Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Recurrent sustained ventricular tachycardia (VT) is a fast heart rhythm that lasts for more than one minute and requires cardioversion (i.e. using electricity or drugs) for termination. This condition may precede a significant hemodynamic collapse; hence medical attention should be sought immediately. Causes of recurrent sustained VT can be explained by the re-entrant mechanism, and the cyclic adenosine monophosphate (cAMP) protein kinase A (PKA) signalling pathway. This mechanism is based on the conditions of predictable and reproducible initiation and termination of tachyarrhythmia by programmed stimulation at the ventricles.