Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare condition that has been associated with two genes that make proteins found inside the cell – the human ryanodine receptor (a calcium ion channel) and calsequestrin (a protein that interacts with the calcium channel). These regulate the release of calcium ions into the rest of the cell. If these do not function normally, the level of calcium inside the cell becomes too high, resulting in arrhythmias.
What are the symptoms?
Some people with CPVT have no symptoms at all. Others may have palpitations (with or without an irregular heart beat), or blackouts while exerting themselves or suffering emotional stress. The condition may be found in most age groups but appears to be most severe in children and adolescents and in males.
Are there any physical signs?
There are no physical signs.
How is it diagnosed?
The diagnosis is usually made after the recording of arrhythmias that are characteristic of CPVT, while the person is doing exercise. The exercise ECG is therefore useful although some doctors use adrenaline testing as well. Genetic testing is of use as 1 in 2 people with the condition carry a ryanodine receptor mutation and are more likely to have blackouts or a cardiac arrest. When a member of a family has been found to carry a mutation, testing is then useful in detecting carriers who have not yet shown any signs of the condition.
Treatment and advice
Your doctor will advise you to take beta-blockers, to restrict the amount of exercise you do, and avoid medications that stimulate the heart. This combination can greatly improve the outlook for people with CPVT. Up to 1 in every 3 people with the condition, however, may also need to have an implantable cardioverter defibrillator (ICD) fitted, particularly if they have blackouts while taking beta-blockers.
Watch CRY’s myheart cardiologist, Dr Michael Papadakis, talk about things to avoid if you have an ion-channel disease below.
Surgery
Recently some doctors have used the cervical sympathectomy (already used in long QT syndrome) to treat CPVT with some success.