Monomorphic Ventricular Tachycardia (VT)

Introduction

Monomorphic Ventricular Tachycardia (VT) is a life-threatening arrhythmia that originates from the ventricles of the heart. It is characterized by a rapid heart rate (>100 beats per minute) with a uniform QRS complex morphology on an electrocardiogram (ECG). Understanding this condition is crucial because it can lead to life-threatening complications such as hemodynamic instability and cardiac arrest.

Causes and Risk Factors

Monomorphic VT usually occurs due to underlying structural heart disease, including: - Coronary artery disease (CAD) – common after myocardial infarction. - Cardiomyopathy – hypertrophic or dilated cardiomyopathy can be a contributing factor. - Scarring from previous heart damage – fibrotic tissues may cause reentrant circuits. - Electrolyte Imbalances – low potassium or magnesium levels can trigger VT. - Genetic conditions – such as Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC).

Symptoms

• Palpitations (rapid heartbeats)
• Dizziness or fainting (syncope)
• Chest pain or discomfort
• Shortness of breath
• Sudden cardiac arrest in severe cases

Diagnosis

Diagnosis is primarily made using an ECG, where monomorphic VT is characterized by: - A wide QRS complex that remains consistent in shape - A heart rate usually between 120-250 bpm - AV dissociation (atrial and ventricular rhythms are independent)

Additional tests may include: - Echocardiogram (to assess heart structure) - Cardiac MRI (for detecting fibrosis or cardiomyopathies) - Electrophysiological study (EPS) (to identify arrhythmic substrates)

Treatment Approaches

Emergency Treatment

• If the patient is hemodynamically unstable, immediate electrical cardioversion is required.
• If stable, intravenous anti-arrhythmic drugs such as amiodarone, procainamide, or lidocaine may be used.

Long-Term Management

• Implantable Cardioverter Defibrillator (ICD) – for patients at risk of sudden cardiac arrest.
• Catheter Ablation – for patients with recurrent VT not controlled by medication.
• Beta-blockers and anti-arrhythmic drugs – to prevent episodes in specific cases.

Prevention and Lifestyle Changes

• Regular follow-ups with a cardiologist
• Controlling underlying diseases (e.g., hypertension, coronary artery disease)
• Avoiding triggers (e.g., electrolyte disturbances, excessive caffeine or alcohol)

Conclusion

Monomorphic VT is a significant cardiac arrhythmia that requires accurate diagnosis and timely intervention. With appropriate treatment and preventive strategies, patients can lead a stable life and reduce the risk of sudden cardiac death.

Source recommendations

1. American Heart Association Guidelines on Tachyarrhythmias

1. https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia/tachycardia--fast-heart-rate
2. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000549
3. https://www.heart.org/en/health-topics/arrhythmia
4. https://www.ahajournals.org/doi/10.1161/cir.0000000000000311
5. https://cpr.heart.org/-/media/cpr-files/cpr-guidelines-files/algorithms/algorithmacls_tachycardia_200612.pdf

2. European Society of Cardiology Guidelines on Ventricular Arrhythmias

1. https://academic.oup.com/eurheartj/article/43/40/3997/6675633
2. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Ventricular-Arrhythmias-and-the-Prevention-of-Sudden-Cardiac-Death
3. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000549
4. https://pubmed.ncbi.nlm.nih.gov/36017572/
5. https://www.sciencedirect.com/science/article/pii/S2405500X22010945