Catecholaminergic polymorphic ventricular tachycardia(patient information)
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mounika Reddy Vadiyala, M.B.B.S.[2]
Overview
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare condition characterized by an irregular heart rhythm (arrhythmia) that can be life-threatening. In people with CPVT, these episodes typically begin in childhood but symptoms can also show up later in life. As the heart rate increases in response to physical activity or emotional stress, it can trigger an abnormally fast and irregular heartbeat called ventricular tachycardia. With this condition, the heart beats so quickly that it doesn't have enough time to fill blood between beats. As a result, not enough blood gets pumped to the body. The first sign is often fainting or near fainting during exercise or strong emotion. Other symptoms include light-headedness, dizziness, and also may cause the heart to stop beating (cardiac arrest), leading to sudden death. If untreated, it is very lethal.
What are the symptoms of Catecholaminergic polymorphic ventricular tachycardia?
The symptoms typically start with ventricular tachycardia (VT) during physical activity or emotional stress:
- Fainting is commonly the first sign of the disease
- Light-headedness or dizziness
- Palpitations or unpleasant awareness of the heartbeat
Sometimes the ventricular tachycardia goes away, and symptoms stop. At times, ventricular tachycardia can turn into ventricular fibrillation (VF) in which the ventricles quiver and are unable to pump blood. This sudden loss of heart function leads to sudden cardiac arrest. A person stops breathing and becomes unresponsive. Unfortunately, sudden cardiac arrest is sometimes the first sign of CPVT. Sudden cardiac arrest can lead to sudden cardiac death.
What causes Catecholaminergic polymorphic ventricular tachycardia?
- CPVT is caused by a gene defect (abnormal gene). Genes are part of your DNA, the material passed down from parents to children, which can be passed down through families and inherited in different ways (from either one or both parents).
- In some cases, CPVT is autosomal dominant which means you need an abnormal gene from only one of your parents to have it. In other cases, CPVT is autosomal recessive which means you need an abnormal gene from both of your parents to get the disease.
- CPVT can result from mutations in genes such as RYR2 and CASQ2. RYR2 gene mutations cause about half of all cases, while mutations in the CASQ2 gene account for 1 percent to 2 percent of cases.
- 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 handling calcium within myocytes, which is critical for the regular contraction of these cells.
- Mutations in either the RYR2 and CASQ2 gene disrupt the handling of calcium within myocytes. During exercise or emotional stress, impaired calcium regulation in the heart can lead to ventricular tachycardia in people with CPVT.
- Stress and exercise can trigger episodes. Certain medicines, such as catecholamines, can also make it worse.
Who is at highest risk?
- Children and young adults
- Having a relative with CPVT
- Family history of fainting (syncope) or sudden death.
Thus, if you or someone in your family has CPVT, you and all other family members should see a healthcare provider to get checked. You may need a genetic test.
Diagnosis
CPVT is often diagnosed at a young age. This usually happens when a child faints from physical or emotional stress. The healthcare provider will ask about the child’s health history and symptoms and also ask about your family's health history. The child will have a physical exam. These tests are usually advised:
- Electrocardiography (ECG): This is to check heartbeat and rhythm. Resting ECG results are usually normal in people with CPVT. Slow heart rate is a subtle but non-diagnostic clue.
- Exercise stress testing: This is the most important test to diagnose CPVT as most people with CPVT have VT when their heart rate is high. It also looks at the heart rhythm during exercise. The key findings involve irregular heartbeat arising from the pumping chambers of the heart that are induced during the treadmill stress test usually when the heart rate gets faster than 120 beats per minute.
- Medicine challenge or catecholamine provocation testing: An infusion of an adrenaline-like chemical is given that makes the heart work harder. This simulates exercise. This may be done if a person can’t exercise.
- Holter monitoring: Continuous portable ECG monitoring helps to further analyze heart rhythms.
- Echocardiography: This is an ultrasound of the heart to check for abnormalities in the heart's structure and function.
- MRI of the heart: This test gives a more detailed view of the structures in and around the heart.
- Genetic testing: This is to check for gene defects.
When to seek urgent medical care?
Go to the emergency room or call the local emergency number (such as 911) if you have a rapid, irregular pulse, faint, or have chest pain. All of these may be signs of ventricular tachycardia.
Treatment options
- All the patients are advised to avoid competitive sports and strenuous exercise
- All symptomatic patients should receive treatment. All children and young adults should be treated even if they do not have symptoms. This is because symptoms might occur and sudden death may be the first symptom.
- The usual treatment involves taking beta-blocker and/or calcium channel-blocker medications daily. These help in controlling the heart rhythm. The dose needs to be monitored closely to prevent CPVT spells and to avoid unwanted side effects. Repeat treadmill stress tests may help establish an effective dose of medication.
- Patients who continue to have symptoms in spite of appropriate doses of medication may need an implantable cardioverter defibrillator (ICD) and/or additional interventions. Patients who have experienced a cardiac arrest or continued syncope while on medication usually receive an ICD in addition to the beta-blocker. This is a small device put under the skin of the chest. It has wires that lead to the heart. The device can reset the heart rhythm when needed.
- Left cardiac sympathetic denervation (LCSD) surgery provides another important treatment option for those patients who have either experienced appropriate ICD shocks or are not tolerating their beta-blocker therapy. This is a surgery to remove the nerves that can signal the heart to beat faster.
- Ventricular tachycardia can also lead to Ventricular fibrillation. This is a medical emergency and needs treatment right away. Treatment includes a shock to the heart to help restore normal heart rhythm
Prevention
- There isn’t anything you can do to decrease your risk of CPVT, since it's likely inherited.
- But you can do certain things to reduce the chance of having episodes such as
- Avoiding triggers such as exercise and stress.
- Taking the medications prescribed regularly.
- Talking with your healthcare provider about what kind of exercise is safe for you.
- Monitoring your symptoms carefully.
- Make sure you see a healthcare provider regularly, even if you don’t have any symptoms.
- Making sure all your healthcare providers know about your CPVT.
- Limiting caffeine intake.
Your healthcare provider may also recommend an implantable cardioverter defibrillator (ICD). An ICD can detect a problem heart rhythm and give a shock to help stop it.
What to expect (Outlook/Prognosis)?
Prognosis is generally poor. But CPVT can be managed with medication compliance, ICD, regular monitoring with exercise testing and follow-ups.
Possible complications
If left untreated, patients can develop:
- Venticular fibrillation, in which heart quicker and cannot pump blood to the rest of the body
- Sudden cardiac arrest, in which heart stops functioning
- Sudden cardiac death