Anatomy

ECG Electrodes

ECG Waveform

The 12 lead ECG

How does the heart work

AV node activated by Atrial depolarizationSends signal through His-purkinje bundleGet depolarization of SEPTUM

Left and Right BUNDLES transmit signal to Left and Right VENTRICLESNet “Vector” towards the LVShould be narrow (<120msec) if bundles working properlyThen have REPOLARIZATION = Twave

The appearance of this electrical activity depends on which lead you are using to look at it

Review of waveforms

How to Look at an ECG• Rate: Is the heart rate too fast or slow?• Rhythm: Sinus rhythm or not?• Axis: Where does the majority of

electrical activity point?• P wave: How big are the atria?• PR interval: How healthy is the AV node?• QRS wave: Is there abnormal conduction

or a ventricular source?• QT: Long is bad• Ischemia and hypertrophy

ECG PaperCan Determine Heart Rate

Rule: 300, 150, 100, 75, 60, 50 counting over for each big sqaure

What is the heart rate?

Answer = 75 per min

Rhythm : Is there a p wave? = Sinus

Is it followed by a QRS?

Is the rhythm regular or irregular?

Reasons to have an irregular rhythm

• Irregular pacemaker– Multifocal atrial

rhythm

– Atrial fibrillation

– Atrial fib/flutter

• Ectopic beats– PVC

– PAC

– PJC

• Irregular conduction– AV node block

• 1st degree:– PR interval > 200 msec

• 2nd degree:– Type 1: Wenkebach

– Type 2: dropped beat

• 3rd degree:– p waves marching

independent to QRS

Examples of Rhythms

Multifocal Atrial Rhythm

AFIB

Atrial Flutter

AFIB

V TACH

Example of a PVC

Telling the Axis from the leads

The axis wheel

The P wave

The QRS

QRS < 120 msec

QRS > 120 msecRabbit ears in V1 & V2

Wide S wave in V5 & V6

R axis deviation

QRS > 120 msecDeep slurred S wave in V1

Wide R wave in V6, I & avL

L axis deviation

Ishcemia vs Acute Infarct

Example of Ischemia

Examples of Infarctions

Review• Rate: Is the heart rate too fast or slow?• Rhythm: Sinus rhythm or not?• Axis: Where does the majority of

electrical activity point?• P wave: How big are the atria?• PR interval: How healthy is the AV node?• QRS wave: Is there abnormal conduction

or a ventricular source?• QT: Long is bad• Ischemia and hypertrophy

Describe this ECG

Describe this Strip