Download ECG - This Is Not A Clinic

1.
Remember the clinical correlation and ask for previous ECGs
Descriptive Analysis
a. Rate
b. Rhythm
i. P waves (upright in II/v1)
ii. QRS width/morphology (if sinus, shortcut to RBBB, LBBB, IVCD or WPW)
iii. Relation of P to QRS
iv. Regularity of Rhythm (completely regular, fairly regular, regularity irregular, completely irregular)
v. Premature (early) or Escape (late) beats
c. Intervals
i. PR
ii. QRS (in lead with widest QRS)
iii. QT
d. Axis and Hemiblocks
Clincal Interpretation
e. Hypertrophy
f. Infarct
i. Q waves (Normal septal q’s I, aVL,V4,V5,V6)
ii. R wave progression
iii. ST segment
iv. T waves
Intervals
PR (0.12-.20): short WPW, long heart block
QRS (<.10): Ventricular rhythm, vent hypertrophy (+0.020.03), abnormaility in conduction (RBBB, LBBB, or IVCD)
QT (time from ventricular depolarization to ventricular
repolarization):
J point (early repolarization)
Q waves: loss of positive forces
Six Essential Lists
Common Causes of a Regular SVT
1. Sinus Tachycardia (rarely exceeds 150-160)
2. Atrial Flutter (usually 2:1 at 150)
3. PSVT (process of elimination)
Common Causes of Regular, WIDE-complex
Tachycardia of Uncertain Etiology
1. Ventricular Tachycardia
2. SVT with pre-existing bundle branch block
3. SVT with aberrant conduction
Causes of ST depression
1. Ischemia
2. Strain
3. Digitalis
4. HypoK/Mg
5. Rate-related changes
6. Any combo of above
Causes of Tall R Wave in Lead V1
1. WPW
2. RBBB
3. RVH
4. Posterior Infarct
5. Normal Variant
Right Bundle Branch Block
The difference in I/V6 is in the terminal wave as
conduction on right passes over unspecialized fibers
Left Bundle Branch Block
Causes of Anterior ST Depression in Infarct Setting
1. Reciprocal Changes
2. Concomitant Anterior Ischemia
3. Posterior Infarct
The direction of septal depolarization changes from
left-to-right to right-to-left
T wave discordance is expected. Concordance >1 mm
is a problem.
IVCD
Wide QRS and the typical morphology for RBBB or
LBBB are missing in any of the 3 leads
Blocks result in non-ischemic ST-T changes.
Orientation of the ST segment and T wave with typical
blocks should be opposite that of the last QRS
deflection in each of the 3 key leads. If not, suspect a
primary T-wave change from ischemia
WPW (3 criteria): shortened PR, wide QRS, delta wave
(pos or neg)
Causes of QTc Prolongation QT/sqrt(R-R)
1. Drugs (type 1A/3, TCAs)
2. Lytes (hypoK/Mg/Ca)
3. CNS (stroke, coma, seizures)
4. BBB or IVCD
5. Ischemia or infarction
Axis
Normal: average between I and aVF
LAD: check II, if – then > -30
Indeterminate is isoelectric in all leads
Poor R Wave Progression
1. LVH, RVH
2. COPD, asthma
3. Ant/Septal defect
4. Conduction defects
5. CM
6. Normal Variant
7. Lead Misplacement (loss of R wave in single
lead)
ST Elevation
Upward Concavity (Smiley): Benign
Downwd Concavity/Coving (Frowney): Ischemia
T waves
Hemiblocks
Left Anterior Hemiblocks: LAD >--45۫ with Q’s in I
and aVL (look for LAD with negative sum in II)
Causes: HTN, CAD, and infiltrative disease
Left Posterior Hemiblocks (less common due to dual
blood supply): RAD >120۫
Hypertrophy (specific but not sensitive)
RAA: peaked, >= 2.5 mm in II, III, aVF
RVH: RAA, RAD, tall R in V1
LAA: wide M >0.12 mm in I, II, aVL or wide negative
in V1
LVH:
1. Deepest S in V1/2 + tallest R in V5/6 > 35
2. Age > 35
3. R in aVL >= 12 mm
4. Strain pattern in I, aVL, V5, V6
Strain: asymmetric ST, slow ST depression with rapid
T wave
Strain equivalent: ST flat and depressed, T wave
amplitude is decreased
Indeterminate Axis: Obese, RVH, Severe pulmonary
disease
Q patterns
Inferior: II, III, aVF
Septal: V1, V2 (no R in V1/V2)
Anterior: V1-V4
Lateral Precordial V4 -V6
High Lateral: I, aVL
Can dx high lateral with LBBB by Q’s in aVL and I.
Move V4 to right side to look for right ventricular
infarct.
Isolated aVR ST elevation = proximal infarct in LAD
or main coronary.
Q wave significance: 1 box wide, 25% of R wave
Q waves: MI, IHSS, Dilated CM, IVCD, COPD
Zone of Transition: V2 – V4
Early (V1-V2): Severe RVH
Later (V5,V6): COPD, Pulmonary Dz
Right Heart Strain Pattern (think PE)
R1Q3T3 (inverted T in III)
Differential Diagnosis of U Waves
Hypokalemia
Sinus bradycardia
Medications (including antiarrhythmics)
CNS disease
Hyperthyroidism
An inverted T in aVL is a sign of an Inferior MI
A Practical Guide to ECG Interpretation - Grauer