1: Bradyarrthymias

Question 1

Define an AV block

Answer 1

Interrupted conduction between the atria and ventricles

Question 2

What are the different types of heart block

Answer 2

First degree
Second degree
Third degree

Question 3

Define first-degree heart block

Answer 3

a PR interval of >200ms

Question 4

How many squares is the PR interval

Answer 4

3-5

Question 5

How many ms is the PR interval

Answer 5

120-200ms

Question 6

What are 6 causes of first degree heart block

Answer 6

Increased Vagal Tone 
Inferior MI
Athlete 
Myocarditis
Hyperkalaemia
AV node blocking drugs

Question 7

What are 4 AV blocking drugs

Answer 7

B blockers
Calcium channel blockers
Digoxin
Amiodarone

Question 8

How does first-degree heart block present

Answer 8

Asymptomatic

Question 9

Explain the pathophysiology of first degree HB

Answer 9

Damage or fibrosis to the AV node results in impaired conduction from atria to ventricles

Question 10

What is first-line investigation for HB

Answer 10

ECG

Question 11

How will first degree HB present on ECG

Answer 11

Prolonged PR interval >200ms

Question 12

What is second investigation for first-degree heart block

Answer 12

Medication review

Question 13

How is first-degree HB managed

Answer 13

No management plan

Question 14

What are the two types of second degree HB

Answer 14

1. Mobitz type I

2. Mobitz type II

Question 15

What is mobitz type I

Answer 15

Progressive prolongation of the PR interval until a QRS complex is dropped

Question 16

What is mobitz type I also referred to as

Answer 16

Wenckebach phenomenon

Question 17

What is mobitz type II heart block

Answer 17

Constant PR interval. Intermittent non conducting p waves without QRS

Question 18

What causes mobitz type I heart block

Answer 18

Increased vagal tone with NO underlying structural HD

Question 19

What are 4 causes of mobitz type I heart block

Answer 19

1. Medications
2. Ischaemia
3. Hyperkalaemia
4. Myopathy (eg. Lyme disease)

Question 20

What causes mobitz type II heart block

Answer 20

1. Anterior MI
2. Lev Lenegre’s Disease
3. Infiltrative (amyloidosis, sarcoidosis, haemochromatosis)
4. Medication
5. Autoimmune (SLE, sarcoidosis)
6. Cardiac surgery involving septal repair

Question 21

What is Lev Lenegre’s Disease

Answer 21

Idiopathic fibrosis of the AV node

Question 22

What medications may cause type II HB

Answer 22

Amiodarone
Digoxin
Calcium channel blocker
B blocker

Question 23

How may mobitz type I present clinically

Answer 23

Asymptomatic. May present with symptoms of dizziness, syncope and bradycardia

Question 24

How will mobitz type II present clinically

Answer 24

Symptoms of reduced cardiac output:

• bradycardia
• fatigue
• chest pain
• dyspneoa
• dizziness
• syncope

Question 25

What causes mobitz type I heart block

Answer 25

Suppression of AV conduction

Question 26

What causes mobitz type II heart block

Answer 26

Failure of conduction system in bundle of His or Purkenje system

Question 27

How will Mobitz type I appear on ECG

Answer 27

Increasing length of the PR interval until a QRS complex is dropped

Question 28

How long is a normal PR Interval

Answer 28

0.12-0.2s

Question 29

How many small squares is the PR interval

Answer 29

3-5

Question 30

How will mobitz type II present on ECG

Answer 30

Regular PR Interval. The conduction of atrial impulses to ventricles follows regular patterns. For example, P (P-1)

Question 31

Explain 2:1 AB block

Answer 31

The AV block, inhibits conduction of every other wave to ventricles

Question 32

How is mobitz type I managed

Answer 32

no treatment, regular follow up

Question 33

How is mobitz type II managed if harm-dynamically stable

Answer 33

- transcutaneous pacing pads | - permanent pace maker

Question 34

How is mobitz type II managed if haemodynamically unstable

Answer 34

atropine

Question 35

What is third degree heart block

Answer 35

No impulses are conducted from atria to ventricles causing complete dissascociation

Question 36

What can cause 3rd degree HB

Answer 36

- Inferior MI - Worsening of first and second degree HB - AV blocking medication - Lev lenegre's disease

Question 37

Name 3 AV blocking drugs

Answer 37

B blocker Calcium channel blockers Digoxin

Question 38

How will 3rd degree heart block present clinically

Answer 38

Bradycardia Severe chest pain Sx of hypoperfusion (dizziness, syncope) Heart failure

Question 39

What rate will the HR be in 3rd degree heart block and why

Answer 39

40bpm. As there is no conduction of impulses from atria to ventricles it causes a ventricular escape rhythm

Question 40

What are signs of hypoperfusion

Answer 40

``` Dizziness Apathy + Irritability Fatigue Breathlessness Syncope ```

Question 41

Explain the pathophysiology of 3rd degree heart block

Answer 41

There is complete obstruction of impulses between atria and ventricles meaning the two rates are independent. Atria contract at 100bpm and ventricles 40bpm.

Question 42

How will 3rd degree heart block present on ECG

Answer 42

P waves and QRS complexes have no association

Question 43

How is 3rd degree heart block managed if haemodynamically stable

Answer 43

Transcutaneous pacing | Permanent pacemaker

Question 44

How is third degree heart block managed if haemodynamically unstable

Answer 44

Transcuatenous pacing dopamine if hypotensive OR, dobutamine if HF

Question 45

What is a complication of 3rd degree HB

Answer 45

Sudden cardiac death