What is Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)?

Catecholaminergic Polymorphic Ventricular Tachycardia or CPVT is an inherited cardiac condition that causes sudden, abnormal heart rhythms (arrhythmias) which can lead to fainting or cardiac arrest. These events usually occur during physical exercise or with emotional stress. The average age at which symptoms of CPVT appear is between 7 and 9 years, although symptoms may appear as late as the fourth decade of life. If untreated, this condition can be lethal. 

CPVT is an inherited channelopathy resulting from mutations in one or more of the genes that control the amount of calcium inside the heart muscle cells, which results in too much calcium in the heart muscle. The excess calcium affects the heart’s electrical system, causing extra heart beats in the lower chambers of the heart.  Arrhythmias can be triggered by conditions involving emotional or physical stress that leads to a release of adrenaline, a stress hormone that prepares the body to “fight”.

Effects and Symptoms

Patients with CPVT may experience palpitations, seizures or fainting when the body is producing high levels of adrenaline, such as during exercise or in times of stress. CPVT is suspected when an individual has an episode of fainting, seizures or cardiac arrest associated with exercise or emotional stress.

Diagnosis

Testing for CPVT includes a resting ECG (which is usually normal) and an exercise stress test to provoke the rhythm abnormalities. Children that are too young for a treadmill or bicycle exercise test can be monitored during routine activities by wearing a Holter monitor. An alternative to exercise stress testing in someone who cannot exercise is catecholamine provocation testing, in which adrenaline is administered through an intravenous (IV) line while the heart rhythm is being monitored. A diagnosis of CPVT is made when the characteristic arrhythmias are observed. These include frequent premature ventricular beats, or electrical signals from the lower chambers of the heart, and ventricular arrhythmias such as bidirectional ventricular tachycardia or VT. Prolonged or sustained VT that can affect blood pressure and ventricular fibrillation, a disorganized rhythm that can develop from VT, are life-threatening rhythms.

Management and Treatment

There is no cure for CPVT, but there are effective treatments. All patients who have CPVT symptoms should receive treatment. All children and young adults with CPVT should be treated even if they do not have symptoms. This is because symptoms might occur at any time, with sudden death sometimes being the first symptom.

The usual treatment involves taking a medication called a beta blocker every day. Beta blockers prevent the response of the heart to adrenaline, reducing the likelihood of arrhythmia. Repeated exercise stress tests may help to determine the correct dose. If the beta blocker does not adequately control arrhythmia, an additional medication, flecainide, has also been found to be useful. These medications are usually very successful at controlling arrhythmias if they are taken regularly. Regular follow up with your cardiologist is advised to monitor if the arrhythmia is well controlled. Growing children need their medication dose adjusted regularly. 

If symptoms continue despite appropriate doses of medication, there are other treatments. Left cardiac sympathetic denervation (LCSD) is a surgery in which the nerves that are responsible for adrenaline delivery to the heart are removed. An ICD or implantable cardioverter defibrillator, a device that can abort an abnormal rhythm when it happens, is rarely needed.

It is very important that medications are taken regularly. Preteens and teenagers should be supervised when taking medications. Because strenuous physical exercise increases the risk of arrhythmia, competitive or high-intensity activities are avoided, but regular exercise is important and can be done if the arrhythmia is appropriately controlled with medications.