Aryythmias

Question 1

Causes of arrhythmias

Answer 1

Impulse formation

Impulse conduction

Question 2

Where do supraventricular arrhythmias originate from?

Answer 2

Atria, SA and AV node

Question 3

What is overdrive suppression?

Answer 3

As the SA node fires at the highest frequency its impulses mask those of the other nodal tissue specifically the AV and purkinje fibres

Question 4

What is a latent pacemaker?

Answer 4

AV node or purkinjes fibres these are nodal tissues that can initiate the impulses but as they fire at a lower rate are masked by the SA node

Question 5

What is an escape beat or rhythm

Answer 5

When a latent pacemaker initiates a contraction outside off vagus rhythm

Question 6

What is an ectopic beat or rhythm?

Answer 6

When a latent pacemaker fires at an intrinsic rate faster than the SA node

Question 7

Reasons for at ectopic heart beat?

Answer 7

Ischeamia , hypokalaemia, increased sympathetic activity

Question 8

What heart rate is associated with early afterdepolarisations?

Answer 8

Slow

Question 9

What are afterdepolarisations and what two types of them are there?

Answer 9

Abnormal oscillations in membrane potential

Early and delayed afterdepolarizations occur

Question 10

In what tissues of the heart do early afterdepolarisations generally occur in?

Answer 10

Purkinje or bundle of His fibres, areas with a pronounced phase 1 and 2

Question 11

What arrhythmia is related too early after depolarisations?

Answer 11

Torsades de pointes- life threatening

Question 12

When do delayed afterdepolarisations occur?

Answer 12

Upon complete depolarisations in Phase 4 due to increased Ca2+

Question 13

What heart rate are delayed AD likely to occur?

Answer 13

Fast

Question 14

What are the risks associated with?

Answer 14

Increasing duration of Action potential decreases the risk as less Ca2+ so longer phase 2

Question 15

What two drugs increase likelyhood of delayed AD

Answer 15

Catecholamines , digoxin both increase intracellular conc of Ca2+

Question 16

What two things allow are re-entry cycle to occur?

Answer 16

An alternate pathway to the AV node e.g. bundle of Kent

Or an area of unconducting scarred tissue due to an MI etc

Question 17

Why does an re-entry occur

Answer 17

If one side of the unconducting tissue only allows conductance to occur in one direction then when the wave of depolarisation passes around the scarred tissue it can pass back up.
If long enough has passed the tissue can repolarise above the scarred tissue allowing the depolarisation to pass back down and trigger a second contraction out of sinus rhythm.
This circuit can continue around the unconducting tissue

Question 18

What is partial block

Answer 18

First degree AV node block

Tissue conducts all impulses but at a slower rate

Question 19

ECG reading of First degree AV node Block

Answer 19

Prolonged gap between P wave and QRS complex

Question 20

What is intermittent block?

Answer 20

Second degree AV node block

Node conducts some but not all of the impulses

Question 21

Mobitz type 1

Answer 21

PR interval gradually increases from cycle to cycle until AV node fails completely so ventricular QRS wave is not present

Question 22

Mobitz type 2

Answer 22

PR interval is consistent but every nth QRS cycle is missed

Question 23

In what mobitz type is atropine used?

Answer 23

ONLY type 1

Question 24

What is complete block?

Answer 24

Tissue conductance doesn’t occur

Third degree AV node block

Question 25

What happens in third degree block?

Answer 25

Atria and ventricles beat independently, purkinje fires take over as dominant pacemaker

Question 26

Clinical aspects of third degree block?

Answer 26

Bradychardia and very low CO

Question 27

Atrial fibrillation symptoms

Answer 27

SOB, palpitations, dizziness, loss of consciousness, faintness, sudden cardiac death, angina, heart failure

Question 28

Treatment for Tachy-Brady

Answer 28

Pacemaker to prevent bradychardia, beta blockers to prevent tachychardia

Question 29

Sinus Bradychardia

Answer 29

Atropine if acute | Pacemaker if harm-dynamic compromise

Question 30

Sinus Tachychardia >100bpm

Answer 30

Anxiety fever hypotension anaemia | treatment with beta blockers

Question 31

Atrial Ectopic beats

Answer 31

generally no treatment can burn of areas inducing B adrenergic blockers may help avoid stimulants e.g. coffee caffein

Question 32

Regular Superventricular tachychardia

Answer 32

Acute- increased vagal tone, valsalva manoeuvre carotid massage - Iv adenosine and Ca2+ blockers Chronic- radio frequency ablation, avoid stimulants, beta blockers and antiarrythmic drugs

Question 33

Paroxysmal

Answer 33

Last less than 48 hours often reccurent

Question 34

Persistant

Answer 34

last 48 hours

Question 35

Permanent

Answer 35

Constant

Question 36

Lone Idiopathic

Answer 36

Absence of any. heart disease and no supporting evidence | often genetic and increased risk of strokes

Question 37

What drugs are used for Atrial Fibrillation?

Answer 37

Diltiazem or verapamil - Rate slowing Ca2+ channel Beta blockers Digoxin

Question 38

What treatment is used in younger AF sufferers

Answer 38

Ablation radiofrequency is used to destroy tissue creating impulses

Question 39

Which antiarrythmic should never be used with digoxin?

Answer 39

Amiodarone

Question 40

What anti-arrythmic drugs are used?

Answer 40

Na+ blockers- slows phase 0 K+ blockers - slows repolarisation Amiodarone- blocks everything

Question 41

How can you monitor the antiarrythmic drugs?

Answer 41

Using an ECG Na+ blockers- wider QRS K+ blockers - wider QT interval

Question 42

Treatment for ventricular tachychardia/fibrillation

Answer 42

Implantable cardioverter-defibrillator | Ablation - has better outcomes

Question 43

What drug is used in the treatment of ventricular tachycardia

Answer 43

Amiodarone