Ventricular Tachycardia


VT is the occurrence of 3 or more successive beats from a ventricular ectopic pacemaker at rate faster than 100 bpm.

Wide QRS complexes
Rate >100 beats/min (most commonly 150–200 beats/min)
QRS axis usually constant
A regular rhythm, although there may be some initial bear-to-beat variation

Pathophysiology

Causes:

Forms

Morbidity/mortality

History / symptoms

Physical exam

Diagnostic testing

Differential Diagnosis

Acute Treatment

  1. ABCs, IV, O2, monitor
  2. Clinical situation:
  3. Hemodynamically UNSTABLE:
  4. Hemodynamically STABLE
  5. Torsades de Pointes
    ( Polymorphic VTach, prolonged QT)
  6. Treat underlying cause
Treatment Comment
100% O2  
If stable & Dx unclear
- May try Adenosine (little harm in VT)
 
If UNstable, Pulseless VT 
- Synchronized cardioversion (100 J)
Sedate if time allows
First-line pharmacotherapy for clinically stable, monomorphic ventricular tachycardia
Amiodarone, 150 mg over 10 min, may repeated boluses q 10 min up to a total dose of 2 g (alternative to repeat boluses: maintenance dose of 0.5 mg/min over 18 h) Amiodarone is the antiarrhythmic of choice in setting of AMI, LV dysfunction, or unknown cardiac function
Procainamide, 50 mg/min IV, up to 17 mg/kg in normal patients (12 mg/kg in patients with congestive heart failure) Procainamide can be used in patients without evidence of AMI or LV dysfunction
Maintenance infusion, 2.8 mg/kg/h in normal subjects (1.4 mg/kg/h in patients with renal insufficiency) Stop bolus therapy if:
Arrhythmia converts
Early signs of toxicity (hypotension or QRS prolongation)
Second-line pharmacotherapy
Lidocaine, 1.0-1.5 mg/kg IV every 5 min, repeat until effect up to 300 mg/h

 

Torsades de pointes

Magnesium sulfate, 1 to 2 g IV over 60-90 s, followed by an infusion of 1-2 g/h

Magnesium is unlikely to be helpful in patients with a normal QT interval
Withdraw offending agents  
Correct electrolyte abnormalities

 

Pacing Pacing may be attempted if torsades de pointes is secondary to bradycardia or heart block.
Try overdrive pacing set at 90 to 120 bpm to terminate torsades de pointes.
Isoproterenol 2-10 mcg/min IV infusion For Refractory Torades de pointes but carries risk of increased myocardial oxygen demand.

 
V-Tach Algorhythm
PULSE ?


(-)


(+)

Pulseless VT
 


Defibrillate starting at 100J
(UNsynchronized)

STABLE ?
Chest pain, SOB, Hypotension, Confusion


UNSTABLE

STABLE
Synchronized Cardioversion - O2
- Amiodarone
- Lidocaine
- Procainamine

Does not convert

Converts
Synchronized Cardioversion

Further Management

  1. Tx underlying conditions as appropriate
  2. Diagnostic testing
  3. Long term treatment

Disposition

  1. Admit