Arrhythmias

• What is the definition of an arrhythmia?

  An abnormal heart rhythm which results from an interruption to the normal electrical signals that coordinate the contraction of the heart muscle.
• What are the 4 possible rhythms in a pulseless patient?

  • Ventricular tachycardia
  • Ventricular fibrillation
  • Pulseless electrical activity
  • Asystole
• What are the 2 shockable rhythms in a pulseless patient?

  • Ventricular tachycardia
  • Ventricular fibrillation
• What are the two non-shockable rhythms in a pulseless patient?

  • Pulseless electrical activity
  • Asystole
• What defines a narrow complex tachycardia?

  1. Fast heart rate
  2. QRS complex duration of less than 0.12 seconds which is the equivalent of 3 small squares.
• What are the four types of narrow complex tachycardia?

  1. Sinus tachycardia
  2. Supraventricular tachycardia
  3. Atrial fibrillation
  4. Atrial flutter
• How is supraventricular tachycardia treated?

  Vagal manouvres first line

  Then administer adenosine if not worked
• Which 2 narrow complex tachycardias would radiofrequency ablation be considered?

  1. Atrial fibrillation
  2. Atrial flutter
• What score is anticoagulation based on in atrial fibrillation/flutter?

  CHA2DS2VASc score
• When would you see sinus tachycardia?

  When someone is in pain or sepsis.
• Is sinus tachycardia regular or irregular?

  Regular
• Are there P waves in supraventricular tachycardia?

  There are P waves, but you cannot see them on ECG due to them being buried in the T waves.
• When does SVT occur?

  At rest with no apparent cause.
• Is SVT regular or irregular?

  Regular
• What rhythm do you see in atrial fibrillation?

  Irregularly irregular
• What causes atrial flutter?

  Re-entrant rhythm in either atria. Recirculates in a self-perpetuating loop due to an extra pathway in the atrium.
• When would you treat someone who has a narrow complex tachycardia with synchronised DC cardioversion or IV amiodarone?

  • Syncope
  • Chest pain
  • Shock
  • Severe heart failure
• What defines a broad complex tachycardia?

  Fast heart rate

  QRS duration of more than 0.12 seconds or 3 small squares on ECG
• What are the 4 broad complex tachycardias?

  1. Ventricular tachycardia
  2. Polymorphic ventricular tachycardia e.g. Torsades de pointes
  3. Atrial fibrillation with bundle branch block
  4. Supraventricular tachycardia with bundle branch block
• How do you treat ventricular tachycardia?

  IV amiodarone
• How is torsades de pointes treated?

  IV magnesium
• Where is the QT interval measured from and to?

  Start of QRS, end of T wave
• How many milliseconds is the QT prolonged in men?

  440 milliseconds
• How many milliseconds is the QT prolonged in women?

  460 milliseconds
• What is the pathophysiology of a prolonged QT inteval?

  It represents prolonged repolarisation of the heart muscle cells after contraction.
• When there is prolonged repolarisation (long QT interval), what can happen that can cause cardiac arrest?

  Can get spontaneous depolarisation of some cardiac muscle cells, which are called 'after depolarisations', which spread through the ventricles causing contraction before proper repolarisation. This results in Torsades de pointes which can become Ventricular tachycardia and is life-threatening.
• What are the 3 causes of prolonged QT?

  1. Medications
  2. Electrolyte imbalances
  3. Long QT syndrome
• What are some examples of medications which cause prolonged QT?

  • Antipsychotics
  • Citalopram
  • Flecainide
  • Sotalol
  • Amiodarone
  • Macrolide antibiotics
• Which electrolyte imbalances cause prolonged QT?

  • Hypokalaemia
  • Hypomagnesaemia
  • Hypocalcaemia
• How is prolonged QT interval managed?

  • Review medications and stop those that may be contributing
  • Correct electrolyte disturbances
  • Beta blockers (not sotalol)
  • Pacemakers/implantable cardioverter defibrillators
• What is a ventricular ectopic?

  A premature ventricular beat caused by random electrical discharges outside the atria. Most common in patients with pre-existing heart conditions but can be present in healthy patients. Do not need treatment.
• What is bigeminy?

  Every other beat is a ventricular ectopic. Again, don't need treatment.
• What is first degree heart block?

  Prolonged PR interval = >0.2 seconds/5 small squares
• What is second degree heart block mobitz type 1?

  Increasing PR interval with dropped QRS.
• What is second degree heart block mobitz type 2?

  PR normal with dropped QRS.
• What is third degree heart block?

  No relationship between P and QRS complexes. Significant risk of asystole.
• What are three causes of bradycardias?

  1. Medications e.g. beta blockers
  2. Heart block
  3. Sick sinus syndrome
• What is sick sinus syndrome?

  Dysfunction in the SA node
• What do you give those who have bradycardias and are at risk of asystole?

  • IV atropine
  • Adrenaline
  • Temporary cardiac pacing
  • Permanent implantable pacemaker
• What drug class is atropine and what are the side effects?

  Atropine is an Antimuscarinic thereby inhibits the parasympathetic nervous system.

  Side effects include pupil dilation, dry mouth, urinary retention, contipation.