Daniel Kim, MD FRCPC (biography, no disclosures)
What I did before
Supraventricular tachycardia (SVT) is a dysrhythmia characterized by abrupt onset, regular rate that usually exceeds 150 beats/minute, and lack of identifiable P waves on ECG. SVT is caused by an abnormal circuit that allows a wave of depolarization to repeatedly travel in circular fashion in cardiac tissue via a reentry circuit that may reside in the atrioventricular (AV) node or outside the AV node in an accessory pathway. The goal of treatment is to terminate this circular depolarization.
The American Heart Association (AHA) Guidelines suggest that vagal maneuvers are the preferred initial therapy to terminate stable SVT. <1> The literature shows that cardioversion is rarely successful with vagal maneuvers (<20%), <2> and my personal success rate with vagal maneuvers was so low I didn’t even bother attempting them.
My initial treatment for stable SVT was a rapid intravenous push of adenosine because of its high efficacy in terminating SVT. However adenosine results in transient asystole and a feeling of imminent death that many patients find unpleasant and frightening. <1>
What changed my practice
In August 2015, Appelboam and colleagues published the results of the REVERT trial (Randomized Evaluation of modified Valsalva Effectiveness in Re-entrant Tachycardias). <3> They studied the effectiveness of a modified Valsalva maneuver that involved a 15-second Valsalva strain to a pressure of 40 mm Hg followed immediately by being laid flat and having ones legs raised to 45° for 15 seconds.
They performed a pragmatic, randomized controlled study in adult patients presenting with SVT. They randomly assigned patients to undergo either this modified Valsalva maneuver, or a standard semi-recumbent Valsalva strain to a pressure of 40 mm Hg without any postural modification afterwards.
During a 2-year period, 433 patients were randomly assigned to either a standard Valsalva group or a modified Valsalva group. After excluding repeat visits by 5 patients, 214 patients in each group were included in the intention-to-treat analysis. Only 37 (17%) patients in the standard Valsalva group achieved sinus rhythm compared with 93 (43%) patients in the modified Valsalva group. Adenosine use was significantly higher in the standard Valsalva group (69% vs 50%). There were no serious adverse events in either group.
What I do now
My initial treatment for stable SVT is now the modified Vasalva maneuver. We don’t have a manometer to ensure a measurable 40 mm Hg Valsalva strain, but a 10-ml syringe blown to just move the plunger generates similar pressures. I have the patient blow on a 10-ml syringe for 15 seconds, then lay them supine and raise their legs in the air for 15 seconds. I’ve successfully cardioverted more than one-third of my SVT patients using this technique.
This intervention is free, safe, effective, does not require an intravenous, and can be taught to patients. There are very few treatments in medicine that are free, safe, and effective.
- Neumar RW, Otto CW, Link MS, et al. Part 8: Adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2010; 122:S729-67. (View with CPSBC or UBC)
- Lim SH, Anantharaman V, Teo WS, et al. Comparison of treatment of supraventricular tachycardia by Valsalva maneuver and carotid sinus massage. Ann Emerg Med 1998; 31:30-5. (View with CPSBC or UBC)
- Appelboam A, Reuben A, Mann C, et al. Postural modification to the standard Valsalva manoeuvre for emergency treatment of supraventricular tachycardias (REVERT): a randomised controlled trial. Lancet 2015; 386:1747-53. (View with CPSBC or UBC)