C. Hypomagnesaemia – Explanation

Hypokalemia is the most important cause of ventricular tachycardia (VT) clinically, followed by
hypomagnesaemia. Severe hyperkalaemia may cause VT in certain circumstances, for example in
patients with structural heart disease, but it is not as common a cause as hypomagnesaemia.
Ventricular tachycardia
Ventricular tachycardia (VT)is broad-complex tachycardia originating from a ventricular ectopic
focus. It has the potential to precipitate ventricular fibrillation and hence requires urgent treatment.
There are two main types of VT:

• monomorphic VT: most commonly caused by myocardial infarction
• polymorphic VT: A subtype of polymorphic VT is torsades de pointes which is precipitated by
  prolongation of the QT interval. The causes of a long QT interval are listed below

Causes of a prolonged QT interval