Polymorphic Catecholergic Ventricular Tachycardia
Polymorphic Catecholergic Ventricular Tachycardia ( also known as Catecholaminergic polymorphic ventricular tachycardia (CPVT), familial polymorphic ventricular tachycardia (FPVT) or catecholamine-induced polymorphic ventricular tachycardia), is a disorder characterized by an abnormal heart rhythm (arrhythmia). 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.
The most common symptom is dizziness or syncope which often occurs during exercise or as a response to emotional stress.
Age at Onset
CPVT typically start manifesting during the first or second decade of life. The majority of events occur during childhood with more than 60% of affected individuals having their first episode of syncope or cardiac arrest by age 12-20.
Symptoms are typically precipitated ("triggered") by exercise-induced ventricular arrhythmias during periods of physical activity or acute emotional stress.
First recognized in 1975, this condition is due to mutations in genes encoding a calcium channel or proteins related to this channel. All mutated proteins participate in the regulation of calcium ion flow in and out of the sarcoplasmatic reticulum of cardiac cells. Therefore, reduced electrical stability of cardiomyocytes may cause the heart to enter a life-threatening state of ventricular arrhythmia as response to the natural release of catecholamines from nerve endings on the heart muscle and from the adrenal glands into the circulation. This rhythm disturbance prevents the heart from pumping blood appropriately. Ventricular tachycardia may self-terminate or degenerate into ventricular fibrillation, causing sudden death unless immediate cardiopulmonary resuscitation is applied.
Affected patients demonstrate no structural problems of the heart upon echocardiographic, CT or MRI imaging.
CPVT diagnosis is based on reproducing irregularly shaped ventricular arrhythmias during ECG 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.
Because its symptoms are usually only triggered when the body is subjected to intense emotional or physical stress, the condition is often not detected by the traditional methods of electrophysiologic examination such as a resting electrocardiogram.
Medications to treat CPVT include beta blockers and verapamil.
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-defibrillators are used to prevent sudden death.
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.