1mm, Depth < 2mm.
T wave: Width 6 mm, Height 4mm [Ventricular repolarization].
(B) Intervals & Segments:
N.B. The term interval includes a wave. The term segment does NOT include a wave.
 PR Interval: from beginning of P to beginning of R. 3-5 mm.
 ST segment: normally 1 mm above or below isoelectric line.
 QT interval: from beginning of Q to end of T wave. Corrected according to HR.
QTc < 440 ms. QTc = QT x 0.04 / √RR x 0.04.
► Calculate the Rate:
 Regular: 300 / no. of large squares. Or 1500/no.of small squares.
 Irregular: count the number of R waves in 30 large squares and multiply by x10.
From the long strip at the end lead II.
Between these 2 marks = 15 squares.
► Regular or Irregular?
 Are the R waves at equal distances from each other?
 Mark the distance between 2 successive R waves on a piece of paper and
measure it against other R waves.
► Axis Deviation:
Normally QRS complex is +ve in both leads I and III.
Put ur left hand on lead I and ur right hand on III.
 If QRS complex in lead III points upwards like ur fingers (tall R in III) while S in lead I
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points towards ur fingers = Right axis deviation.
If QRS complex in lead I points upwards like ur fingers (tall R in I) while S in lead III
points towards ur fingers = Left axis deviation.
Rt axis = tall R in III, deep S in I.
Lt axis = tall R in I, deep S in III.
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by Dr.Doaa Kamal
ECG Interpretation
Right axis deviation
Left axis deviation
► Connected correctly? P-QRS complex is –ve in aVR.
(A)Disturbance in impulse initiation.
(B) Disturbance in impulse conduction.
(C) Abnormalities of: P, QRS, ST, T.
(A) Disturbance in Impulse Initiation
 Sinus: tachycardia, bradycardia.
 Atrial: PAC, PSVT, atrial flutter, AF.
 Ventricular: PVC, VT, VF.
► Sinus Tachycardia:
 P wave: +ve in lead II, -ve in aVR.
 Each QRS is preceded by a P wave.
 HR = 100-180.
► Sinus Bradycardia:
 P wave: +ve in lead II, -ve in aVR.
 Each QRS is preceded by a P wave.
 HR < 60.
 PR < 5 mm. (No heart block).
ATRIAL ARRHYTHMIAS
► PAC (premature atrial contraction):
 QRS complex = normal shape.
 P wave may be present/fused with preceding T wave.
 Beat is premature (earlier than expected).
 Followed by a compensatory pause.
► PSVT Paroxysmal supraventricular tachycardia:
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Sudden run of 3 or more PACs.
Regular. ‫مثل أسنان المشط‬
Normal QRS complex.
HR ˃ 150/min.
Sudden onset, sudden offset.
P wave: may be absent (hidden/overriden by the QRS complex) or
retrograde: abnormal (-ve in lead II & +ve in aVR).
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by Dr.Doaa Kamal
ECG Interpretation
► Atrial flutter:
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Irregular.
Atrial rate: up to 300.
Ventricular rate: according to AV nodal conduction.
P wave replaced by saw-tooth appearance.‫أسنان المنشار‬
► Atrial Fibrillation AF:
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Atrial rate: up to 600.
Ventricular rate: according to AVN conduction.
˃ 90: Rapid AF.
< 90: Slow AF.
P waves: absent. Replaced by F waves.
Irregular iiregularity: cannot count 4 successive regular beats.
VENTRICULAR ARRHYTHMIAS
► PVC (premature ventricular contraction):
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QRS: wide (˃3mm) bizarre shaped (abnormal depolarization).
T wave: inverted (abnormal repolarization).
Beat is premature: earlier than expected.
Followed by compensatory pause.
► VT: ventricular tachycardia
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3 or more consecutive PVCs.
HR ˃ 160/min.
Sine wave appearance: QRS: wide & bizarre shaped.
T wave: inverted.
► VF: ventricular fibrillation:
 Irregular fibrillation pattern.
 May be coarse or fine VF.
 Is a form of cardiac arrest.
(B) Disturbance in Impulse Conduction
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1st, 2nd, 3rd degree heart block.
LBBB, RBBB, bifasicular block.
WPW Syndrome.
Pacemaker.
► 1st Degree heart block:
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Prolongation of PR interval ˃ 5mm.
Each P wave is followed by a QRS complex.
► 2nd Degree heart block: Mobitz I
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Progressive prolongation of PR interval until a beat is dropped (P wave not
followed by QRS complex).
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by Dr.Doaa Kamal
ECG Interpretation
► 2nd Degree heart block: Mobitz II
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Non-conducted P wave followed by a conducted P wave in a fixed ratio.
Ratio of P to QRS may be 2:1 3:1 or 4:1.
► Complete heart block:
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No relation between P and QRS waves.
► LBBB (Lt bundle branch block):
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Wide QRS complex ˃4mm.
Notched: M-shaped.
Inverted T waves in V5, V6.
Usually ischemic in origin.
► LAHB (Lt anterior hemi-block):
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QRS complex 2.5-4mm (incomplete LBBB).
With Left axis deviation.
► LPHB (Lt posterior hemi-block):
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QRS complex 2.5-4mm (incomplete LBBB).
With Right axis deviation.
► RBBB (Rt bundle branch block):
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rSR’ + inverted T waves in V1,V2.
May be seen in healthy individuals.
► Bifasicular block:
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RBBB + LAHB (Left axis deviation).
► WPW Syndrome (Prexcitation syndromes):
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Short PR-interval <3mm.
Wide QRS complex (abnormal conduction in ventricles).
Delta wave δ: (shoulder) slurred initial deflection in the upstroke of R wave.
± T wave may be inverted.
► Pacemaker Pattern:
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Notice pacemaker spikes. ‫شوكة‬
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by Dr.Doaa Kamal
ECG Interpretation
TachyArrhythmias
Narrow Complex
Regular
Irregular
-Sinus tachycardia.
-PSVT.
Broad Complex
-VT.
-Torsade de pointes.
- AF with LBBB.
- AF with WPW $.
-Atrial flutter.
-AF.
(B) ©Abnormalities of P, QRS & T
► P wave:
 P pulmonale: tall peaked P wave. Right atrial enlargement/dilation (RAD).
 P mitrale: broad bifid P wave. Left atrial enlargement/dilation (LAD).
P-pulmonale
P-mitrale (m-shaped P wave)
► QRS Complex
 LV Hypertrophy: (LVH)
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Depth of S in V1 + height of R in V6 ˃ 35 mm (7 large squares).
Lt axis deviation.
± LV strain pattern: inverted T in V4,5,6.
 RV Hypertrophy: (RVH)
 Tall R in V1.
 Rt axis deviation.
 ± RV strain pattern: inverted T in V1,2,3.
 Pathological Q waves: ˃ 1mm wide, ˃ 2mm deep.
 If it is preceded by an R wave (+ve wave) then it is S not a Q.
 Indicate old myocardial infarction. Observe the distribution.
 II, III, aVF = inferior wall.
 I, aVL + V1,2 = anterior wall.
+ V3,4 = antero-septal.
+ V5,6 = antero-lateral wall.
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by Dr.Doaa Kamal
ECG Interpretation
 R wave progression:
 Normally R wave ↑ in size (height) progressively from V1-V6.
► ST Segment: ˃ 1mm above or below the isoelectric line.
 ST elevation: indicates acute myocardial infarction.
 ST depression: indicates myocardial ischemia.
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Observe the distribution.
II, III, aVF = inferior wall.
I, aVL + V1,2 = anterior wall.
+ V3,4 = antero-septal.
+ V5,6 = antero-lateral wall.
► T wave:
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Normally it is +ve in leads: II, V3-6.
-ve in aVR, V1, V2.
► Signs of myocardial ischemia in ECG:
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T wave inversion.
Poor R wave progression.
ST segment depression.
ST elevation = Acute/ recent MI (up to 2 days).
Pathological Q = old MI.
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