Related Subjects:
|ECG Basics
|ECG Axis
|ECG Analysis
|ECG LAD
|ECG RAD
|ECG Low voltage
|ECG Pathological Q waves
|ECG ST/T wave changes
|ECG LBBB
|ECG RBBB
|ECG short PR
|ECG Heart Block
|ECG Asystole and P wave asystole
|ECG QRS complex
|ECG ST segment
|ECG: QT interval
|ECG: LVH
|ECG RVH
|ECG: Bundle branch blocks
|ECG Dominant R wave in V1
|ECG Acute Coronary Syndrome
|ECG Narrow complex tachycardia
|ECG Ventricular fibrillation
|ECG Regular Broad complex tachycardia
|ECG Crib sheets
📌 Causes of Broad Complex Tachycardia
- Ventricular Tachycardia (VT): 🚨 The most dangerous cause, usually linked to structural heart disease (e.g., post-MI scar tissue, cardiomyopathy). Always assume VT until proven otherwise.
- Atrial Fibrillation with Aberrant Conduction: 🌀 An irregularly irregular rhythm with broad QRS complexes due to bundle branch block or accessory pathway involvement.
- SVT with Aberrant Conduction: ⚡ A supraventricular rhythm (e.g., AVNRT, AVRT) that appears broad because of pre-existing or rate-related bundle branch block.
- Atrial Flutter with Aberrant Conduction: 🪶 Flutter waves at ~300 bpm, with variable conduction producing broad QRS complexes.
- Sinus Tachycardia with Aberrant Conduction: 🌡️ Less common, but can occur if the patient has a bundle branch block during a physiological tachycardia (e.g., fever, sepsis).
🫀 Ventricular Tachycardia (VT)
- Definition: VT = ≥3 consecutive ventricular complexes at >100 bpm. Rates usually 120–250 bpm.
- ECG Features: Broad QRS (>120 ms), often monomorphic (same shape) but may be polymorphic (different shapes, e.g., Torsades de Pointes).
- AV Dissociation: 🔑 Classic sign—atria and ventricles beat independently. P waves may be hidden but look for "capture beats" or "fusion beats" as clues.
- Associated Conditions:
- 💔 Coronary artery disease (especially previous MI—scar tissue acts as a re-entry circuit).
- 🫀 Dilated or hypertrophic cardiomyopathy.
- ⚡ Severe structural heart disease or electrolyte disturbance.
- Non-sustained VT: Runs lasting <30 seconds, sometimes in otherwise healthy hearts (e.g., athletes, idiopathic VT from RV outflow tract).
💡 Clinical Pearl: In an adult with broad complex tachycardia, always assume VT unless there is compelling evidence otherwise. Misdiagnosing VT as SVT with aberrancy and giving verapamil can be fatal.
