Ventricular Tachycardia (VT) is a type of arrhythmia (abnormal heart rhythm) that originates in the heart’s lower chambers (ventricles). It is characterized by a very rapid heartbeat, typically 100 beats per minute or more, with at least three consecutive abnormal heartbeats. VT can be a life-threatening condition because the rapid, uncoordinated beating of the ventricles may prevent the heart from pumping enough blood to the body, potentially leading to cardiac arrest.
Causes:
VT often occurs in individuals with underlying heart conditions or structural heart abnormalities. It can also be triggered by certain factors.
- Heart Attack (Myocardial Infarction): Scar tissue left behind after a heart attack can create abnormal electrical pathways that trigger VT. This is the most common cause.
- Coronary Artery Disease (CAD): Narrowed arteries reduce blood flow to the heart, potentially damaging heart muscle and creating unstable electrical areas.
- Cardiomyopathy: Diseases of the heart muscle that cause it to become enlarged, thickened, or rigid (e.g., dilated cardiomyopathy, hypertrophic cardiomyopathy). These structural changes can disrupt electrical signals.
- Heart Failure: A weakened heart that struggles to pump blood effectively.
- Valvular Heart Disease: Damaged or diseased heart valves can lead to heart enlargement and electrical instability.
- Electrolyte Imbalances: Abnormal levels of potassium, sodium, calcium, or magnesium in the blood can interfere with the heart’s electrical activity.
- Certain Medications: Some drugs, including certain antiarrhythmics or cold medicines, can sometimes trigger VT.
- Congenital Heart Defects: Heart abnormalities present at birth.
- Sarcoidosis or Myocarditis: Inflammatory conditions affecting the heart muscle.
- Long QT Syndrome: An inherited disorder that affects the heart’s electrical system, increasing the risk of fast, chaotic heartbeats.
- Brugada Syndrome: A rare, inherited heart rhythm disorder.
- Illicit Drug Use: Stimulants like cocaine or methamphetamine.
Symptoms:
Symptoms of VT can vary depending on the duration of the rapid heartbeat, the presence of underlying heart disease, and how well the heart is able to pump blood. VT can be sustained (lasting more than 30 seconds) or non-sustained (lasting less than 30 seconds).
- Palpitations: A sensation of a rapid, fluttering, or pounding heartbeat.
- Dizziness or lightheadedness.
- Shortness of breath.
- Chest pain (angina).
- Syncope (fainting or loss of consciousness): Occurs if the heart can’t pump enough blood to the brain.
- Near-syncope (feeling faint).
- Weakness and fatigue.
- Cardiac arrest: In severe cases, sustained VT can degenerate into ventricular fibrillation (VFib) and lead to sudden cardiac death.
Diagnosis:
Diagnosing VT involves assessing heart rhythm and underlying heart conditions.
- Medical History and Physical Exam: The doctor will ask about your symptoms, medical history (especially heart conditions), and family history. They will check your pulse and blood pressure.
- Electrocardiogram (ECG/EKG): This is the primary diagnostic tool. It records the electrical activity of your heart and can show the rapid, abnormal rhythm characteristic of VT.
- Holter Monitor: A portable ECG device worn for 24-48 hours (or longer) to record heart activity during daily routines, helping to capture intermittent VT episodes.
- Event Recorder: A portable device worn for weeks or months that you activate when you feel symptoms, or it may automatically record abnormal rhythms.
- Implantable Loop Recorder: A small device implanted under the skin for long-term monitoring.
- Electrophysiology (EP) Study: An invasive procedure where catheters with electrodes are threaded into the heart to map its electrical activity and identify the source of the VT. This can also be used to induce VT in a controlled setting.
- Echocardiogram: An ultrasound of the heart to visualize its structure and function, assess for cardiomyopathy, valve problems, or areas of scar tissue.
- Cardiac MRI (Magnetic Resonance Imaging): Provides detailed images of the heart muscle.
- Cardiac CT Scan: Visualizes heart structure and coronary arteries.
- Blood Tests: To check for electrolyte imbalances, thyroid problems, or other conditions.
- Coronary Angiography: To check for blockages in the coronary arteries (CAD) if suspected.
Treatment:
Treatment for VT depends on whether the VT is sustained or non-sustained, the underlying cause, and the patient’s overall health and risk of sudden cardiac death.
- For Acute Episodes (especially sustained VT or unstable patients):
- Cardioversion: An electrical shock delivered to the chest to reset the heart’s rhythm.
- Antiarrhythmic Medications (Intravenous): Administered to stabilize the heart rhythm (e.g., amiodarone, procainamide, lidocaine).
- Long-Term Management (to prevent future episodes):
- Treating the Underlying Heart Condition: Managing CAD, heart failure, or cardiomyopathy is crucial.
- Antiarrhythmic Medications (Oral): Prescribed to suppress VT (e.g., amiodarone, sotalol, mexiletine).
- Implantable Cardioverter-Defibrillator (ICD): A small device surgically implanted in the chest that continuously monitors heart rhythm. If it detects VT or VFib, it delivers an electrical shock to restore a normal rhythm. This is a primary treatment for individuals at high risk of sudden cardiac death.
- Catheter Ablation: An EP study procedure where specific areas of heart tissue causing the VT are identified and then destroyed (ablated) using heat (radiofrequency) or cold (cryoablation) energy. This can be effective for certain types of VT.
- Lifestyle Changes: Managing risk factors for heart disease (e.g., healthy diet, exercise, quitting smoking, controlling blood pressure and diabetes).
- Correction of Electrolyte Imbalances.
- Surgery: Rarely, surgical ablation may be considered for complex cases of VT not amenable to catheter ablation.
Regular follow-up with a cardiologist or electrophysiologist (a heart rhythm specialist) is essential for individuals with VT to monitor their condition, adjust medications, and ensure the effectiveness of implanted devices.
