The complexity of mechanisms in ventricular tachycardia.

Several pathophysiological substrates may be responsible for ventricular tachycardia (VT) occurring in the chronic phase of a myocardial infarction. Reentrant circuits can have anatomical or functional characteristics. Macroreentrant or microreentrant circuits have been described. Activation maps have shown that the circuit can be represented as a single loop or as a figure-of-eight reentrant pattern. All these different substrates have in common that they result in sustained monomorphic VT. The adequate treatment will probably be different for each one of them. In this article, some possible pathophysiological substrates of VT occurring in the chronic phase of a myocardial infarction are reviewed. Finally, we speculate on how catheter ablation may modify each one of the substrates.