Definition of Ventricular Tachycardia (VT)

Introduction

Ventricular tachycardia (VT) is a potentially life-threatening heart rhythm disorder (arrhythmia) that originates in the ventricles, the lower chambers of the heart. It is characterized by a fast heart rate exceeding 100 beats per minute (bpm) with at least three consecutive abnormal heartbeats originating from the ventricles.

Classification of VT

VT can be classified into several types based on duration, morphology, and cause:

1. By Duration:

• Sustained VT: Lasts more than 30 seconds or requires medical intervention due to hemodynamic instability.
• Non-sustained VT (NSVT): Lasts less than 30 seconds and often does not cause significant symptoms.

2. By Morphology:

• Monomorphic VT: All QRS complexes appear uniform, usually indicating a structural heart disease cause.
• Polymorphic VT: Varying QRS appearance, commonly associated with ischemia or genetic conditions like Long QT Syndrome.

3. By Cause:

• Ischemic VT: Seen after myocardial infarction due to scar-related reentry.
• Idiopathic VT: Occurs in structurally normal hearts, often benign.
• Inherited VT: Includes conditions such as Brugada syndrome or catecholaminergic polymorphic VT (CPVT).

Symptoms of VT

VT can be asymptomatic or cause a range of symptoms, including: - Palpitations (rapid heartbeat) - Dizziness or lightheadedness - Shortness of breath - Chest pain or discomfort - Syncope (fainting) - Cardiac arrest (in the case of severe or prolonged VT)

Why is VT Dangerous?

• VT can reduce the heart’s ability to pump blood effectively, leading to hypotension (low blood pressure) and inadequate organ perfusion.
• It may degenerate into ventricular fibrillation (VF), a life-threatening arrhythmia leading to sudden cardiac arrest.

Diagnosis

VT is diagnosed using: - Electrocardiogram (ECG): Identifies wide QRS tachycardia. - Holter Monitoring: Detects intermittent occurrences of VT. - Echocardiography & MRI: Assesses structural heart disease. - Electrophysiology Study (EPS): Helps determine the precise origin of the arrhythmia.

Treatment

Acute Management:

• Hemodynamically unstable VT: Immediate synchronized cardioversion.
• Stable VT: Antiarrhythmic drugs such as amiodarone or lidocaine.

Long-term Management:

• Medications: Beta-blockers, antiarrhythmics.
• Implantable Cardioverter Defibrillator (ICD): Prevents sudden cardiac death in high-risk patients.
• Catheter Ablation: Used for recurrent VT not controlled by medication.

Conclusion

VT is a serious condition requiring prompt diagnosis and appropriate treatment. Patients with risk factors should be evaluated and managed according to clinical guidelines to prevent complications such as sudden cardiac death.

Source recommendations

1. American Heart Association (AHA) Guidelines on Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death

1. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000549
2. https://pubmed.ncbi.nlm.nih.gov/29097320/
3. https://www.sciencedirect.com/science/article/pii/S2405500X22010945
4. https://pubmed.ncbi.nlm.nih.gov/29084733/
5. https://www.hrsonline.org/guidance/clinical-resources/2017-ahaacchrs-guideline-management-patients-ventricular-arrhythmias-and-prevention-sudden-cardiac

2. European Society of Cardiology (ESC) Guidelines for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death

1. https://pubmed.ncbi.nlm.nih.gov/36017572/
2. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Ventricular-Arrhythmias-and-the-Prevention-of-Sudden-Cardiac-Death
3. https://academic.oup.com/eurheartj/article/43/40/3997/6675633
4. https://pubmed.ncbi.nlm.nih.gov/26320108/
5. https://academic.oup.com/eurheartj/article/36/41/2793/2293363