Catecholaminergic polymorphic ventricular tachycardia

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a condition characterized by an abnormal heart rhythm (arrhythmia). As the heart rate increases in response to physical activity or emotional stress, it can trigger an abnormally fast heartbeat called ventricular tachycardia. Episodes of ventricular tachycardia can cause light-headedness, dizziness, and fainting (syncope). In people with CPVT, these episodes typically begin in childhood.

If CPVT is not recognized and treated, an episode of ventricular tachycardia may cause the heart to stop beating (cardiac arrest), leading to sudden death. Researchers suspect that CPVT may be a significant cause of sudden death in children and young adults without recognized heart abnormalities.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

CPVT most commonly results from mutations in two genes, RYR2 and CASQ2. RYR2 gene mutations cause about half of all cases, while mutations in the CASQ2 gene account for up to 5 percent of cases. Mutations in other genes are rare causes of the condition.

The RYR2 and CASQ2 genes provide instructions for making proteins that help maintain a regular heartbeat. For the heart to beat normally, heart muscle cells called myocytes must tense (contract) and relax in a coordinated way. Both the RYR2 and CASQ2 proteins are involved in the movement of calcium within myocytes, which is critical for the regular contraction of these cells.

Mutations in either the RYR2 or CASQ2 gene disrupt the handling of calcium within myocytes, which interferes with the coordination of contraction and relaxation of the heart, particularly during exercise or emotional stress. Impaired calcium regulation in the heart can lead to ventricular tachycardia in people with CPVT.

Similarly, other genes involved in CPVT play roles in calcium regulation in myocytes. Mutations in these genes also disrupt the normal movement of calcium inside these cells, impairing the coordination of heart beats.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

When CPVT results from mutations in the RYR2 gene, it follows an autosomal dominant inheritance pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In about half of cases, an affected person inherits an RYR2 gene mutation from one affected parent. The remaining cases result from new (de novo) mutations in the RYR2 gene that occur during the formation of reproductive cells (eggs or sperm) in an affected individual's parent or in early embryonic development. These cases occur in people with no history of the disorder in their family.

When CPVT is caused by mutations in the CASQ2 gene, the condition almost always has an autosomal recessive pattern of inheritance. Autosomal recessive inheritance means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. Very rarely, CASQ2-related CPVT may follow an autosomal dominant pattern of inheritance.

When caused by mutations in other genes, CPVT can be inherited in an autosomal dominant or autosomal recessive pattern.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

The prevalence of CPVT is estimated to be about 1 in 10,000 people. However, the true prevalence of this condition is unknown.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Ventricular tachycardia · Very frequent (99-80%)

A tachycardia originating in the ventricles characterized by rapid heart rate (over 100 beats per minute) and broad QRS complexes (over 120 ms).

Atrial fibrillation · Frequent (79-30%)

An atrial arrhythmia characterized by disorganized atrial activity without discrete P waves on the surface EKG, but instead by an undulating baseline or more sharply circumscribed atrial deflections of varying amplitude an frequency ranging from 350 to 600 per minute.

Cardiac arrest · Frequent (79-30%)

An abrupt loss of heart function.

Palpitations · Frequent (79-30%)

A sensation that the heart is pounding or racing, which is a non-specific sign but may be a manifestation of arrhythmia.

Polymorphic ventricular tachycardia · Frequent (79-30%)

A type of ventricular tachycardia that is characterized by variable QRS complexes within each lead (i.e., QRS complexes may be different from beat to beat).

Supraventricular tachycardia · Frequent (79-30%)

Supraventricular tachycardia (SVT) is an abnormally increased heart rate (over 100 beats per minute at rest) with origin above the level of the ventricles.

Vertigo · Frequent (79-30%)

An abnormal sensation of spinning while the body is actually stationary.

Sudden cardiac death · Occasional (29-5%)

The heart suddenly and unexpectedly stops beating resulting in death within a short time period (generally within 1 h of symptom onset).

Other findings in the same source

From: Orphanet

Additional reported features include Syncope (Occasional (29-5%)); Ventricular fibrillation (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Catecholaminergic polymorphic ventricular tachycardia is Cardiology, with a cardiologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Is the main concern heart structure, rhythm, circulation or another cause?
• Which symptoms should change the timing of follow-up?
• How would a proposed investigation change the care plan?

Treatment discussions and follow-up

Where the source describes treatments, these are an overview of possible care, not a prescription for an individual. Ask which option applies to the confirmed diagnosis, what benefit is expected, what adverse effects to watch for and how progress will be assessed. Availability, approvals and local practice can differ from the country described in the source.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.