Pulseless Ventricular Tachycardia (VT)

Introduction

Pulseless ventricular tachycardia (VT) is a life-threatening cardiac arrhythmia that leads to a loss of effective cardiac output. It requires immediate intervention to prevent cardiac arrest and death.

Understanding Ventricular Tachycardia

Ventricular tachycardia is a rapid heart rhythm that originates in the ventricles. It can be classified as with a pulse or pulseless. Pulseless VT is a form of cardiac arrest, meaning the heart is not effectively pumping blood despite its electrical activity.

Causes of Pulseless VT

Pulseless VT usually occurs as a result of: - Coronary artery disease (CAD) (e.g., myocardial infarction) - Electrolyte imbalances (e.g., hypokalemia, hyperkalemia) - Structural heart disease - Drug toxicity (e.g., digitalis, antiarrhythmic drugs) - Inherited arrhythmia syndromes (e.g., long QT syndrome, Brugada syndrome)

Emergency Management

Pulseless VT is treated as a cardiac arrest. The key steps in management follow the Advanced Cardiovascular Life Support (ACLS) algorithm.

1. Immediate High-Quality CPR and Defibrillation

• Initiate chest compressions (depth of at least 5 cm, rate of 100-120/min).
• Defibrillation is the most effective treatment. A biphasic shock (usually 120-200 J) or a monophasic shock (360 J) should be delivered as soon as possible.

2. Epinephrine and Antiarrhythmic Drugs

• Epinephrine (1 mg IV every 3-5 minutes) to maintain blood pressure and improve perfusion.
• Amiodarone (300 mg IV bolus, then 150 mg if needed) OR Lidocaine as an alternative antiarrhythmic.

3. Identifying and Treating Reversible Causes (H’s & T’s)

Common reversible causes of cardiac arrest include: - H’s: Hypoxia, Hypovolemia, Hydrogen ion (acidosis), Hypo-/Hyperkalemia, Hypothermia - T’s: Tension pneumothorax, Tamponade (cardiac), Toxins, Thrombosis (cardiac/pulmonary)

Prognosis and Prevention

The prognosis depends on the rapidity of care. Early defibrillation within minutes significantly improves survival outcomes. Prevention includes: - Managing cardiac risk factors (hypertension, diabetes, high cholesterol) - Screening for inherited arrhythmias - Use of Implantable Cardioverter-Defibrillators (ICDs) in high-risk patients

Conclusion

Pulseless VT is a medical emergency requiring immediate CPR, defibrillation, and advanced life support. Recognizing risk factors and early intervention can significantly improve outcomes.

Source recommendations

1. American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

1. https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines
2. https://professional.heart.org/en/science-news/2020-aha-guidelines-for-cpr-and-ecc
3. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001194
4. https://pubmed.ncbi.nlm.nih.gov/33081530/
5. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000918

2. European Resuscitation Council Guidelines

1. https://cprguidelines.eu/guidelines-2021
2. https://www.erc.edu/
3. https://cprguidelines.eu/
4. https://www.sciencedirect.com/science/article/pii/S0300957221000551
5. https://pubmed.ncbi.nlm.nih.gov/33773835/