Catecholaminergic polymorphic ventricular tachycardia

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is an electrophysiological disorder of the heart that occurs in genetically predisposed individuals. Thought to affect as many as one in ten thousand people, it is estimated to cause 15% of all unexplained sudden cardiac deaths in young people.

First recognized in 1975, the voltage gated ion channel mutation intermittently causes the heart to enter a life threatening state of arrhythmia as response to the natural release of catecholamines. The most common symptom is syncope, which most commonly appears during the first or second decade of life.

Because its symptoms are most prevalent when the body is subjected to intense emotional or physical stress, the condition can elude traditional methods of heart examination such as echocardiogram and resting electrocardiogram.

Syncopal
CPVT may cause exercise-induced ventricular arrhythmias and/or syncope occurring during physical activity or acute emotion, but demonstrates no structural problems of the heart. Ventricular tachycardia may self-terminate or degenerate into ventricular fibrillation, causing sudden death without immediate cardiopulmonary resuscitation. The majority of events occur during childhood and more than 60% of affected individuals will have a first episode of syncope or cardiac arrest by age 20.

Diagnosis
CPVT diagnosis is based on reproducing ventricular arrhythmias during exercise stress testing, syncope occurring during physical activity and acute emotion, and a history of exercise or emotion-related palpitations and dizziness with an absence of structural cardiac abnormalities.


 * The Ryanodine receptor (RYR2) is involved in intracardiac Ca2+ handling; Ca2+ overload triggers abnormal cardiac activity.
 * Calsequestrin (CASQ2) is a calcium buffering protein of the sarcoplasmic reticulum.

Medication
Medications to treat CPVT include beta blockers and verapamil.

According to recent research published in Nature Medicine, flecainide inhibits the release of the cardiac ryanodine receptor–mediated Ca2+, and is therefore believed to medicate the underlying molecular cause of CPVT in both mice and humans.

Implantable cardioverter-defibrillator
Implantable cardioverter-defibrillators are used to prevent sudden death.

Sympathectomy
In recent reports, left cardiac sympathetic denervation and bilateral thoracoscopic sympathectomy have shown promising results in individuals whose symptoms cannot be controlled by beta blockers.