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ECG Mneumonics

Written By Rizki A. Noviar on Sunday, August 18, 2013 | 19:20

Indonersia - ECG MNEUMONICS - rule of 3............

P wave - Maximum ht<= 3 small squares,maximum width <=3 small squares (lead 2)
PR segment -max 3 small squares
QRS duration- max 3 small squares
QT interval (corrected )- usually < 12 small squares ( multiple of 3)
T wave width - usually less than 3 small squares
T wave ht- usually less than 1/3 - 1/4th QRS voltage
p.s - small square = 40 milliseconds


p wave - ht > 3 small squares - right atrial enlargement
p wave - width > 3 small squares- left atrial enlargement

PR segment > 3 small squares - AV nodal conduction disturbance - first degree heart block

QRS duration > 3 small squares - intraventicular conduction delay

QT interval (corrected ) - 12 or more small squares - Long QT syndrome

T wave width > 3 small squares..... broad based t waves seen in hypokalemia

Tall T wave - hyperkalemia

ECG MNEUMONICS: left vs right bundle block:

Left bundle block is (WiLLiaM) W pattern in V1-V2 and M pattern in V3-V6.

Right bundle block is (MaRRoW) M pattern in V1-V2 and W in V3-V6.

*consider bundle branch blocks when QRS complex is wide.

Causes of ST elevation

E- Early repolarisation
E-Electrolyte abnormality (hyperkallemia)
V-ventricular aneurysm
A-Adult variant (normal)
I-Infarction, Inflammation (pericarditis, myocarditis)
O-Osborne wave
N- Na channel defect (Brugada)


ST elevation causes in ECG, ELEVATION:

E-Electrolytes (hyperkalemia)
E-Early repolarization (high take off)
V-Ventricular hypertrophy (LVH)
T-Treatment (eg pericardiocentesis)
I-Injury (AMI, contusion)
0-Osborne waves (hypothermia)
N-Non-occlusive vasospasm

Depressed ST-segment: causes DEPRESSED ST:

D-Drooping valve (MVP)
E-Enlargement of LV with strain
P-Potassium loss (hypokalemia)
R-Reciprocal ST- depression (in I/W AMI)
E-Embolism in lungs (pulmonary embolism)
S-Subendocardial ischemia
S-Subendocardial infarct
E-Encephalon haemorrhage (intracranial haemorrhage)
D-Dilated cardiomyopathy

T-Toxicity of digitalis, quinidine

Sinus bradycardia: aetiology "SINUS BRADICARDIA" (sinus bradycardia):

I-Infections (myocarditis)
N-Neap thyroid (hypothyroid)
U-Unconsciousness (vasovagal syncope)
S-Subnormal temperatures (hypothermia)

B-Biliary obstruction
R-Raised CO2 (hypercapnia)
D-Deficient blood sugar (hypoglycemia)
I-Imbalance of electrolytes
C-Cushing's reflex (raised ICP)
R-Rx (drugs, such as high-dose atropine)
D-Deep anaesthesia
I-Ischemic heart disease (IHD)

ECG: T wave inversion causes INVERT:

N-Normality [esp. young, black]
V-Ventricular hypertrophy
E-Ectopic foci [eg calcified plaques]
T-Treatments [digoxin]

Pericarditis: ECG “PericarditiS”:
PR depression in precordial leads.
ST elevation.

if ? L) or R) BBB. look at V1. work back from T wave and first inflection / deflection. is like L) hand indicator in car. up is to R), down is to L). thanks Anthony Webber.

quick axis reference. this is a litle rough but seems to work most of the time.
hold out two thumbs in front of you. your right thumb represents lead III, your left thumb lead I. Turn your thumb upright or upside down depending on the main QRS delfection of the correlating lead. Both thumbs up=normal axis. Which ever thumb is remaining (left or right hand) denotes the axis.



P - Pulmonary embolus.
A - Acidosis.
T - Tension pneumothorax.
C - Cardiac tamponade.
H - Hypo - Hyperkalemia / Hypoxia / Hypothermia / Hypovolemia.

M - Myocardial infarction.
E - Electrolyte derangements.
D - Drugs.


A - Arrhythmia's (SVT, VT, VF).
C - Congestive cardiac failure.
T - Tamponade / Thromboembolic disorders.

R - Rupture (Ventricle, septum, papillary muscle).
A - Aneurysm (Ventricle).
P - Pericarditis.
I - Infarction (A second one).
D - Death / Dresslers's syndrome.



T - Thyroid.
H - Hypothermia.
E - Embolism (P.E.).

A - Alcohol
T - Trauma (Cardiac contusion).
R - Recent surgery (Post CABG).
I - Ischemia.
A - Atrial enlargement.
L - Lone or idiopathic.

F - Fever, anemia, high-output states.
I - Infarct.
B - Bad valves (Mitral stenosis).
S - Stimulants (Cocaine, theo, amphet, caffeine).

Beck's Triad (Cardiac Tamponade)

3 D's:

Distant heart sounds.
Distended jugular veins.
Decreased arterial pressure.


ECG manifestations of chamber enlargement:

A-Left atrial enlargement:
a. P wave duration equal or more than 0.12 sec.
b. Notched, slurred P wave in lead I and II (P mitrale).
c. Biphasic P wave in lead V1 wit ha wide ,deep and negative terminal component.
d. Mean P wave axis shifted to the left ( between +45 to – 30 degree ).

B-Right atrial enlargement:
a. P wave duration equal or less than 0.11 sec.
b. Tall, peaked T wave equal or more than 2.5 mm in amplitude in lead II,III or aVF (P pulmonale).
c. Mean P wave axis shifted to the right( more than +70 degree).

C-Left ventricular enlargement :
a. "Voltage criteria":
1-R or S wave in limb lead equal or more than 20mm
2-S wave in V1,V2 or V3 equal or more than 30mm
3-R wave in V4,V5 or V6 equal or more than 30mm.
b. Depressed ST segment with inverted T waves in lateral leads(strain pattern ;more reliable in the absence of digitalis therapy.
c. Left axis of -30 degree or more.
d. QRS duration equal or more than 0.09 sec.
e. Time of onset of the intrinsicoid deflection ( time from the beginning of the QRS to the peak of the R wave ) equal or more than 0.05 sec in lead V5 or V6.

D-Right ventricular enlargement :
a. Tall R waves over the right precordium and deep S waves over the left precordium ( R:S ratio in lead V1 > 1.0)
b. Normal QRS duration (if no bundle branch block)
c. Right axis deviation.
d. ST-T "strain" pattern over the right precordium.
e. Late intrinsicoid deflection in lead V1 or V2.

A-Left bundle branch block :
a. QRS duration equal or more than 0.12 sec.
b. Broad , notched or slurred R wave in lateral leads( I, aVL , V5,V6 )
c. QS or rS pattern in the anterior precordium.
d. Secondary ST-T wave changes ( ST and T wave vectors are opposite to the terminal QRS vectors).
e. Late intrinsicoid deflection in lead V5 and V6.

B-Right bundle branch block:
a. QRS duration equal or more than 0.12 sec.
b. Large R' wave in lead V1( rsR' ).
c. Deep terminal S wave in lead V6.
d. Normal septal Q wave.
e. Inverted T wave in lead V1 ( secondary T wave changes ).
f. Late intinsicoid deflection in lead V1 and V2.

ECG manifestations of fascicular blocks:

A-Left anterior fascicular block
a. QRS duration equal or more than 0.10 sec.
b. Left axis deviation ( -45 degree or greater ).
c. rS pattern in lead II, III and aVF.
d. qR pattern in lead I and aVL.

B-Left posterior fascicular block:
a. QRS duration equal or more than 0.10 sec.
b. Right axis deviation ( +90 degree or greater ).
c. qR pattern in lead II,III ands aVF.
d. rS pattern in lead I and aVL.
e. Exclusion of other causes of right axis deviation ( COPD, RVH, lateral MI ).

Localization of myocardial infarction:

Infarct location Leads depicting primary ECG changes Likely vessel * involved
Inferior II,III,aVF RCA
Septal V1-V2 LAD
Anterior V3-V4 LAD
Antero-septal V1-V4 LAD
Extensiveanterior I,aVL,V1-V6 LAD
Lateral I,aVL,V5-V6 CIRC
High Lateral I, aVL CIRC
Posterior ** Prominent R in lead V1 RCA or CIRC
Right ventricular*** ST elevation in lead V1,and more specifically, V4R in the setting of inferior infarction RCA
*this is a simple generalization, variations occur.
** Usually in association with inferior or lateral infarctions.
***Usually in association with inferior infarctions.

Mirror image dextro-cardia:
1-Inverted P waves in standard lead I
2-all other deflections –QRS complex and T wave- are also negative in standard lead I.
2-This lead now resembles a normal lead aVR.
3-the normal appearances of standard leads II and lead III are interchanged .
4-the QRS complexes are tallest in the right precordial leads –V1 and V2- and diminished progressively towards the left.

Limb lead reversal:
This will manifest as a mirror image dextro-cardia but the precordial lead complexes are NORMAL.

Anomalous left coronary artery:
When the left coronary artery arises from the pulmonary artery ,the ECG reflects the pattern of ANTERO-LATERAL myocardial infarction, viz pathological q waves, raised coved ST segments and inverted T waves in standard lead I and aVL and the left precordial leads.

Some ECG finding in heart diseases:
Mitral stenosis:
1-atrial fibrillation
2-RVH ,right axis deviation
3-P mitrale, P pulmonale

Mitral reflux:
1-P mitrale
2-atrial fibrillation
3-left ventricular "diastolic" overload
4-RVH, Right axis deviation.

Tricuspid stenosis:
1-VERY TALL right atrial P wave in standard lead II.
2-1st degree AV block
3-normal QRS axis

Hypertensive heart disease:
1-left atrial P wave
2-left ventricular "systolic " overload

Arrhythmias associated with HYPERthyroidism:
1-sinus tachycardia
2-atrial extrasystoles
3-paroxysmal atrial tachycardia
4-paroxysmal atrial flutter
5-paroxysmal atrial fibrillation
6-idionodal tachycardia
7-paroxysmal nodal tachycardia
NB: Ventricular rhythms are NOT usually associated with hyperthyroidism unless there is a cardiac DECOMPENSATION.

Pulmonic styenosis:
1-P congenitale
2-right ventricular systolic overload
3-right axis deviation

Tricuspid atresia:
1-left axis deviation
2-left ventricular dominance
NB: MOST cases of cyanotic congenital heart disease are associated with RIGHT ventricular dominance and RIGHT axis deviation ; tricuspid atresia is a notable exception .

Ebstein's anormally:
1-TALL peaked P waves in standard lead II
2-RBBB with small amplitude QRS complexes
3-WPW syndrome type B, ie the QRS complex is negative in the right precordial leads
4-paroxysmal supra-ventricular tachycardia

Remember: TALL symmetrical T waves in the precordial leads might be due to :
1-acute subendocardial ischemia , injury or infarction.
2-recovering inferior wall myocardial infarction.
3-hyperacute phase of anterior wall myocardial infarction.
4-Prinzmetal 's angina.
5-true posterior wall myocardial infarctions.

: Generalized LOW voltage might be due to :
1-incorrect standardization.
3-marked obesity or thick chest wall.
4-pericardial effusion.
7-Cardiac Amyloid.
8-Severe cardiomyopathy
9-Global Myocardial iscehmia.

Remember: Acute rheumatic frequently associated with :
1-sinus tachycardia.
2-non paroxysmal AV nodal tachycardia( idionodal tachycardia).
3-prolonged PR interval.
4-2nd degree AV block .
5-prolonged QT interval.
NB: it is NEVER associated with 3rd degree AV bloc

Some observations on abnormal rhythms:

Remember: A slow regular ventricular rhythm might be due to :
1-Sinus bradycardia.
2-Complete AV block with idioventricualr rhythm.
3-Normal sinus rhythm with 2:1 AV block.
4-Normal sinus rhythm with 2:1 SA block (very rare).
5-Atrial flutter with high grade 4:1 AV block.
6-Sinus default with idionodal escape rhythm.
7-Sinus default with idioventricualr escape rhythm.

Remember: Causes of IRREGULAR ventricular rhythm:
1-Atrial fibrillation.
2-frequent and irregularly occurring atrial and or ventricular extrasystoles.
3-Atrial flutter with second degree AV blockand varying AV conduction ratios.
4-Paroxysmal atrial tachycardia with variable second degree AV block .
5-Marked respiratory sinus arrhythmia.

"SLOW' atrial fibrillation:
Slow atrial fibrillation usually reflects treatment with digitalis ; or in the absence of digitalis therapy , a structural nodal disease ( sick sinus syndrome ).A more correct description is " atrial fibrillation with slow or diminished ventricular response".

Remember: Common causes of bigeminal rhythm:
1-alternate ventricular extrasystoles( the commonest cause ).
2-alternate atrial or nodal extrasystoles.
3-any form of 3:2 AV block.
4-atrial flutter with alternating 4:1 and 2:1 AV block.

Remember: Absent P wave might be due to :
1-SA block.
2-Atrial fibrillation.
3-Severe hyperkalemia.
4-AV nodal rhythm ( the P wave might be hidden within the QRS complexes).

Remember: A long PAUSE interrupting a regular rhythm might be caused by:
1-a dropped beat as a result of 2nd degree AV block.
2-a dropped beat as a result of SA block.
3-a blocked or non conducted atrial extrasystole.

NB: extrasystoles occur PREMATURELY , escape beats occur LATE.
NB: when the PR interval becomes progressively shorter, AV dissociation is usually present.

Remember: Paroxysmal atrial rhythm (tachycardia, paroxysmal or flutter fibrillation ) in a young person without obvious evidence of cardiac disease rises the possibility of :
2-WPW syndrome.
3-Lone atrial fibrillation .

Causes of SA block:
SA block is a rare ECG finding and might be caused ny:
1-marked sinus bradycardia
2-marked sinus arrhythmia
3-highly trained young athletes
4-digitalis toxixity
7-sick sinus syndrome

1st degree AV block is associated with:
1-coronary artery disease
2-acute rheumatic carditis
3-Beta blockers
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