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High lateral leads


Low lateral leads

V5, V6

Septal leads

V1, V2

Anterior leads

V3, V4

Inferior leads


Posterior leads

None! Check the RECIPROCAL waves of Anterior leads

Left axis deviation indicators

aVL positive, aVF negative

Right axis deviation indicators

aVL negative, aVF positive

No Man's Land Axis Deviation


R wave transition

In V1-V6, the QRS complex changes from predominately negative (QrS) to predominately positive (qRs) w/ the R/S ratio becoming >1. This usually occurs at V3 or V4

R atrial enlargement indicators

1. P in INFERIOR leads PEAKED (>2.5 mm); 2. UPWARD half of diphasic P in V1 is 2X larger than downward part

L atrial enlargement indicators

1. P waves in INFERIOR leads >120 ms & DOUBLE-peaked;
2. DOWNWARD part of diphasic P waves in V1 is 2X larger than upward part

P-wave indicators of mitral valve Dz (p-mitrale)

1. Camel-humped P in INFERIOR leads
2. BOTH L & R Atrial abnormality

RVH indicators

1. RAD ((aVL NEG, aVF POS)
2. R-progression in V1-V6 reversed;
3. In V1: R > 7mm or HT of R >Depth of S


1. DEEP S waves thru-out precordium
2. RAD
3. Delayed R-wave transition

LVH indicators

1. S in V1+ R in V5 >35 mm;
2. R in V5 >26 mm
3. R in Lead 1 >14 mm
4. ST depression and T inversion in LEFT precordial leads (V4-6) show LVH ischemia

LVH w/ diastolic overload indicators

LVH + tall, peaked T's & deep Q's in lateral leads

RBBB indicators

MaRRoW: (M is RsR' in V1 and W is rSr" in V6
QRS always >120 ms
1. RsR' in V1, V2, or V3 (Septal or Anterior)
2. DEEP/WIDE S in Lead (1 or) 2 & V6
3. T may be inverted in Septal (V1/V2) leads

LBBB indicators

WiLLiaM: (W is rSr' in V1 and M is RsR' in V6).
QRS always >120 ms
1. W is DEEP/WIDE (r)S(r') complex in V1;
2. M is TALL/WIDE R(s) in lead (1 or) 2 & V6
3. T wave is always opposite QRS.

Ischemia indicators

PEAKED T-waves or DEPRESSED ST in 2 contiguous leads

Injury/Infarction indicators

ELEVATED ST in 2 contiguous leads

MI & Post-MI indicators

ELEVATED ST & abnormal Q's in 2 contiguous leads, INVERTED T

Coronary occlusion associated w/ Anterior MI

Left Anterior Descending (LAD) = Anterior Interventricular

Coronary occlusion associated with Lateral MI


Coronary occlusion associated with Inferior MI

Right Coronary

Coronary occlusion associated with Posterior MI

(Distal) Right Coronary

Anterior MI Indicators

Peaked T, Altered ST in V1-V4 (Anterior or Septal leads)

Lateral or Antero-lateral MI Indicators

Peaked T, Altered ST in V3-V6, or I/AVL

Inferior MI Indicators

Peaked T, Altered ST in II, III, aVF (Inferior leads)

Posterior MI Indicators

ST DEPRESSION in anterior (V3, V4) (RECIPROCAL anterior ST elevation); TALL R in V1, V2 w/ no RAD

Mobitz type 1 (Wenkebach) appearance

PR interval gets longer until QRS drops

Mobitz type 2

Constant PR intervals w/ intermittently dropped QRS

Escape pacemaker indicators

Increased PR, altered P on delayed beats

Left Anterior Fascicular Block (Left Hemi-block)

1. Left axis deviation (-45 to -90 degrees) 2. Tiny Q's & Large R's in 1 & aVL
3. rS in inferior leads (II, III, aVF)
4. Delayed R wave transition. S wave in V5-V6

Left Posterior Fascicular Block indicators

RAD >100
2. Tiny R & Deep S in 1 & aVL
3. Tiny Q & Large R in inferior leads (II, III, aVF)

S1-Q3-T3 & Significance

Deep S in I
Tiny Q in III
Inverted T in III
Voila! Pulmonary Edema

Chronology MI Indicators

Peaked T waves-->
ST Depression -->
ST Elevation-->
Inverted T waves

A-Fib etiologies

High Atrial pressure from HTN, CHF, or VHD

A-Fib Indicators

Quivering or saw-tooth baseline

A-Flutter etiologies

High Atrial pressure from HTN, CHF, or VHD cause re-entry around a counter-clockwise path at Tricuspid valve

A-Flutter Indicators

Atrial rate 220-320, typically right at 300;
Sawtooth "flutter waves" in Inferior leads;
Normal QRS in 2:1, 4:1 other pattern

Jim's 2nd Law

A heart rate of exactly 150 is 2:1 A-flutter until proven otherwise (Look for flutter waves in Inferior leads)

How to prove a 300 bpm trace is 2:1 A-Flutter

Adenosine stops QRS for 6-10 sec; Now count the p waves. One/box = 300. See any flutter waves

2nd degree block, 2:1

A-Fib, Rapid Ventricle

3rd Degree AV block

Left Atrial Enlargement

2nd Degree Mobitz 1 (Wenkebach)

A-Fib, Slow Ventricles

A Flutter, 2:1

1st Degree AV Block

A Flutter, 4:1

Left Ventricular Hypertrophy

Left Atrial Enlargement

Right Atrial Enlargement

Right Ventricular Hypertrophy

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