reading ecg

READING ECGFor paramedic

Presented by : SN NORLIZA ALI

UNIT KECEMASAN & TRAUMA

Anatomy Revisited RCA

› right ventricle› inferior wall of LV› posterior wall of LV (75%)

› SA Node (>80%)› AV Node (60%)

LCA› septal wall of LV› anterior wall of LV› lateral wall of LV› posterior wall of LV (10%)

Anatomy Revisited

ECG lead placement

Pericordial lead

Right sided ECG lead placement

Posterior ECG placement

Limb Leads Chest Leads

I aVR V1 V4II aVL V2 V5III aVF V3 V6

Lead Groups

ECG Graph Paper

Horizontal axis - time 1 small box = 1 mm = 0.04 sec.

o Every 5 lines (boxes) are bolded

Vertical axis - voltage1 small box = 1 mm = 0.1 mV

ECG amplitude scale

Normal amplitude10 mm/mV

Half amplitude5 mm/mV

Double amplitude20 mm/mV

Paper Speed - 25 mm/sec standard

Calibration of Voltage is Automatic

Both Speed and voltage calibration can be changed on most devices

Paper Speed & Calibration

ECG Waves and Intervals P wave : atrial

contraction; QRS complex :

ventricular contraction;

T wave : ventricular repolarization.

PR interval : time from onset of atrial activation to onset of ventricular activation.

QRS duration : duration of ventricular activation.

PR interval = 0.2 sec (5 small boxes)QRS interval = < 0.12 sec (3 small boxes)QT interval = 0.42 sec (10 small boxes)

Normal ECG

From Kumar and Clark

Remember: Look at lead I QRS deflection first

WHAT WE WANT TO READ IN ECG

RHYTHM RATE P WAVE PR INTERVAL Q WAVE QRS COMPLEX ST SEGMENT T WAVE

RHYTHM Measure R-R intervals across strip Should find regular distance between R waves Classification• Regular• Irregular

SEE R to R INTERVALR R R

Normal heart rhythm has consistent R-R interval.Mild variations due to breathing also normal

RHYTHM Regular

P P P

Irregular rhythm has no consistent between R-R interval.

RHYTHM Irregular

Triplicate method›300-150-100-75-60-50

R-R method›divide 300 by # of large squares between consecutive R waves

6 Second method›multiply # of R waves in a 6 second strip by 10

Measuring heart rate

HR = 300 / 4.2 = 71 bpm

P wave

PR interval Time between onset of atrial depolarisation and the onset of ventricular depolarisation

N: 3-5 small squares (0.12-0.20 sec)

Abnormalities of conduction system

prolonged PR interval

Q WAVE

Pathological Q wave ; > 1/3 of total QRS height> 0.03 sec wide> 2 mm deep

QRS complex

QRS complex

Ventricular depolarisation N: ≤ 2 ½ small squares (0.10 sec)

Delays in ventricular depolarisation

Abnormally wide QRS complex

ST segment

ISO ELECTRIC LINE

T wave Ventricular repolarisation

Hyperkalemia

ECGIn Acute Coronary Syndrome

HYPERACUTE PHASE

Tall T waves :• more then 50% of preceding R wave•Become more symmetrical and pointed •Usually finding not recorded because they have typically resolve by the time the patients seeks Medical assistamce – within minutes

Usually last within minutes

DYNAMIC ECG CHANGES DURING ACUTE MYOCARDIAL INFARCTION

Occur within first hour or first few hours of infarction

1. Occurs a few hours later2. Development of significant

Pathological Q wave3. Q wave when happened with

or combine with T wave change and ST elevation is consider Acute MI

1. Presence of T wave inversion

2. Suggestive of presence of ischemia

3. T wave inversion may presence before ST segment elevation or may occur at the same time

1. T wave regain normal shape2. ST segment return to baseline3. Q wave remain as evidence that

infarction occurred4. Establishing time of infarction

impossible5. Only possible to recognize the

presence of previous MI

DYNAMIC ECG CHANGES DURING ACUTE MYOCARDIAL INFARCTION

Anterior infarctionAnterior infarction

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

Left coronary artery

Inferior infarctionInferior infarction


Right coronary artery

Lateral infarctionLateral infarction


Left circumflexcoronary artery

1. During angina attack the ST segment be temporarily depressed

2. The ST segment will depressed when the infarct does not extend the full thickness of the wall

3. Subendocardial Infarction or injury is identify by flat ST segment depression which may be horizontal or down sloping

High take off ECG

Localizing ECG Changes

Criteria In ECG

Normal Sinus Rhythm

Sinus Bradycardia

Sinus Tachycardia

Atrial Tachycardia& fibrillation

Atrial Tachycardia

SVT (abnormal focus in the atrium).Atria contract faster than 150 per minute.

Atrial Flutter With Variable AV Block

P waves seen at 300 per min – ‘saw-tooth’ appearance.

Atrial Fibrillation

No P – irregular baseline.Irregular QRS complexesQRS normal shape

Ventricular Tachycardia

& fibrillation


No P.Wide QRS tachycardia.QRS slightly irregular shaped.


The main features of this wide QRS tachycardia that indicate its ventricular origin is the condordance of QRS's in the precordial leads (all QRS's are in the same direction). No P waves.

Ventricular Fibrillation

No QRS complex can be identified.ECG totally disorganised.

Extrasystole(ectopic beats)

Isolated PAC (atrial ectopic)

Sinus rhythm with atrial extrasystoleP has abnormal shapeQRS normal

A

Atrial Bigeminy

Unifocal PVCs (ventricular ectopic)

Ventricular extrasystole.QRS wide and abnormal, identical. T abnormal.

Multifocal PVC's

PVC Couplet

PVC Triplet

Electronic Atrial Pacing

Atrial Pacemaker Rhythm

Pacemaker spikes are seen before each QRS complex and initiate a tiny P wave.

RBBB and LBBB RBBB = MaRroW LBBB = WiLLiaM

Miscelllaneous

Artifact

Wandering Baseline Artifact

Muscle Tremor Artifact

Sinus Pause or Arrest

Sick Sinus Syndrome

Emergency Rhythm

SUPRAVENTRICULAR TACHYCARDIA

Characteristic: Absent P wave Rate: 150-300 beats per minute Regular rhythm

Fine VF

Ventricular Asystole

ThankYou

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