Supraventricular Tachydysrhythmias in the Emergency Department

Points & Pearls Excerpt

• Supraventricular tachycardias (SVTs) arise at or above the atrioventricular (AV) node due either to abnormal automaticity or abnormal conduction.
• AV nodal re-entry tachycardia (AVNRT) makes up 60%-70% of SVT cases due to a functional obstruction with 2 conduction systems within the node.
• Ventricular pre-excitation (VPE) occurs when circus movements rely on anatomical accessory pathways from the atria to the ventricle. This is the mechanism of AV re-entry tachycardia (AVRT).
• Wolff-Parkinson-White syndrome (WPW) involves conduction through a congenital accessory pathway, leading to pre-excitation to the ventricle. An ECG will reveal a shortened PR wave and up-swerving initiation of the R wave, called a delta wave.
• Orthodromic (antegrade) conduction depolarizes through the bundle, resulting in a narrow QRS.
• Antidromic (retrograde) conduction causes depolarization through the accessory pathway and retrograde progression through the AV node, leading to a wide QRS.

Most Important References

• Page RL, Joglar JA, Caldwell MA, et al. 2015 ACC/AHA/ HRS guideline for the management of adult patients with supraventricular tachycardia: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. [Erratum appears in Circulation. 2016 Sep 13;134(11):e234- e235; PMID: 27619722]. Circulation. 2016;133(14):e506-e574. (Expert consensus) 
• Delacretaz E. Clinical practice. Supraventricular tachycardia. N Engl J Med. 2006;354(10):1039-1051. (Review) 
• 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(10005):1747-1753. (Randomized controlled trial; 433 patients) 
• Alabed S, Sabouni A, Providencia R, et al. Adenosine versus intravenous calcium channel antagonists for supraventricular tachycardia. Cochrane Database Syst Rev. 2017 Oct 12;10(10):CD005154. (Cochrane review; 7 trials, 622 participants) 
• Link MS, Atkins DL, Passman RS, et al. Part 6: electrical therapies: automated external defibrillators, defibrillation, cardioversion, and pacing: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2010;122(18 Suppl 3):S706- S719. (Guidelines) 
• Lewis SR, Nicholson A, Reed SS, et al. Anaesthetic and sedative agents used for electrical cardioversion. Cochrane Database Syst Rev. 2015(3):CD010824. (Cochrane review; 23 studies, 1250 participants)