Introduction to Cardiac Arrhythmias

Question 1

Name the 2 types of Electrical disfunction

Answer 1

Altered automaticity

Triggered activity

Question 2

What happens in altered automaticity?

Answer 2

latent pacemaker subverts SA node function as normal pacemaker of the heart

Question 3

When does Altered automaticity occur?

Answer 3

when SA node firing is pathologically low or impaired

Question 4

Name the 2 types of triggered activity

Answer 4

EAD - early afterdepolarisation

DAD- delayed afterdepolarisation

Question 5

Name 2 defects in Impulse conduction

Answer 5

re-entry

conduction block

Question 6

Name the 2 types of conduction Block

Answer 6

Partial

Complete

Question 7

What shows a partial block on ECG of 1st AV degree?

Answer 7

slower conduction=lower PR interval

Question 8

Name the 2 types of 2nd degree AV block

Answer 8

Mobitz 1

Mobitz 2

Question 9

Describe the PR interval in morbitz 1?

Answer 9

PR interval gradually increases from cycle to cycle until AV node fails completely and a ventricular beat is missed

Question 10

Describe the PR interval in morbitz 2?

Answer 10

PR interval is constant but every nth. ventricular depolarization is missing

Question 11

What is a 3rd degree AV block? A complete block aka?

Answer 11

atria and ventricles beat independent of one another

Question 12

Name some accessory pathways

Answer 12

bundle of kent

WPW syndrome

Question 13

What is an accessory pathway?

Answer 13

some individuals possess electrical pathways that bypass the AV node

Question 14

What are anti-arrhythmic drugs put into for classification?

Answer 14

Vaughan Williams Classification

Question 15

Name the 3 classes that target Na+ channels?

Answer 15

Class IA
IB
IC

Question 16

Name a class IA drug and describe rate

Answer 16

disopyramide

intermediate

Question 17

Name a class IB drug and describe rate

Answer 17

lignocaine

rapid

Question 18

Name a class IC drug and describe rate

Answer 18

Flecainide

slow rate

Question 19

Name the class of drugs that are B-receptor antagonists? Name a drug and effect/

Answer 19

Class II
Metoprolol
decrease the rate of depolarisation in SA and AV

Question 20

Name the class of drugs that target voltage activated K+ channels? Name a drug and effect?

Answer 20

Class III
Amiodarone
prolong AP duration

Question 21

Name the class of drugs that target voltage activated Ca+ channels? Name a drug and effect?

Answer 21

Class IV
Verapamil
Slows conduction in SA and AV nodes

Question 22

What classes are rhythm control drugs?

Answer 22

I+III

Question 23

What classes are rate control drugs?

Answer 23

II + IV

Question 24

Name the 3 drugs used in Supraventricular Arrhythmias?

Answer 24

Adenosine
Digoxin
Verapamil

Question 25

When is adenosine used and what does it do?

Answer 25

– hyperpolarises the AV node briefly, suppressing impulse conduction. Treats PSVT atrial firing rate 140-250 bpm Use this in acute phase

Question 26

When is Digoxin used and does it have a low therapeutic index?

Answer 26

stimulates vagal activity stimulates vagal activity (slows conduction and prolongs refractory period in AV node and bundle of His). Used to treat AF (narrow therapeutic index )

Question 27

Name some effects of the narrow therapeutic index of digoxin?

Answer 27

nausea, yellow vision, bradycardia, ventricular arrhythmias

Question 28

What does Verapamil do and when is it used?

Answer 28

– type IV agent – blocks L type Ca+ channel. Slows conduction and prolongs refractory period in AV node and bundle of His. Treats atrial flutter and AF. (Mostly replaced by adenosine acutely) This is a cardio selective blocker.

Question 29

Name the drug used to treat ventricular arrhythmias? what it does and when its used?

Answer 29

Lignocaine – type IB agent – rapid block of voltage activated Na+ channels. Primarily affects Na+ channels in areas of the myocardium that discharge action potentials at high rate (e.g. an ischaemic zone). Used to treat Ventricular arrhythmias following MI

Question 30

Name some drugs used in atrial and ventricular arrhythmias?

Answer 30

``` Disopyramide + procainamide Flecainide Propranolol and atenolol amiodarone and sotolol Amiodarone ```

Question 31

What type of agents are disopyramide and procainamide and what they do?

Answer 31

type Ia agents – moderate block of Na+ channels

Question 32

What type of agent are flecainide and what they do?

Answer 32

type Ic agent – slow block of Na+ channels. Prophylaxis of paroxysmal AF

Question 33

What type of agents are propanolol and atenolol and what they do?

Answer 33

type II agents – control SVT suppressing impulse conduction through AV node. Suppress excessive sympathetic drive that may trigger VT

Question 34

What type of agents are Amiodarone and sotolol and what they do?

Answer 34

type III – slow repolarisation of the action potential by blocking K+ channel so increases action potential duration and refractory period

Question 35

What type of agents are Amiodarone and what they do?

Answer 35

effective against SVT and VT (it has class IA, II and IV actions and blocks B adrenoceptors). Reduces mortality following MI and Congestive heart failure. Not recommended for long term can cause Pulmonary fibrosis, thyroid disorders, photosensitivity, peripheral neuropathy