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In 1924, he was awarded the Nobel Prize in Medicine for his discovery.- limb leads Many advancements such as Goldbergers chest leads... EKG LeadsThe standard EKG has 12 leads: 3 Standar

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History of the ECG/EKG

• During the late 1800’s and early 1900’s, Dutch physiologist Willem Einthoven developed the early electrocardiogram He won the Nobel prize

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• Hubert Mann first uses the electrocardiogram to describe

electrographic changes associated with a heart attack in 1920

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• Electrocardiograms must be viewed in the context of demographics, health history, and other clinical test correlates They are especially useful when compared across time to see how electrical activity of the heart has changed (perhaps as the result of some pathology).


1887 British physiologist Augustus D Waller of St Mary's Medical School, London publishes the first human electrocardiogram It is recorded with a capilliary electrometer from Thomas

Goswell, a technician in the laboratory Waller AD A demonstration on man of electromotive

changes accompanying the heart's beat J Physiol (London) 1887;8:229-234 1889 Dutch

physiologist Willem Einthoven sees Waller demonstrate his technique at the First International Congress of Physiologists in Bale Waller often demonstrated by using his dog "Jimmy" who would patiently stand with paws in glass jars of saline 1889

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R.E.Mason., I.Likar

( 1966)

Augustus waller first to His electrocardiograph machine consisted of a Lippmann capillary electrometer fixed to a projector The trace from the heartbeat was projected onto a photographic plate which was itself fixed to a toy train This allowed a heartbeat

to be recorded in real time In 1911 he still saw little clinical application for his work

An initial breakthrough came when Willem Einthoven , working in Leiden , Netherlands , used the string galvanometer that he invented in 1903 [8] This device was much more sensitive than both the capillary electrometer that Waller used and the string galvanometer that had been invented separately in 1897 by the French engineer Clément Ader [9] Rather than using today's self-adhesive electrodes Einthoven's subjects would immerse each of their limbs into containers of salt solutions from which the ECG was recorded

Einthoven assigned the letters P, Q, R, S and T to the various deflections, and described the electrocardiographic features of a number of cardiovascular disorders In 1924, he was awarded the Nobel Prize in Medicine for his discovery.- limb leads

Many advancements such as Goldbergers chest leads

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

• Gold standard for diagnosis of cardiac arrhythmias

• Helps detect electrolyte disturbances (hyper- &

hypokalemia), arrhythmias, myocardial ischemia and

infarction, pericarditis, chamber hypertrophy, drug toxicity (i.e digoxin and drugs which prolong the QT interval)

• 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)

Cardiac Electrical Activity

• SA Node - Dominant pacemaker with an intrinsic rate of 60 - 100 beats/minute

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• AV Node - Back-up pacemaker with an intrinsic rate of 40 - 60 beats/minute

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• Ventricular cells -

Back-up pacemaker with an intrinsic rate of 20 - 40 bpm.

Lead “Views”

EKG Leads

Leads are electrodes which measure the

difference in electrical potential between

EKG Leads

The standard EKG has 12 leads: 3 Standard Limb Leads

3 Augmented Limb Leads

6 Precordial Leads

The axis of a particular lead represents the viewpoint from which it looks at the heart

Standard Limb Leads

Augmented Limb Leads

All Limb Leads

Precordial Leads

Adapted from: www.numed.co.uk/electrodepl.html

Precordial Leads

Summary of Leads

Limb Leads Precordial Leads

Bipolar I, II, III

(standard limb leads)

-Unipolar aVR, aVL, aVF

(augmented limb leads)

V

Limb Leads Chest Leads

Lead “Views”

V4 V5 V6

V4 V5 V6

aVR aVL aVF

V1 V2 V3

V4 V5 V6

aVR aVL aVF

V1 V2 V3

V4 V5 V6

V1 V2 V3

V4 V5 V6

Lateral Wall

aVR aVL aVF

V1 V2 V3

V4 V5 V6

Anterior Wall

• V3, V4

I

II III

aVR aVL aVF

V1 V2 V3

V4 V5 V6

aVR aVL aVF

V1 V2 V3

V4 V5 V6

• V1,V2

I

II III

aVR aVL aVF

V1 V2 V3

V4 V5 V6

• P wave – khử cực nhĩ (Atrial depolarization)

• T wave – tái cực thất (Ventricular repolarization)

• QRS – khử cực thất (Ventricular depolarization)

Why PQRST and not ABCDE? The choice of P is a mathematical convention

dating from Descartes by using letters from the second half of the alphabet N has

other meanings in mathematics and O is used for the origin of the Cartesian

coordinates P is simply the next letter (For more on Descartes see Henson JR

Descartes and the ECG lettering series J Hist Med Allied Sci April

1971;181�186)

Khoảng PR

Atrial depolarization

+ delay in AV junction

(AV node/Bundle of His)

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(cho phép thời gian để

nhĩ co thắt trước khi

thắt co thắt)

R Wave

Q Wave

S Wave

• J point - end of QRS complex & beginning

of ST segment

ST Segment

• Find J-points and ST segments

• Find J-points and ST segments

The ECG Paper

• Horizontally

– One small box - 0.04 s

– One large box - 0.20 s

• Vertically

– One large box - 0.5 mV

The ECG Paper (cont)

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• Every 3 seconds (15 large boxes) is

marked by a vertical line

• This helps when calculating the heart rate.

Calibration

Normal Sinus Rhythm

• J point - end of QRS complex & beginning

of ST segment

Criteria - P wave

An upright rounded P-wave in leads II, III and AVF, and an inverted P-Wave in AVR which precede each QRS Complex

• The P wave does not exceed 2.5mm in height

• It does not exceed 3mm in width

• A biphid P wave is seen in lead V1.

Criteria QRS complex

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• Should not exceed 0.12 seconds in duration

• Should not exceed 27mm in height

• Sharp narrow complex

• RS in V1, QRS in V6

Vectors: directions and amplitude

Typical complexes in the Pre-cordial

leads

V1 V2 V3 V4 V5 V6

Progression of R waves throughout the

• V4 Usually at the Apex (Transitional Zone

where the first negative wave appears).

R Wave Progression

Criteria U wave

• The origin is uncertain

• May represent repolarisation if the IVS

• May represent slow conduction of

ventricular myocardium

• Prominent U waves are abnormal

• Usually most visible in V1-V4

ECG Rhythm Interpretation

How to Analyze a Rhythm

Rhythm Analysis

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• Step 1: Calculate rate

• Step 2: Determine regularity

• Step 3: Assess the P waves

• Step 4: Determine PR interval

• Step 5: Determine QRS duration.

– Find a R wave that lands on a bold line

– Count the number of large boxes to the next R wave If the second R wave is 1 large box away the rate is 300, 2 boxes - 150, 3 boxes - 100, 4 boxes - 75, etc (cont)

R wave

1 5 0

1 0 0

7 5

6 0

5 0

Approx 1 box less than 100 = 95 bpm

Step 2: Determine regularity

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• Look at the R-R distances (using a caliper or

markings on a pen or paper)

• Regular (are they equidistant apart)?

Occasionally irregular? Regularly irregular?

Step 3: Assess the P waves

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• Are there P waves?

• Do the P waves all look alike?

• Do the P waves occur at a regular rate?

• Is there one P wave before each QRS?

Interpretation?

Normal P waves with 1 P wave for every QRS

ECG INTERPRETATION

• If the normal ECG is known then

interpretation of abnormals becomes easier

EASY ?

Approaching the ECG:


Read Right In A Minute

BGSMC Cardiology Study Group

Nick Sparicino, DO Mohamad Lazkani, MD Tomas Rivera-Bonilla, MD

February 3, 2011

Approach to the ECG

• Systematic Approach

• rhythm, rate, intervals, axis, morphology

RRIAM : R ead R ight I n A M inute

• Search for other clues

• Interpret the rhythm in

the clinical setting

• Determining rate:

– Regular rhythm:

• Big box: 300, 150, 100,

75, 60, 50 – Irregular rhythm:

• # cycles in a 6 second strip x10

• # cycles in a 12 second strip x5

• remember to use halves

if half a cycle is present

in the strip

RATE

10mm = 1mV 1mm = 0.1mV

What is the heart rate?

33 x 6 = 198 bpm

The Alan E Lindsay ECG Learning Center ; http://medstat.med.utah.edu/kw/ecg/

ATRIAL COMPONENTS

• P wave – atrial depolarization

– Duration 0.08 to 0.12 sec

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• PR interval - impulse initiation,

atrial depol, atrial repol, AV/His/

QT Interval - all the events of

ventricular systole

• Beginning of QRS to end of T wave

• Duration varies with heart rate, age,

sex but should be less than half the

RR interval

• Correction formulas exist to balance

HR, a major variable (as HR

decreases, QT interval increases)

– Fridericia Correction (QTf):

• QTf = QT interval / cubed root of the RR interval (in sec)

– Bazett’s formula (QTc):

• QTc = QT interval / square root of the RR interval (in sec)

VENTRICULAR COMPONENTS

• ST segment - electrically

neutral period between

ventricular depol and repol

Determining the Axis

• The Quadrant Approach

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• The Equiphasic Approach

AXIS - Quadrant Graphing Method

AXIS - Isoelectric Method

1 Find isoelectric lead

2 Find perpendicular lead

3 If QRS positive, vector towards lead, if negative, away

1

2

Determining the Axis

Predominantly

Positive

Predominantly Negative

Equiphasic

Quadrant Approach: Example 1

Negative in I, positive in aVF à

RAD

The Alan E Lindsay ECG Learning Center http:// medstat.med.utah.edu/ kw/ecg/

Quadrant Approach: Example 2

Positive in I, negative in aVF à Predominantly positive

in II à

Normal Axis (non-pathologic LAD)

The Alan E Lindsay ECG Learning Center http:// medstat.med.utah.edu/ kw/ecg/

Equiphasic Approach: Example 1

Equiphasic in aVF à Predominantly positive in I à QRS axis ≈ 0°

The Alan E Lindsay ECG Learning Center ; http://medstat.med.utah.edu/kw/ecg/

Equiphasic Approach: Example 2

Equiphasic in II à Predominantly negative in aVL à QRS axis ≈ +150°

The Alan E Lindsay ECG Learning Center ; http://medstat.med.utah.edu/kw/ecg/

• Hypertrophy (atrial & ventricular)

• Bundle branch blocks and hemiblocks

• Segment depressions & elevations

Analyzing ECGs

• The nine-step process can be used to analyze ECGs

Heart Rate

Regularity

P Waves

QRS Complexes

PR Intervals

ST Segments

T Waves

QT Intervals

U Waves

Questions to Ask

1 Is the rate of this dysrhythmia slow, normal or fast?

2 Is this rhythm regular or irregular? If it is irregular, what type

7 Are the T waves present? If so, are they normal or abnormal?

8 Are the QT intervals measurable? If so, are they normal or

abnormal?

9 Are U waves present?

Practice!
 Practice!


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