Tachycardia, Paroxysmal Supraventricular

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.

• Paroxysmal supraventricular tachycardia (PSVT) is rapid heart rhythm originating above ventricles that occurs episodically.

• May occur in healthy individuals.
• Premature atrial or ventricular ectopic beats
• Hyperthyroidism
• Stimulant use (including caffeine)
• Previous myocardial infarction, mitral valve prolapse, rheumatic heart disease, pericarditis, pneumonia, chronic lung disease, alcohol intoxication
• Digoxin toxicity

• PSVT arising by reentrant mechanisms includes arrhythmias caused by atrioventricular (AV) nodal reentry, AV reentry incorporating an anomalous AV pathway, sinoatrial (SA) nodal reentry, and intra-atrial reentry.

• Prevalence: ~2 cases per 1000 persons in United States.
• Incidence: 35 cases per 100,000 person-years.

• See Etiology.

Signs and Symptoms

• Many patients asymptomatic or have only occasional minor palpitations or irregular pulse.
• Patients may experience:
  • Choking or pressure sensation
  • Dizziness
  • Lightheadedness
  • Shortness of breath
  • Syncope
  • Symptoms of heart failure
  • Anginal chest pain
• Symptoms may be severe and even life threatening in some patients.
• Heart rate ranges from 140–240 beats/min and is regular.

Means of Confirmation and Diagnosis

• Electrocardiogram (ECG) shows regular rhythm with rate between 140–240 beats/min.

Laboratory Tests

• May be performed if underlying causes suspected (e.g., hyperthyroidism, digoxin toxicity).

Differential Diagnosis

• Atrial tachycardia, flutter, or fibrillation
• Atrioventricular nodal reentrant tachycardia (AVNRT)
• Sinus node dysfunction
• Ventricular tachycardia or fibrillation

• Identify and correct underlying causes.
• Terminate acute episodes and resolve symptoms.
• Prevent recurrences.
• Avoid complications from therapy.

• For mild to moderate symptoms, measures that increase vagal tone to AV node (unilateral carotid sinus massage, Valsalva maneuver) used initially.
• For severe symptoms, synchronized direct current cardioversion (DCC) treatment of choice.

• Used for mild to moderate symptoms if nondrug measures fail.
• Drug selection based on QRS complex (Figure 1).
  • Directly or indirectly increase vagal tone to AV node, with digoxin.
  • Depress conduction through slow, calcium-dependent tissue:
    • Adenosine
    • β-blockers
    • Nondihydropyridine calcium channel blockers
  • Depress conduction through fast, sodium-dependent tissue
    • Quinidine
    • Procainamide
    • Disopyramide
    • Flecainide
• Adenosine a drug of first choice because its short duration of action will not cause prolonged hemodynamic compromise in patients with wide QRS complexes who actually have ventricular tachycardia rather than PSVT.