The ECG - Identifying some basic disturbances of rhythm

Question 1

Sinus tachycardia

Answer 1

Everything normal, heart rate >100bpm

Regular ventricular rhythm but high ventricular rate

Question 2

What can cause sinus tachycardia?

Answer 2

Often a physiological response e.g. hypovolaemia sepsis, stress

Question 3

Atrial fibrillation

P waves
ventricular rhythm
atrial rate
ventricular rate
QRS complex

no need to memorise numbers

Answer 3

Absent P waves, oscillating baseline fibrillation waves (f waves)
Irregular ventricular rhythm
350-650bpm
100-180bpm
normal QRS

Question 4

Pacemaker recharging - what are you gonna see on the ECG

Answer 4

straight lines with no duration

Question 5

Why are the ventricles irregularly irregular in atrial fibrillation?

Answer 5

They receive their signals from the atria

Question 6

What does it mean when atria are fibrilating?

Answer 6

Bits of cardiac muscle are contracting at different times

Question 7

Most common cause of arrhythmia?

Answer 7

Atrial fibrillation

Question 8

What is atrial flutter?

Answer 8

Arrhythmia of the atrium around the tricuspid valve
atria are continuously activating

More regular than atrial fibrillation

Question 9

What is the key feature of atrial flatter on the ECG and in which leads is this feature best seen

P wave has this feature

Answer 9

saw toothed patterns after atrial contraction

Inferior leads
Lead II, III, aVF

Question 10

Heart rate in atrial flutter? (A, V)

QRS?

Ventricular rhythm?

Answer 10

A: 220-430bpm
V: <300bpm

Normal

Regular ventricular rhythm

Question 11

How to calculate heart rate from an ECG ?

Answer 11

300/number of large squares bn two points

Question 12

What does AVNRT stand for

Answer 12

AV nodal reentrant tachycardia

Question 13

What does SVT stand for and give two different types

Answer 13

Supraventriular tachycardia

AVNRT, AVRT

Question 14

What causes SVT?

Answer 14

Impulses rotating around the AV node –> synchronous atrial and ventricular depolarisation

Question 15

SVT

QRS complex
P waves

Answer 15

Regular but narrowed

No clear P waves (often buried within QRS or just after QRS)

Question 16

What can treat SVT and how?

Answer 16

Adenosine, blocks AV node

Question 17

What can cause a preexcitation syndrome

Answer 17

Accessory pathway that connects atrium to ventricle

Question 18

PR interval of preexcitation syndrome + explanation

Answer 18

Short, <120ms because it bypasses the AVN

Question 19

Characteristic of preexcitation syndrome

Answer 19

Early ventricular activation without isoelectric line

Question 20

How can you cure preexcitation syndrome?

Answer 20

Ablation of accessory pathway –> enter catheter in heart and deliver heat to destroy it

Question 21

Heart block, AV nodal block - what are the 3 degrees

Answer 21

1st degree - prolonged PR interval
2nd degree- Mobitz Type 1, Mobitz Type 2
3rd degree - complete heart block

Question 22

1st degree heart block

treatment
p:qrs

Answer 22

no treatment required

1:1

Question 23

Mobitz type I

Answer 23

Some P waves not getting down to AV node
PR gradually prolonging every single beat
Misses a bit then recovers

Question 24

Mobitz type II

describe + treatment

Answer 24

No gradual PR prolongation
Normal PR then suddenly stops a bit
requires a pacemaker

Question 25

3rd degree AV block

qrs:p
rate of p waves

Answer 25

No p waves conducted to ventricles
none of the p waves related to QRS complexes
fixed rate of p waves

Question 26

Bundle branch block

how would the ECG change (2 changes)

Answer 26

Change in the QRS complex

1. QRS complex widens (takes longer for electrical signal to pass throughout the ventricles)
2. morphology of QRS changes

Question 27

RIGHT bundle branch block

QRS morphology
in which leads is the change observable and why?

Answer 27

Rabbit ears
1st rabbit ear is smaller than the second one
QRS is also wider

V1 V2 –> these leads are overlying the right ventricle

Question 28

LEFT bundle branch block

QRS morphology
in which leads is the change observable and why?

Answer 28

Deep negative deflection

QRS is also wider

V1 V2 –> right ventricular leads

Question 29

Ventricular Tachycardia

rhythm
QRS complexes
P waves
consequences if not treated

Answer 29

Inefficient rhythm
wide QRS
no clear P waves proceeding
if left untreated can proceed to ventricular fibrilaion

Question 30

Ventricular fibrilation

QRS complexes
P wave
Rhythm
Hear rate

Answer 30

Wide and irregular
Absent p wave
Extremely irregular
300-600 bpm