Supraventricular Tachycardia (SVT) can be a very rewarding condition to treat! It is generally easy to diagnose and can be very satisfying to treat. When treating it, we also get to use one of the “coolest” medicines (ok, it isn’t quite as cool as Ketamine): Adenosine. Unfortunately, sometimes SVT can be recalcitrant (like a teenager) and won’t respond to the 1st dose of Adenosine. Let us take a second to review refractory SVT and the Adenosine Dose:
- Adenosine is an endogenous nucleoside found ubiquitously in people.
- Rapidly metabolized in the plasma by adenosine deaminase.
- Half-life is extremely short < 10 seconds… some even report < 2 seconds.
- Binds to the adenosine receptors in SA and AV nodes and atrial myocytes
- Causes hyper-polarization of the cell membranes.
- Causes AV block.
- Leads to decrease in heart rate.
- Adenosine is safe and effective at treating SVT. [Lewis, 2017; Losek, 1999; Reyes, 1992]
- Doses of 0.1 – 0.3 mg/kg are most effective [Losek, 1999]
- 0.1 mg/kg effective in ~20%-66% cases [Quail, 2012]
- 0.2 mg/kg effective in ~72-100% cases [Quail, 2012]
- Adverse/Side Effects:
- Sinus bradycardia
- Long sinus node pauses (which makes you have intestinal distress while watching it.)
- SVT is the most common encountered tachyarrhythmia in pediatrics.
- Refractory SVT = SVT that did not resolve with 1st or 2nd therapy (it is super annoying!).
- Occurs in ~ 15% of all pediatric cases. [Lewis, 2017; Paul, 1997]
- Current guidelines from American Heart Association: [de Caen, 2010]
- 1st dose of Adenosine – 0.1 mg/kg (or 6 mg for adult sized humans)
- 2nd dose of Adenosine – 0.2 mg/kg (or 12 mg for adult sized humans)
- Cardioversion for:
- Altered Mental Status.
- Also cadrioversion if delay in giving adenosine anticipated with associated:
- Impaired perfusion
- Of note, there has been a documented “reluctance” for providers to use electric cardioversion in children. [Lewis, 2017]
- 11 of 13 patients who had unstable SVT were treated without electric cardioversion [Lewis, 2017]
- In 10 years of study, synchronized cardioversion was performed in only in 3 patients and only once while in the ED (so everyone is reluctant to use this safe therapy).
- Children do, generally tolerate SVT for prolonged time, but can lead to morbidity…
- Refractory SVT is seen with greater frequency in infants! [Lewis, 2017]
- Especially infants that are given 0.1 mg/kg as 1st dose.
- Lower response rate thought to be due to:
- Inadequate delivery of adenosine in infants
- Smaller gauge IV
- Using 3-way stopcock method in children < 10 kg (usually kids are ~10kg at 1yr) leads to lower than intended dose delivery. [Weberding, 2017]
- Relatively resistance of infants’ AV node to adenosine
- Infants presenting later in course of illness (i.e., present more subtly – “poor feeding”)
- Inadequate delivery of adenosine in infants
- Using higher initial dose (0.2 mg/kg) as initial therapy has been advocated. [Lewis, 2017; Quail, 2012; Qureshi, 2012]
- Higher dose can reduce risk of unsuccessful cardioversion by 35% in both infants and children [Quail, 2012]
- Number Needed to Treat = 3 [Quail, 2012]
- SVT is common (up to 50% of patients) after heart transplantation. [Flyer, 2017]
- Adenosine often considered contraindicated in heart transplant patients due to parasympathetic denervation -> increased sensitivity of SA and AV receptors. [Flyer, 2017]
- Now know to be safe, but can use much LOWER doses (0.025 mg/kg; 1.5 mg for >60kg). [Flyer, 2017]
Moral of the Morsel:
- Adenosine is Awesome!… but it isn’t perfect.
- Go Big! Since Adenosine has such a short half-life, larger dose has the benefit of better efficacy with little added risk.
- Avoid Refractory! 0.2 mg/kg starting dose may make your life (and the kids’) a little easier!
- Anticipate Refractory! Especially for the children who are under 1 year of age. Know what your next steps are.
- Use electricity for SVT and altered mental status! While kids can tolerate SVT well, I cannot tolerate poor perfusion to my patients’ brains!
Lewis J1, Arora G2, Tudorascu DL3, Hickey RW1, Saladino RA1, Manole MD4. Acute Management of Refractory and Unstable Pediatric Supraventricular Tachycardia. J Pediatr. 2017 Feb;181:177-182. PMID: 27912926. [PubMed] [Read by QxMD]
Weberding NT1, Saladino RA1, Minnigh MB2, Oberly PJ2, Tudorascu DL3, Poloyac SM2, Manole MD4. Adenosine Administration With a Stopcock Technique Delivers Lower-Than-Intended Drug Doses. Ann Emerg Med. 2017 Oct 28. PMID: 29089171. [PubMed] [Read by QxMD]
Flyer JN1, Zuckerman WA1, Richmond ME1, Anderson BR1, Mendelsberg TG1, McAllister JM1, Liberman L1, Addonizio LJ1, Silver ES2. Prospective Study of Adenosine on Atrioventricular Nodal Conduction in Pediatric and Young Adult Patients After Heart Transplantation. Circulation. 2017 Jun 20;135(25):2485-2493. PMID: 28450351. [PubMed] [Read by QxMD]
Goodman IS1, Lu CJ. Intraosseous infusion is unreliable for adenosine delivery in the treatment of supraventricular tachycardia. Pediatr Emerg Care. 2012 Jan;28(1):47-8. PMID: 22217885. [PubMed] [Read by QxMD]
Qureshi AU1, Hyder SN, Sheikh AM, Sadiq M. Optimal dose of adenosine effective for supraventricular tachycardia in children. J Coll Physicians Surg Pak. 2012 Oct;22(10):648-51. PMID: 23058149. [PubMed] [Read by QxMD]
Quail MA1, Till J. Question 3 Does a higher initial dose of adenosine improve cardioversion rates in supraventricular tachycardia? Arch Dis Child. 2012 Feb;97(2):177-9. PMID: 22241922. [PubMed] [Read by QxMD]
Kleinman ME, de Caen AR, Chameides L, Atkins DL, Berg RA, Berg MD, Bhanji F, Biarent D, Bingham R, Coovadia AH, Hazinski MF, Hickey RW, Nadkarni VM, Reis AG, Rodriguez-Nunez A, Tibballs J, Zaritsky AL, Zideman D; Pediatric Basic and Advanced Life Support Chapter Collaborators. Part 10: Pediatric basic and advanced life support: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2010 Oct 19;122(16 Suppl 2):S466-515. PMID: 20956258. [PubMed] [Read by QxMD]
Losek JD1, Endom E, Dietrich A, Stewart G, Zempsky W, Smith K. Adenosine and pediatric supraventricular tachycardia in the emergency department: multicenter study and review. Ann Emerg Med. 1999 Feb;33(2):185-91. PMID: 9922414. [PubMed] [Read by QxMD]
Paul T1, Pfammatter JP. Adenosine: an effective and safe antiarrhythmic drug in pediatrics. Pediatr Cardiol. 1997 Mar-Apr;18(2):118-26. PMID: 9049125. [PubMed] [Read by QxMD]
Reyes G1, Stanton R, Galvis AG. Adenosine in the treatment of paroxysmal supraventricular tachycardia in children. Ann Emerg Med. 1992 Dec;21(12):1499-501. PMID: 1443850. [PubMed] [Read by QxMD]
[…] removing a Nasal Foreign Body) and other times it is through more exotic means (like administering Adenosine or Ketamine). One condition that we often don’t consider, but perhaps we should more, is a […]
Great article! I will certainly keep your suggestions in mind when treating my next pediatric SVT patient.
Dale Mole’, DO, FACEP
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