Arrhythmia Types
- PVC: Premature abnormal QRS ≥120ms
- VT: ≥3 consecutive beats >100bpm
- VF: Chaotic rhythm, no discrete QRS
Acute Management
- Unstable VT: Immediate cardioversion
- Stable VT: Procainamide/amiodarone
- VF: Defibrillation, ICD implantation
VT Subtypes
- Monomorphic: Same QRS morphology
- Polymorphic: Changing QRS morphology
- Torsades: Polymorphic + QT prolongation
- NSVT: 3 beats to 30s duration
- Sustained: ≥30s or requiring intervention
Idiopathic VT
- RVOT (75-90%): LBBB, inferior axis
- Fascicular (10-25%): RBBB, left axis
- 90% monomorphic VT has structural heart disease
Pharmacological Options
- General: Procainamide, amiodarone
- RVOT: Beta-blockers
- Fascicular: Verapamil
- Digoxin-induced: Digoxin Immune Fab
Diagnostic Clues
- AV dissociation
- Fusion/capture beats
- No preceding P-wave
- Broad QRS ≥120ms
- T-wave opposite QRS direction
Long-term Management
- ICD for VF (68% risk reduction)
- Catheter ablation for PVC-triggered VF
- NSVT: Asymptomatic → monitoring
- Symptomatic NSVT: Beta-blockers/CCBs
Ventricular Arrhythmia Subtypes
Premature Ventricular Complex (PVC)
- Premature occurrence of an abnormal QRS complex
- QRS duration ≥120ms
- T-wave typically broad and opposite direction of QRS
- No preceding P-wave
- Types:
- Unifocal/monomorphic - single QRS morphology
- Multifocal/polymorphic - different QRS morphologies
- Short-coupled - interrupts T-wave of preceding beat
Ventricular Tachycardia (VT)
- ≥3 consecutive beats >100bpm from ventricles
- Types:
- Non-sustained (NSVT) - 3 beats to 30s
- Monomorphic (MVT) - same QRS morphology
- Polymorphic (PVT) - changing QRS morphology
- Sustained (SMVT/SPVT) - ≥30s or requiring intervention
- Torsades de pointes - polymorphic VT with QT prolongation
Ventricular Fibrillation (VF)
- Chaotic rhythm with irregular undulations
- No discrete QRS complexes
Acute Management of Sustained Monomorphic VT
Unstable Patient
- Immediate synchronized cardioversion
- If synchronization not possible, use unsynchronized shock
- Not indicated for repetitive NSVT
Hemodynamically Stable Patient
- Consider adenosine/vagal maneuvers if SVT likely (with 12-lead ECG)
- Prompt termination recommended (electrical, pharmacological, or pacing)
- Pharmacological options:
- IV procainamide or amiodarone (unknown etiology)
- Avoid procainamide in severe HF, acute MI, ESRD
- For idiopathic VT:
- Beta-blockers for RVOT tachycardia
- Verapamil for fascicular VT
Specific VT Types
Idiopathic Fascicular VT
- 90-95% of idiopathic left VT cases
- ECG Features:
- RBBB morphology (RSR' in V1)
- Left axis deviation (-90°)
- Narrow-complex capture beats
- Dissociated P waves
- Management:
- Verapamil
- Digoxin Immune Fab for digoxin-induced
- Cardioversion if refractory
Right Ventricular Outflow Tract (RVOT) Tachycardia
- 75-90% of idiopathic VT cases
- ECG Features:
- LBBB morphology
- Inferior axis (+90°)
- rS in V1, R in V6
- Precordial transition ≥V3 (septal origin ≤V3)
- Management:
- Beta-blockers
- Cardioversion if refractory
Non-Sustained Ventricular Tachycardia (NSVT)
- Definition: ≥3 consecutive ventricular beats (QRS ≥120ms, rate >100bpm) resolving in <30s
- Risk Factors:
- CAD, LVF, HCM
- Brugada's, Long QT syndrome
- Electrolyte imbalance, digoxin toxicity
- Management:
- Asymptomatic: reassurance & monitoring
- Symptomatic: beta-blockers/CCBs
- Correct electrolyte imbalance
- ICD if criteria met
Ventricular Fibrillation (VF)
- Diagnosis: Documented VF after excluding structural/channelopathic causes
- Workup:
- ECG (including high lead), cardiac CT/angiography
- Holter, stress test, echocardiogram
- Sodium-channel blocker testing, CMR
- Genetic testing (consider)
- Management:
- ICD implantation (68% risk reduction)
- For recurrent discharges: isoproterenol, verapamil, quinidine
- Catheter ablation for PVC-triggered VF
Key Clinical Pearls
- 90% monomorphic VT associated with structural heart disease
- 10% are idiopathic (75-90% RVOT, 10-25% fascicular)
- Fascicular VT often misdiagnosed as SVT with RBBB
- Look for AV dissociation, fusion/capture beats for VT diagnosis