Ventricular Tachycardia - ECG
Ventricular tachycardia can occur unexpectedly, even in a previously healthy person. Much more common it is in patients with chronic heart diseases including ischemic disease and in early periods after myocardial infarction.
Short ventricular tachycardia may not have serious manifestation. The patient sometimes feels an unpleasant sensations or palpitations. Prolonged ventricular tachycardia, however, is associated with an acute heart failure and causes a sudden loss of consciousness. Ventricular tachycardia can turn back to a normal heart rhythm or progress into life-threatening ventricular fibrillation.
Ventricular tachycardia can be distinguished as non-sustained (lasting less than 30 seconds) and sustained (lasting longer than 30 seconds).
The ECG shows us wide repetitive waves occurring with a high frequency. In the record we can not see the conventional QRS complexes. According to the shape of the waves, ventricular tachycardia may be referred to as monomorphic or polymorphic. Monomorphic waves have the same appearance and the polymorphic are variable. The most known type of polymorphic ventricular tachycardia is called Torsades de pointes and the amplitudes of its waves gradually increase and decrease (see bellow). Torsades de pointes ventricular tachycardia is associated with prolonged QT interval.
Monomorphic ventricular tachycardia Episode of a polymorphic ventricular tachycardia with gradually changing amplitudes of its waves (red) is characteristic for Torsades de pointes.
Conclusion: Discovery of an asymptomatic short ventricular tachycardia should be evaluated by a cardiologist. The doctor than evaluates the clinical significance and possibly recommends regular administration of anti-arrhythmic agents or directly indicates ICD implantation. In acute cases, the loss of consciousness must be solved by a classic cardiopulmonary resuscitation including cardioversion by an electrical discharge.