Skip to Main Content

Source: Sanoski CA, Bauman JL. The Arrhythmias. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=7972803. Accessed June 30, 2012.

  • Ventricular tachycardia (VT) is rapid heart rhythm (more than 100 beats/min) originating in one of the ventricles of the heart.

  • Acute myocardial infarction (MI)
  • Cardiomyopathy
  • Heart failure
  • Electrolyte abnormalities (hypokalemia, hypomagnesemia)
  • Hypoxia
  • Drug toxicity (e.g., digoxin)

  • Defined by ≥3 repetitive premature ventricular contractions (PVCs) occurring at rate of >100 beats/min.
  • Nonsustained VT self-terminates after brief duration (usually <30 sec).
  • Sustained VT lasts >30 sec.
  • Monomorphic VT has consistent QRS configuration, whereas polymorphic VT has varying QRS complexes.
  • Torsades de pointes (TdP) is polymorphic VT in which QRS complexes appear to undulate around central axis.

  • Incidence not known precisely because clinical findings overlap with ventricular fibrillation (VF).
  • Approximately 300,000 deaths per year in United States are caused by VT or VF.
  • Incidence of sudden cardiac death is 53 per 100,000 population.

  • Prior MI
  • Structural heart disease
  • Family history of premature sudden death

Signs and Symptoms

  • Symptoms:
    • Palpitations
    • Dizziness
    • Lightheadedness
    • Shortness of breath
    • Chest pain
    • Syncope
  • Signs: Weak or absent pulse.

Means of Confirmation and Diagnosis

  • Electrocardiogram (ECG) shows runs of ⩾3 PVCs with rate >100 beats/min.
  • TdP characterized by long QT intervals or prominent U waves on ECG.

Laboratory Tests

  • Performed if underlying causes suspected, for example:
    • MI
    • Electrolyte imbalances
    • Digoxin toxicity

Imaging

  • ECG

Diagnostic Procedures

  • Electrophysiologic testing may help identify patients at increased risk for sudden death or candidates for radiofrequency ablation of tachycardia focus.

Differential Diagnosis

  • Identify and correct underlying causes.
  • Resolve symptoms.
  • Prevent recurrences.
  • Avoid complications from treatment.

  • If severe symptoms present, perform synchronized direct current cardioversion (DCC) immediately to restore sinus rhythm.
  • Correct precipitating factors if possible.
  • If VT isolated event with transient initiating factor (e.g., acute MI, digitalis toxicity), long-term antiarrhythmic therapy not needed after correction of precipitating factors.
  • Most patients with acute TdP require and respond to DCC, but TdP tends to be paroxysmal and often recurs rapidly after DCC.
  • Automatic implantable cardioverter-defibrillator (ICD) highly effective for preventing sudden death due to recurrent VT or VF.

  • Acute VT
    • Treat patients with mild or no symptoms initially with antiarrhythmic drugs:
      • IV procainamide, amiodarone, or sotalol
      • Lidocaine is alternative agent.
    • Deliver synchronized DCC if:
      • Patient’s status deteriorates
      • VT degenerates to VF
      • Drug therapy fails
  • Acute TdP
    • IV magnesium sulfate drug of choice for preventing recurrences of TdP.
    • If magnesium ineffective, initiate strategies to increase heart rate and shorten ventricular repolarization (i.e., temporary transvenous pacing at 105–120 beats/min or pharmacologic pacing with isoproterenol or epinephrine infusion).
    • Discontinue agents that prolong QT interval.
    • Correct ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.