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OSCE examinations > 3 Lead, 12 Lead ECGs and Interpretation > Flashcards

3 Lead, 12 Lead ECGs and Interpretation Flashcards

1
Q

Why do a 3 lead ECG?

Why do a 12 lead ECG

A

3 lead ECG

  • cardiac, pulmonary, electrolyte problems
  • monitoring pre, post-op
  • 24hr ambulatory monitoring for arrythmias

12 lead ECG
-diagnostic tool for arrythmias, cardiac events, cardiac arrest

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2
Q

Introduction and preparation for 3 and 12 lead

A

WIPE - 45deg
Hello, I’m An Nakamura, a 3rd year medical student.
Can I confirm your name and DOB?
I’d like to do a 3 lead ECG on you
I will be putting 3 stickers on your chest and recording the electrical activity of your heart. It will not hurt but I would like you to lower your gown so I can put the stickers on your chest.

Will this be ok?
Do you have any questions?
Are you in any pain?

If necassery, use razors to remove excess hair in places you’d like to place the electrodes
If oily, wipe with soap and water => air dry
Rub skin with gauze => remove dead skin, improve contact where you’ll place electrodes

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3
Q

Application of electrodes for 3 lead

A

Connect leads to cable and monitor
-ensure correct colours are connected to the right body parts

WHITE => RA above clavicle
BLACK => LA above clavicle
RED => just above and left of umbilicus

Avoid areas where muscle movement, bony prominences, skin folds could disrupt readings

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4
Q

3 lead ECG monitoring

  • what lead would you monitor normally
  • what lead would you monitor in bundle branch block/wide complex beats
A

In most cases, monitor in Lead II

Monitor bundle branch block/wide complex beats
-LL (RED) => 4ICS right sternal border

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5
Q

How would you adjust the 3 lead ECG monitor

What would you notes down in the records

A

Set monitor alarm for 20 beats higher and lower than HR

Obtain a 6s strip at

  • the start of monitoring
  • when rhythm changes
  • when monitoring lead is changed

Note when ECG monitoring

  • has been started, discontinued
  • reasons
  • lead selections
  • rhythm interpretations
  • PR, QRS, QT measurements

Place strip in patient’s records

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6
Q

Application of electrodes for 12 lead ECG

  • chest leads
  • limb leads
A

Razor away chest hair, prepare skin for good contact

V1 R4ICS
V2 L4ICS
V4 L5ICS MCL
V3 between 2 and 4
V5 L AAL
V6 L MAL

V1-3 in horizontal line
V4-6 in oblique line

R wrist => Red
L wrist => Yellow
R ankle => Green
L ankle => Black

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7
Q

12 lead ECG machine use

-how would you it and get a reading

A

Switch on ECG machine
Ensure paper loaded

Ask patient to stay still and quiet whilst recording
-if poor, check electrodes and repeat

Switch off ECG, detach leads from electrodes
Remove electrodes
Tells patients when procedure is finished, offer to help them get dressed

Wash hands
Label ECG with patient’s details

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8
Q

How would you interpret the ECG

-structure

A 
Rate => tachy, Brady?
Rhythm => regular, irregular?
Axis => L or R
P wave found?
PR interval? => type of block
QRS => narrow/broad, tall/short
ST => elevation/depression
T => tall, inverted?
Summarise abnormalities, differentials
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9
Q

12 lead Interpretation

1. Detail check

A

Patient name
DOB
Presenting symptoms

ECG date and time

Calibration check

  • speed 25mm/s
  • voltage - analogue peak 10mm/mV (2 large squares tall)
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10
Q

12 lead interpretation

2. Rate and rhythm check

A

Use rhythm strip
Rate
-regular => 300/no of big squares between 2 Rs
-irregular => 6R

Rhythm
Sinus? => P and QRS in all waves
-can be regular or irregular
Regularity of irregularity?
-regularly irregular
-irregularly irregular
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11
Q

Reasons for

  • bradycardia
  • tachycardia
A

Bradycardia - U60

  • physical fitness
  • hypothermia
  • hypothyroid
  • SAN problem
  • Bb, digoxin

Tachycardia - 100+

  • exercise
  • pain
  • anxiety
  • pregnancy
  • anemia
  • PE
  • hypovolemia
  • fever/sepsis
  • hyperthyroid
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12
Q

Rhythm issues

-possible findings and how you’d recognise them

A

Sinus arrythmia - normal in young people

AF => no P, fibrillations, irregularly irregular
Atrial flutter => regularly irregular, saw tooth baseline
SVT => abnormal/no P, narrow complex tachycardia
VT => broad complex tachy, no P
VF => chaotic tachy

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13
Q

12 lead ECG interpretation

3. Axis

A

I, III

Both positive => normal
Both negative => extreme
Towards => RA
Away => LA

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14
Q

Axis issues

  • reasons for left axis deviation
  • reasons for right axis deviation
A

Left - LVH

  • LBBB
  • WPW

Right - RVH

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15
Q

12 lead ECG interpretation

4. P wave - what can you tell from this?

A

Do they exist?

Height - U2 ss
Shape
-peaked => right atrial enlargement, typically in pulmonary HTN from lung disease
-p pulmonale
-bifid (m) => dyssynchrony between R and LA depolarisation, LA enlargement, typically from mitral stenosis
-p mitrale

Not there - AF?

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16
Q

12 lead ECG interpretation

5. PR interval

A

Normal - 3-5 ss

U3 - WPW
5+ - HB

17
Q

PR interval

  • types of HB
  • causes of HB
A

1st degree - LOOONG PR, regular
2nd degree Wenckeback - PR gets longer and longer until QRS droppepd
2nd degree Mobitz 2 (MORE SERIOUS) - PR long and constant, intermittently dropped QRS
3rd degree - irregular PR, dissociation between P and QRS

Causes of HB

  • antiarrythmic drugs - amiodarone, Bb, CCB, digoxin
  • athletes - increased vagal tone
  • electrolyte imbalances
18
Q

12 lead ECG interpretation

6. QRS complex

A

Normal - U3ss
-narrow or broad?

Width

  • normal = U3ss (NARROW)
  • 3ss+ (BROAD)

Morphology

  • RBBB - M (V1) W (V6
  • LBBB - W (V1) M (V6)
  • WPW - delta

Pathological Q waves - height 2ss+, width 4ss+
-look for Q waves in entire territories => past MI

19
Q

Reasons for a

  • broad QRS complex
  • RBBB
  • LBBB
A

Abnormal ventricular depolarisation

  • BBB
  • ventricular ectopic

RBBB

  • RVH from cor pulmonale
  • PE
  • cardiomyopathy, CHD

LBBB

  • LVH from aortic stenosis, HTN
  • cardiomyopathy, CHD
20
Q

12 lead ECG interpretation

7. ST segment

A

From isoelectric line <=> start of T
-isoelectric and concave - normal

ST elevation - infarction
-1ss+ in 2+ contiguous limb leads OR
-2ss+ in 2+ chest leads
If elevated in all leads => pericarditis or tamponade

ST depression - ischemia

ST morphology

  • convex - infarct
  • concave - early repolarisation, LVH
  • saddled - pericarditis, tamponade
21
Q

12 lead ECG interpretation

8. T wave

A

Normal
-inversion - III aVR V1 (right leads)

Abnormal inversion

  • ischemia/post MI
  • RBBB (V1-3)
  • LBBB (V4-6)
  • LVH (lateral)
Morphology
Tented => HIGH K
Flat => LOW K
Biphasic 
-ischemia = up then down
-LOW = down then up
22
Q

ECG lead changes by infarct territory

A

Inferior - RCA
-II, III, aVF

Anterior - LAD
-V3-4

Anteroseptal - LAD
-V1-4

Anterolateral - LAD, LCx
-V4-6, I, aVL

Lateral - V5-6, I, aVL

Posterior - PDA
-V1-4 ST DEPRESSION

23
Q

STEMI

  • ECG findings
  • investigations
  • management
A

ECG findings
-ST elevation in contiguous leads

Investigations
Bedside
-Hx, cardiac exam, 3 lead monitoring ECG
Bloods
-FBC, U&E, LFT, CRP - baseline
-TnT - proof of MI
-Lipids, HbA1c, glucose - cardiac risk factors
Imaging
-CXR - rule out other possible causes of chest pain
-echo - valve function

Management
Immediate - morphine, O2 if sats U94%, nitrates, aspirin 300mg,
PCI if possible within 2hrs
Fibrinolysis if PCI not possible within 2hrs
Secondary prevention - DAPT, ACEi/ARB, Bb, statin, GTN

24
Q

AF

  • ECG findings
  • investigations
  • management
A

ECG findings
-high HR, no p waves, fibrillations, irregularly irregular

Investigations
Bedside
-Hx, cardiac exam, vital signs (hemodynamic instability)
Bloods - assess for underlying triggers
-FBC - anemia
-U&E, bone profile - electrolyte derangement
-TFT - hyperthyroid
-CRP - infection
Imaging
-CXR - HF
-echo - rule out thrombus before cardioversion

Management
Acute - A-E, emergency cardioversion if unstable
Definitive - address underlying cause
Anticoagulation - CHADSVASC (DOAC, warfarin)
Addressing AF - rate (Bb, diltizem, digoxin) or rhythm control (amiodarone, synch DCC), surgical ablation and pacing

25
Q

Acute pericarditis

  • ECG findings
  • investigations
  • management
A

ECG findings
-high HR, widespread ST elevation

Investigations
Bedside
-Hx, cardiac exam, vital signs, 3 lead ECG for monitoring
Bloods
-FBC, CRP, TnT - raised in infection and inflammation
-LFT, U&E - for baseline
Imaging
-CXR - goblet shaped cardiac shadow
-Echo - pericardial effusion
Management
OP - avoid strenuous activity, NSAIDs or colchicine
IP if
-not resolving within 2wks
-SOB, non resolving chest pain, syncope

Complications

  • pericardial effusions
  • cardiac tamponade
  • chronic constrictive pericarditis
26
Q

VT

  • ECG findings
  • investigations
  • management
A

ECG findings

  • tachy, regular
  • cannot access axis, p, pr, qrs, st, t

Chest pain, palpitations
SOB, dizzy
Resp distress, high JVP, basal lung creps, low BP

Bedside
-Hx, vital obs
Bloods
-U&E - electrolyte disturbance
-TnT - ischemia
Imaging
-CXR - HF
-echo - valvulopathy, myopathy
A-E => escalate to senior
Pulseless VT => crash call, DF
Hemodynamically unstable => amiodarone, synch DC
Hemodynamically stable => amiodarone 
Long term - amiodarone, ICD
27
Q

Hyperkalemia

  • ECG findings
  • investigations
  • management
A

Tall tent T
Flat P
Prolonged PR, QRS
Sine wave => AF/asystole

VBG - quick K

TREAT URGENTLY IF ECG CHANGES OR 7mmol/L+
CaGluconate
IV insulin, dextrose
NEB salbutamol
CaREsonium
Dialysis if not responsive

Impaired excretion - AKI, CKD, spironolactone, NSAIDs, ACEi, Bb, low ALD
Increased K - cell lysis, DKA, low insulin

OSCE examinations (142 decks)

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