Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is characterised by polymorphic ventricular tachycardia initiated by conditions which increase catecholamine levels like exercise or emotional stress. In its classical form, bidirectional ventricular tachycardia appears during exercise and disappears on rest, in a rate dependent fashion. The onset is mostly in childhood and most cases respond to adequate doses of beta blockers, which is the sheet anchor of therapy. Some cases which do not respond well to beta blockers may need implantation of an implantable cardioverter defibrillator (ICD). But the ICD shock itself may trigger off an electrical storm due to the associated stress. Hence patients implanted with an ICD should also be given beta blockers to prevent such episodes. Another option for reducing the number of shocks and the consequent electrical storms, is programming a longer detection interval. This will avoid shocks being given for self limiting episodes of ventricular tachycardia, but has the potential to delay treatment in case of ventricular fibrillation. Another reason proposed by the proponents of longer detection interval is that the ventricular tachycardia in CPVT is initiated by triggered activity while ventricular fibrillation has a reentrant mechanism and may respond better to the shock.

The disorder is genetically determined, with mutations being described in cardiac ryanodine receptor (RyR2), calsequestrin, ankyrin B, calmodulin and triadin related genes. These varieties have also been designated CPVT1, CPVT2, CPVT3, CPVT4 and CPVT5 respectively.

Reference

1. Johnson Francis, Vikram Sankar, Venugopal Krishnan Nair, Silvia G Priori. Catecholaminergic polymorphic ventricular tachycardia. Heart Rhythm. 2005 May;2(5):550-4.