ECG basics Flashcards

1
Q

If the PR (atrial) rate was 80 per min and the QRS (ventricular) rate was 45 per min what block would you suspect?

A

3rd-degree block

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2
Q

Where do you measure the PR interval from and to?

A

The beginning of the P wave to the beginning of the QRS complex

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3
Q

What is the most likely rhythm?

A

1st-degree heart block

Rate: ~80bpm (300/3.6)

Rhythm: regular

QRS: Narrow (<3 small squares)

P-waves: Constantly prolonged (> 5 small squares)

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4
Q

How would you calculate the rate on a rhythm strip?

A

300 divided by the number of large square between consecutive R waves

or

1500 divided by the number of small squares between consecutive R waves

or

Number of R waves across the bottom of a standard 12 lead ECG (10 seconds) multiplied by 6

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5
Q

What common arrhythmias have a broad QRS complex?

A

Ventricular in origin

Ventricular tachycardia (VT)

3rd degree hear block

Conduction

Left bundle branch block (LBBB)

Right bundle branch block (RBBB)

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6
Q

If the PR interval was…

5 small squares with every 4th beat dropped…

what type of block would you suspect?

A

2nd-degree block

Mobitz II

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7
Q

Whats the most likely rhythm?

A

Normal Sinus Rhythm (NSR)

Rate: ~90 (300/3.3)

Rhythm: regular

QRS: narrow (<3 small squares)

P waves: P-R interval normal and constant (3-5 small squares)

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8
Q

Describe 1st-degree heart block

A

Prolonged PR interval > 0.2 sec (5 small squares).

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9
Q

If the PR interval on you ECG was…

4 small square then 5 small squares then 6 small squares then 7 small squares then QRS missing…

what type of block would you suspect?

A

2nd-degree block

Mobitz I (Wenckebach)

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10
Q

Define a Q wave

A

The negative (downward) deflection PRECEDING an R wave

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11
Q

What are the criteria for right bundle branch block (RBBB)

A

Broad QRS

RSR pattern in V1 (2 R waves like an M shape)

Slurred S wave in V6

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12
Q

Describe 3rd-degree heart block

A

No relationship between the P waves and the QRS complexes

QRS rate usually <60 QRS

Width frequently broad (> 3 small squares)

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13
Q

Describe 2nd-degree heart block

Mobitz I (Wenckebach)

A

Ever increasing PR interval until a QRS complex is missed completely and the cycle begins again.

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14
Q

Which are the anterior leads?

A

V1, V2, V3

(some texts consider V1-2 septal and V3-4 anterior)

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15
Q

If the PR interval on an ECG was 7 small squares what type of block would you suspect?

A

1st-degree block

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16
Q

Whats the most likely rhythm?

A

Ventricular Tachycardia (VT/V-Tach)

Rate: ~250 (1500/6)

Rhythm: regular

QRS: Broad (>3 small squares)

P-waves: no

17
Q

Define an R wave

A

The positive (upward) deflection of the QRS complex

18
Q

Describe 2nd-degree heart block

Mobitz II

A

A regular PR interval until a QRS complex is missed

Often happens at regular intervals such as every 4th QRS missed

19
Q

Which are the inferior leads?

A

II, III, aVF

20
Q

Which are the lateral leads?

A

V4, V5, V6, aVL, I

(some texts consider V3-4 to be anterior and V5-6)

21
Q

What is the normal QRS width?

A

Less than 0.12 sec (3 small squares)

22
Q

Describe atrial fibrillation (AF)

A

Irregularly-irregular QRS rate

No clear P waves visible

23
Q

What is the most likely rhythm?

A

Atrial flutter

Rate: ~150bpm

Rhythm: regular

QRS: Narrow

P-waves: saw-tooth appearance

24
Q

What is the most likely rhythm?

A

2nd-degree heart block (Mobitz I)

Rate: ~35 - 66 (300/8 to 300/4.5)

Rhythm: Regularly irregular

QRS: Narrow

P-waves: Ever increasing P-R interval until QRS complex dropped

25
Q

What is the voltage criteria for ST elevation?

A

>1mm above the isoelectric line with the exception of V1 and V2 where >2mm is appropriate

26
Q

What is the normal PR interval?

A

0.12 - 0.2 seconds (3 - 5 small squares)

27
Q

If lead I is predominantly POSITIVE and lead II is predominantly NEGATIVE what is the cardiac axis likely to be?

A

Left axis deviation

28
Q

What is the most likely rhythm?

A

Atrial Fibrillation (AF/A-Fib)

Rate: ~150-300

Rhythm: Irregularly-irregular

QRS: Narrow (<3 small squares)

P-waves: not clearly visible

29
Q

If lead I is predominantly NEGATIVE and lead II is predominantly POSITIVE what is the cardiac axis likely to be?

A

Right axis deviation

30
Q

Define an S wave

A

The negative (downward) deflection FOLLOWING an R wave

31
Q

If lead I is predominantly POSITIVE and lead II is predominantly POSITIVE what is the cardiac axis likely to be?

A

Normal

32
Q

What is the most likely rhythm?

A

Supra-Ventricular Tachycardia

Rate: ~250 (1500/6)

Rhythm: regular

QRS: Narrow (< 3 small squares)

P-waves: ?

33
Q

Whats the most likely rhythm?

A

2nd-degree heart block

Rate:

Rhythm: Regular (mostly)

QRS: Narrow (<3 small squares)

P-waves: regular but every 4th beat dropped

34
Q

What are the criteria for left bundle branch block (LBBB)

A

Broad QRS (>0.12sec)

Dominant S wave in V1

No q wave in V6, I or aVL (high lateral leads)

35
Q
A