ECG Basics

What are the standard leads?

I, II, III

What are the precordial leads?

V1 to V6

What are the augmented leads?

aVR, aVF, aVL

What is the standard paper speed?

When Would You Change the Speed?

25 mm/sec

To See Fast Rhythms Clearly (set 50 mm/sec; stretches ECG out)

To Fit a Long Rhythm Strip or slow Rhythm (set 12.5 mm/sec; compresses horizontally)

What is the standard gain sensitivity

What does it represent?

When Would You Change the Gain?

10 mm/mV

Height (amplitude) of the waveform

Change gains when the amplitude is too large (ex. pediatrics typically reduce 5mm/mV)

Change gains when the amplitude is too small (ex. COPD up the gains to 20mm/mV)

Always document the gain setting on the ECG strip

1 small box represents?

1 large represents?

0.04 sec (1mm)

0.20 secs (5mm)

Tracings should be kept for how many years?

7 years

Horizontal line represents?

Vertical line represents?

time (1mm = 0.04 secs)

voltage (1 mm = 0.1 V)

aVR + aVL + aVF always equal?

0

Which is correct?

A) i + ii = iii

B) ii + iii = i

C) i + iii = ii

D) ii + iii = iii

C) i + iii = ii

RA-LA reversal results in?

inverted lead I & aVL

LA-LL reversal results in?

inverted III & avF downwards*

RA-LL reversal results in?

I/II/III inverted & positive aVR

RA-RL reversal; results in?

zero potential lead II

what CA perfuses the inferior leads

RCA

what CA perfuses V1 and V2

LCA septal branch

What CA perfuses V3 and V4

LAD

what CA perfuses the lateral leads

LCx

Intrinsicoid deflection

How long it took for the impulse to go from endocardial surface to the epicardial surface. From beginning of Q to end of S wave.

What are the Brugada Leads?

V1 and V2 are in either 2nd or 3d ICS to unmask coved STE or saddleback STE

Frank leads

used for signal averaging

X+ = left 4th ICS midaxillary

X- = right 4th ICS midaxillary

Y+ = left illac crest

Y- = superior manubrum

Z+ = 4th ICS LSB

Z- = posterior to Z+

Ground =8th lower rib

Lewis Leads

used for atrial activity/arrhythmias, better visualization of P waves, typically on the right side

Negative electrode on 2nd ICS RSB

Positive electrode on 4th ICS RSB

Dextrocardia and Lead Position

when the heart lies towards the right sides, signs:

inverted Lead I

positive aVR

poor R wave progression (dominant S throughout)

Leads: V4R-V6R

Method A: V1/V2, V4R-V6R

Method B: Reverse LA-RA, V1R-V6R

Pediatrics Leads Position

15 lead (V3R, V4R and V7)

Posterior Leads, when to use and what leads?

Posterior leads are used when suspected posterior MI as seen in significant STD in V1 to V4 or inferior MI shown.

Double the gains as the waveform will be small

V7-V9 or V4R/V8/V9

Positions for V7 to V9

V7: left posterior axillary line same lvl as V6

V8: left midscapula line same lvl as V6

V9: left paraspinal border same lvl as V6

V1 to V6 placement

V1: 4th ICS RSB

V2: 4th ICS LSB

V3: midway between V2 and V4

V4: left 5th ICS midclavicular

V5: left anterior axillary line, same lvl V4

V6: left mid axillary lin, same lvl asV4

Deep Inspiration

looking for old inferior MI, if patient takes a breath in and Q disappears (normal) if Q wave persists then they possibly have old inferior MI.

Done when inferior leads have a q wave.

Vagal Maneuvers

1. Carotid Massage

2. Valsalva Maneuver

3. Diving reflex

4. Trendelenburg Position

Stimulate the vagus nerve to releases Ach to slow conduction and increase refractory to slow down atrial arrhythmias, and terminate SVTs.

Normal PRI

0.12s to 0.20s

Normal QRS

0.06s to 0.10s

Normal QT

0.36s to 0.44s

Septal Depolarization occurs?

Left to Right

What is Wilson Central Terminal?

common zero potential by joining the 3 extremity leads (allows for the chest leads to work) and measure potential from zero rather than a difference

Wire colours:

LL = red

RA= white

LA= black

RL= green

V1 = red

V2= yellow

V3= green

V4= blue

V5= orange

V6= pruple

What are the Frontal Leads?

Limb leads

What are the transverse leads?

precordial leads