Ecg final pp ts; 19 06-2012

BASICS OF ELECTROCARDIOGRAPH

Y

DR. MVN Suresh.AHA Instructor for BLS & ACLS

Introduction

• A recording of the electrical activity of the heart over time

• Gold standard for diagnosis of cardiac arrhythmias

• Helps detect electrolyte disturbances (hyper- & hypokalemia)

• Allows for detection of conduction abnormalities• Screening tool for ischemic heart disease during

stress tests• Helpful with non-cardiac diseases (e.g.

pulmonary embolism or hypothermia )

Recording of the ECG:

Leads used:• Limb leads are I, II, II. So called because at one

time subjects had to literally place arms and legs in buckets of salt water.

• Each of the leads are bipolar; i.e., it requires two sensors on the skin to make a lead.

• If one connects a line between two sensors, one has a vector.

• There will be a positive end at one electrode and negative at the other.

• The positioning for leads I, II, and III were first given by Einthoven, form the basis of Einthoven’s triangle

Important Precautions

Correct Lead placement and good contact Proper earth connection, avoid other

gadgets Deep inspiration record of L3, aVF Compare serial ECGs if available Relate the changes to Age, Sex, Clinical

history Consider the co-morbidities that may

effect ECG Make a xerox copy of the record for future

use Interpret systematically to avoid errors

ECG Bipolar Limb Leads

Bipolar leads record voltage between electrodes placed on wrists & legs (right leg is ground)

Lead I records between right arm & left arm

Lead II: right arm & left leg

Lead III: left arm & left leg

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+

+ +

- - -

ECG Bipolar Limb Leads

R L

F

R

F

L

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Standard ECG is recorded in 12 leads Six Limb leads – L1, L2, L3, aVR, aVL,

aVF Six Chest Leads – V1 V2 V3 V4 V5 and

V6 L1, L2 and L3 are called bipolar leads L1 between LA and RA L2 between LF and RA L3 between LF and LA

ECG Bipolar Limb Leads

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ECG Chest Leads

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Precardial (chest) Lead Position V1 Fourth ICS, right sternal border V2 Fourth ICS, left sternal border V3 Equidistant between V2 and V4 V4 Fifth ICS, left Mid clavicular Line V5 Fifth ICS Left anterior axillary line V6 Fifth ICS Left mid axillary line

ECG Chest Leads

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The Six Chest Leads

TRANSVERSE PLANE

ECG Complex

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ECG ComplexP wave

PR Interval

QRS complex

ST segment

T Wave

QT Interval

RR Interval

3 distinct waves are produced during cardiac cyc3 distinct waves are produced during cardiac cycleP wave caused by atrial depolarizationQRS complex caused by ventricular depolarizationT wave results from ventricular repolarizationle

ECG Complex

Cardiac Impulse

SA node -> atrial muscle -> AV node -> bundle of His -> Left and Right Bundle Branches -> Ventricular muscle

ECG ComplexElements of the ECG:• P wave: Depolarization of both atria;

• Relationship between P and QRS helps distinguish various cardiac arrhythmias

• Shape and duration of P may indicate Atrial enlargement

• PR interval: from onset of P wave to onset of QRS

• Normal duration = 0.12-2.0 sec (120-200 ms) (3-4 horizontal boxes)

• Represents atria to ventricular conduction time (through His bundle)

• Prolonged PR interval may indicate a 1st degree heart block

• QRS complex: Ventricular depolarization

• Larger than P wave because of greater muscle mass of ventricles

• Normal duration = 0.08-0.12 seconds

• Its duration, amplitude, and morphology are useful in diagnosing cardiac arrhythmias, ventricular hypertrophy, MI, electrolyte derangement, etc.

• Q wave greater than 1/3 the height of the R wave, greater than 0.04 sec are abnormal and may represent MI

ST segment:• Connects the QRS complex and T wave• Duration of 0.08-0.12 sec (80-120 msec

T wave: • Represents Repolarization or recovery of ventricles

• Interval from beginning of QRS to apex of T is referred to as the absolute refractory period

QT Interval:• Measured from beginning of QRS to the end of the T wave

• Normal QT is usually about 0.40 sec• QT interval varies based on heart rate

ECG Complex

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X-Axis represents time - Scale X-Axis – 1 mm = 0.04 sec Y-Axis represents voltage - Scale Y-Axis – 1 mm = 0.1

mV Runs at a paper speed of 25mm/sec One big square on X-Axis = 0.2 sec (big box) Two big squares on Y-Axis = 1 milli volt (mV) Each small square is 0.04 sec (1 mm in size at a speed

of 25mm/sec) Each big square on the ECG represents 5 small squares

= 0.04 x 5 = 0.2 seconds 5 such big squares = 0.2 x 5 = 1sec = 25 mm One second is 25 mm or 5 big squares One minute is 5 x 60 = 300 big squares

ECG Graph Paper

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Next QRS

Rate Determination

QRS

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No. of Big Boxes

R – R Interval Rate Cal.

Rate

One 0.2 sec 60 ÷ 0.2 300

Two 0.4 sec 60 ÷ 0.4 150

Three 0.6 sec 60 ÷ 0.6 100

Four 0.8 sec 60 ÷ 0.8 75

Five 1.0 sec 60 ÷ 1.0 60

Six 1.2 sec 60 ÷ 1.2 50

Seven 1.4 sec 60 ÷ 1.4 43

Eight 1.6 sec 60 ÷ 1.6 37

BRADY

T ACHY

NORMA L

Rate Determination

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What is the Heart Rate ?

Answer on next slide

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To find out the heart rate we need to know The R-R interval in terms of # of big

squares If the R-R intervals are constant

In this ECG the R-R intervals are constant

R-R are approximately 3 big squares apart

So the heart rate is 300 ÷ 3 = 100

What is the Heart Rate ?

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What is the Heart Rate ?

Answer on next slide

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To find out the heart rate we need to know The R-R interval in terms of # of big

squares If the R-R intervals are constant

In this ECG the R-R intervals are constant R-R are approximately 4.5 big squares apart So the heart rate is 300 ÷ 4.5 = 67

What is the Heart Rate ?

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What is the Heart Rate ?

Answer on next slide

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To find out the heart rate we need to know The R-R interval in terms of # of Big

Squares If the R-R intervals are constant

In this ECG the R-R intervals are not constant

R-R are varying from 2 boxes to 3 boxes It is an irregular rhythm – Sinus arrhythmia Heart rate is 300 ÷ 2 to 3 = 150 to 100

approx

What is the Heart Rate ?

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QRS Axis

SE

NENW

SW

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QRS Axis

The QRS electrical (vector) axis can have 4 directions

Normal Axis - when it is downward and to the left – southeast quadrant – from -30 to +90 degrees

Right Axis – when it is downward and to the right – southwest quadrant – from +90 to 180 degrees

Left Axis – when it is upward and to the left – Northeast quadrant –from -30 to -90 degrees

Indeterminate Axis – when it is upward & to the right – Northwest quadrant – from -90 to +180

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Axis Determination

NORMAL RIGHT LEFT

MEET LEAVEALL UPRIGHT

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Axis LI LIII aVF TIP

Normal Positive Positive Both Up

Right Negative Positive Meet

Left Positive Negative Leave

Indeterminae Negative Positive Meet

Axis Determination

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LEAD 1

LEAD 2

LEAD 3

aVR

aVL

aVF

What is the Axis ?

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ECG With Normal Axis

Note the QRS voltages are positive and upright in the leads - L1, L2, L3 and aVF

L2, L3 and aVF tell that it is downward

L1, aVL tell that it is to the left Downward and leftward is

Normal Axis Normal QRS axis

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LEAD 1

LEAD 2

LEAD 3

aVR

aVL

aVF

What is the Axis ?

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ECG With Left Axis

Note the QRS voltages are positive and upright in leads L1and aVL

Negative in L2, L3 and aVF L1, aVL tell that it is leftward L2, L3, and aVF tell that it is not down ward

- instead it is upward Upward and Leftward is Left Axis See the Left - Leave criterion QRS in L1

and L3 leave each other Left Axis Deviation - LAD

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Normal ECG

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Normal ECG Standardization – 10 mm (2 boxes) = 1 mV Double and half standardization if required Sinus Rhythm – Each P followed by QRS, R-R constant P waves – always examine for in L2, V1, L1 QRS positive in L1, L2, L3, aVF and aVL. – Neg in aVR QRS is < 0.08 narrow, Q in V5, V6 < 0.04, < 3 mm R wave progression from V1 to V6, QT interval < 0.4 Axis normal – L1, L3, and aVF all will be positive ST Isoelectric, T waves ↑, Normal T↓ in aVR,V1, V2

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Pediatric ECG

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This is the ECG of a 6 year old child Heart rate is 100 – Normal for the

age See V1 + V5 R >> 35 – Not LVH –

Normal T↓ in V1, V2, V3 – Normal in child Base line disturbances in V5, V6 –

due to movement by child

Pediatric ECG

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Juvenile ECG

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Be aware of normal ECG Normal Resting ECG – cannot exclude disease Ischemia may be covert – supply / demand equation Changes of MI take some time to develop in ECG Mild Ventricular hypertrophy - not detectable in ECG Some of the ECG abnormalities are non specific Single ECG cannot give progress – Need serial ECGs ECG changes not always correlate with Angio results Paroxysmal events will be missed in single ECG

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Normal Variations in ECG May have slight left axis due to rotation of

heart May have high voltage QRS – simulating LVH Mild slurring of QRS but duration < 0.09 J point depression, early repolarization T inversions in V2, V3 and V4 – Juvenile T ↓ Similarly in women also T↓ Low voltages in obese women and men Non cardiac causes of ECG changes may occur

Normal Variations in ECG

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Early Repolarization

This ECG has all normal featuresThe ST-T (J) Junction point is elevated. T waves are tall, May be inverted in LIII, The ST segment initial portion is concave. This does not signify

Ischemia

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Pseudo Normalization

Before Chest pain

During Chest pain

Chest pain Relieved

T↓

T↓

T↑

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Atrial Waves

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Left Atrial Enlargement

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Left Atrial Enlargement

P wave duration is 4 boxes-0.04 x 4 = 0.16

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Always examine V 1 and Lead 1 for LAE Biphasic P Waves, Prolonged P waves P wave 0.16 sec, ↑ Downward component Systemic Hypertension, MS and or MR Aortic Stenosis and Regurgitation Left ventricular hypertrophy with dysfunction Atrial Septal Defect with R to L shunt

Left Atrial Enlargement

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Right Atrial Enlargement

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Right Atrial Enlargement

P wave voltage is 4 boxes or 4 mm

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Always examine Lead 2 for RAE Tall Peaked P Waves, Arrow head P

waves Amplitude is 4 mm ( 0.4 mV) -

abnormal Pulmonary Hypertension, Mitral

Stenosis Tricuspid Stenosis, Regurgitation Pulmonary Valvular Stenosis Pulmonary Embolism Atrial Septal Defect with L to R shunt

Right Atrial Enlargement

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Ventricular Hypertrophy Ventricular Muscle

Hypertrophy QRS voltages in V1 and

V6, L 1 and aVL We may have to record

to ½ standardization T wave changes

opposite to QRS direction

Associated Axis shifts Associated Atrial

hypertrophy

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Right Ventricular Hypertrophy

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Tall R in V1 with R >> S, or R/S ratio > 1 Deep S waves in V4, V5 and V6 The DD is RVH, Posterior MI, Anti-clock

wise rotation of Heart Associated Right Axis Deviation, RAE Deep T inversions in V1, V2 and V3 Absence of Inferior MI

Right Ventricular Hypertrophy

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Is there any hypertrophy ?

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Criteria and Causes of RVH Criteria of RVH Tall R in V1 with R >> S, or R/S ratio > 1 Deep S waves in V4, V5 and V6 The DD is RVH, Posterior MI, Rotation Associated Right Axis Deviation, RAE Deep T inversion in V1, V2 and V3Cause of RVH Long standing Mitral Stenosis Pulmonary Hypertension of any cause VSD or ASD with initial L to R shunt Congenital heart with RV over load Tricuspid regurgitation, Pulmonary stenosis

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What is in this ECG ?

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ECG OF MS with RVH, RAE

Classical changes seen are Right ventricular hypertrophy Right axis deviation Right Bundle Branch Block P – Pulmonale - Right Atrial enlargement P – Mitrale – Left Atrial enlargement If Atrial Fibrillation develops – ‘P’

disappears

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Left Ventricular Hypertrophy

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High QRS voltages in limb leads R in Lead I + S in Lead III > 25 mm S in V1 + R in V5 > 35 mm R in aVL > 11 mm or S V3 + R aVL >

24 ♂, > 20 ♀ Deep symmetric T inversion in V4, V5

& V6 QRS duration > 0.09 sec Associated Left Axis Deviation, LAE Cornell Voltage criteria, Estes point

scoring

Left Ventricular Hypertrophy

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What is in this ECG ?

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Causes of LVH Pressure overload - Systemic Hypertension, Aortic

Stenosis Volume overload - AR or MR - dilated cardiomyopathy VSD - cause both right & left ventricular volume

overload Hypertrophic cardiomyopathy – No pressure or volume

overloadCriteria of LVH High QRS voltages in limb leads R in Lead I + S in Lead III > 25 mm or S in V1 + R in V5

> 35 mm R in aVL > 11 mm or S V3 + R aVL > 24 ♂, > 20 ♀ Deep symmetric T inversion in V4, V5 & V6 QRS duration > 0.09 sec, Associated Left Axis

Deviation, LAE

Causes and Criteria of LVH

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Atrial EctopicsAPC

APCAPC

APC

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Note the premature (ectopic) beats marked as

APC (Atrial Premature Contractions) These occurred before the next

expected QRS complex (premature) Each APC has a P wave preceding

the QRS of that beat – So impulse has originated in the atria

The QRS duration is normal < 0.08, not wide

Atrial Ectopics

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Complete RBBB

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Complete LBBB

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Complete LBBB Complete LBBB has a QRS duration > 0.12 sec Prominent S waves in lead V1, R in L I, aVL, V6 Usually broad, Bizarre R waves are seen, M

pattern Poor R progression from V1 to V3 is common. The "normal" ST-T waves in LBBB should be

oriented opposite to the direction of the QRS Incomplete LBBB looks like LBBB but QRS

duration is 0.10 to 0.12 sec, with less ST-T change.

This is often a progression of LVH changes.

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Blood Supply of Heart

LCA

RCA

LAD

LCX

RCA

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Heart has four surfaces Anterior surface – LAD, Left Circumflex (LCx) Left lateral surface – LCx, partly LAD Inferior surface – RCA, LAD terminal portion Posterior surface – RCA, LCx branches Rt. and Lt. coronary arteries arise from aorta They are 2.5 mm at origin, 0.5 mm at the end Coronary arteries fill during diastole Flow - epicardium to endocardium –

poverty/plenty

Blood Supply of Heart

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Ischemia, Injury & Infarction

Myocardial Ischemia

Myocardial Injury

Myocardial Infarction

1. Ischemia produces ST segment depression with or without T inversion

2. Injury causes ST segment elevation with or without loss of R wave voltage

3. Infarction causes deep Q waves with loss of R wave voltage.

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Ischemia and Infarction

TRANSMURAL Injury ST Elevation

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Ischemic Heart Disease (IHD)

Blood supply Sub-endocardial

Transmural

IschemiaTransient loss

StableAngina

Variant Angina

InfarctionPersistent loss

NSTEMIACS

STEMIACS

ST Segment Depressed Elevated

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Interpret this ECG

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NSTEMI

Non ST ↑ MI or NSTEMI, Non Q MI Or also called sub-endocardial Infarction Non transmural, restricted to the sub-

endocardial region - there will be no ST ↑ or Q waves

ST depressions in anterio-lateral & inferior leads

Prolonged chest pain, autonomic symptoms like nausea, vomiting, diaphoresis

Persistent ST-segment ↓even after resolution of pain

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What are these ECGs

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STEMI and QWMI

STEMI and QWMI ST ↑ signifies severe transmural myocardial

injury – This is early stage before death of the muscle tissue – the infarction

Q waves signify muscle death – They appear late in the sequence of MI and remain for a long time

Presence of either is an indication for thrombolysis

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Evolution of Acute MI

A – Normal ST segment and T waves

B – ST mild ↑ and prominent T waves

C – Marked ST ↑ + merging upright T

D – ST elevation reduced, T↓,Q starts

E – Deep Q waves, ST segment returning to baseline, T wave is inverted

F – ST became normal, T Upright, Only Q+

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Critical Narrowing of LAD

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Normal Q waves

Notice the small

Normal Q in Lead I

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Pathological Q wave

Notice the deep & wide

Infarction Q in Lead I

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Very Striking

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Hyper Acute MI

Note the hyper acute elevation of ST The R wave is continuing with ST and

the complexes are looking rectangular Some times tall and peaked T waves in

the precardial leads may be the only evidence of impending infarct

Sudden appearance LBBB indicates MI MI in Dextro-cardia – right sided leads

are to be recorded

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Hyper Acute MI

Note the hyper acute elevation of ST The R wave is continuing with ST and

the complexes are looking rectangular

Some times tall and peaked T waves in the precardial leads may be the only evidence of impending infarct

Sudden appearance LBBB indicates MI

MI in Dextro-cardia – right sided leads are to be recorded

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Severe Chest Pain – Why ?

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Acute Anterio-lateral MI

Note the marked ST elevations in chest leads V2 to V5 and also ST↑ in L1 & aVL

T inversions have not appeared as yet

R wave voltages have dropped markedly in V3, V4, V5 and V6

Small R in L1 and aVL.

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Which wall MI ?

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Acute True Posterior MI

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Due to occlusion of the distal Left circumflex artery or posterior descending or distal right coronary artery

Mirror image changes or reciprocal changes in the anterior precardial leads

Lead V1 shows unusually tall R wave (it is the mirror image of deep Q)

V1 R/S > 1, Differential Diagnosis - RVH

Acute True Posterior MI

Sinus Bradycardia

What is the rhythm?

Tachyarrhythmias

What is the rhythm?

Tachyarrhythmias

Ectopic rate nomenclature:

[150-250] Paroxysmal tachycardia

[250-350] Flutter

[350+] Fibrillation

AV Block

What is the rhythm?

AV Block

AV Block

Tachyarrhythmias

What is the rhythm?

Atrial Fibrillation

Monomorphic VT

V1

Polymorphic VT

“Torsade de Pointes”(Polymorphic VT Associated with Prolonged Repolarization)

Ventricular Fibrillation (VF)

• Totally chaotic rapid ventricular rhythm• Often precipitated by VT• Fatal unless promptly terminated (DC shock)

Sustained VT: Degeneration to VF

Atrial Fibrillation with Rapid Conduction ;Via Accessory Pathway: Degeneration to VF

Representation in culture:

• In TV medical dramas, an isoelectric ECG (no cardiac electrical activity, aka, flatline, is used as a symbol of death or extreme medical peril.

• Technically, this is known as asystole, a form of cardiac arrest, with a partcularly bad prognosis.

• Defibrillation, which can be used to correct arrythmias such as ventricular fibrillation and pulseless ventricular tachycardia, cannot correct asystole.

In common

SUMMARY Rate Rhythm Axis Intervals Hypertrophy Infarct

To summarize:1. Calculate RATE2. Determine RHYTHM3. Determine QRS AXIS4. Calculate INTERVALS5. Assess for HYPERTROPHY6. Look for evidence of INFARCTION

The End

Dr.M.V.N.Suresh<drsuresh10k@gmail.com>

Ph: 99 851 9999 3, 988 535 7848