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Key Features

Essentials of Diagnosis

  • Rapid, regular tachycardia most commonly seen in young adults

  • QRS duration narrow (< 120 msec) except in the presence of bundle branch block or accessory pathway

  • Often responsive to vagal maneuvers, atrioventricular (AV) nodal blockers, or adenosine

  • Cardioversion rarely required

General Considerations

  • Characterized by a sudden onset and offset and a regular ventricular response

  • Episodes may last from a few seconds to several hours or longer

  • Often occurs in patients without structural heart disease

  • The most common mechanism is reentry, which may be initiated or terminated by a fortuitously timed atrial or ventricular premature beat

    • AV nodal reentrant tachycardia (AVNRT)

      • The reentrant circuit usually involves dual pathways (a slow and a fast pathway) within the AV node

      • Accounts for 60% of cases of PSVT

    • AV reciprocating tachycardia (AVRT)

      • Reentry is due to an accessory pathway between the atria and ventricles

      • Less commonly (30% of cases)

Clinical Findings

  • Symptoms can be variable depending on the degree of heart rate elevation, resultant hypotension, or the presence of other comorbidities

  • Symptoms may include

    • Palpitations

    • Diaphoresis

    • Dyspnea

    • Dizziness

    • Mild chest pain (even in the absence of associated coronary heart disease [CHD])

  • Syncope is rare


  • 12-lead ECG

    • Should be obtained when feasible to help determine the tachycardia mechanism

    • The QRS duration will be narrow (< 120 ms), except in cases of PSVT with aberrant conduction (left bundle branch block, right bundle branch block, or antegrade conducting accessory pathway)

    • Heart rate

      • Regular

      • Usually 160–220 beats/min

      • May be > 250 beats/min

    • P wave

      • Usually differs in contour from sinus beats

      • Often simultaneous with or just after the QRS complex


  • In the absence of structural heart disease, serious effects are rare, and most episodes resolve spontaneously

  • Particular effort should be made to terminate the episode quickly if cardiac failure, syncope, or anginal pain develops or if there is underlying cardiac or (particularly) coronary disease

  • Effective therapy requires that conduction be interrupted at some point in the reentry circuit and the majority of these circuits involve the AV node

Mechanical measures

  • The Valsalva maneuver

    • Performed with the patient semirecumbent (45 degrees), exerting around 40 mm Hg of intrathoracic pressure (by blowing through a 10 mL syringe) for at least 15 seconds

    • Moving the patient supine immediately following the strain maneuver and passively raising the patient's legs for an additional 15 seconds may increase effectiveness of the maneuver

  • Carotid sinus massage

    • Often performed by clinicians but should be avoided if the patient has a carotid bruit

    • Firm but gentle pressure and massage are applied first over the right carotid sinus for 10–20 seconds and, if unsuccessful, then ...

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