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ICM > ECG > Flashcards

ECG Flashcards

1
Q

What are the first things to check on every ECG? (Before looking at the ECG recording itself)

A

Patient details
Date/ time of ECG
Calibration

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2
Q

How to check the calibration of an ECG?

A

In most patients, the ECG is recorded at a paper-speed of 25 mm = 1 second with a voltage calibration of 10 mm = 1 mV.

The calibration marker is displayed at the beginning of each ECG

Y axis = Voltage; 10mm = 1mV
X axis = Time; 1 large sq = 5 small squares = 0.20 secs = 5 x 40 msecs

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3
Q

What is a normal PR interval?

A

<0.20 seconds = 1 large or 5 small squares

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4
Q

What is a normal QT interval?

A

<0.44 seconds = 12 small squares

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5
Q

What is the QTc?

A

QT interval corrected for heart rate.

QTc = QT interval in seconds/ Square root of RR interval in seconds

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6
Q

What is the normal QRS duration?

A

<0.10 seconds

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7
Q

What does the axis of an ECG show? (Specifically the vertical axis)

A

The vertical axis gives a measure of the relative myocardial mass of the two ventricles and is abnormal in various disease states.

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8
Q

What leads are used to determine the axis of an ECG?

A

Lead I measures the electrical vector of the heart at 0 degrees
Lead II is the +60 vector
Lead III is the +120 vector

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9
Q

How do you calculate the axis deflection in each lead? (i.e. the formula)

A

(Height of R wave) - (Height of Q wave) - (Height of S wave)

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10
Q

What is the normal axis of an ECG?

A

Between -30 and +90 degrees

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11
Q

What are the causes of Right axis deviation?

A

RBBB
RVH (e.g. COPD, PE, ASD, Pulmonary Stenosis)
Normal variant in young

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12
Q

What are the causes of left axis deviation?

A 
Inferior MI
Left anterior hemiblock
LBBB
Cardiomyopathy 
Pregnancy (mechanical displacement)
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13
Q

What are the criteria for LVH?

A

(S wave voltage in V1) + (R wave voltage in V5 or V6 whichever is largest) = >=35mm

You might also see T wave inversion in leads V3-V6

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14
Q

What would be seen on an ECG in an inferior MI?

A

1mm ST elevation in two of leads II, III, aVF

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15
Q

What would be seen on an ECG in a posterior MI?

A

ST depression in leads V1 and V2 with prominence of the R wave in these leads, often associated with concurrent inferior infarction.

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16
Q

What would be seen on an ECG in hyperkalaemia?

A 
Peak T waves
Prolonged QRS (>0.12 seconds)
Prolonged QT interval (>0.44 seconds)
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17
Q

What would be seen on an ECG in digoxin use (not toxicity)?

A

Digoxin has an effect on the ECG: Slurring and inversion of the ST segments in the lateral leads, V4, V5 and V6

18
Q

What would be seen on an ECG in olanzapine overdose?

A

Prolonged QT interval

19
Q

In a normal ECG, which leads is the R wave NOT dominant in?

A

aVR, V1 and V2

20
Q

In a normal ECG, which leads have a dominant S wave?

A

V1 and V2

21
Q

In a normal ECG, in which leads can a Q wave be a normal variant?

A

V1 and/or lead III

22
Q

Which leads represent the territory supplied by the LAD?

A

V1 to V3

This is the anterior wall of the heart

23
Q

Which leads represent the territory supplied by the circumflex artery?

A

I, aVL, V5 and V6

This is the lateral wall of the heart

24
Q

Which leads represent the territory supplied by the RCA?

A

II, III and aVF

This is the inferior wall of the heart

25
Q

Which leads represent the septum?

A

V3 to V5

26
Q

What is the purpose of lead aVR?

A

The sole use of aVR is to determine whether the limb leads are on correctly.

The QRS complex must be negative.

27
Q

How do you calculate the HR?

A

Rate = 300/ Number of large squares between R wavesor

or

Rate = 60/RR interval in seconds

or

Take 4 beats, count the number of large squares, then - (300/ number of large sqares) x4

28
Q

What abnormalities are seen in RBBB?

A

QRS duration >120 msecs
Tall R wave in V1
S wave in V6

29
Q

What abnormalities are seen in LBBB?

A

QRS duration >120 msecs
Q waves across anteroseptal leads
T wave inversion in lateral leads

30
Q

What are the ECG features of 1st degree heart block?

A

Prolonged PR interval

31
Q

What are the ECG features of Mobitz type I AV block (Wenckebach AV block)?

A

Progressive prolongation of the PR interval culminating in a non-conducted P wave

32
Q

What are the causes of Mobitz type I AV block (Wenckebach AV block)?

A

Increased vagal tone (athletes)
Acute MI
Myocarditis
Beta blockers, CCBs, digoxin, amiodarone

33
Q

How do you distinguish SVT from sinus tachycardia?

A

By asking the patient to take a deep breath in and out. A sinus tachycardia first slows a little and then speeds up, natural sinus arrhythmia with deep inspiration.

An SVT is not affected by deep inspiration as the sinus node is not active during SVT.

34
Q

What does a delta wave signify?

A

Wolf-Parkinson-White syndrome.

35
Q

If the QRS morphology in a broad complex tachycardia is identical to that in the patient’s normal sinus rhythm ECG - what is the rhythm?

A

Supraventricular tachycardia (SVT) with aberrant conduction

36
Q

Pacemaker Code

A 
I Chamber paced 0 A V D
II Chamber sensed 0 A V D
III Response 0 T I D
IV Rate modulation 0 R
V Anti arryrhythmia function 0 P S D
37
Q

What are the types of cardiomyopathy?

A

Dilated: Severe dilatation without heart valve abnormalities.

Hypertrophic: Enlarged heart with asymetric hypertrophy

Restrictive: Development of scar tissue causing incomplete ventricular filling

Arrhythmogenic: RV tissue death and scarring

38
Q

Causes of Dilated Cardiomyopathy

A 
Genetic: Duchennes
Infection: Post myocarditis
Autoimmune: RA, SLE, MG, GPA
Toxic: Alcohol, cocaine, amphetamines, anabolic steroids, amyloidosis
Drugs: SACT, lithium
Endocrine: DM, thyroid dysfunction
Peripartum
39
Q

What are the causes of hypertrophic cardiomyopathy?

A

Genetic
Storage diseases
Neuromuscular

40
Q

What are the causes of restrictive cardiomyopathy?

A

Idiopathic
Infiltrative: amyloidosis, sarcoidosis
Storage disease: iron overload
Endomyocardial: Carcinoid, XRT, SACT

41
Q

What is Bazett’s formula

A

QTc = QT / √RR

ICM (16 decks)

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