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Date: March 30th, 2018

Reference: Bronzetti et al. Upside-down position for the out of hospital management of children with supraventricular tachycardia.  International Journal of Cardiology. February 2018.

Guest Skeptic: Dr. Robert Edmonds is an Emergency physician in the US Air Force. This is his 6th visit to the SGEM.

DISCLAIMER: The views and opinions of this podcast do not represent the United States Government or the US Air Force.

Case: A seven-year-old girl presents to your emergency department complaining of palpitations.  On exam she appears anxious and begs you not to give “that drug that makes my heart stop like that last doctor did.”  You know vagal maneuvers are first-line, but there’s variation in techniques.  As the patient already tried breathing out of her clenched nose, you wonder if there is another safe method you can try prior to medications.

Background: Supraventricular tachycardia (SVT) has a prevalence anywhere from 1 in 250 to 1 in 1,000 in children and is the most common arrhythmia in children. Forty percent of patients experience the first episode of SVT in the first month of life, and over 50% have their first episode in their first year of life [1].

Vagal maneuvers are thought to be first-line treatment as they are non-invasive and can rapidly resolve the episode when successful.  Several methods exist, such as carotid sinus massage, mammalian dive reflex, and the Valsalva maneuver [2].

We have covered SVT on the SGEM a couple of times. The first time was a Cochrane systematic review done by Smith et al on the effectiveness of the Valsalva maneuver for reversion of SVT (SGEM#67). Only one study in that review was from the emergency department and it reported a reversion rate of 19%.

The second time we covered SVT was a critical review of the REVERT Trial (SGEM#147). It was an randomized control trial using a modified Valsalva maneurer to convert SVT. The result was a return to sinus rhythm at one minute in 43% of patients treated with the modified Valsalva vs. 17% of patients treated with the standard Valsalva.

This gives an NNT of 4. Four patients needed to be treated with the modified Valsalva for one more patients to return to sinus rhythm at one minute.  The authors of the study we are talking about today were aware of case studies of a modification to the Valsalva maneuver in children [3-5]. The maneuver involves the child doing a handstand or being held upside down. 

Clinical Question: Is the upside-down position a safe and effective modified Valsalva maneuver?

Reference: Bronzetti et al. Upside-down position for the out of hospital management of children with supraventricular tachycardia.  International Journal of Cardiology. February 2018.

  • Population: Patients age 1-18 years followed at the pediatric arrhythmology outpatient clinic with SVT. SVT was defined by a regular, narrow complex tachycardia with QRS duration <0.12 s on ECG and/or for the demonstrated sensitivity to adenosine diagnosed by a pediatric cardiologist with >15 years of experience in pediatric arrhythmia management.
    • Exclusion Criteria:
      • Age – Greater than 18 years or  less than one year
      • Unstable – Patients with hypotension or those who required immediate cardioversion
      • ECG diagnosis of automatic atrial tachycardia, permanent form of junctional reciprocating tachycardia, atrial fibrillation or flutter
      • Underlying congenital heart disease
      • Contraindications to Valsalva Maneuver/upside down position or inability to perform them
    • Intervention: Upside-down position treatment
      • Parents manually flipped patients <30 kg or uncooperative and <30 kg upside-down for 30 seconds.
      • Cooperative patients >30 kg were asked to perform a handstand for 30 seconds.
    • Comparison: Standard Valsalva maneuver treatment
      • The semi-recumbent patient blew into a 10 ml syringe to move the plunger for 15 seconds.
    • Outcome:
      • Primary Outcome: Cardioversion out of SVT
      • Secondary Outcome: “Rescue” cardioversion – If the patients failed the maneuver, they then attempted the other group’s technique and this rate of cardioversion was measured.
      • Relapse: At the patient’s first relapse, the patients underwent the opposite intervention, with the protocol to switch techniques in event of failure.

Authors’ Conclusions: “The upside-down position was safe and tended to be more effective than standard VM (Valsalva Maneuver) for out of hospital SVT treatment.  Doctors and parents should be more aware of this effective but overlooked manoeuvre.”

checklistQuality Checklist for Randomized Clinical Trials:

  1. The study population included or focused on those in the emergency department. No
  2. The patients were adequately randomized. Yes
  3. The randomization process was concealed. Unsure
  4. The patients were analyzed in the groups to which they were randomized. Yes
  5. The study patients were recruited consecutively (i.e. no selection bias). No
  6. The patients in both groups were similar with respect to prognostic factors. Yes and No
  7. All participants (patients, clinicians, outcome assessors) were unaware of group allocation. No 
  8. All groups were treated equally except for the intervention. Yes
  9. Follow-up was complete (i.e. at least 80% for both groups). Yes
  10. All patient-important outcomes were considered. Yes
  11. The treatment effect was large enough and precise enough to be clinically significant. No

Key Results: There were 15 girls and 9 boys enrolled in this study with a mean age of 7 years. They had different types of SVT and eight were on pharmacological SVT prophylaxis.

  • 16 patients had atrioventricular re-entry tachycardia
  • 4 patients had atrioventricular nodal re-entry tachycardia
  • 4 patients’ ECG features were consistent with both of the aforementioned SVT types

The upside-down Valsalva maneuver did not statistically convert more children out of SVT compared to standard Valsalva maneuver.

  • Primary Outcome: The upside-down position terminated SVT in 67% of the study group versus 33% of the standard Valsalva maneuver group on the first try (p=0.1)
  • Secondary Outcomes: Rescue, Relapse and Relapse Rescue
    • There was no statistical difference in these outcomes either and the details will be put in the show notes.
    • Rescue: The upside-down position terminated SVT as a rescue attempt after a failed Valsalva maneuver 50% of the time, and the Valsalva maneuver terminated SVT as a rescue after a failed upside-down 0% of the time (p=0.2).
    • Relapse: The upside-down terminated SVT in 67% of patients vs 42% of controls (p=0.2)
    • Relapse Rescue: The upside-down terminated SVT as a rescue attempt after a failed Valsalva maneuver 71% of the time and the Valsalva maneuver terminated SVT as a rescue after a failed upside-down 25% of the time (p=0.2)
  • Adverse Events: There were no adverse events recorded

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Because this is Bob’s sixth visit to the SGEM as the guest skeptic we are going to have six nerdy points to discuss.

  1. Selection Bias – The authors address this, but patients were selected exclusively from a tertiary referral center. The authors also state that they selected patients and families that seemed very reliable. This makes it hard to apply these results to all children presenting to an emergency department with SVT
  2. Misleading Figure – Figure 1 shows a flow chart to help describe the manner in which the patients flipped between methods. When describing the patients in the study group for the first episode of SVT, the authors show how 4 of 12 patients failed the upside-down modified Valsalva maneuver. The figure then shows these 4 patients undergoing a rescue Valsalva maneuver but depicts how 8 of 8 patients that failed the upside-down modified Valsalva maneuver failed the rescue Valsalva maneuver.  It is unclear how the patients doubled, and this sort of error unfortunately detracts from the study.
  3. Adverse Events – The authors confidently state that the method is safe but do not describe any sort of monitoring for adverse events. It is unclear if the parents were given instructions on needing to document and adverse events. The study was also far too small to claim safety as it was not powered to investigate this outcome. It would have been more accurate to state that there were no adverse events. This is what they did say in the result section of the paper.
  4. Study Size – This was a relatively small study with only 24 patients. It should to be replicated in a larger and preferably multi-center study.
  5. Trend – They report a trend towards greater effectiveness of the upside-down modified version of the Valsalva maneuver compared to the standard maneuver. What that means is the intervention was not statistically significant.
  6. p-value-statistics-memeP-Values – Dr. Ioannidis just published a paper suggesting we move the threshold for p-values to 0.005 (JAMA 2018). He is the same author who wrote a paper called “Why Most Published Research Findings Are False” (PLoS 2005). This caused a bit of a twitter storm about the misunderstanding and misuse of p-values. This study relied on p-values to interpret the data. P-values do not provide information on effect size, precision or clinical significance of a result. We need to move away from interpreting anything <0.05 as “significant” and anything >0.05 as “not significant”. This is a much larger topic and I will put some links in the show notes to better understand this issue.
    • S. Greenland et al. Statistical tests, P values, confidence intervals, and power: a guide to misinterpretations. Eur J Epidemiol 2016 
    • Letter to the Editor.P-values are misunderstood, but do not confound
      J Clin Epi 2011

Comment on Authors’ Conclusion Compared to SGEM Conclusion: We disagree with the authors conclusions. In part because they claimed safety but did not design the study for safety or adequately explain how adverse events were monitored. Additionally, we do not believe doctors and parents should be told this is an effective maneuver until it has been demonstrated in a high-quality study.

SGEM Bottom Line: The upside-down maneuver exists, but further research is needed to determine if it has efficacy in children with SVT.

Case Resolution: You attempt a standard vagal maneuver with the patient, which fails.  The patient then undergoes chemical cardioversion with adenosine successfully.

Dr. Robert Edmonds

Dr. Robert Edmonds

Clinical Application: There is no clinical application for this upside-down modified Valsalva maneuver unless future research demonstrates its safety and efficacy.

What Do I Tell My Patient?  You inform the family that the upside-down technique is still under investigation and not been demonstrated to be better than usual treatment. However, they can always discuss the modified Valsalva maneuver with their cardiologist at their next follow-up.

Keener Kontest: Last weeks’ winner was Dave Lemonick from Pittsburgh. He knew MOOSE stood for Meta-analyses Of Observation Studies in Epidemiology and PRISMA stood for Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Listen to the SGEM podcast on iTunes to hear this weeks’ question. If you know the answer send an email to TheSGEM@gmail.com with “keener” in the subject line. The first correct answer will receive a cool skeptical prize.

Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine.

References:

  1. J.C.Salerno,M.M.Garrison,C.Larison,S.P.Seslar,Case fatality in children with supraventricular tachycardia in the United States, Pacing Clin. Electrophysiol. 34 (7) (2011) 832–836
  2. J. Brugada et al. Pharmacological and non-pharmacological therapy for arrhythmias in the pediatric population: EHRA and AEPC-Arrhythmia Working Group joint consensus statement. EP Europace, Volume 15, Issue 9, 1 September 2013, Pages 1337–1382
  3. I. Constantiniu, Unusual treatment of paroxysmal tachycardia, Br. Med. J. 1 (5744) (1971) 347.
  4. Y.P. Tai, C.B. Colaco, Upside-down position for paroxysmal supraventricular tachycardia, Lancet 2 (8258) (1981) 1289.
  5. M. Hare, S. Ramlakhan, Handstands: a treatment for supraventricular tachycardia? Arch. Dis. Child. 100 (1) (2015) 54–55

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