Ecg part introduction

ECG diagnosis

The Normal Conduction System

Lead Position

• A typical ECG report shows the cardiac cycle from 12 different vantage points (I, II, III, aVR, aVL, aVF, V1-V6), like viewing the event electrically from 12 different locations (like a 3D perspective).BUT only 10 electrodes are used.

• Lead I represents activity that is going from the right arm to the left arm

• Lead II represents activity that is going from the right arm to the left leg

• Lead III represents activity that is going from the left arm to the left leg

• aVL is placed on the left arm (or shoulder)• aVF is placed on the left leg (or hip)• aVR is placed on the right arm (or shoulder)• V1- 4th intercostal space to the right of sternum• V2- 4th intercostal space to the left of sternum• V3- halfway between V2 and V4• V4- 5th intercostal space in the left mid-clavicular line• V5- 5th intercostal space in the left anterior axillary line• V6- 5th intercostal space in the left mid axillary line

NSR

• NORMAL

• NORMAL

• NSR , Juvenile T-wave inversion.

• NORMAL

WPW Syndrome

AF, Inferior Q waves

RBBB

28 years with palpitations

• SVT

4 years later

• DEVELOPPED AF

50 years old syrian with mild CAD

• VT,THIS PT HAD SEVERE DCM,waiting for AICD

• Paced Rhythm

Waveforms and Intervals

Aims

• 10 ECG rules

• Heart Rate

• ECG signs of M.I.

• Evolution of changes in M.I.

• Classical Appearences

QRS waveform nomenclature

R r qR qRs Qrs QS

Qr Rs rS qs rSr’ rSR’

The 10 rules for a normal ECG

I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

.2

Rule 1

PRinterval

Mil

liv

olt

s

Milliseconds

0 200 400 600

-0.5

0

0.5

1.0

P

R

T

Q

S

PR interval should be 120 to 200 milliseconds or 3 to 5 little squares

Rule 2

Mil

liv

olt

s

Milliseconds

0 200 400 600

-0.5

0

0.5

1.0

QRS

P

R

T

Q

S

The width of the QRS complex should not exceed 110 ms, less than 3 little squares

Rule 3

I II III aVR aVL aVF

The QRS complex should be dominantly upright in leads I and II

Rule 4

I II III aVR aVL aVF

QRS and T waves tend to have the same general direction in the limb leads

Rule 5

P

Q

T

S

All waves are negative in lead aVR

Rule 6

V1

V2

V3

V4

V5

V6

The R wave in the precordial leads must grow from V1 to at least V4


Rule 7

The ST segment should start isoelectric except in V1 and V2 where it may be elevated

Rule 8


The P waves should be upright in I, II, and V2 to V6

Rule 9


There should be no Q wave or only a small q less than 0.04 seconds in width in I, II, V2 to V6

Rule 10


The T wave must be upright in I, II, V2 to V6

What is the heart rate?

•(300 / 6) = 50 bpm

•www.uptodate.com


•(300 / ~ 4) = ~ 75 bpm

•www.uptodate.com


•(300 / 1.5) = 200 bpm

10 Second Rule

As most EKGs record 10 seconds of rhythm per page, one can simply count the number of beats present on the EKG and multiply by 6 to get the number of beats per 60 seconds.

This method works well for irregular rhythms.


•33 x 6 = 198 bpm

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

Characteristic changes in AMI

• ST segment elevation over area of damage• ST depression in leads opposite infarction• Pathological Q waves• Reduced R waves• Inverted T waves

ST elevation

R

P

Q

ST

• Occurs in the early stages

• Occurs in the leads facing the infarction

• Slight ST elevation may be normal in V1 or V2

Deep Q wave

R

P

Q

T

ST

• Only diagnostic change of myocardial infarction

• At least 0.04 seconds in duration

• Depth of more than 25% of ensuing R wave

T wave changes

R

P

Q

T

ST

• Late change

• Occurs as ST elevation is returning to normal

• Apparent in many leads

Bundle branch block

I II III aVR aVL aVF V1 V2 V3 V4 V5 V6 I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

Anterior wall MI Left bundle branch block

Sequence of changes in evolving AMI

1 minute after onset 1 hour or so after onset A few hours after onset

A day or so after onset Later changes A few months after AMI

Q

R

P

QT

STR

P

Q

ST

P

Q

T

ST

R

P

S

T

P

QT

ST

R

P

Q

T

Anterior infarction

Anterior infarction


Left anterior descending artery (LAD)

Inferior infarction

Inferior infarction


Right coronary Artery( RCA) OR Circumflex (LCX)

Lateral infarction

Lateral infarction


Left circumflexcoronary Artery OR DAIAGONAL branch of LAD

Location of infarct combinations

aVR V1 V4I

II

III

LATERAL OR HIGH

LATERAL

INFERIOR

SEPTAL

ANT

ANT

LAT

aVL

aVF

V2

V3

V5

V6

Diagnostic criteria for AMI

• Q wave duration of more than 0.04 seconds

• Q wave depth of more than 25% of ensuing r wave

• ST elevation in leads facing infarct (or depression in opposite leads)

• Deep T wave inversion overlying and adjacent to infarct

• Cardiac arrhythmias

Left axis deviation - negative QRS in lead AVF

Right axis deviation - negative QRS in lead I

Severe Right axis deviation negative QRS in BOTH lead I and AVF

Quick & Easy AXIS DETERMINATION

AVF

AVF

AVF

AVF

AVF

AVF

I

I

I

I

I

I

The QRS Axis

By near-consensus, the normal QRS axis is defined as ranging from -30° to +90°.

-30° to -90° is referred to as a left axis deviation (LAD)

+90° to +180° is referred to as a right axis deviation (RAD)

Determining the Axis

Predominantly Positive

Predominantly Negative

Equiphasic

The Quadrant Approach

1. Examine the QRS complex in leads I and aVF to determine if they are predominantly positive or predominantly negative. The combination should place the axis into one of the 4 quadrants below.

Quadrant Approach: Example 1

Negative in I, positive in aVF 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 Predominantly positive in II

Normal Axis (non-pathologic LAD)

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

Thank U Very Much

Health & Medicine

Ecg part introduction