Introduction:
Ventricular tachycardia is an abnormal rhythm in heart rhythm that arises from the ventricles of the heart. This is due to disruption in the electrical signals of the heart, thus leading to irregular heart rhythm (arrhythmia). Ventricular tachycardia can be classified as monomorphic or polymorphic based on the pattern of electrical activity seen on an electrocardiogram (ECG).
What Is Monomorphic Ventricular Tachycardia?
Monomorphic ventricular tachycardia refers to an abnormal heart rhythm that arises from a single location of the ventricles, thus resulting in a stable and consistent QRS complex on an electrocardiogram (ECG). In this condition, the heart beats regularly but rapidly, leading to more than 90 heartbeats per minute.
What Are the Causes of Monomorphic Ventricular Tachycardia?
The common causes of monomorphic ventricular tachycardia include:
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Coronary Artery Disease: Lack of blood supply to the heart due to accumulation of plaque in the blood vessels can lead to lack of oxygen. This results in abnormal heart rhythms.
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Structural Disorders of the Heart: Abnormalities such as congenital heart diseases, cardiomyopathy, and disorders of the heart valve, can affect the functioning of the heart. This can result in disruption of the normal electrical activity of the heart.
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Electrolyte Imbalances: Electrolytes are minerals such as sodium, potassium, calcium, and magnesium that help regulate the electrical activity of the heart. Abnormal levels of these minerals in the blood can disrupt the normal rhythm of the heart and cause monomorphic ventricular tachycardia.
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Medications: Certain medications, such as antiarrhythmics, beta-blockers, and Digoxin, can increase the risk of monomorphic ventricular tachycardia by altering the normal electrical activity of the heart.
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Genetics: In some cases, monomorphic ventricular tachycardia can be caused by inherited genetic mutations that affect the structure or function of ion channels in the heart, leading to abnormal electrical activity. Common examples include long QT syndrome and Brugada syndrome.
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Autoimmune Disorders: Autoimmune disorders, such as systemic lupus erythematosus and rheumatoid arthritis, can cause abnormal heart rhythms.
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Inflammations: Inflammation of the heart muscles due to infection can also disrupt the electrical activity of the heart.
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Idiopathic: In some cases, the exact cause of monomorphic ventricular tachycardia may not be known, and it is referred to as idiopathic ventricular tachycardia.
The exact cause of tachycardia should be identified for proper management of the condition and to reduce the risk of complications.
What Are the Signs and Symptoms of Monomorphic Ventricular Tachycardia?
The following are some of the common symptoms experienced by individuals with monomorphic ventricular tachycardia.
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Increased and Rapid Heartbeat: Monomorphic ventricular tachycardia can cause a heart rate of more than 130 beats per minute.
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Palpitations: Individuals with monomorphic ventricular tachycardia may experience a sensation of a pounding or fluttering heartbeat.
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Dyspnoea: Shortness of breath is noted.
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Chest Pain: Some people can experience discomfort or angina due to reduced blood supply to the heart.
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Dizziness: Insufficient blood flow to the brain can cause symptoms like dizziness and syncope.
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Complete Loss of Consciousness: In severe cases, loss of blood supply to the brain can cause complete loss of consciousness.
How Is Monomorphic Ventricular Tachycardia Diagnosed?
The diagnosis of monomorphic ventricular tachycardia is made by a comprehensive evaluation of the patient's medical history, physical examination, and investigations.
Medical history reveals the symptoms experienced by the patient, and physical examination reveals abnormal heart sounds. The diagnosis is confirmed by an electrocardiogram that measures the electrical activity of the heart. An ECG shows a consistent and widened QRS complex with regular heart rhythm, which is pathognomonic of monomorphic ventricular tachycardia. ECG can also show an absence of P waves.
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Holter Monitor: This is a portable ECG device that records the heart's activity over a 24- or 48-hour period and helps in continuous monitoring of the electrical activity of the heart.
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Electrophysiology Study: This is an invasive test that involves inserting catheters into the heart to measure its electrical activity, locate the source of the abnormal rhythm, and determine the best treatment option.
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Echocardiogram: This is a non-invasive test that uses ultrasound waves to create images of the heart. It can help identify any underlying structural abnormalities in the heart that may be contributing to the development of monomorphic ventricular tachycardia.
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Coronary Angiography: This is indicated for patients who experienced sudden cardiac arrest.
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Laboratory Investigations: Investigations may reveal low levels of electrolytes like magnesium, potassium, and calcium in some individuals.
What Is the Treatment for Monomorphic Ventricular Tachycardia?
The treatment for monomorphic ventricular tachycardia is based on the symptoms experienced by the patient and the abnormalities of the heart:
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Administration of Medicines: The first line of treatment for monomorphic ventricular tachycardia is the administration of antiarrhythmic agents like beta blockers, Procainamide (blocks the sodium channels), or calcium channel blockers.
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Cardioversion: If the patient is unstable, cardioversion is done to restore the normal heart rhythm and treat arrhythmias. Cardioversion is achieved by electrical or chemical methods. Electrocardioversion involves electrical stimulation of the heart using a high-energy wave. Chemical cardioversion is done by the administration of medicines like Adenosine.
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Catheter Ablation: This is a procedure that involves the insertion of a catheter into the heart to remove the tissue responsible for abnormal electrical activity. This can be an effective treatment for people with monomorphic ventricular tachycardia who do not respond to other treatment modalities.
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Implantable Cardioverter-Defibrillator (ICD): An ICD is a device that is implanted under the skin and connected to the heart with leads. It can detect and treat abnormal heart rhythms, including monomorphic ventricular tachycardia, by delivering an electrical shock to the heart to restore a normal rhythm. This acts as a continuous monitoring device by recording the heart rhythm and responding to abnormal heart rhythms.
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Lifestyle Modifications: Making lifestyle changes, such as quitting smoking, reducing alcohol and caffeine intake, and managing stress, can help reduce the risk of monomorphic ventricular tachycardia.
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Management of Underlying Conditions: Treating underlying health conditions that contribute to the development of monomorphic ventricular tachycardia, such as coronary artery disease, hypertension, or heart failure, can help prevent future episodes.
What Are the Complications of Monomorphic Ventricular Tachycardia?
If left untreated, this condition can cause serious complications, which include:
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Sudden Cardiac Arrest: This is a sudden loss of the functions of the heart due to irregular electrical activity of the heart. This results in reduced blood supply to the brain, leading to loss of consciousness, dyspnoea, and death.
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Ventricular Fibrillation: Ventricular fibrillation is a medical emergency that occurs due to prolonged tachycardia and requires immediate management by cardiopulmonary resuscitation or defibrillation.
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Cardiomyopathy: Heart muscles get affected due to prolonged monomorphic ventricular tachycardia, causing difficulty to pump blood.
Conclusion
Preventing monomorphic ventricular tachycardia depends on managing any underlying health conditions and avoiding triggers like smoking, alcohol, or stress. Staying fit and following a balanced diet can maintain a healthy heart and prevent any complications. It is advisable to consult a medical professional for an early diagnosis and management in the event of any symptoms.
