Catecholaminergic polymorphic ventricular tachycardia (CPVT), also known as familial polymorphic ventricular tachycardia (FPVT), is a severe inherited cardiac arrhythmic disorder characterized by adrenergically induced ventricular tachycardia (VT). The age of onset is between 7 and 9 years. In some cases, sudden death can be the first manifestation of the CPTV. Other manifestations that may occur without warnings during physical activity or acute emotion include dizziness, heart palpitations and syncope. Bidirectional ventricular tachycardia is present in less than half of CPVT cases. CPVT diagnosis is based on an exercise stress test or Holter test that is performed to document ventricular arrhythmias. Genetic testing for mutation in the four causative genes (RYR2, CASQ2, TRDN, and CALM1) of family members is recommended if there is a family history of CPVT with known gene mutation. The usual treatment includes taking beta-blocker and/or calcium channel-blocker medications. Also Flecainide, a sodium channel blocker, has proven efficacious in suppressing arrhythmias in CPVT patients. Despite all that, CPVT is a severe and deadly disease, early diagnosis and treatment can increase life expectancy.
Al-Hassnan et al. (2013) described a consanguineous Saudi family with two siblings affected with catecholaminergic polymorphic ventricular tachycardia. The proband had a history of exercise-induced syncope since he was 9 years of old. At the age of 15 years ventricular ectopic beats then nonsustaind then sustained polymorphic VT was observed on Holter monitor and treadmill exercise testing. He was on Atenolol therapy; however, he had recurrent syncope. Subsequently, a transvenous single-chamber cardioverter defibrillator was implanted. One year later, he had an appropriate implantable cardioverter defibrillator (ICD) shock. His 8-year-old sister developed the same symptoms that were well controlled with Atenolol. Using direct sequencing for the CASQ2 gene, a novel homozygous c.230 T>C missense mutation was found in both affected siblings. This mutation resulted in a substitution of leucine to proline at position 77 (p.L77P). The parents and the two unaffected siblings were heterozygous carriers.