100 ECG’s
Uncommon ECG's: (2 questions)

Questions

• 1
  22 year old third year medical student presents to A&E complaining of an episode of palpitations. He is a keen footballer. He reports an episode of a fast heart beat while he was playing football which made him feel dizzy and stop playing. The episode lasted a few minutes and has now resolved. He reports having similar episodes in the past but is now more worried since he was doing cardiology at hospital placement. He has no past medical history and no family history of relevance. His current ECG is shown. What is the diagnosis ?
  
  Difficulty: Hard     Topic: Uncommon arrhythmias
  a

  Normal Sinus Rhythm with Right Bundle Branch Block

  b

  Normal Sinus Rhythm with Right Axis Deviation

  c

  Paroxysmal Atrial Fibrillation (PAF)

  d

  Atrioventricular nodal re-entry tachycardia (AVNRT)

  e

  Atrioventricular reciprocating tachycardia (AVRT)
  Explanation: This is a classical case of AVRT in the form of Wolff-Parkinson-White (WPW) syndrome. Patients with WPW are normally asymptomatic but may experience episodes of supraventricular tachycardia during which they may experience palpitations, dizziness, shortness of breath or syncope. The resting ECG (when the AVRT resolves) shows a broad QRS complex and a short PR interval as a result of ventricular pre-excitation identified as a "delta wave" on the ECG (upslur in the QRS complex). In WPW, patients have an accessory pathway (accessory to the main pathway: AV node) which may conduct electrical activity at a higher rate than the AV node leading to a tachycardia. Treatment is by ablation of the accessory pathway.
• 2
  A 68 year old lady attends the emergency department complaining of palpitations. She started feeling her heart racing 30 minutes ago. She is otherwise well. An ECG is done (shown). Which of the following antiarrhythmic agents is the drug of choice to manage her condition ?
  
  Difficulty: Hard     Topic: Uncommon arrhythmias
  a

  Amiodarone

  b

  Flecainide

  c

  Nebivilol

  d

  Magnesium

  e

  Digoxin
  Explanation: The lady's ECG is shown polymorphic ventricular tachycardia, otherwise known as Torsade de pointes. Generally, this is a self-terminating arrhythmia but it is not uncommon for it to degenerate intro ventricular fibrillation which is why it is important to manage it. The drug of choice is Magnesium, which has membrane stabilising properties by acting on calcium channels.