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EKG Calibration

If additional step halfway up then half-standard; means peaks were too high (multiply by 2)

Tp Wave

Atrial repolarization - deflects opposite direction of P wave

Usually not seen since at same time as QRS wave (obscured)

PR Interval

Beginning of P - Beginning of QRS

.12-.20 seconds

QRS Interval

0.06-0.11 seconds

Normal Axis -30 -- +105

Significant Q Waves

0.03 seconds or wider
Height >1/3 R wave height

Insignificant Q waves found in I, aVL, V6

Where are Insignificant Q waves found?

I, aVL, V6

Normal Shape of T-wave

(slow upstroke... fast downstroke)

T-P Segment Significance...

Serves as the BASELINE for determining whether something is depressed or elevated

From end of T of last beat to start of P of next beat

QTc Interval

Normal = .410
(=QT/sqroot RR)

Should be <1/2 RR

Calculating EKG Rates

1 big box = 300 bpm
2 big boxes = 150 bpm
3 big boxes = 100 bpm
4 big boxes = 75 bpm
5 big boxes = 60
6 big boxes = 50

Sinus Pause/Arrest vs
Sinoatrial Block

Sinoatrial Block occurs in MULTIPLES of P-P interval

Wandering Atrial Pacemaker (WAT) vs
Multifocal Atrial Tachycardia (MAT)

WAT = irregularly irregular rhythm; multiple atrial pacemakers firing at own pace (3 different P-waves

MAT = WAT w/ tachycardia (seen in severe lung disease)

Junctional Premature Contraction (JPC)

Beat originates prematurely in AV node - normal electrical conduction system of ventricles, so QRS complex is normal

Junctional Escape Beat

Normal pacemaker fails to fire... next available pacemaker fires in its place (AV nodal pacer senses and fires)

Distance of escape beat from preceding complex is always longer than normal P-P interval

Junctional Rhythm

Escape Rhythm when normal pacemaking function of atria and SA node absent

Only ventricles contract (40-60 bpm) via AV node

Accelerated Junctional Rhythm if = 60-100 bpm

Ventricular Premature Contraction (VPC)

Premature firing of ventricular cell (ventricular pacer fires before normal SA or AV pacer)... wide/bizarre QRS!

Ventricular Escape Beat

Normal pacer does not fire... so have ventricle fires... wide/bizarre QRS

Idioventricular Rhythm

When ventricular focus acts as primary pacemaker for heart (QRS wide/bizarre) -- no P waves

(Accelerated Idioventricular Rhythm if 40-100bpm)

Ventricular Tachycardia (VTach)

Fast ventricular rate dissociated from underlying atrial rate (still have sinus beats)

Can see complete negativity of all precordial leads

FUSION BEAT - sinus beat falls on spot that allows innervation of ventricle through normal ventricular conduction system; morphology between abnormal ventricular beat and normal QRS... SA node and ventricular pacer together

CAPTURE BEAT - complete innervation by sinus beat; indistinguishable from patient's normal complex (sinus beat 'captures' chance to go through AV node and depolarize ventricles normally)

BRUGADA SIGN - interval from R to bottom of S is >.10 seconds

JOSEPHSON'S SIGN - small notching near low point of S wave

Bachman Bundle

Internodal pathway that connects both atria

Where is P-wave normally negative?


(should be upright in I, II, V4-V6)

ECG 9-4

Inverted P waves II, III, avF (should be upright in I, II); retrograde conduction via pacaemaker near AV node, or low atrial ectopic pacemaker

LVH (R wave in aVL); with strain via slight ST elevation with asymmetrical T wave in anterior precordials


P wave > .12 seconds in I and II, with notched (m-shaped); need space between two humps .04+ sec

LAE (left atrial enlargement)

Usually caused by severe mitral valve disease

ECG 9-5


also LVH with strain via flipped asymmetrical T-waves everywhere

ECG 9-6


also left axis deviation with left anterior hemiblock (LAD with LAH)


Peaked and >2.5mm in limb leads

RAE (right atrial enlargement)

ECG 9-9

P-pulmonale (can be via hypertrophy or dilatation)

ECG 9-10

APC in 3rd beat
RBBB with right axis

Dx - right ventricular strain or COPD...

Intraatrial Conduction Delay (IACD)

Biphasic P-waves in V1; usually via atrial enlargement, but not enough to form P-mitrale or P-pulmonale

If 1st half of wave taller in V1 than first half in V6 = RAE
(COPD, PE, pulm HTN, mitral/tricuscipd/pulm valve disease)

If 2nd half of wave wider and deeper than .04 sec = LAE
(systemic HTN, aortic/mitral valve disease, restrictive cardiomyopathy, LV failure)
if height*width = 0.3.... 95% LAE

ECG 9-11

LAD with LAH
Lack of R-R progression (indeterminate Z-axis... no transition!)

ECG 9-12

LVH with strain
slight QT prolongation
jPC or VPC

ECG 9-18

Biatrial enlargement
P-Pulmonale- RAE
Biphasic waves in V1 - LAE

LVH (accounts for slight ST elevation in V2, V3, depression V5, V6)

ECG 9-19

P-mitrale and biphasic P-wave (RAE)
1st degree heart block

Interventicular Conduction Block (ICVD) - RBBB + LAH

ECG 9-21

Biaatrial Enlargement - V1 shows bigger positive P than negative; but P-negative has height*width >0.3

PR Depression DDx

Normal variant (if <0.8mm depression)
Atrial Infarction


PR depression
Diffuse ST segment elevation (concave up with scooped-out appearance)
Notching of terminal portion of QRS complex, especially in lateral precordial leads

ECG 10-1


PR depression
Diffuse ST segment elevation (concave up with scooped-out appearance)
Notching of terminal portion of QRS complex, especially in lateral precordial leads

Short PR Interval DDx

Retrograde junctional P waves
Lown-Ganong-Levine Syndrome (LGL)
Wolff-Parkinson-White Pattern and Syndrome (WPW)

Lown-Ganong-Levine Syndrome

Short PR interval due to impulse transmitted through bypass tract called James fibers - bypass upper and central portions of AV node; normal QRS since conduction through His bundles and bundle branches is normal

ECG 10-2

LGL (Lown-Ganong Levine Syndrome) - benign!

Short PR interval and normal waves

Wolff-Parkinson-White Syndrome (WPW)

Bypass tract = Kent bundle; have impulses go down normal tract and bypass tract...

Delta wave = nitial slurring of QRS in fusion beat, represents small amount of tissue stimulated by Kent bundle early impulse wave when superimposed on normal impulse (fusion beat)

Shortened PR interval with normal P wave (12% have normal PR interval...)
Wide QRS complex
Delta wave
St-T wave changes
Association with paroxysmal tachycardias

Life threatening!

Type A - all QRS complexes UPRIGHT in precordials (Kent on the left)
Type B - QRS complexes NEGATIVE in V1-2
(Kent on the Right... B looks like an R in 'right')
Type C - QRS complexes NEGATIVE in V5-6

ANTIDROMIC - impulse down Kent and back up AV node (wide-complex tachycardia)
ORTHODROMIC - impulse down AV node and return up Kent bundle (narrow complex... less tachycardic)

ECG 10-3


Short PR interval and delta waves

'Pseudoinfarct' pattern Q waves in III and aVF

ST and T waves changes - ST elevation in V1-V3, flipped Ts in I, aVL and V4-V6 (NOT ischemia); due to abnormal repolarization

ECG 10-5

WPW Type B
(also see APC)

ECG 10-15

AMI in Inferior leads
(Q waves II, III, aVF, ST elevation V1; ST depression aVL)

Some LAE (see in V1)

ECG 10-16

1st Degree Heart Block
(axis is 0)

ECG 10-17

See 1st degree hear block on right side of ECG

Which leads are best for visualizing P-wave?

aVL, V1, V2
(have flattest T-wave and most isoelectric)

ECG 10-20

3rd Degree Heart Block

ECG 10-21

Third Degree Heart Block
LAH (left anterior hemiblock)

Pathological QRS Amplitude
(Pericardial Effusion)

<5mm limb leads
<10mm precordials

ECG 11-1

Pericardial effusion

<5mm limb leads
<10mm precordials

Left Ventricular Hypertrophy

S wave in V1,V2 + R wave in V5,V6 >35mm

Any precordial lead >45mm
R wave in aVL >11m
R wave in lead I >12mm
R wave in aVF >20mm

ECG 11-5

(due to volume overload; ST segments upwardly concave in V6.. like smiley face... with asymmetrical T-wave)
Sinus tachycardia

ECG 11-7

LVH (aVL>11mm)
Sinus bradycardia
P-mitrale (two humps in II, .12 sec)

Right Ventricular Hypertrophy

R:S ratio in V1 or V2 > 1

R:S Ratio >1 in V1, V2
(Differential Diagnosis)

1. RVH
3. Young children/adolescents
4. Posterior AMI
5. WPW Type A

ECG 11-12

RVH (strain with pressure overload, systolic... ST concave downward in V1)

ECG 11-13


Prolonged QRS
(Differential Dx)

>.12 sec

1. Hyperkalemia
2. Ventricular tachycardia
3. Idioventricular rhythms, including heart block
4. Drug effects and overdoses (TCAs)
5. WPW
6. BBB and IVCD
7. VPC
8. Aberrantly conducted complexes

ECG 11-14

Idioventricular Conduction Delay (ICVD)... cause not RBBB or LBBB; so need to rule out hyperkalemia!

ECG 11-15

(also possible ischemia - see concordance in V2, V3; means last portion of QRS and Twave in same direction; normally should be discordant if no ischemia)
IACD possibly via LAE

Concordance in BBB

Concordance = last section of QRS in same direction as T-wave --- ISCHEMIA

Discordance = normal; when last section of QRS in opposite direction as T-wave

ECG 11-16

Wide complex tachycardia -- could be VTach but consider Hyperkalemia!!

ECG 11-17

3rd Degree Heart Block
APC causes switch in pacemakers - first 3 QRS have LBBB, next 3 have RBBB

5th beat = fusion beat (green star)
7th beat = capture beat (gold star)

ECG 11-18

Morphology shift - blue star = fusion beat; has characteristics of normal + abnormal beat (red star)... then VTach

Also VPCs and aberrantly conducted beats

Axis in left quadrant + LAH

Transition between Leads V1,V2

Significant vs Insignificant Q-waves

Significant = dead myocardium
(>1/3 of total QRS height, wider than .03 sec)

Insignificant = first vector of ventricular depolarization
See in leads I and aVL

QS Waves: when no intervening R-wave... if only in V1, BENIGN.... if extend to V2 = infarct of anteroseptal areas of heart at some time in past/present

Respiratory Variation of Q Waves
INSPIRATION (↓Q) - heart more upright; depolariation of Q-wave almost totally horizontal; shallow Q!

EXPIRATION (↑Q) - heart more horizontal; depolarization of Q-wave more vertical as goes L->R; deep Q!

Significant Pathological Q Waves Definition

1. >1/3 of total QRS height
2. wider than .03 sec (more important)

ECG 11-20

Benign QS waves only in V1

Pathological QS waves go through V3

ECG 11-21

Q-wave variation with respiration
(see changes peak every 3-4 seconds... breathing!)

If electrical alterans - see more abrupt changes; bigger swings (not as gradual)

ECG 11-22

Significant Q-waves in I, II, III, aVF, V5-V6
(old infarct of inferolateral walls)

ECG 11-23

Sig Q waves in III, aVF

Normal Transition Zone in Precordials


Earlier = Counterclockwise rotation
Later = Clockwise rotation

Osborn (J) Wave

Big notch right after QRS (don't all have to look the same)

Hypothermia! (colder temp -- higher wave)
Also bradycardia, atrial fibrilation, Addison's, sepsis, severe hypothyroidism

Associated with cardiac irritiability (ventricular common)... be careful moving patient into a stretcher or heating blanket... when see Osborn wave on ECG be extra cautious in moving patient

ECG 11-30

Notches in V4-V6

ECG 11-32

Osborn waves and QT prolongation
Lots of artifact too -- common in hypothermic patients (not via shaking)

Positive Depolarization Leads and Axis...

I: -90 to +90
II: -30 to +150
III: +30 to -150

aVR: +120 to -60
aVL: -120 to +60
aVF: 0 to +180

Isolating the Axis

1. Find Quadrant with I and aVF
2. Isolate isolectric lead
3. Isolate closest lead (make 'T')
4. Isolate vector (if isoelectric is more negative than positive, move vector 10-20 degrees towards negative POLE of the 'T')
5. Double-check

Causes of Right Axis Deviation

1. Normal in adolescents/children
2. RVH
3. LPH (Left Posterior Hemiblock)
4. Dextrocardia
5. Ectopic Ventricular Beats/Rhythms

Causes of Left Axis Deviation

1. LAH (Left Anterior Hemiblock)
2. Ectopic ventricular beats/Rhythms


Normal transition between 20-40 degrees (posteriorly; since most cardiac tissue in left ventricle)

Z-Axis Precordial Lead System: V2 = 90 degrees (straight out to front)

Put 'T' between leads indicating transition zone...
EXAMPLE - transition zone is between V4-V5; put 'T' on 40 degrees (between 30 and 50 degrees) -- look negative/counterclockwise 90 degrees for Z-axis if left axis--- posterior 50 degrees

Right Bundle Branch Block Criteria

1. QRS Prolongation >.12 sec
2. Slurred S wave leads I, V6 (crucial!!)
3. RSR' pattern in lead V1; R' > R

QR' wave - when have anteroseptal MI + RBBB (first ear of bunny is Q wave flopped down) - see in V1

1. Congenital Heart Defects
2. MI
3. Myocarditis
4. PE
5. Scar tissue post-heart surgery

QR' Wave

Anteroseptal MI + RBBB
(first ear of bunny is Q wave flopped down)

See in V1

ECG 13-1


ECG 13-2


Causes of RBBB

1. Congenital Heart Defects
2. MI
3. Myocarditis
4. PE
5. Scar tissue post-heart surgery

ECG 13-6


You CAN make Dx of LVH with RBBB
CAN'T make Dx of RVH in RBBB
CAN'T make Dx of LVH/RVH in LBBB

ECG 13-9

U-waves in V2-V6
Supraventricular Bigeminy
(since first 0.03 sec of normal and aberrant complexes identical... similar origins of complexes- down AV node)

Left Bundle Branch Block Criteria

1. Duration >0.12 sec
2. Broad, monomorphic R waves in I and V6, can see notching (no Q)
3. Broad, monomorphic S waves in V1

1. Hypertension
2. Coronary Artery Disease
3. Dilated Cardiomyopathy
4. Rheumatic Heart Disease
5. Infiltrative Disease of Heart
6. Benign/Idiopathic

ECG 13-11


ECG 13-12

(can't comment on LVH...)

ECG 13-14

(vs LVH - this ECG has notching in V6, also wide QRS)

Causes of LBBB

1. Hypertension
2. Coronary Artery Disease
3. Dilated Cardiomyopathy
4. Rheumatic Heart Disease
5. Infiltrative Disease of Heart
6. Benign/Idiopathic

ECG 13-16

(see long QT too... common in BBB, not as medically significant)

Intraventricular Conduction Delay

If localized - NOT greater than .12 wide QRS

Throughout ECG = QRS>.12sec, but not all characteristics of LBBB/RBBB

Think about HYPERKALEMIA!!

ECG 13-21

(PR prolongation, tall/broad T-waves, widened QRS)

Prolonged QT via hypocalcemia (common in renal failure w/ hyperkalemia

ECG 13-22

(no p-waves)

Left Anterior Fascicle vs Left Posterior Fascicle

Left Anterior Fascicle - comes off the left bundle and give rise to Purknje fibers; innervates ANTERIOR and LATERAL walls of left ventricle

Left Posterior Fascicle - comes off left bundle, disperse loosely; innervates INFERIOR and POSTERIOR walls of left ventricle

Left Anterior Hemiblock

1. Left Axis Deviation (-30 to -90)
2. qR complex or R wave in lead 1
3. rS complex in lead III (also II, aVF)

Shortcut: + in lead I, - in lead aVF, - in lead II

ECG 13-24


ECG 13-26


Low voltage QRS due to obesity (respiratory variation) - causes heart to be more horizontal so QRS overall is smaller

Left Posterior Hemiblock

Difficult to block since fibers are dispersed/spread throughout posterior/inferior walls left ventricle (rare-- need large lesion)

1. Axis +90 to +180 (right quadrant)
2. S wave in lead I, Q in III
3. Exclusion of RAE and/or RVH

What % of PE have S1Q3T3?


ECG 13-27


ECG 13-30

RVH (not LPH!)

Bifascicular Blocks

1. Lead I:+, with slurred S
2. Lead II: -
3. Lead aVF: -
4. V1: rabbit ears RsR'
5. V6: slurred S

RBBB + LPH (more common than just LPH)
1. Lead I: -, with slurred S
2. Lead aVF: +
3. Lead V1: rabbit ears RsR'
4. Lead V6: slurred S

ECG 13-32


ECG 13-34


ECG 13-38

(unstable! worrisome...)


Transition from QRS to ST segment

T-Wave Shape
(Symmetry, Concavity, Height, Polarity)

Asymmetrical: Normal
(ischemia, electrolyte abnorm, CNS problems)

ST-Concave Up (smiley): early repolarization, pericarditis
ST-Concave Down (frown): strain pattern

Height - shouldn't be more than 2/3 of R

- in aVR
+ in I, II, V3-V6

Which lead has a negative P and negative T?


ECG 14-4

SYMMETRICAL flipped T waves

Irregularly irregular rhythm with varying P-waves/PR intervals (wandering atrial pacemaker!) -- COPD pathology

ECG 14-7

(peaked T-waves in mid-precordials; long QT via hypocalcemia; low voltage via pericardial effusion)

ECG 14-8


ECG 14-9

Wide-complex tachycardia
Peaked, symmetrical T-waves

AV-Dissociation: not 3rd degree heart block because P waves not much faster than QRS-complexes

ECG 14-11

3rd Degree Heat block with atrial tachycardia and ventricular escape rhythm

ECG 14-12

Inferior Wall MI with hyperacute Right Ventricular Failure
(IWMI, ST elevation in III>II, ST elevation in V1)

ECG 14-15

Intracranial bleeds/stroke - wide ST segments with broad T-waves

Little spike pattern = artifact (electrical interference)

Intracranial Bleeds/Stroke

Wide ST-segments with broad T-waves

ECG 14-17

(ST-segment elevation in precordials; flipped T-waves and symmetrical in I, aVL, V2-V6)

ST signs of Ischemia

ST flat and/or downward sloping
T wave symmetrical
(if biphasic, should start with negative deflection)

See regional distribution of ST-elevation or depression

ECG 14-19

Inferior heart ISCHEMIA
(ST-depression in II, III, aVF... reciprocal ST-elevation in aVR)

ECG 14-20

1st Degree Heart Block

Strain Pattern

ST and T wave configurations that arise from repolarization abnormalities in RVH or LVH

Right Ventricular Strain Pattern (w/ RVH)

Concave-downward depressed ST segment, and a flipped, asymmetric T-wave

In V1, V2

Criteria for RVH

Need more than one

1. P-pulmonale (RAE)
2. Right axis deviation
3. Increased R:S ratio in V1 and V2
4. RVH strain pattern
5. S1Q3T3

ECG 14-23

RVH with strain
(see concave downward ST in V1)

Right axis deviation
Increased R:S ratio in V1, V2
RVH strain pattern

ECG 14-24

RBBB (not RVH!)

See concordance in inferior leads + precordials (ischemia)

Left Ventricular Strain Pattern (w/ LVH)

ST depression with downward concavity, flipped and asymmetric T wave in V4-V6

In V1-V2 see reciprocal (ST elevation with upward concavity; upright, asymmetric T-wave)

if NO LVH, then CAN'T diagnose STRAIN

Concave, downward ST-depression, flipped T-wave at V5,V6

DIASTOLIC PRESSURE OVERLOAD (High Volume/Mitral-Aortic Regurg)
Concave, upward deflection of ST-segment V5,V6

Two Types of LVH with Strain
(Systolic vs. Diastolic)

Concave, downward ST-depression, flipped T-wave at V5,V6

(High Volume/Mitral-Aortic Regurg)
Concave, upward deflection of ST-segment V5,V6

Ischemia vs. Strain
(general difference...)

STRAIN - sharper ST-slope; concave!

ECG 14-26

LVH with strain
(LVH + downward concave in V5,V6; upward concae in V1,V2)

ECG 14-27

LVH with strain
T-waves asymmetrical, so no ischemia

ECG 14-30

LVH with strain
(artifact at beginning)

ECG 14-31

LVH with strain (due to DIASTOLIC pressure)
---either mitral regurg, aortic regurg.

See LVH + V5,V6 with upward concave ST depressions

ECG 14-32

A: 'good' - LVH with strain; asymmetrical T-waves
B: 'bad' - see flat elevated/depressed ST-segments (elevation in II, III, aVF; reciprocal depression aVL)

ECG 14-37

A: 'good' - concave upward; repolarization or pericarditis?
B: 'bad' - flatter elevated ST-segments... lateral wall infarct

ECG 14-43

A: 'good' - LVH with strain (upward concavity V1-V3
B: 'bad' - anteroseptal MI; flat ST segments (V1 and V2!)

ECG 14-45

A: 'good' - LVH with strain
B: 'bad' - Anteroseptal infarct with lateral extension from V1-V6; ST elevation and flat

ECG 14-47

A: 'good' - LVH with strain in right precordial leads
B: 'bad' - Anteroseptal MI.... ST-segments flat with positive slope

Pericarditis on ECG

1. PR depression
2. Diffuse ST elevation
3. Scooping, upward concave ST segments
4. Notching at end of QRS

Via irritation of pericardium causing net positivity

ECG 14-53

(not much PR depression; but see upward scooping diffuse ST-eelvation, notching at end of QRS)

ECG 14-54

(PR-depression in II!)

ECG 14-58

Concordant leads: III, aVL, aVF, V2, V3
Disconrdant leads: everything else...

Reciprocal Changes in Inferior Wall MI

ST-segment depressions in:
aV, I

Often first sign of MI!

Reciprocal Changes in Anteroseptal Wall MI

ST-segment depressions in:

Often first sign of MI!

ECG 15-1

Anteroseptal MI
ST-elevations in V1, V2, V3; see reciprocal ST-depressions in II, III, aVF

Anteroseptal AMI with Lateral Extension

ST-elevation with flipped T-wave in V1-V6
(also in I and aVL)

ECG 15-4

Anteroseptal AMI with lateral extension
(hyperacute changes of early AMI since huge ST and T; first 15-30 minutes of MI)

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