Arrythmias

Question 1

What are the 2 types of arrhythmia based on where they occur?

Answer 1

Ventricular- within the ventricles
Supraventricular- above the AV node (Atrial), at av junction, within av node

Question 2

What is bradychardia?

Answer 2

Slow heart rate <60bpm

Question 3

What is tachycardia?

Answer 3

Fast heart rate >100bpm

Question 4

What are the symptoms of an arrhythmia?

Answer 4

May be asymptomatic
- dizzy, light-headed
- palpitations
- chest pain
- fatigue
- loss of consciousness
- can result in cardiac arrest

Question 5

What is the management of arryhmias?

Answer 5

-identify any underlying cause e.g thyroid disease- hyper or hypo, Electrolyte imbalances- K+, CA2+, MG2+

treatment:
- Drug therapy e.g. beta blockers, sodium channel blockers, CCBs
- Electrical cardio version, radio frequency ablation, pacemakers, defibrillation

Question 6

What are they types of bradychardic arrythmias?

Answer 6

• sinus bradychardia- sinoatrial node fires slowly
• Sinus node disease- sa node fails ro generate an electrical impulse. Mainly idiopathic cause e.g. fibrosis of conductive tissue, secondary to MI or cardiomyopathy
• Atrioventricular node disease ‘Heart block’- (most common!)- failure of the av node to conduct the electrical impulse to the ventricles. Often secondary to MI, congenial defects, infection, surgery

Question 7

What are the treatment options for a bradychardic arrhythmia?

Answer 7

ACUTE= Atropine (increases heart rate)
May require stat dose if HR too low

• look fo underlying cause e.g. if drug-induced- stop drug. Treat disease if causing it e.g. hypothyroidism
• Permanent pacemaker- inserted into the ‘skin pocket’ below the collar bone
• leads sense the electrical activity of the heart and then it delivers small electrical impulses to the myocardial tissue if it detects inappropriate rhythm.

Question 8

What are the divisions of tachycardia arrythmias?

Answer 8

• Supraventricular (atria originating) e.g. Sinus tachycardia, AF, atria, atrial flutter
  (AV junction originating) e.g. wolff-parkinson white syndrome, av functional tachycardia
• ventricular tachycardias - MOST PROBLEMATIC
  e.g. ventricular ectopics, torsades de pointes, ventricular fibrillation (most serious- is a cardiac arrest)

Question 9

What is atrial flutter?

Answer 9

Atria ‘flutter’
Caused by re-entry circuit with the right atrium - rapid atrial rhythm (300bpm)
- Ventricles usually beat once for every 2-4 atrial flutter waves = cause stasis of blood in atria = need anticoagulation

Question 10

What is Wolff-Parkinson white syndrome?

Answer 10

Where there is extra pathways that conduct an electrical pulse direct from atria to ventricles BUT bypasses the AV node- this is what slows the HR normally
- can cause up to 600 bpm

Question 11

What is Torsades de pointes?

Answer 11

A ventricular tachycardia where the QRS complex twists due to prolongation of QT

Question 12

What is ventricular fibrillation?

Answer 12

= cardiac arrest!
Rapid, uncoordinated contraction of ventricles= severely decreases cardiac output
- will lose consciousness within 10-20 seconds
- most common cause of death
- urgently requires a defibrillator

Question 13

What are the non-pharmacological management options for arrythmias?

Answer 13

Direct current cardio version:
Application of a controlled electric current shock across the chest wall- – - This overrides the disordered conduction
- The SA node can regain control of HR
This is unpleasant- so patient is anaesthetised
Has increased risk of thromboembolism- need anti-coagulation 3 weeks before and 4 weeks after

Radiofreuency/cyoablation:
- Have to find the exact location of the point responsible for generating the arrhythmia via electrophysiological studies
- Then guide a catheter with an electrode at the tip to this location
- This then freezes or uses RF energy to freeze the point and destroy the tissue and disrupts the faulty conduction pathway

Defibrillation
- Electric shock delivery to myocardium via the chest wall
- needed asap in cardiac arrest
- used in combination with CPR

Internal cardio version defibrillator (ICDs)
- Is implanted into patients into a pocket beneath the collar bone
- Used in patients who are high risk e.g. those who had suffered a cardiac arrest and are at risk of another
- They monitor the rate and rhythm of the heart - if they detect ventricular tachycardias- it delivers a rapid rate impulse that is faster than the arrythmia
- This allows it to try and regain control of the HR and then it slowly brings it down
- If the above fails, t delivers an internal electric shock to the heart- this is unpleasant and would likely knock the patient to the ground

Question 14

What medication needs to be given alongside a direct current cardio version?

Answer 14

Has increased risk of thromboembolism- need anti-coagulation 3 weeks before and 4 weeks after

Question 15

How do internal cardioversion defibrillators work?

Answer 15

Internal cardio version defibrillator (ICDs)
- Is implanted into patients into a pocket beneath the collar bone
- Used in patients who are high risk e.g. those who had suffered a cardiac arrest and are at risk of another
- They monitor the rate and rhythm of the heart - if they detect ventricular tachycardias- it delivers a rapid rate impulse that is faster than the arrythmia
- This allows it to try and regain control of the HR and then it slowly brings it down
- If the above fails, t delivers an internal electric shock to the heart- this is unpleasant and would likely knock the patient to the ground

Question 16

What should be given during the insertion of a permanent pacemaker?

Answer 16

Swish in some Gentamicin into the atrial pocket- prevents infection

Question 17

What is the difference between first, second and third degree heart block?

Answer 17

In heart block there is always a p-wave but not always a qrs complex

First:
- 1:1 ratio of p wave to QRS complex
but the PR interval is long
conduction through av node is delayed

Second:
Not very p wave results in a QRS complex- not all atrial contraction are followed by ventricular contractions

Third:
= complete heart block
No conduction through av node
Atrial conduction continues due to sa nose = always p-wave
- There is a slight ventricular contraction due to automatic rhythm of AV node= this produces an ‘Escape rhythm’ - this is weak, slow but prevents immediate death- nor forever so medical emergency

Question 18

What drugs need to be stopped and restarted in admission of a heartblock patient?

Answer 18

On admission:
Stop any rate controlling drugs e.g. CCBs, beta-blockers
Stop anti-coagulants
Review eye drops- e.g timolol containing drops- beta blocker and can have systemic effects

Prior to discharge:
Restart anticoagulant and eye drops
Consider restart rate control depending on indication/consider aternative

Question 19

Why dose Amiodarone need a loading dose (+ what is it)?

Answer 19

because it has a long half-life- 40-50 days so takes a while to work
200mg TDS fir 1 week
200mg BD for 1 week
200mg OD maintenance

As half life is so long- may have an add on therapy:
Digoxin - 500mcg x2 STAT dose (6 hours apart)
Then 125mcg OD maintenance

Question 20

What base line functions are needed before starting amiodarone+side effects?

Answer 20

Liver function- as can cause dysfunction
Report SOB etc as can cause pulmonary toxicity
Thyroid function- as can cause dysfunction- contains iodine and can lead to hypo or hyper thyroidism

other side effects
- bradychardia
- phototoxicity- need high spf, sit in shade, cover skin
- gray skin
- metallic taste
- corneal microdeposits- glow/halo in eyes

Question 21

What is the important interaction between amiodarone and another drug?

Answer 21

Amiodarone increases levels of digoxin by up to 50%
Digoxin has a narrow therapeutic index- so reduce digoxin dose by 50% if continued use with amiodarone
- often digoxin is only used short term- until ventricular rate decreases