Supraventricular Tachydysrhythmias in the Emergency Department

Table of Contents

 

Patients presenting to the ED with supraventricular tachydysrhythmias (SVT) require prompt diagnosis of their underlying condition in order to determine the causes and to offer treatment that is not only effective, but takes into account their comfort and safety.

What are the primary ways to determine the cause of tachycardia?

What are the ECG characteristics that differentiate unifocal, junctional, and multifocal atrial tachycardia?

What is the difference between atrioventricular re-entry tachycardia (AVRT) and atrioventricular nodal re-entry tachycardia (AVNRT)? How does treatment differ?

How does a history of Wolff-Parkinson-White syndrome affect diagnosis and treatment of SVT?

What are the toxicologic, metabolic, and behavioral conditions that can present as SVT?

Is troponin testing necessary?

Why is large-bore, proximal IV access needed for patients with SVT?

How are narrow complex and wide complex tachycardia treatments different?

How are posture-modified vagal maneuvers performed?

When is adenosine indicated and when can (and should) it be delayed?

Vagal maneuvers, calcium channel blockers, beta blockers: what is the evidence on their effectiveness?

When should synchronized electrical cardioversion be the first-line treatment?

1. Abstract
2. Case Presentations
3. Introduction
4. Critical Appraisal of the Literature
5. Etiology and Pathophysiology
6. Differential Diagnosis
   1. Atrioventricular Nodal Re-Entry Tachycardia
   2. Atrioventricular Re-Entry Tachycardia/Ventricular Pre-Excitation
   3. Pre-Excited States and Atrial Fibrillation
7. Prehospital Care
8. Emergency Department Evaluation
   1. History
   2. Physical Examination
9. Diagnostic Studies
   1. Laboratory Testing
      1. Troponin Testing
   2. 12-Lead Electrocardiogram
   3. Chest Radiograph
10. Treatment
    1. General Approach
    2. Vagal Maneuvers
    3. Pharmacotherapy
       1. Adenosine
          • Adenosine Side Effects
          • Adenosine Versus Calcium Channel Blockers
       2. Beta Blockers
    4. Synchronized Electrical Cardioversion
11. Special Populations
    1. Supraventricular Tachycardia in Pregnant Patients
    2. Supraventricular Tachycardia in Pediatric Patients
12. Controversies and Cutting Edge
    1. Intranasal Etripamil
    2. Patients With Asymptomatic Ventricular Pre-Excitation
    3. Anticoagulation for Patients With Paroxysmal Supraventricular Tachydysrhythmias
13. Disposition
    1. Outpatient Monitoring
14. Summary
15. Time- and Cost-Effective Strategies
16. Risk Management Pitfalls for Supraventricular Tachycardia in the Emergency Department
17. Case Conclusions
18. Disclaimer
19. Clinical Pathways
    1. Clinical Pathway for Emergency Department Management of Patients With Narrow Complex Supraventricular Tachycardia
    2. Clinical Pathway for Emergency Department Management of Patients With Wide Complex Supraventricular Tachycardia
20. Tables, Figures, and Appendix
    1. Table 1. Supraventricular Tachycardia Differential Diagnosis
    2. Table 2. Acute Pharmacotherapy for Narrow Complex Supraventricular Tachycardia
    3. Table 3. Recommendations for the Management of Asymptomatic Patients With Pre-Excitation
    4. Figure 1. Suspected Tachydysrhythmia
    5. Figure 2. Circus Movement Entry Arrhythmias
    6. Figure 3. Single-Lead Electrocardiogram Showing Sinus Node Re-Entry Tachycardia
    7. Figure 4. Electrocardiogram of Unifocal Atrial Tachycardia
    8. Figure 5. Electrocardiogram of Junctional Tachycardia
    9. Figure 6. Electrocardiogram of Multifocal Atrial Tachycardia With Additional Features of COPD
    10. Figure 7. Electrocardiogram of Slow-Fast (Typical) Atrioventricular Nodal Re-Entry Tachycardia
    11. Figure 8. Electrocardiogram of AVNRT With Left Bundle Branch Block
    12. Figure 9. Concealed Retrograde Conduction
    13. Figure 10. Pre-Excitation, Orthodromic, and Antidromic AVRT
    14. Figure 11. Electrocardiogram of Orthodromic (Antegrade) AVRT
    15. Figure 12. Electrocardiogram of Antidromic (Retrograde) AVRT With Wolff-Parkinson-White Syndrome
    16. Figure 13. Electrocardiogram of Wolff-Parkinson-White Syndrome With Atrial Fibrillation
    17. Figure 14. Sinus Electrocardiogram Status Post Conversion From Wolff-Parkinson-White Syndrome With Atrial Fibrillation
    18. Appendix 1. Class of Recommendation and Level of Evidence for AHA/ACC/HRS Guidelines
21. References

Abstract

Diagnosing and treating supraventricular tachycardias is routine in emergency medicine, and new strategies can improve efficiency and outcomes. This review provides an overview of supraventricular tachycardias, their pathophysiology, differential diagnosis, and electrocardiographic features. Clinical evidence guiding contemporary practice is determined largely by multiple observational studies, with few randomized controlled trials. Current prehospital and emergency department management strategies beyond the use of adenosine and calcium channel blockers are addressed. Diagnostic and therapeutic recommendations are provided, based on the best available evidence.

Case Presentations

A 31-year-old woman presents to the ED with palpitations. The ECG shows a regular, narrow complex tachycardia with a rate of 170 beats/min. She has a history of AV nodal re-entry tachycardia. Her vital signs are reassuring, with a blood pressure of 127/81 mm Hg. Adenosine has successfully converted her dysrhythmia in the past, but she asks whether there is an alternative treatment, because she hates the way it makes her feel. You are considering this patient’s request when another patient’s ECG is handed to you. (See Figure 1.)

The ECG belongs to a 49-year-old man who was brought in by ambulance for “lightheadedness.” The patient reports that he feels his “heart is pounding,” but he is not in extremis. He states he has not had these symptoms before and reports only a history of hypertension. His blood pressure is 141/89 mm Hg, and he appears stable. You suspect that this is a supraventricular tachydysrhythmia, but question yourself and wonder how best to make the diagnosis and treat it.

Introduction

The complaint of “heart palpitations” accounts for an estimated 50,000 visits a year to emergency departments in the United States.¹ While the complaint of palpitations is often benign, emergency clinicians must rapidly and accurately recognize and treat serious dysrhythmias to maximize good outcomes. Tachycardic dysrhythmias can be challenging, with one study reporting only 18% positive recognition of Wolff-Parkinson-White (WPW) syndrome in patients with concomitant atrial fibrillation.²

Supraventricular tachycardias (SVTs) are narrow complex dysrhythmias that are dependent on the atrioventricular (AV) node or atrial tissue for their genesis and continuation. Typically, patients with SVT are awake and stable, which provides time to consider treatment options, but patients who are unstable require immediate action. The first step in approaching the patient with SVT is to correctly identify the electrocardiogram (ECG) rhythm; misdiagnosis can lead to providing the wrong treatment and concomitant clinical deterioration. Treatment options for SVT are evolving, with the recent emergence of new Valsalva techniques and a renewed interest in calcium channel blockers (CCBs), both of which pose alternatives to adenosine in select patients. This issue of Emergency Medicine Practice provides a comprehensive review of the literature on SVT and an update on the advances and controversies of management.

Critical Appraisal of the Literature

Pertinent guidelines from American College of Cardiology (ACC), American Heart Association (AHA), Heart Rhythm Society (HRS), and European Society of Cardiology (ESC) were identified and reviewed. The terms paroxysmal tachycardia, reciprocating tachycardia, atrioventricular re-entry tachycardia, atrioventricular nodal re-entry tachycardia, sinoatrial nodal re-entry tachycardia, supraventricular tachycardia, junctional tachycardia, sinus tachycardia, pre-excitation, and Wolff-Parkinson-White were searched in Ovid MEDLINE^®. The Cochrane Database of Systematic Reviews, the National Guidelines Clearinghouse, and Evidence-Based Medicine Reviews, Best Evidence (ACP), Database of Abstracts of Reviews of Effectiveness (DARE), and Evidence-Based Medicine Reviews Multifile (EBMZ) were also searched. Citations were limited to full text, English-language references relating to adult patients, from 1995 to March 2020; 449 abstracts were examined for relevance to emergency medicine. The final list included several well-designed randomized controlled trials, meta-analyses, and prospective studies providing robust evidence for Valsalva maneuvers, calcium channel blockers, and adenosine. There is a paucity of studies associated with other treatment strategies. The ACC/AHA/HRS classes of recommendation (COR) and levels of evidence (LOE) linked to specific treatments are provided when available. (See Appendix 1.)

Etiology and Pathophysiology

By definition, an SVT arises at or above the AV node. The tachycardias are divided into groups based on whether the QRS is narrow or wide (> 120 ms). SVTs occur by one of two mechanisms: (1) abnormal automaticity or (2) abnormal conduction. SVTs resulting from abnormal automaticity occur when sinoatrial (SA) nodal cells or an ectopic focus of cells rapidly generate action potentials that are then propagated through the normal conduction system. These include atrial fibrillation, atrial flutter, and atrial tachycardias as well as junctional tachycardia. SVTs resulting from abnormal conduction occur when the electrical impulse is propagated though an existing pathway that is typically refractory or through an accessory pathway. These pathways may be intranodal or extranodal and include atrioventricular re-entry tachycardia (AVRT) and atrioventricular nodal re-entry tachycardia (AVNRT).

Circus movement re-entry arrhythmias, or set conduction systems, follow a course of propagation around an anatomic or functional obstacle. They allow for a secondary pathway of electrical conduction that is subject to a cellular effective refractory period. Thus, each of these rhythms is dependent on allowing sufficient time for the cells to regenerate their action potential. In normal conduction, the impulse preferentially chooses the faster of the 2 conduction pathways. In the presence of an antegrade block, however, the slower re-entry pathway is chosen. This allows for the transition from the normal conduction pathway to the aberrant one. (See Figure 2.)

Differential Diagnosis

SVTs encompass a broad range of rhythms. While the term SVT is often used synonymously in reference to AVNRT or AVRT, there are other conditions that must be taken into account. (See Table 1. The ECG characteristics are noted in Figures 3, 4, 5, and 6.)

Risk Management Pitfalls for Supraventricular Tachycardia in the Emergency Department

2. “That patient had WCT, so it must be ventricular tachycardia, SVT with aberrancy, antidromic AVRT, or WPW with atrial fibrillation.”

Don’t forget about other causes of WCT. Overdoses of myocardial sodium channel blockers, illicit substances such as cocaine, over-the-counter medications such as diphenhydramine, and tricyclic antidepressants can lead to WCT. WCT may also be the result of hyperkalemia and cardiac arrest post resuscitation. Ensure you get a good patient history and consider these diagnoses, as their management is acutely distinct and nuanced. It will save your patient and your license.

6. “The patient had a history of SVT and came in for a recurrence. She was otherwise stable and healthy. Why muck around with vagal maneuvers? I gave her a dose of adenosine to expediently treat her tachycardia. Why was she so angry afterwards?”

Adenosine is a useful agent, but the experience of its administration can be quite difficult and terrifying for patients. Not all patients are alike, and some would rather try some other strategies prior to committing to 6- or 12-mg of adenosine IV push and all that entails, especially if they have suffered through adenosine in the past. Be respectful and mindful of their wishes. Remember to treat the patient, and not just the dysrhythmia. In patients with a first-time occurrence of SVT, take the time to explain the possible symptoms they may experience when adenosine is administered. With patients with recurrent episodes, remind yourself to reassure them, address fears, and consider other management strategies. Vagal maneuvers can still work, and CCBs have become a great first-line option as well.

10. “I gave the patient with WPW and tachycardia a dose of adenosine. What can possibly go wrong?”

In patients with WPW, take care to ensure that they are not presenting with atrial fibrillation. Administering adenosine, beta blockers, or a CCB to patients presenting with WPW with atrial fibrillation/atrial flutter can lead to unimpeded impulse transmission over the accessory pathway, exceptionally high ventricular rates, and decline to ventricular fibrillation. Characterization of these arrhythmias on ECG can be challenging. If ever in doubt, Synchronized electrical cardioversion or defibrillation is the wisest choice.

Tables, Figures, and Appendix

References

Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.

To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study is included in bold type following the references, where available. In addition, the most informative references cited in this paper, as determined by the author, are highlighted.

1. Probst MA, Mower WR, Kanzaria HK, et al. Analysis of emergency department visits for palpitations (from the National Hospital Ambulatory Medical Care Survey). Am J Cardiol. 2014;113(10):1685-1690. (Descriptive epidemiologic review)
2. Kozluk E, Timler D, Zysko D, et al. Members of the emergency medical team may have difficulty diagnosing rapid atrial fibrillation in Wolff-Parkinson-White syndrome. Cardiol J. 2015;22(3):247-252. (Observational study; 71 questionnaires)
3. 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) 
4. Goldberger ZD, Rho RW, Page RL. Approach to the diagnosis and initial management of the stable adult patient with a wide complex tachycardia. Am J Cardiol. 2008;101(10):1456-1466. (Review)
5. Haynes BE. Two deaths after prehospital use of adenosine. J Emerg Med. 2001;21(2):151-154. (Case report)
6. Gausche M, Persse DE, Sugarman T, et al. Adenosine for the prehospital treatment of paroxysmal supraventricular tachycardia. Ann Emerg Med. 1994;24(2):183-189. (Prospective; 129 patients)
7. McCabe JL, Adhar GC, Menegazzi JJ, et al. Intravenous adenosine in the prehospital treatment of paroxysmal supraventricular tachycardia. Ann Emerg Med. 1992;21(4):358-361. (Prospective study; 37 patients)
8. Honarbakhsh S, Baker V, Kirkby C, et al. Safety and efficacy of paramedic treatment of regular supraventricular tachycardia: a randomised controlled trial. Heart. 2017;103(18):1413-1418. (Randomized controlled trial; 86 patients)
9. Minhas R, Vogelaar G, Wang D, et al. A prehospital treat-and-release protocol for supraventricular tachycardia. CJEM. 2015;17(4):395-402. (Retrospective cohort trial; 229 patients)
10. Morrison LJ, Allan R, Vermeulen M, et al. Conversion rates for prehospital paroxysmal supraventricular tachycardia (PSVT) with the addition of adenosine: a before-and-after trial. Prehosp Emerg Care. 2001;5(4):353-359. (Case-control study; 211 patients)
11. Morrison LJ, Deakin CD, Morley PT, et al. Part 8: Advanced Life Support: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2010;122(16 Suppl 2):S345-S421. (Consensus statement)
12. Delacretaz E. Clinical practice. Supraventricular tachycardia. N Engl J Med. 2006;354(10):1039-1051. (Review) 
13. O’Connell M, Bernard A. A serious cause of panic attack. Case Rep Emerg Med. 2012:393275. (Case report)
14. Leitch JW, Klein GJ, Yee R, et al. Syncope associated with supraventricular tachycardia. An expression of tachycardia rate or vasomotor response? Circulation. 1992;85(3):1064-1071. (Prospective study; 13 patients)
15. Fox DJ, Tischenko A, Krahn AD, et al. Supraventricular tachycardia: diagnosis and management. Mayo Clinic Proceedings. 2008;83(12):1400-1411. (Review)
16. Bukkapatnam RN, Robinson M, Turnipseed S, et al. Relationship of myocardial ischemia and injury to coronary artery disease in patients with supraventricular tachycardia. Am J Cardiol. 2010;106(3):374-377. (Retrospective study; 14 patients)
17. Probst MA, Kanzaria HK, Hoffman JR, et al. Emergency physicians’ perceptions and decision-making processes regarding patients presenting with palpitations. J Emerg Med. 2015;49(2):236-243. (Survey; 21 interviews)
18. Slovis C, Jenkins R. ABC of clinical electrocardiography: conditions not primarily affecting the heart. BMJ. 2002;324(7349):1320-1323. (Review)
19. Fernando H, Adams N, Mitra B. Review article: the utility of troponin and other investigations in patients presenting to the emergency department with supraventricular tachycardia. Emerg Med Australas. 2019;31(1):35-42. (Meta-analysis; 7 observational studies; 1155 patients)
20. Ashok A, Cabalag M, Taylor DM. Usefulness of laboratory and radiological investigations in the management of supraventricular tachycardia. Emerg Med Australas. 2017;29(4):394-399. (Retrospective study; 633 patients)
21. Chow GV, Hirsch GA, Spragg DD, et al. Prognostic significance of cardiac troponin I levels in hospitalized patients presenting with supraventricular tachycardia. Medicine (Baltimore). 2010;89(3):141-148. (Retrospective study; 78 patients)
22. Redfearn DP, Ratib K, Marshall HJ, et al. Supraventricular tachycardia promotes release of troponin I in patients with normal coronary arteries. Int J Cardiol. 2005;102(3):521-522. (Retrospective study; 7 patients)
23. Zellweger MJ, Schaer BA, Cron TA, et al. Elevated troponin levels in absence of coronary artery disease after supraventricular tachycardia. Swiss Med Wkly. 2003;133(31-32):439-441. (Case series; 4 patients)
24. Ben Yedder N, Roux JF, Paredes FA. Troponin elevation in supraventricular tachycardia: primary dependence on heart rate. Can J Cardiol. 2011;27(1):105-109. (Retrospective study; 73 patients)
25. Dorenkamp M, Zabel M, Sticherling C. Role of coronary angiography before radiofrequency ablation in patients presenting with paroxysmal supraventricular tachycardia. J Cardiovasc Pharmacol Ther. 2007;12(2):137-144. (Retrospective review; 114 patients)
26. Carlberg DJ, Tsuchitani S, Barlotta KS, et al. Serum troponin testing in patients with paroxysmal supraventricular tachycardia: outcome after ED care. Am J Emerg Med. 2011;29(5):545-548. (Retrospective study; 54 patients)
27. Noorvash D, Ramos R, Hatch L, et al. Assessment of the utility of ordering a troponin in low- and intermediate-risk patients presenting to the emergency department with supraventricular tachycardia: a retrospective chart review. J Emerg Med. 2018. (Retrospective study; 46 patients)
28. deSouza IS, Peterson AC, Marill KA. Differentiating types of wide-complex tachycardia to determine appropriate treatment in the emergency department. Emerg Med Pract. 2015;17(7):1-22. (Review)
29. Accardi AJ, Miller R, Holmes JF. Enhanced diagnosis of narrow complex tachycardias with increased electrocardiograph speed. J Emerg Med. 2002;22(2):123-126. (Comparative trial; 45 ECGs)
30. Brubaker S, Long B, Koyfman A. Alternative treatment options for atrioventricular-nodal-reentry tachycardia: an emergency medicine review. J Emerg Med. 2018;54(2):198-206. (Review)
31. Ha SM, Cho YS, Cho GC, et al. Modified carotid sinus massage using an ultrasonography for maximizing vagal tone: a crossover simulation study. Am J Emerg Med. 2015;33(7):963-965. (Prospective study; 30 patients)
32. Taylor DM, Wong LF. Incorrect instruction in the use of the Valsalva manoeuvre for paroxysmal supra-ventricular tachycardia is common. Emerg Med Australas. 2004;16(4):284-287. (Multicenter observational study; 52 physicians)
33. Walker S, Cutting P. Impact of a modified Valsalva manoeuvre in the termination of paroxysmal supraventricular tachycardia. Emerg Med J. 2010;27(4):287-291. (Retrospective study; 19 patients)
34. 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) 
35. Corbacioglu SK, Akinci E, Cevik Y, et al. Comparing the success rates of standard and modified Valsalva maneuvers to terminate PSVT: a randomized controlled trial. Am J Emerg Med. 2017;35(11):1662-1665. (Randomized controlled trial; 56 patients)
36. Smith G, Morgans A, Taylor DM, et al. Use of the human dive reflex for the management of supraventricular tachycardia: a review of the literature. Emerg Med J. 2012;29(8):611-616. (Review)
37. Belhassen B, Viskin S. What is the drug of choice for the acute termination of paroxysmal supraventricular tachycardia: verapamil, adenosine triphosphate, or adenosine? Pacing Clin Electrophysiol. 1993;16(8):1735-1741. (Review)
38. Brady WJ Jr, DeBehnke DJ, Wickman LL, et al. Treatment of out-of-hospital supraventricular tachycardia: adenosine vs verapamil. Acad Emerg Med. 1996;3(6):574-585. (Prospective; 211 patients)
39. DiMarco JP, Miles W, Akhtar M, et al. Adenosine for paroxysmal supraventricular tachycardia: dose ranging and comparison with verapamil. Assessment in placebo-controlled, multicenter trials. The Adenosine for PSVT Study Group. Ann Intern Med. 1990;113(2):104-110. (Multicenter study; 359 patients)
40. Riccardi A, Arboscello E, Ghinatti M, et al. Adenosine in the treatment of supraventricular tachycardia: 5 years of experience (2002-2006). Am J Emerg Med. 2008;26(8):879-882. (Retrospective study; 454 patients)
41. Link MS, Berkow LC, Kudenchuk PJ, et al. Part 7: Adult Advanced Cardiovascular Life Support: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2015;132(18 Suppl 2):S444-S464. (Guidelines)
42. Marill KA, Wolfram S, Desouza IS, et al. Adenosine for wide-complex tachycardia: efficacy and safety. Crit Care Med. 2009;37(9):2512-2518. (Prospective study; 197 patients)
43. Innes JA. Review article: adenosine use in the emergency department. Emerg Med Australas. 2008;20(3):209-215. (Review)
44. Cabalag MS, Taylor DM, Knott JC, et al. Recent caffeine ingestion reduces adenosine efficacy in the treatment of paroxysmal supraventricular tachycardia. Acad Emerg Med. 2010;17(1):44-49. (Multicenter case-control study; 68 patients)
45. Chang M, Wrenn K. Adenosine dose should be less when administered through a central line. J Emerg Med. 2002;22(2):195-198. (Case report)
46. Flyer JN, Zuckerman WA, Richmond ME, et al. Prospective study of adenosine on atrioventricular nodal conduction in pediatric and young adult patients after heart transplantation. Circulation. 2017;135(25):2485-2493. (Prospective study; 80 patients)
47. Burkhart KK. Respiratory failure following adenosine administration. Am J Emerg Med. 1993;11(3):249-250. (Case report)
48. Coli S, Mantovani F, Ferro J, et al. Adenosine-induced severe bronchospasm in a patient without pulmonary disease. Am J Emerg Med. 2012;30(9):2082. (Case report)
49. DeGroff CG, Silka MJ. Bronchospasm after intravenous administration of adenosine in a patient with asthma. J Pediatr. 1994;125(5 Pt 1):822-823. (Case report)
50. Arora P, Bhatia V, Arora M, et al. Adenosine induced coronary spasm - a rare presentation. Indian Heart J. 2014;66(1):87-90. (Case report)
51. Ertan C, Atar I, Gulmez O, et al. Adenosine-induced ventricular arrhythmias in patients with supraventricular tachycardias. Ann Noninvasive Electrocardiol. 2008;13(4):386-390. (Retrospective review; 52 patients)
52. Harvey MG, Safih S, Wallace M. Adenosine-induced complete heart block: not so transient. Emerg Med Australas. 2007;19(6):559-562. (Case report)
53. Quevedo HC, Munoz-Mendoza J, Pinto Miranda V, et al. Coronary vasospasm while treating supraventricular tachycardia: is adenosine really to blame? Case Rep Cardiol. 2013;2013:897813. (Case report)
54. Rajkumar CA, Qureshi N, Ng FS, et al. Adenosine induced ventricular fibrillation in a structurally normal heart: a case report. J Med Case Rep. 2017;11(1):21. (Case report)
55. Walsh RC, Felice KL, Meehan TJ, et al. Adenosine-induced cardiopulmonary arrest in a patient with paroxysmal supraventricular tachycardia. Am J Emerg Med. 2009;27(7):901. (Case report)
56. Alabed S, Providencia R, Chico TJA. Cochrane corner: adenosine versus intravenous calcium channel antagonists for supraventricular tachycardia. Heart. 2018;104(24):1993-1994. (Editorial)
57. Delaney B, Loy J, Kelly AM. The relative efficacy of adenosine versus verapamil for the treatment of stable paroxysmal supraventricular tachycardia in adults: a meta-analysis. Eur J Emerg Med. 2011;18(3):148-152. (Meta-analysis; 8 trials)
58. Dadi G, Fink D, Weiser G. High-dose adenosine for refractory supraventricular tachycardia: a case report and literature review. Cardiol Young. 2017;27(5):981-984. (Case report)
59. 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) 
60. Lim SH, Anantharaman V, Teo WS, et al. Slow infusion of calcium channel blockers compared with intravenous adenosine in the emergency treatment of supraventricular tachycardia. Resuscitation. 2009;80(5):523-528. (Randomized controlled trial; 206 patients)
61. Holdgate A, Foo A. Adenosine versus intravenous calcium channel antagonists for the treatment of supraventricular tachycardia in adults. Cochrane Database Syst Rev. 2006(4):CD005154. (Meta-analysis)
62. Sung RJ, Blanski L, Kirshenbaum J, et al. Clinical experience with esmolol, a short-acting beta-adrenergic blocker in cardiac arrhythmias and myocardial ischemia. J Clin Pharmacol. 1986;26(S1):A15-A26. (Prospective study; 358 patients)
63. Gupta A, Naik A, Vora A, et al. Comparison of efficacy of intravenous diltiazem and esmolol in terminating supraventricular tachycardia. J Assoc Physicians India. 1999;47(10):969-972. (Prospective randomized crossover study; 32 patients)
64. 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) 
65. Roth A, Elkayam I, Shapira I, et al. Effectiveness of prehospital synchronous direct-current cardioversion for supraventricular tachyarrhythmias causing unstable hemodynamic states. Am J Cardiol. 2003;91(4):489-491. (Prospective study; 84 patients)
66. 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) 
67. Robins K, Lyons G. Supraventricular tachycardia in pregnancy. Br J Anaesth. 2004;92(1):140-143. (Case series; 4 patients)
68. Banhidy F, Acs N, Puho EH, et al. Paroxysmal supraventricular tachycardia in pregnant women and birth outcomes of their children: a population-based study. Am J Med Genet A. 2015;167a(8):1779-1786. (Prospective study; 252 patients)
69. Chang SH, Kuo CF, Chou IJ, et al. Outcomes associated with paroxysmal supraventricular tachycardia during pregnancy. Circulation. 2017;135(6):616-618. (Prospective study; 2,350,328 patients)
70. Klepper I. Cardioversion in late pregnancy. The anaesthetic management of a case of Wolff-Parkinson-White syndrome. Anaesthesia. 1981;36(6):611-616. (Case report)
71. Harrison JK, Greenfield RA, Wharton JM. Acute termination of supraventricular tachycardia by adenosine during pregnancy. Am Heart J. 1992;123(5):1386-1388. (Review)
72. Gillette PC. Supraventricular arrhythmias in children. J Am Coll Cardiol. 1985;5(6 Suppl):122b-129b. (Review)
73. Stambler BS, Dorian P, Sager PT, et al. Etripamil nasal spray for rapid conversion of supraventricular tachycardia to sinus rhythm. J Am Coll Cardiol. 2018;72(5):489-497. (Prospective study; 104 patients)
74. Gaita F, Giustetto C, Riccardi R, et al. Stress and pharmacologic tests as methods to identify patients with Wolff-Parkinson-White syndrome at risk of sudden death. Am J Cardiol. 1989;64(8):487-490. (Prospective study; 65 patients)
75. Sharma AD, Yee R, Guiraudon G, et al. Sensitivity and specificity of invasive and noninvasive testing for risk of sudden death in Wolff-Parkinson-White syndrome. J Am Coll Cardiol. 1987;10(2):373-381. (Prospective study; 67 patients)
76. Obeyesekere MN, Klein GJ. Application of the 2015 ACC/AHA/HRS guidelines for risk stratification for sudden death in adult patients with asymptomatic pre-excitation. J Cardiovasc Electrophysiol. 2017;28(7):841-848. (Review)
77. Al-Khatib SM, Arshad A, Balk EM, et al. Risk stratification for arrhythmic events in patients with asymptomatic pre-excitation: a systematic review for the 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. Circulation. 2016;133(14):e575-e586. (Systematic review)
78. Pappone C, Vicedomini G, Manguso F, et al. Wolff-Parkinson-White syndrome in the era of catheter ablation: insights from a registry study of 2169 patients. Circulation. 2014;130(10):811-819. (Prospective study; 2169 patients)
79. Munger TM, Packer DL, Hammill SC, et al. A population study of the natural history of Wolff-Parkinson-White syndrome in Olmsted County, Minnesota, 1953-1989. Circulation. 1993;87(3):866-873. (Retrospective study; 113 patients)
80. Flensted-Jensen E. Wolff-Parkinson-White syndrome. A long-term follow-up of 47 cases. Acta Med Scand. 1969;186(1-2):65-74. (Prospective study; 47 patients)
81. Hindricks G. The Multicentre European Radiofrequency Survey (MERFS): complications of radiofrequency catheter ablation of arrhythmias. The Multicentre European Radiofrequency Survey (MERFS) Investigators of the Working Group on Arrhythmias of the European Society of Cardiology. Eur Heart J. 1993;14(12):1644-1653. (Retrospective study; 4398 patients)
82. Calkins H, Yong P, Miller JM, et al. Catheter ablation of accessory pathways, atrioventricular nodal reentrant tachycardia, and the atrioventricular junction: final results of a prospective, multicenter clinical trial. The Atakr Multicenter Investigators Group. Circulation. 1999;99(2):262-270. (Prospective study; 1050 patients )
83. Scheinman MM. NASPE survey on catheter ablation. Pacing Clin Electrophysiol. 1995;18(8):1474-1478. (Survey study; 147 laboratories)
84. Pappone C, Santinelli V, Rosanio S, et al. Usefulness of invasive electrophysiologic testing to stratify the risk of arrhythmic events in asymptomatic patients with Wolff-Parkinson-White pattern: results from a large prospective long-term follow-up study. J Am Coll Cardiol. 2003;41(2):239-244. (Prospective study; 212 patients)
85. Cohen MI, Triedman JK, Cannon BC, et al. PACES/HRS expert consensus statement on the management of the asymptomatic young patient with a Wolff-Parkinson-White (WPW, ventricular preexcitation) electrocardiographic pattern: developed in partnership between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the governing bodies of PACES, HRS, the American College of Cardiology Foundation (ACCF), the American Heart Association (AHA), the American Academy of Pediatrics (AAP), and the Canadian Heart Rhythm Society (CHRS). Heart Rhythm. 2012;9(6):1006-1024. (Consensus statement)
86. Kamel H, Elkind MS, Bhave PD, et al. Paroxysmal supraventricular tachycardia and the risk of ischemic stroke. Stroke. 2013;44(6):1550-1554. (Retrospective study; 4,806,803 patients)
87. Murman DH, McDonald AJ, Pelletier AJ, et al. U.S. emergency department visits for supraventricular tachycardia, 1993-2003. Acad Emerg Med. 2007;14(6):578-581. (Retrospective study; 550,000 visits)
88. Luber S, Brady WJ, Joyce T, et al. Paroxysmal supraventricular tachycardia: outcome after ED care. Am J Emerg Med. 2001;19(1):40-42. (Retrospective study; 111 patients)
89. Wood KA, Drew BJ, Scheinman MM. Frequency of disabling symptoms in supraventricular tachycardia. Am J Cardiol. 1997;79(2):145-149. (Prospective study; 167 patients)
90. Attanasio P, Huemer M, Loehr L, et al. Use of a patient-activated event recording system in patients with tachycardic palpitations: how long to follow up? Ann Noninvasive Electrocardiol. 2015;20(6):566-569. (Prospective study; 1404 patients)
91. de Asmundis C, Conte G, Sieira J, et al. Comparison of the patient-activated event recording system vs. traditional 24 h Holter electrocardiography in individuals with paroxysmal palpitations or dizziness. Europace. 2014;16(8):1231-1235. (Prospective study; 577 patients)
92. Brugada P, Brugada J, Mont L, et al. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Circulation. 1991;83(5):1649-1659. (Prospective; 544 patients)
93. Vereckei A, Duray G, Szenasi G, et al. New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia. Heart Rhythm. 2008;5(1):89-98. (Retrospective; 103 patients)
94. Herbert ME, Votey SR, Morgan MT, et al. Failure to agree on the electrocardiographic diagnosis of ventricular tachycardia. Ann Emerg Med. 1996;27(1):35-38. (Observational study; 178 ECGs)
95. Isenhour JL, Craig S, Gibbs M, et al. Wide-complex tachycardia: continued evaluation of diagnostic criteria. Acad Emerg Med. 2000;7(7):769-773. (Observational study; 157 ECGs)