Ventricular Fibrillation (VF) vs Ventricular Tachycardia (VT) on ECG

Introduction

Ventricular Fibrillation (VF) and Ventricular Tachycardia (VT) are two life-threatening arrhythmias that originate in the ventricles. They have distinct features on an electrocardiogram (ECG), and their identification is crucial for appropriate emergency management.

Ventricular Tachycardia (VT)

ECG Characteristics:

• Regular Wide QRS Complexes: The QRS complexes are typically wider than 120 ms (0.12 seconds), often around 160 ms.
• Monomorphic vs Polymorphic:
  • Monomorphic VT: All QRS complexes have the same shape.
  • Polymorphic VT: QRS complexes vary in shape due to fluctuating ventricular foci.
• AV Dissociation: The atrial and ventricular rhythms are independent.
• Fusion and Capture Beats: These are signs distinguishing VT from supraventricular tachycardia with aberrancy.
• Heart Rate: Usually between 100–250 bpm.

Clinical Significance:

• Can cause hemodynamic instability due to the rapid ventricular rate.
• Sustained VT (lasting >30 seconds) increases the risk of deterioration into VF.
• Common causes: Coronary artery disease, prior myocardial infarction, electrolyte disturbances, drug toxicity.

Ventricular Fibrillation (VF)

ECG Characteristics:

• Totally Chaotic, Disorganized Activity: No discernible P waves, QRS complexes, or T waves.
• Irregular and Varying Amplitudes: High-amplitude waves in early VF, progressing to low-amplitude waves (fine VF), which may resemble asystole.
• Rate: Extremely rapid (300–600 bpm), but no organized contractions.

Clinical Significance:

• Leads to immediate cardiac arrest and requires rapid defibrillation.
• Common causes: Myocardial infarction, electrolyte imbalances (especially hyperkalemia or hypokalemia), electrical shock, severe heart failure.

VF vs VT: Key Differences

Management Guidelines

• VT Management:

  • Stable VT: Antiarrhythmic drugs (e.g., amiodarone, lidocaine, procainamide)
  • Unstable VT: Synchronized cardioversion
  • Pulseless VT: Treat as VF (immediate defibrillation)

• VF Management:

  • Immediate high-energy defibrillation is necessary.
  • Advanced Cardiac Life Support (ACLS) protocols should be followed, including CPR and epinephrine administration.

Conclusion

Recognition of VT and VF is essential in emergency medicine and cardiology. VF is immediately life-threatening and requires defibrillation, while VT can sometimes be managed with medications or cardioversion depending on the patient’s stability.

References for Further Reading:

Refer to official guidelines for management and algorithm details.

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 (ERC) Guidelines

1. https://cprguidelines.eu/guidelines-2021
2. https://www.erc.edu/
3. https://cprguidelines.eu/
4. https://www.resuscitationjournal.com/article/S0300-9572(21)00063-0/fulltext
5. https://pubmed.ncbi.nlm.nih.gov/33773825/

3. European Society of Cardiology (ESC) Guidelines on Ventricular Arrhythmias and Sudden Cardiac Death

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