Differentiating Types Of Wide-Complex Tachycardia To Determine Appropriate Treatment In The Emergency Department

Table of Contents

 

1. Abstract
2. Case Presentations
3. Introduction
4. Critical Appraisal of the Literature
5. Etiology And Pathophysiology
6. Differential Diagnosis
7. Prehospital Care
8. Emergency Department Evaluation
   1. History
   2. Physical Examination
9. Diagnostic Studies
   1. The Diagnostic Utility Of Electrocardiography
      1. Rate
      2. Axis
      3. QRS Duration And Morphology
      4. Concordance
      5. Atrioventricular Dissociation, Capture Beats, And Fusion Beats
      6. Comparison To Prior Electrocardiograms
   2. Diagnostic Algorithms
   3. The Role Of Adenosine
      1. Diagnostic Utility
   4. Laboratory Analysis
      1. Electrolytes
      2. Cardiac Biomarkers
      3. Toxicology Screening
10. Treatment
11. Special Circumstances
    1. Irregular Wide-Complex Tachycardia With Wolff-Parkinson-White Syndrome
    2. Ventricular Tachycardia As A Consequence Of Acute Myocardial Infarction
    3. Right Ventricular Outflow Tract Ventricular Tachycardia
    4. Wide-Complex Tachycardia In The Patient With An Implantable Pacemaker
12. Controversies/Cutting Edge
    1. Predicting Tachydysrhythmias
    2. Electrical Therapy
    3. New Medications
13. Disposition
    1. Patients Appropriate For Discharge
14. Summary
15. Selected Abbreviations
16. Risk Management Pitfalls In Managing Wide-Complex Tachycardia
17. Case Conclusions
18. Clinical Pathway For Initial Management Of Stable, Regular Wide-Complex Tachycardia
19. Clinical Pathway For Medical Management Of Stable, Irregular Wide-Complex Tachycardia
20. Tables and Figures
    1. Table 1. Types Of Wide-Complex Tachycardia With Historical Factors And Electrocardiographic
    2. Table 2. Point Estimates Of Pooled Data, Historical Factors And Electrocardiogram Findings In Patients With Ventricular Tachycardia Or Supraventricular Tachycardia
    3. Figure 1. Wide-Complex Tachycardia Due To Hyperkalemia
    4. Figure 2. Wide-Complex Tachycardia With Right Bundle Branch Block Pattern Before And After Adenosine
    5. Figure 3. Types Of Supraventricular Tachycardia
    6. Figure 4. Extreme Right Axis Deviation (Between -180 and -90)
    7. Figure 5. Precordial Concordance
    8. Figure 6. Atrioventricular Dissociation
    9. Figure 7. Capture And Fusion Beats
    10. Figure 8. Supraventricular Tachycardia And Response To Adenosine
    11. Figure 9. Wide-Complex Tachycardia In Special Populations
    12. Figure 10. Pacemaker-Mediated Tachycardia
21. References

Abstract

Wide-complex tachycardia is a rare disease entity among patients presenting to the emergency department. However, due to its potential life-threatening nature, emergency clinicians must know how to assess and manage this condition. Wide-complex tachycardia encompasses a range of cardiac dysrhythmias, some of which can be difficult to distinguish and may require specific treatment approaches. This review summarizes the etiology and pathophysiology of wide-complex tachycardia, describes the differential diagnosis, and presents an evidence-based approach to identification of the different types of tachycardias through the use of a thorough history and physical examination, vagal maneuvers, electrocardiography, and adenosine. The treatment options and disposition for patients with various wide-complex tachycardias are also discussed, with attention to special circumstances and select controversial/contemporary topics.

Case Presentations

You're dictating a chart when EMS brings in an ashen-looking middle-aged man clutching his chest and gasping, “I can’t breathe.” You follow him into the room, and, as he’s attached to the monitor, you see a wide-complex tachycardia with a rate of 146 beats/min. His blood pressure is 86/50 mm Hg, and his pulse oximetry is 86%. The tech is already attaching ECG leads, and you note a sternotomy scar on the patient’s chest. You ask for pads to be placed for direct cardioversion; as you’re getting ready to shock, you think, “Should I wait for the ECG? Is this ventricular tachycardia or supraventricular tachycardia? Do I even need to know that before shocking him?”

Later during your shift, you are called into the room by the nurse of a patient you’ve just admitted for syncope. The nurse points at the monitor and yells, "He's in v-tach!" The patient is looking at you quizzically and asks, “What’s going on?” The monitor shows a wide-complex tachycardia. His blood pressure is 135/96 mm Hg, and his pulse oximetry is 94%. You calmly ask for a stat ECG and pads to be placed on the patient. As you watch his ECG print out, you think, “I’m not sure that’s ventricular tachycardia, but it's possibly supraventricular tachycardia with aberrancy. I need to check his potassium levels. Should I use amiodarone first or should I try adenosine?”

In the next room, there is a young female patient you’ve seen every shift for the past 3 days who was checked in with “anxiety.” You think that she is possibly looking for benzodiazepines except, this time, her triage vital signs show a heart rate of 190 beats/min. There is no blood pressure recorded. You go to see her immediately, and she’s hyperventilating and appears anxious. You hook her up to the monitor yourself and note an irregular wide-complex tachycardia. Her blood pressure is 102/69 mm Hg. As you’re calling for a nurse and a tech, you think, “She’s too young for ventricular tachycardia, isn’t she? Maybe she overdosed, or maybe she has a conduction issue. I really need to see this ECG.”

Introduction

Wide-complex tachycardia (WCT) describes a rhythm in which the heart rate is > 100 beats/min and the QRS complex is > 120 milliseconds. It is essential for emergency clinicians to have a comprehensive understanding of the recognition and management of the different types of WCTs, as many of these rhythms may progress to other sudden, life-threatening dysrhythmias or progressive cardiomyopathy without prompt treatment. Furthermore, if a WCT is misdiagnosed, subsequent delayed or inappropriate therapeutic decisions can portend further hemodynamic compromise.

Unfortunately, despite the numerous algorithms published in the literature, there are no electrocardiographic criteria that can definitively diagnose aspecific WCT, and agreement with regard to rhythm identification is inconsistent.^1,2 This issue of Emergency Medicine Practice will provide you with the tools that are required to recognize, diagnose, and treat common etiologies of WCT.

Critical Appraisal Of The Literature

Risk Management Pitfalls In Managing Wide-Complex Tachycardia

1. “There’s no way that’s VT. The patient is completely stable.”
A patient’s hemodynamic status is a poor predictor of VT. The diagnosis should be made based on examination of the 12-lead ECG, and treatment should be tailored appropriately.

2. “Maybe if I just try to shock him at 200 J again, it’ll work.”
Be cautious when repeating treatments, including electrical cardioversion, if the patient is not responding as expected. Hyperkalemia and drug toxicity can mimic VT, as can sinus tachycardia with a BBB, and all such cases will be refractory to DCCV.

3. “She’s got a pacemaker, so I’ll bet that’s just sinus tachycardia on the monitor.”
Patients with pacemakers that trigger ventricular contraction will, by definition, demonstrate a WCT while in sinus tachycardia. However, these patients may also have underlying ischemic or structural heart disease that can put them at risk for slow VT. Always obtain a 12-lead ECG and do not rely solely on the single lead displayed on the monitor.

4. “This kid’s barely 18 years old, so this irregular WCT has to be WPW with AF, right?”
In young adults, be sure to consider the risk of VT before assuming that the dysrhythmia is secondary to SVT. Long-QT syndrome, congenital heart defects, and drugs can increase the risk of ventricular dysrhythmias.

5. “This QRS complex doesn’t look that different from the BBB seen on prior ECGs, so I’m sure it’s just SVT with aberrancy.”
VT in patients with underlying BBB can demonstrate major changes, minor changes, or no change at all in QRS morphology. Look for other ECG criteria associated with VT before assuming that it is SVT with aberrancy.

6. “I know this has to be torsades de pointes! Let’s just give 2 g of magnesium.”
Remember that torsades de pointes secondary to prolonged QT is only one etiology of polymorphic VT, so consider acute cardiac ischemia when a patient presents in this rhythm.

7. “Well, he’s stable, so let’s avoid electrical cardioversion and just use amiodarone.”
Although amiodarone is the first-line agent for treatment of VT in the ERC guidelines, several studies have suggested that amiodarone may be less effective than other drugs, and procainamide is the first-line treatment recommended by the ACC/AHA.

8. “He didn’t respond to adenosine, so it must be VT.”
Although the vast majority of SVTs will demonstrate some response to adenosine, there are some SVTs that will not respond. Furthermore, right ventricular outflow tract tachycardia may terminate with adenosine administration. Keep in mind that adenosine must be pushed rapidly with a flush and that some patients will respond to a 12-mg dose, even when they don’t respond to 6 mg.

9. “This patient’s WCT could be related to hyperkalemia, but she’s pretty stable, so I’ll just start procainamide and wait for her potassium level to come back from the lab.”
WCT secondary to hyperkalemia will not respond to antidysrhythmics, and it carries a high risk of hemodynamic decompensation and cardiac arrest. If hyperkalemia is suspected, administer calcium to stabilize the myocyte membrane. Calcium administration will have minimal adverse effects on other mechanisms of WCT.

10. “This is new-onset SVT, so this patient has got to be admitted.”
Young patients with a primary SVT who do not have symptoms or signs of myocardial ischemia, and who are stable throughout the ED course after conversion to sinus rhythm, can be safely discharged home.

Tables and Figures

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 will be included in bold type following the reference, where available. In addition, the most informative references cited in this paper, as determined by the authors, will be noted by an asterisk (*) next to the number of the reference.

1. Isenhour JL, Craig S, Gibbs M, et al. Wide-complex tachycardia: continued evaluation of diagnostic criteria. Acad Emerg Med. 2000;7(7):769-773. (Survey; 4 participants)
2. 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. (Survey; 3 participants)
3. * Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (writing committee to develop guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation. 2006;114(10):e385-e484. (Guideline)
4. Deakin CD, Nolan JP, Soar J, et al. European Resuscitation Council guidelines for resuscitation 2010 section 4. Adult advanced life support. Resuscitation. 2010;81(10):1305-1352. (Guideline)
5. * 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(18 Suppl 3):S729-S767. (Guideline)
6. Singh N, Singh HK, Khan IA. Serial electrocardiographic changes as a predictor of cardiovascular toxicity in acute tricyclic antidepressant overdose. Am J Ther. 2002;9(1):75-79. (Case report)
7. Kerns W, 2nd, Garvey L, Owens J. Cocaine-induced wide complex dysrhythmia. J Emerg Med. 1997;15(3):321-329. (Case series; 3 patients)
8. Hollowell H, Mattu A, Perron AD, et al. Wide-complex tachycardia: beyond the traditional differential diagnosis of ventricular tachycardia vs supraventricular tachycardia with aberrant conduction. Am J Emerg Med. 2005;23(7):876-889. (Review)
9. Dharmarajan TS, Villanueva HJ, Dharmarajan L. Wide complex tachycardia in a dialysis patient. Semin Dial. 2001;14(1):67-69. (Case report)
10. Scheuermeyer FX, Pourvali R, Rowe BH, et al. Emergency department patients with atrial fibrillation or flutter and an acute underlying medical illness may not benefit from attempts to control rate or rhythm. Ann Emerg Med. 2015;65(5):511-522. (Retrospective; 416 patients)
11. Ray IB. Wide complex tachycardia: recognition and management in the emergency room. J Assoc Physicians India. 2004;52:882-887. (Review)
12. Gupta A, Bhatt AP, Khaira A, et al. Hyperkalemia presenting as wide-complex tachycardia in a dialysis patient. Saudi J Kidney Dis Transpl. 2010;21(2):339-341. (Case report)
13. Datino T, Almendral J, Gonzalez-Torrecilla E, et al. Raterelated changes in QRS morphology in patients with fixed bundle branch block: implications for differential diagnosis of wide QRS complex tachycardia. Eur Heart J. 2008;29(19):2351-2358. (Prospective; 59 patients)
14. Halperin BD, Kron J, Cutler JE, et al. Misdiagnosing ventricular tachycardia in patients with underlying conduction disease and similar sinus and tachycardia morphologies. West J Med. 1990;152(6):677-682. (Case series; 6 patients)
15. Littmann L, McCall MM. Ventricular tachycardia may masquerade as supraventricular tachycardia in patients with preexisting bundle-branch block. Ann Emerg Med. 1995;26(1):98-101. (Case series; 3 patients)
16. Mann DL, Zipes DP, Libby P, et al. Braunwald’s Heart Disease: Textbook of Cardiovascular Medicine. Vol 10e. Philadelphia, PA: Saunders; 2014. (Textbook)
17. Mase M, Glass L, Disertori M, et al. Nodal recovery, dual pathway physiology, and concealed conduction determine complex AV dynamics in human atrial tachyarrhythmias. Am J Physiol Heart Circ Physiol. 2012;303(10):H1219-H1228. (Retrospective; 10 patients)
18. Eckardt L, Breithardt G, Kirchhof P. Approach to wide complex tachycardias in patients without structural heart disease. Heart. 2006;92(5):704-711. (Review)
19. Rosner MH, Brady WJ Jr, Kefer MP, et al. Electrocardiography in the patient with the Wolff-Parkinson-White syndrome: diagnostic and initial therapeutic issues. Am J Emerg Med. 1999;17(7):705-714. (Review)
20. * Fengler BT, Brady WJ, Plautz CU. Atrial fibrillation in the Wolff-Parkinson-White syndrome: ECG recognition and treatment in the ED. Am J Emerg Med. 2007;25(5):576-583. (Case report)
21. Stewart RB, Bardy GH, Greene HL. Wide complex tachycardia: misdiagnosis and outcome after emergent therapy. Ann Intern Med. 1986;104(6):766-771. (Retrospective; 46 patients)
22. Dancy M, Camm AJ, Ward D. Misdiagnosis of chronic recurrent ventricular tachycardia. Lancet. 1985;2(8450):320-323. (Retrospective; 24 patients)
23. Blanck Z, Jazayeri M, Dhala A, et al. Bundle branch reentry: a mechanism of ventricular tachycardia in the absence of myocardial or valvular dysfunction. J Am Coll Cardiol. 1993;22(6):1718-1722. (Case series; 3 patients)
24. Trohman RG, Kim MH, Pinski SL. Cardiac pacing: the state of the art. Lancet. 2004;364(9446):1701-1719. (Review)
25. Smith GD, Dyson K, Taylor D, et al. Effectiveness of the Valsalva manoeuvre for reversion of supraventricular tachycardia. Cochrane Database Syst Rev. 2013;3:CD009502. (Systematic review)
26. Arnold RW. The human heart rate response profiles to five vagal maneuvers. Yale J Biol Med. 1999;72(4):237-244. (Retrospective; 943 patients)
27. 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(1):30-35. (Prospective; 148 patients)
28. Wen ZC, Chen SA, Tai CT, et al. Electrophysiological mechanisms and determinants of vagal maneuvers for termination of paroxysmal supraventricular tachycardia. Circulation. 1998;98(24):2716-2723. (Prospective; 163 patients)
29. Slovis CM, Kudenchuk PJ, Wayne MA, et al. Prehospital management of acute tachyarrhythmias. Prehosp Emerg Care. 2003;7(1):2-12. (Review)
30. Furlong R, Gerhardt RT, Farber P, et al. Intravenous adenosine as first-line prehospital management of narrow-complex tachycardias by EMS personnel without direct physician control. Am J Emerg Med. 1995;13(4):383-388. (Prospective; 41 patients)
31. Goebel PJ, Daya MR, Gunnels MD. Accuracy of arrhythmia recognition in paramedic treatment of paroxysmal supraventricular tachycardia: a ten-year review. Prehosp Emerg Care. 2004;8(2):166-170. (Retrospective; 224 patients)
32. Goodman IS, Lu CJ. Intraosseous infusion is unreliable for adenosine delivery in the treatment of supraventricular tachycardia. Pediatr Emerg Care. 2012;28(1):47-48. (Case series; 2 patients)
33. Morady F, Shen EN, Bhandari A, et al. Clinical symptoms in patients with sustained ventricular tachycardia. West J Med. 1985;142(3):341-344. (Retrospective; 113 patients)
34. Baerman JM, Morady F, DiCarlo LA Jr, et al. Differentiation of ventricular tachycardia from supraventricular tachycardia with aberration: value of the clinical history. Ann Emerg Med. 1987;16(1):40-43. (Retrospective; 84 patients)
35. * Marill KA, Wolfram S, Desouza IS, et al. Adenosine for wide-complex tachycardia: efficacy and safety. Crit Care Med. 2009;37(9):2512-2518. (Retrospective; 197 patients)
36. Rimmer JM, Horn JF, Gennari F. Hyperkalemia as a complication of drug therapy. Arch Intern Med. 1987;147(5):867-869. (Retrospective; 308 patients)
37. Indermitte J, Burkolter S, Drewe J, et al. Risk factors associated with a high velocity of the development of hyperkalaemia in hospitalised patients. Drug Saf. 2007;30(1):71-80. (Retrospective; 551 patients)
38. Kies P, Boersma E, Bax JJ, et al. Determinants of recurrent ventricular arrhythmia or death in 300 consecutive patients with ischemic heart disease who experienced aborted sudden death: data from the Leiden out-of-hospital cardiac arrest study. J Cardiovasc Electrophysiol. 2005;16(10):1049-1056. (Prospective; 300 patients)
39. Drew BJ, Scheinman MM. ECG criteria to distinguish between aberrantly conducted supraventricular tachycardia and ventricular tachycardia: practical aspects for the immediate care setting. Pacing Clin Electrophysiol. 1995;18(12 Pt 1):2194-2208. (Prospective; 133 patients)
40. Akhtar M, Shenasa M, Jazayeri M, et al. Wide QRS complex tachycardia. Reappraisal of a common clinical problem. Ann Intern Med. 1988;109(11):905-912. (Prospective; 150 patients)
41. Calkins H, Shyr Y, Frumin H, et al. The value of the clinical history in the differentiation of syncope due to ventricular tachycardia, atrioventricular block, and neurocardiogenic syncope. Am J Med. 1995;98(4):365-373. (Prospective; 80 patients)
42. Sheldon R, Hersi A, Ritchie D, et al. Syncope and structural heart disease: historical criteria for vasovagal syncope and ventricular tachycardia. J Cardiovasc Electrophysiol. 2010;21(12):1358-1364. (Prospective cohort; 134 patients)
43. Garratt CJ, Griffith MJ, Young G, et al. Value of physical signs in the diagnosis of ventricular tachycardia. Circulation. 1994;90(6):3103-3107. (Prospective randomized controlled; 26 patients)
44. Wellens HJ, Bar FW, Lie KI. The value of the electrocardiogram in the differential diagnosis of a tachycardia with a widened QRS complex. Am J Med. 1978;64(1):27-33. (Retrospective; 122 patients)
45. Alberca T, Almendral J, Sanz P, et al. Evaluation of the specificity of morphological electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defects. Circulation. 1997;96(10):3527-3533. (Prospective; 232 patients)
46. Datino T, Almendral J, Avila P, et al. Specificity of electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defect. Heart Rhythm. 2013;10(9):1393-1401. (Prospective; 69 patients)
47. Miller JM, Das MK, Yadav AV, et al. Value of the 12-lead ECG in wide QRS tachycardia. Cardiol Clin. 2006;24(3):439-451. (Case series; 385 patients)
48. Marill KA. Diagnostic testing and the average absolute likelihood ratio: application to diagnosing wide QRS complex tachycardia and other ED diseases. Am J Emerg Med. 2012;30(9):1895-1906. (Systematic review)
49. Pollack ML, Chan TC, Brady WJ. Electrocardiographic manifestations: aberrant ventricular conduction. J Emerg Med. 2000;19(4):363-367. (Review)
50. 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; 554 patients)
51. Reithmann C, Steinbigler P, Fiek M. Simultaneous coronary angiography during titration of radiofrequency energy for ablation of left ventricular summit tachycardia in the ‘inaccessible area’. Europace. 2013;15(1):32. (Case report)
52. Greenstein E, Goldberger JJ. Implications of progressive aberrancy versus true fusion for diagnosis of wide complex tachycardia. Am J Cardiol. 2011;108(1):52-55. (Retrospective; 24 patients)
53. Griffith MJ, Garratt CJ, Mounsey P, et al. Ventricular tachycardia as default diagnosis in broad complex tachycardia. Lancet. 1994;343(8894):386-388. (Survey; using 2 observers of 102 patients)
54. Baxi RP, Hart KW, Vereckei A, et al. Vereckei criteria used as a diagnostic tool by emergency medicine residents to distinguish between ventricular tachycardia and supra-ventricular tachycardia with aberrancy. J Cardiol. 2012;59(3):307-312. (Retrospective; 86 patients)
55. Szelenyi Z, Duray G, Katona G, et al. Comparison of the “real-life” diagnostic value of two recently published electrocardiogram methods for the differential diagnosis of wide QRS complex tachycardias. Acad Emerg Med. 2013;20(11):1121-1130. (Retrospective; 145 patients)
56. * Kaiser E, Darrieux FC, Barbosa SA, et al. Differential diagnosis of wide QRS tachycardias: comparison of two electrocardiographic algorithms. Europace. 2015 Jan 18. [Epub ahead of print]. (Prospective; 51 patients)
57. Pinski SL, Maloney JD. Adenosine: a new drug for acute termination of supraventricular tachycardia. Cleve Clin J Med. 1990;57(4):383-388. (Review)
58. Schuller JL, Varosy PD, Nguyen DT. Wide complex tachycardia and adenosine. JAMA Intern Med. 2013;173(17):1644-1646. (Case report)
59. Camaiti A, Pieralli F, Olivotto I, et al. Prospective evaluation of adenosine-induced proarrhythmia in the emergency room. Eur J Emerg Med. 2001;8(2):99-105. (Prospective; 160 patients)
60. Innes JA. Review article: adenosine use in the emergency department. Emerg Med Australas. 2008;20(3):209-215. (Systematic review)
61. Shah CP, Gupta AK, Thakur RK, et al. Adenosine-induced ventricular fibrillation. Indian Heart J. 2001;53(2):208-210. (Case series; 2 patients)
62. Parham WA, Mehdirad AA, Biermann KM, et al. Case report: adenosine induced ventricular fibrillation in a patient with stable ventricular tachycardia. J Interv Card Electrophysiol. 2001;5(1):71-74. (Case report)
63. Khan IA. Clinical and therapeutic aspects of congenital and acquired long QT syndrome. Am J Med. 2002;112(1):58-66. (Review)
64. Gottlieb SS, Baruch L, Kukin ML, et al. Prognostic importance of the serum magnesium concentration in patients with congestive heart failure. J Am Coll Cardiol. 1990;16(4):827-831. (Prospective; 199 patients)
65. Delbridge TR, Yealy DM. Wide complex tachycardia. Emerg Med Clin North Am. 1995;13(4):903-924. (Review)
66. 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; 51 patients)
67. Jacobs I, Sunde K, Deakin CD, et al. Part 6: Defibrillation: 2010 international consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations. Circulation.2010;122(16 Suppl 2):S325-S337. (Systematic review)
68. Sasson C, Rogers MA, Dahl J, et al. Predictors of survival from out-of-hospital cardiac arrest: a systematic review and meta-analysis. Circ Cardiovasc Qual Outcomes. 2010;3(1):63-81. (Systematic review)
69. * Lown B. Electrical reversion of cardiac arrhythmias. Br Heart J. 1967;29(4):469-489. (Retrospective; 470 patients)
70. Richter S, Brugada P. Bidirectional ventricular tachycardia. J Am Coll Cardiol. 2009;54(13):1189.
71. Kiberd MB, Minor SF. Lipid therapy for the treatment of a refractory amitriptyline overdose. CJEM. 2012;14(3):193-197. (Case report)
72. Agarwala R, Ahmed SZ, Wiegand TJ. Prolonged use of intravenous lipid emulsion in a severe tricyclic antidepressant overdose. J Med Toxicol. 2014;10(2):210-214. (Case report)
73. Carbucicchio C, Santamaria M, Trevisi N, et al. Catheter ablation for the treatment of electrical storm in patients with implantable cardioverter-defibrillators: short- and long-term outcomes in a prospective single-center study. Circulation. 2008;117(4):462-469. (Prospective; 95 patients)
74. Manolis AS, Wang PJ, Estes NA 3rd. Radiofrequency catheter ablation for cardiac tachyarrhythmias. Ann Intern Med. 1994;121(6):452-461. (Review)
75. Kulakowski P, Karczmarewicz S, Karpinski G, et al. Effects of intravenous amiodarone on ventricular refractoriness, intraventricular conduction, and ventricular tachycardia induction. Europace. 2000;2(3):207-215. (Case series; 18 patients)
76. Morady F, DiCarlo LA Jr, Krol RB, et al. Acute and chronic effects of amiodarone on ventricular refractoriness, intraventricular conduction and ventricular tachycardia induction. J Am Coll Cardiol. 1986;7(1):148-157. (Case series; 8 patients)
77. * deSouza IS, Martindale JL, Sinert R. Antidysrhythmic drug therapy for the termination of stable, monomorphic ventricular tachycardia: a systematic review. Emerg Med J. 2015;32(2):161-167. (Systematic review)
78. Marill KA, deSouza IS, Nishijima DK, et al. Amiodarone is poorly effective for the acute termination of ventricular tachycardia. Ann Emerg Med. 2006;47(3):217-224. (Retrospective; 33 patients)
79. Tomlinson DR, Cherian P, Betts TR, et al. Intravenous amiodarone for the pharmacological termination of haemodynamically- tolerated sustained ventricular tachycardia: is bolus dose amiodarone an appropriate first-line treatment? Emerg Med J. 2008;25(1):15-18. (Retrospective; 41 patients)
80. Atkins DL, Dorian P, Gonzalez ER, et al. Treatment of tachyarrhythmias. Ann Emerg Med. 2001;37(4 Suppl):S91- S109. (Review)
81. Keren A, Tzivoni D, Gavish D, et al. Etiology, warning signs and therapy of torsade de pointes. A study of 10 patients. Circulation. 1981;64(6):1167-1174. (Case series; 10 patients)
82. Ellenbogen KA, Clemo HF, Stambler BS, et al. Efficacy of ibutilide for termination of atrial fibrillation and flutter. Am J Cardiol. 1996;78(8A):42-45. (Review)
83. Stiell IG, Clement CM, Symington C, et al. Emergency department use of intravenous procainamide for patients with acute atrial fibrillation or flutter. Acad Emerg Med. 2007;14(12):1158-1164. (Retrospective; 341 patients)
84. Vinson DR, Hoehn T, Graber DJ, et al. Managing emergency department patients with recent-onset atrial fibrillation. J Emerg Med. 2012;42(2):139-148. (Prospective; 206 patients)
85. Sobel RM, Dhruva NN. Termination of acute wide QRS complex atrial fibrillation with ibutilide. Am J Emerg Med. 2000;18(4):462-464. (Case report)
86. Haqqani HM, Roberts-Thomson KC. Radiofrequency catheter ablation for ventricular tachycardia. Heart Lung Circ. 2012;21(6-7):402-412. (Review)
87. Mehta RH, Starr AZ, Lopes RD, et al. Incidence of and outcomes associated with ventricular tachycardia or fibrillation in patients undergoing primary percutaneous coronary intervention. JAMA. 2009;301(17):1779-1789. (Prospective; 5745 patients)
88. Henkel DM, Witt BJ, Gersh BJ, et al. Ventricular arrhythmias after acute myocardial infarction: a 20-year community study. Am Heart J. 2006;151(4):806-812. (Retrospective; 2317 patients)
89. * Liang JJ, Prasad A, Cha YM. Temporal evolution and implications of ventricular arrhythmias associated with acute myocardial infarction. Cardiol Rev. 2013;21(6):289-294. (Review)
90. Newby KH, Thompson T, Stebbins A, et al. Sustained ventricular arrhythmias in patients receiving thrombolytic therapy: incidence and outcomes. The GUSTO Investigators. Circulation. 1998;98(23):2567-2573. (Retrospective; 40,895 patients)
91. Wolfe CL, Nibley C, Bhandari A, et al. Polymorphous ventricular tachycardia associated with acute myocardial infarction. Circulation. 1991;84(4):1543-1551. (Retrospective; 11 patients)
92. Lerman BB, Belardinelli L, West GA, et al. Adenosinesensitive ventricular tachycardia: evidence suggesting cyclic AMP-mediated triggered activity. Circulation. 1986;74(2):270- 280. (Prospective; 4 patients)
93. Lerman BB, Belardinelli L. Cardiac electrophysiology of adenosine. Basic and clinical concepts. Circulation. 1991;83(5):1499-1509. (Review)
94. Fishberger SB, Mehta D, Rossi AF, et al. Variable effects of adenosine on retrograde conduction in patients with atrioventricular nodal reentry tachycardia. Pacing Clin Electrophysiol. 1998;21(6):1254-1257. (Prospective; 13 patients)
95. Goy JJ, Tauxe F, Fromer M, et al. Ten-years follow-up of 20 patients with idiopathic ventricular tachycardia. Pacing Clin Electrophysiol. 1990;13(9):1142-1147. (Retrospective; 20 patients)
96. Wilber DJ, Baerman J, Olshansky B, et al. Adenosine-sensitive ventricular tachycardia. Clinical characteristics and response to catheter ablation. Circulation. 1993;87(1):126-134. (Retrospective; 14 patients)
97. Sarko JA, Tiffany BR. Cardiac pacemakers: evaluation and management of malfunctions. Am J Emerg Med. 2000;18(4):435-440. (Review)
98. Sadoul N, Mletzko R, Anselme F, et al. Incidence and clinical relevance of slow ventricular tachycardia in implantable cardioverter-defibrillator recipients: an international multicenter prospective study. Circulation. 2005;112(7):946-953. (Prospective randomized; 374 patients)
99. Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med. 2002;346(12):877-883. (Prospective randomized; 1232 patients)
100. Xie J, Weil MH, Sun S, et al. High-energy defibrillation increases the severity of postresuscitation myocardial dysfunction. Circulation. 1997;96(2):683-688. (Basic science research)
101. Moss AJ, Schuger C, Beck CA, et al. Reduction in inappropriate therapy and mortality through ICD programming. N Engl J Med. 2012;367(24):2275-2283. (Prospective randomized; 1500 patients)
102. Savelieva I, Graydon R, Camm AJ. Pharmacological cardioversion of atrial fibrillation with vernakalant: evidence in support of the ESC Guidelines. Europace. 2014;16(2):162-173. (Review)
103. 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; 111 patients)