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Catecholaminergic polymorphic VT
CPVT is a genetic condition affecting the heart's electrical system, often leading to arrhythmias during physical activity or emotional stress. It can cause fainting spells or, in severe cases, sudden cardiac arrest, and typically affects otherwise healthy individuals.
Overview
Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is a rare, inherited condition that affects the heart's electrical signalling. It typically presents as dangerous heart rhythm disturbances, known as ventricular arrhythmias, which are triggered by physical exercise or strong emotions [PMID:33678080]. These arrhythmias can cause the heart to beat extremely fast and chaotically, potentially leading to symptoms like fainting or, more seriously, sudden cardiac arrest.
CPVT is a type of channelopathy, meaning it involves an issue with the ion channels that control the flow of electrical signals in heart muscle cells. Although the heart's structure appears normal, its electrical function is disrupted. The condition is estimated to affect approximately 1 in 10,000 people, but its exact prevalence may be higher as it can sometimes go undiagnosed [PMID:35800994].
Symptoms & clinical features
The main symptoms of CPVT are typically triggered by situations that increase adrenaline levels, such as exercise, excitement, or stress. Common symptoms include fainting (syncope), dizzy spells, or heart palpitations where a person feels their heart racing or fluttering [PMID:31539423]. These episodes can be frightening and may occur suddenly.
Less commonly, individuals with CPVT might experience chest pain or shortness of breath during an episode. In some severe instances, the first symptom can be sudden cardiac arrest, particularly during intense physical activity. It is important for individuals experiencing these symptoms, especially if they occur during exertion or emotional stress, to seek medical advice.
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Affected organs
CPVT primarily affects the heart, specifically its electrical system. While the heart muscle and its structure usually appear healthy, the problem lies in how electrical signals are generated and transmitted. This electrical instability can lead to life-threatening arrhythmias originating in the ventricles, the heart's main pumping chambers.
Although CPVT is a heart condition, the symptoms experienced, such as fainting, are due to the brain temporarily not receiving enough blood during an arrhythmia. There are no other organs directly affected by the underlying genetic defect in CPVT.
Risks & severity
The severity of CPVT can vary significantly between individuals. Some people may have very few or mild symptoms, while others experience frequent and severe episodes. The primary risk associated with CPVT is the potential for life-threatening ventricular arrhythmias, which can lead to sudden cardiac arrest [PMID:31539423].
The onset of symptoms typically occurs in childhood or adolescence, though it can manifest at any age. Early diagnosis and appropriate management are crucial to reduce the risk of severe events. Family history of sudden unexplained death, especially in young individuals, can also be an important indicator of increased risk within a family.
Genetic causes
CPVT is an inherited condition most commonly caused by genetic changes (variants) in the RYR2 gene. The RYR2 gene provides instructions for making a protein called the ryanodine receptor 2, which is vital for the proper function of calcium channels within heart muscle cells [PMID:33678080]. These channels play a critical role in regulating the flow of calcium, which is essential for the heart's contraction and relaxation.
When a genetic variant in RYR2 leads to a faulty ryanodine receptor 2, it can cause calcium to leak abnormally within heart cells, particularly during times of stress or exercise when adrenaline levels are high. This calcium mishandling disrupts the heart's normal electrical activity, leading to the characteristic arrhythmias seen in CPVT. Less commonly, variants in other genes, such as CASQ2, KCNJ2, and CALM1, can also cause forms of CPVT, though RYR2 is the most frequent genetic cause.
- RYR2 ryanodine receptor 2The RYR2 gene encodes the ryanodine receptor 2 protein, which is crucial for regulating calcium release in cardiac muscle cells, enabling coordinated heartbeats.
Inheritance pattern
CPVT is most commonly inherited in an autosomal dominant pattern. This means that an individual only needs to inherit one copy of the altered gene from one parent to develop the condition. If one parent has CPVT, there is a 50% chance with each pregnancy that their child will inherit the genetic variant and potentially develop the condition.
even within the same family, individuals with the same genetic variant can experience different severities of CPVT. In some cases, CPVT can also arise from a new genetic variant (a de novo mutation) in an individual, meaning neither parent carries the variant. Genetic counselling is often recommended for affected individuals and their families to understand the inheritance patterns and risks.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
Diagnosis & testing
Diagnosing CPVT typically involves a combination of clinical assessment, family history evaluation, and specialised heart tests. An exercise stress test, where heart activity is monitored during physical exertion, is a key diagnostic tool, as it can often trigger the characteristic arrhythmias of CPVT. An electrocardiogram (ECG) at rest may appear normal, making the exercise test particularly important.
Genetic testing is crucial for confirming a diagnosis of CPVT and identifying the specific genetic variant, most commonly in the RYR2 gene. This can be arranged via the NHS Genomic Medicine Service (GMS) pathways. Referral to a clinical geneticist or a cardiologist specialising in inherited heart conditions is usually the first step. The NHS National Genomic Test Directory lists specific R-codes for inherited cardiac conditions, including CPVT, to guide genetic testing.
Management & lifestyle
Management of CPVT focuses on preventing dangerous arrhythmias and reducing the risk of sudden cardiac arrest. This often involves medication, typically beta-blockers, which help to stabilise the heart's electrical activity, especially during periods of stress or exercise. In some cases, other medications or procedures may be considered if beta-blockers are not sufficiently effective or tolerated.
Lifestyle adjustments, such as avoiding strenuous exercise and highly stressful situations, are also often recommended. For individuals at high risk of sudden cardiac arrest, an implantable cardioverter-defibrillator (ICD) may be considered. This device can detect life-threatening arrhythmias and deliver an electrical shock to restore a normal heart rhythm. Regular follow-up with a cardiologist specialising in inherited cardiac conditions is essential to monitor the condition and adjust treatment as needed, in line with NHS care pathways.
UK care pathway
In the UK, individuals suspected of having CPVT are typically referred through their GP to a specialist cardiologist or an inherited cardiac conditions (ICC) clinic within the NHS. These clinics specialise in diagnosing and managing genetic heart conditions. If CPVT is suspected, genetic testing can be arranged via the NHS Genomic Medicine Service (GMS).
Genetic testing for CPVT falls under specific R-codes in the NHS National Genomic Test Directory, allowing for comprehensive gene panel testing. Following a diagnosis, individuals will receive ongoing care from a specialist cardiology team. Access to genetic counsellors is also an integral part of the pathway, offering support and information to patients and their families about the genetic aspects of CPVT and its implications.
Frequently asked questions
What activities should someone with CPVT avoid?
Individuals with CPVT are generally advised to avoid strenuous physical activity and highly stressful or emotional situations that can trigger adrenaline surges. Your cardiologist will provide specific guidance tailored to your condition and treatment plan.
Can CPVT be cured?
Currently, there isn't a cure for CPVT, but it can be effectively managed with medication and lifestyle adjustments to prevent dangerous heart rhythms. Research is ongoing to better understand and treat this condition.
Is CPVT always inherited from a parent?
CPVT is most commonly inherited from a parent in an autosomal dominant pattern. However, in some instances, it can also arise from a new genetic change that occurs in the affected individual and is not present in either parent.
Will my children inherit CPVT if I have it?
If you have autosomal dominant CPVT, there is a 50% chance with each pregnancy that your child will inherit the genetic variant. Genetic counselling can help you understand these risks and discuss options for family planning.
What is the difference between CPVT and a heart attack?
CPVT is an electrical problem causing rhythm disturbances, often in an otherwise healthy heart, whereas a heart attack typically occurs when blood flow to a part of the heart muscle is blocked, leading to tissue damage. They are distinct conditions with different causes and mechanisms.
References
- Francis J, Sankar V, Nair VK. Catecholaminergic polymorphic ventricular tachycardia. Heart rhythm. 2005. PMID: 15840485
- Antzelevitch C, Oliva A. Amplification of spatial dispersion of repolarization underlies sudden cardiac death associated with catecholaminergic polymorphic VT, long QT, short QT and Brugada syndromes. Journal of internal medicine. 2006. PMID: 16336513
- Murakoshi N, Aonuma K. Catheter ablation for ventricular tachyarrhythmia in patients with channelopathies. Journal of arrhythmia. 2016. PMID: 27761165
- Prystowsky EN, Padanilam BJ, Joshi S. Ventricular arrhythmias in the absence of structural heart disease. Journal of the American College of Cardiology. 2012. PMID: 22575310
- Lerman BB, Markowitz SM, Cheung JW. Ventricular Tachycardia Due to Triggered Activity: Role of Early and Delayed Afterdepolarizations. JACC. Clinical electrophysiology. 2024. PMID: 38127010
- Chihara RK, Chan EY, Meisenbach LM. Surgical Cardiac Sympathetic Denervation for Ventricular Arrhythmias: A Systematic Review. Methodist DeBakey cardiovascular journal. 2021. PMID: 34104317
- Schleifer JW, Sorajja D, Shen WK. Advances in the pharmacologic treatment of ventricular arrhythmias. Expert opinion on pharmacotherapy. 2015. PMID: 26513538
- Bai Y, Jones PP, Guo J. Phospholamban knockout breaks arrhythmogenic Ca²⁺ waves and suppresses catecholaminergic polymorphic ventricular tachycardia in mice. Circulation research. 2013. PMID: 23856523