EKG Differentials Flashcards
Lead I
Inverted P wave
• Ectopic atrial premature beat or rhythm
• AV junctional/ventricular premature complex or
rhythm with retrograde atrial activation
• Dextrocardia: Inverted P-QRS-T in leads I and aVL with reverse R wave progression in the precordial leads
• Reversal of right and left arm leads: Inverted PQRS-T in leads I and aVL with normal R wave progression in the precordial leads
Lead II
Tall peaked P wave
- Right atrial abnormality/enlargement
* Bi-atrial abnormality
Lead II
Bifid P wave with peak-to-peak interval > 0.03 sec. and P wave duration > 0.12 sec.
• Left atrial abnormality/enlargement
Lead II
Inverted P wave
• Ectopic atrial premature beat or rhythm
• AV junctional/ventricular premature complex or
rhythm with retrograde atrial activation
Lead II
Sawtooth regular P waves
- Atrial flutter
* Artifact due to tremor (e.g., Parkinson’s disease, shivering)
Lead II
Irregularly irregular baseline
- Atrial fibrillation
- Artifact due to tremor
- Multifocal atrial tachycardia
Lead II
Multiple P wave morphologies
- Wandering atrial pacemaker (rate < 100 bpm)
- Multifocal atrial tachycardia (rate > 100 bpm)
- Sinus or atrial rhythm with multiple atrial premature complexes
Lead V1
Tall upright P wave
• Right atrial abnormality/enlargement
Lead V1
Deep inverted P waves
• Left atrial abnormality/enlargement
Lead V1
Dome and dart P wave
• Ectopic atrial rhythm
No P Waves
P Waves present but hidden
- Ectopic atrial rhythm or APCs (P waves hidden in preceding T wave)
- Junctional rhythm or SVT (P wave buried in QRS)
- Supraventricular rhythm with marked first-degree AV block (P wave hidden in preceding T wave)
No P Waves
P Waves not present
- Sinoventricular conduction due to hyperkalemia
- Marked sinoatrial exit block or sinus bradycardia with junctional or ventricular rhythm (escape or accelerated)
- Sinus pause or arrest
PR Interval
Prolonged (> 0.20 seconds) PR interval
• First-degree AV block
• Complete heart block: PR interval varies, has no
constant relationship to the QRS, and may intermittently exceed 0.20 seconds
• Supraventricular or junctional rhythm with retrograde atrial activation: P wave inverted in lead II
• Atrial premature complex
PR Interval
Short (< 0.12 seconds) PR interval
• Short PR with sinus rhythm and normal QRS
• Wolff-Parkinson-White pattern: Delta wave, wide
QRS, ST-T changes in a direction opposite to main deflection of QRS
• Low ectopic atrial rhythm: PR interval usually > 0.11 seconds; P wave inverted in lead II
• Ectopic junctional beat or rhythm with retrograde atrial activation: PR interval usually < 0.11 seconds; P wave inverted in lead II
PR Segment Depression
- Normals: < 0.8 mm
- Pericarditis
- Pseudodepression due to atrial flutter or Parkinson’s tremor
- Atrial infarction: Reciprocal elevation in opposite leads; inferior MI usually evident
PR Segment Elevation
3
1 Normals: < 0.5 mm
2 Pericarditis: Lead aVR only
3 Atrial infarction: Reciprocal depression in opposite leads
Increased QRS duration 0.10 to < 0.12 seconds
11
1 Left anterior fascicular block 2 Left posterior fascicular block 3 Incomplete LBBB 4 Incomplete RBBB 5 Nonspecific IVCD 6 LVH 7 RVH 8 Supraventricular beat or rhythm with aberrant intraventricular conduction 9 Fusion beats 10 Wolff-Parkinson-White pattern 11 VPCs originating near the bundle of His (i.e., high in the interventricular septum)
Increased QRS duration > 0.12 seconds
9
1 RBBB 2 LBBB 3 Supraventricular beat or rhythm with aberrant intraventricular conduction 4 Fusion beats 5 Wolff-Parkinson-White pattern 6 Ventricular premature complexes 7 Ventricular rhythm 8 Nonspecific IVCD 9 Paced beat
Low voltage QRS
7
1 Chronic lung disease 2 Pericardial effusion 3 Myxedema 4 Obesity 5 Pleural effusion 6 Restrictive or infiltrative cardiomyopathy 7 Diffuse coronary artery disease
Tall QRS
5
1 LVH 2 Hypertrophic cardiomyopathy 3 LBBB 4 Wolff-Parkinson White pattern 5 Normal persons with thin body habitus
Prominent R wave in lead V1
7
1 RVH
2 Posterior wall MI
3 Incorrect lead placement: Electrode for lead V1 placed in 3rd instead of 4th intercostal space
4 Skeletal deformities (e.g., pectus excavatum)
5 RBBB
6 Wolff-Parkinson-White pattern
7 Duchenne’s muscular dystrophy
Left axis deviation
- Left anterior fascicular block (if axis > -45°, item 45)
- Inferior wall MI (items 57, 58)
- LBBB (item 47)
- LVH (item 40)
- Ostium primum ASD (item 79)
- Chronic lung disease (item 81)
- Hyperkalemia (item 74)
Right axis deviation
- RVH (item 41)
- Vertical heart
- Chronic lung disease (item 81)
- Pulmonary embolus (item 82)
- Left posterior fascicular block (item 46)
- Lateral wall MI (items 55, 56)
- Dextrocardia (item 80)
- Lead reversal (item 03)
- Ostium secundum ASD (item 78)
Q wave myocardial infarction
(see items 51-60)
• Anterolateral MI: Abnormal Q waves in leads V4-V6
• Anterior MI: Abnormal Q waves in at least two consecutive
leads in V2-V4
• Anteroseptal MI: Abnormal Q waves in leads V1-V3 (and
sometimes V4)
• Lateral MI: Abnormal Q waves in leads I and aVL
• Inferior MI: Abnormal Q waves in at least two of leads II, III,
and aVF
Pseudoinfarcts (Q waves in absence of MI)
• Wolff-Parkinson-White (item 34): Negative delta waves
mimic Q waves
• Hypertrophic cardiomyopathy (item 85): Q waves in I, aVL,
V4-V6 due to septal hypertrophy
• LVH (item 40): Poor R wave progression, at times with ST
elevation in V1-V3, can mimic anteroseptal MI. Inferior Q
waves may be present and can mimic inferior MI
• LBBB (item 47): QS pattern in V1-V4mimics anteroseptal MI.
Less commonly, Q waves in III and aVF mimic inferior MI
• RVH (item 41)
• Left anterior fascicular block (item 46)
• Chronic lung disease (item 81): Q waves appear in inferior
and/or right and mid-precordial leads
• Amyloid, sarcoid, and other infiltrative cardiomyopathic
diseases: Electrically active tissue replaced by inert substance
• Cardiomyopathy
• Chest deformity (e.g., pectus excavatum)
• Pulmonary embolism (item 82): Q wave in lead III and
sometimes aVF, but Q waves in II are rare
• Myocarditis
• Myocardial tumors
• Hyperkalemia (item 74)
• Pneumothorax: QS complex in right precordial leads
• Pancreatitis
• Lead reversal (item 03)
• Corrected transposition
• Muscular dystrophy
• Mitral valve prolapse: Rare Q wave in III and aVF
• Myocardial contusion: Q waves in areas of intramyocardial
hemorrhage and edema
• Left/right atrial enlargement: Prominent atrial repolarization
wave (Ta) can depress the PR segment and mimic Q waves
• Atrial flutter (item 18): Flutter waves may deform the PR
segment and simulate Q waves
• Dextrocardia (item 80)
Early R wave progression (tall R wave in V1, V2; R/S > 1)
- RVH (item 41)
- Posterior MI (items 59, 60)
- RBBB (item 43)
- Wolff-Parkinson-White pattern (item 34)
- Normals
- Duchenne’s muscular dystrophy
Poor R wave progression (first precordial lead where R
wave amplitude
- Normals (abnormal lead placement)
- Anterior or anteroseptal MI (items 53, 54)
- Dilated or hypertrophic cardiomyopathy
- LVH (item 40)
- Chronic lung disease (item 81)
- Cor pulmonale (item 82)
- RVH (item 41)
- Left anterior fascicular block (item 45)
Reverse R wave progression (decreasing R wave
amplitude across precordial leads)
- Anterior MI (items 53, 54)
* Dextrocardia (item 80)
Initial slurring of R wave (delta wave)
• Wolff-Parkinson-White pattern (item 34)
Terminal notching (of R or S wave)
• Hypothermia (Osborne wave; item 88)
• Early repolarization (item 61)
• Pacemaker spike (failure to sense; item 94)
• Atrial flutter (item 18): Flutter waves may be superimposed on
QRS
ST segment elevation
• Myocardial injury (item 65): Convex upward ST elevation
localized to a few leads and terminates with an inverted T
(unless hyperacute peaked T wave). Reciprocal ST depression
evident in other leads. Q waves frequently present. ST & T
wave changes evolve, and T wave becomes inverted before ST
segment returns to baseline
• Acute pericarditis (item 84): Widespread ST elevation (I-III,
aVF, V3-V6) without reciprocal ST depression in other leads
except aVR. No Q wave. PR segment depression is
sometimes present. ST-T wave changes evolve; T wave often
becomes inverted after ST segment returns to baseline. Note:
Pericarditis (and ST elevation) may be focal
• Ventricular aneurysm: ST elevation usually with deep Q wave
or QS in same leads; ST & T wave changes persist and are
stable over a long period of time
• Early repolarization (item 61): Concave upward ST elevation
that ends with an upward T wave, with notching on the
downstroke of the R wave. T waves are usually large and
symmetrical. ST-T wave changes are stable over a long time
period
• LVH (item 40)
• Bundle branch block (items 43, 47)
• Central nervous system disease (item 86)
• Apical hypertrophic cardiomyopathy (item 85)
• Hyperkalemia (item 74)
• Acute cor pulmonale (item 82)
• Myocarditis
• Myocardial tumor
ST segment depression
• Myocardial ischemia (item 64): horizontal or downsloping
• Repolarization changes secondary to ventricular hypertrophy
(item 67) or bundle branch block (items 43, 47)
• Digitalis effect (item 70)
• “Pseudodepression” due to superimposition of atrial flutter
waves or prominent atrial repolarization wave (as seen with
atrial enlargement, pericarditis, atrial infarction) on the ST
segment
• Central nervous system disorder (item 86)
• Hypokalemia (item 75)
• Antiarrhythmic drug effect (item 72)
• Mitral valve prolapse
Nonspecific ST segment changes
- Organic heart disease
- Drugs (e.g., quinidine)
- Electrolyte disorders (e.g., hypokalemia, item 75)
- Hyperventilation
- Myxedema (item 87)
- Stress
- Pancreatitis
- Pericarditis (item 84)
- Central nervous system disorders (item 86)
- LVH (item 40)
- RVH (item 41)
- Bundle branch block (items 43, 44, 47, 48)
- Healthy adults (normal variant) (item 02)
Tall peaked T waves
• Hyperacute MI
• Angina pectoris
• Normal variant (item 02): Usually effects mid-precordial leads
• Hyperkalemia (item 74): More common when the rise in
serum potassium is acute
• Intracranial bleeding (item 86)
• LVH (item 40)
• RVH (item 41)
• LBBB (item 47)
• Superimposed P wave from APC, sinus rhythm with marked
first-degree AV block, complete heart block, etc.
• Anemia
Deeply inverted T waves
- Myocardial ischemia (item 64)
- LVH (items 40, 67)
- RVH (items 41, 67)
- Central nervous system disorder (item 86)
- Wolff-Parkinson-White pattern (item 34)
Nonspecific T waves
• Persistent juvenile pattern: T wave inversion in V1-V3 in young
adults
• Organic heart disease
• Drugs (e.g., quinidine)
• Electrolyte disorders (e.g., hypokalemia, item 75)
• Hyperventilation
• Myxedema (item 87)
• Stress
• Pancreatitis
• Pericarditis (item 84)
• Central nervous system disorders (item 86)
• LVH (item 40)
• RVH (item 41)
• Bundle branch block (items 43, 44, 47, 48)
• Healthy adults (normal variant) (item 02)
Long QT interval – Acquired conditions
• Drugs (quinidine, procainamide, disopyramide, amiodarone, sotalol, dofetilide, azimilide, phenothiazines, tricyclics, lithium) • Hypomagnesemia • Hypocalcemia (item 77) • Marked bradyarrhythmias • Intracranial hemorrhage (item 86) • Myocarditis • Mitral valve prolapse • Myxedema (item 87) • Hypothermia (item 88) • Liquid protein diets
Long QT interval – Congenital disorders
- Romano-Ward syndrome (normal hearing)
* Jervell and Lange-Nielson syndrome (deafness)
Short QT interval
- Hypercalcemia (item 76)
- Hyperkalemia (item 74)
- Digitalis effect (item 70)
- Acidosis
- Vagal stimulation
- Hyperthyroidism
- Hyperthermia
Prominent U wave
- Hypokalemia (item 75)
- Bradyarrhythmias
- Hypothermia (item 88)
- LVH (item 40)
- Coronary artery disease
- Drugs (digitalis, quinidine, amiodarone, isoproterenol)
Inverted U wave
- LVH (item 40)
- Severe RVH (item 41)
- Myocardial ischemia
Right axis deviation is associated with which conditions?
- Chronic lung disease (e.g. emphysema)
- RVH
- Lateral wall MI
- Dextrocardia
- Vertical heart
- PE
- Ostium secundum ASD
- Left posterior fascicular block
