Ventricular tachycardia (VT) is a life-threatening arrhythmia that originates in the ventricles. It is characterized by rapid, wide QRS complexes on the EKG and may result in severe hemodynamic instability or sudden cardiac death if not recognized and treated promptly.
What is Ventricular Tachycardia?
Ventricular tachycardia is defined as a ventricular rhythm with a heart rate between 100 and 250 beats per minute, arising from abnormal electrical impulses in the ventricles rather than the sinoatrial (SA) node.
The abnormal impulses may result from:
- Re-entry circuits within scarred myocardium
- Triggered activity due to electrolyte or drug-induced abnormalities
- Increased automaticity in diseased ventricular tissue
EKG Features of Ventricular Tachycardia
Identifying VT on an electrocardiogram is critical for timely management.
- Rate: 100–250 bpm
- Rhythm: Usually regular
- P waves: Not visible (ventricular activity dominates)
- PR interval: Absent
- QRS complex: Wide (> 0.12 sec), bizarre, often described as “tombstone” shaped
Memory Trick: The QRS complexes look like tombstones, symbolizing the potential lethality of VT.
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Causes of Ventricular Tachycardia
Several conditions and triggers can precipitate VT:
Cardiac Causes
- Myocardial ischemia or infarction (most common)
- Cardiomyopathy
- Structural heart disease
- Heart failure
Electrolyte Imbalances
- Hypokalemia (low potassium)
- Hyperkalemia (high potassium)
- Hypomagnesemia (low magnesium)
Drug-Induced Causes
- Digoxin toxicity
- Antiarrhythmic drugs (pro-arrhythmic effect)
- Stimulants (caffeine, cocaine, amphetamines, methamphetamines)
Other Medical Conditions
- Hypoxia
- Acidosis
- Post-cardiac surgery arrhythmias
Clinical Manifestations
The presentation of VT depends on whether the patient has a pulse or is pulseless.
Common Symptoms in Patients with a Pulse:
- Palpitations
- Chest pain
- Shortness of breath
- Lethargy and weakness
- Dizziness or syncope
- Anxiety
In Pulseless VT:
- No effective cardiac output
- Loss of consciousness
- Absence of pulse
- Cardiac arrest
Important distinction: In ventricular tachycardia, the patient may still be awake and symptomatic, unlike ventricular fibrillation, where the patient is always unresponsive.
Complications of Untreated VT
If left untreated, ventricular tachycardia can rapidly deteriorate into:
- Ventricular fibrillation (V-fib) → chaotic electrical activity with no contractions
- Cardiac arrest
- Sudden death
Treatment of Ventricular Tachycardia
The management of VT depends on the patient’s stability and presence of a pulse.
1. Stable VT with a Pulse
Oxygen therapy to optimize tissue oxygenationAntidysrhythmic drugs such as:
- Amiodarone (preferred)
- Procainamide
- Lidocaine
Synchronized cardioversion
- Delivers a shock in sync with the QRS wave
- Used when drug therapy is insufficient or if the patient shows signs of worsening
Important Note: Cardioversion is different from defibrillation. Cardioversion is synchronized, while defibrillation delivers an unsynchronized shock.
2. Unstable VT Without a Pulse (Pulseless VT)
This is treated as cardiac arrest under Advanced Cardiac Life Support (ACLS) protocols:
CPR (Cardiopulmonary Resuscitation) – immediate chest compressionsDefibrillation – unsynchronized shock as soon as possible
Drug therapy (IV/IO administration)
- Epinephrine every 3–5 minutes
- Amiodarone
- Vasopressin (alternative)
Long-Term Management and Prevention
For patients who survive VT, preventing recurrence is critical:
- Correct reversible causes (electrolytes, ischemia, drug toxicity)
- Antiarrhythmic medications (Amiodarone, Sotalol)
- Implantable Cardioverter Defibrillator (ICD) for high-risk patients
- Catheter Ablation to eliminate the arrhythmogenic focus
- Lifestyle modifications (avoid stimulants, manage heart disease risk factors)
Comparative Overview: VT vs. Other Rhythms
| Feature | Normal Sinus Rhythm | Sinus Tachycardia | Ventricular Tachycardia |
|---|---|---|---|
| Rate | 60–100 bpm | >100 bpm | 100–250 bpm |
| Rhythm | Regular | Regular | Regular |
| P waves | Upright, before QRS | Upright, before QRS | Absent |
| QRS complex | Narrow, normal | Narrow, normal | Wide, bizarre (“tombstone”) |
| Clinical Impact | Healthy rhythm | Often benign | Life-threatening |
| Treatment | None needed | Treat underlying cause | ACLS protocol, cardioversion, defibrillation |
Frequently Asked Questions (FAQ)
Q1. What is the difference between ventricular tachycardia and ventricular fibrillation?
VT has a regular rhythm with wide QRS complexes, and the patient may still have a pulse. V-fib is chaotic, with no organized rhythm and no pulse, requiring immediate defibrillation.
Q2. Can caffeine really cause VT?
Yes. Excessive caffeine, especially in patients with heart disease, can trigger arrhythmias, though it is a less common cause compared to ischemia or drug toxicity.
Q3. What is the first step if a patient is found pulseless in VT?
Start CPR immediately and prepare for defibrillation according to ACLS guidelines.
Q4. Is ventricular tachycardia always fatal?
Not always, but it is potentially life-threatening. With timely recognition and treatment, patients can survive and live normal lives with preventive strategies.
Q5. How do doctors decide between cardioversion and defibrillation in VT?
- Cardioversion is used in stable VT with a pulse.
- Defibrillation is used in pulseless VT or unstable VT with severe symptoms.
