Guest Skeptic: Dr. Robert Edmonds. Bob is a third year Emergency Medicine Resident at the University of Missouri at Kansas City. Prior to medical school, he graduated from the US Air Force Academy, and when he completes his training will rejoin the Air Force for nine years as an Emergency Medicine physician.
Case: A 24-year-old female presents to the emergency department with palpitations. She feels anxious but is hemodynamically stable and her ECG demonstrates supra ventricular tachycardia (SVT). This condition has happened several times before and she hates the medication she is usually given in the emergency department that makes her feel like she is dying.
Background: Patients with SVT often present to the emergency department. Life in the Fast Lane has a good blog posting about SVT.
Restoring patents back to a sinus rhythm can be done in a number of ways, including electrical, pharmacologic, and non-pharmacologic. For the hemodynamically unstable patient, synchronized cardioversion is usually the preferred treatment.
If they are not hemodynamically unstable, a variety of drugs have been used to stop SVT such as adenosine, calcium channel blockers, and beta blockers. It is the adenosine that people find particularly upsetting and is probably why the woman in this case is anxious about having her heart temporarily stop again.
Another way to convert patients that does not include drugs or electricity uses the mammalian dive reflex. This is used more often in children than in adults. Smith et al also published a review article on this method. The patient puts their face in an ice-cold bath. I have used this one time successfully on a patient who did not want to have adenosine again.
Carotid massage can also be tried but has the risk of adverse outcomes in elderly patients.
The Valsalva manoeuvre is a non-invasive way to convert patients from SVT to sinus. It increases the myocardial refractory period by increasing intrathoracic pressure, thus stimulating baroreceptors in the aortic arch and carotid bodies increasing vagal tone.
The effectiveness of the Valsalva manoeuvre for conversion of SVT was on SGEM#67. It was a systematic review by Smith et al that included three studies. Only one was from the emergency department setting and demonstrated a conversion rate of only 19%.
Clinical Question: Can a modified Valsalva manoeuvre help convert stable patients presenting to the emergency department with SVT to a sinus rhythm more often than a standard Valsalva manoeuvre?
Reference: Appelboam et al. Postural modification to the standard Valsalva manoeuvre for emergency treatment of supraventricular tachycardias (REVERT): a randomised controlled trial. Lancet 2015.
Population: Adult patients presenting to the emergency department with SVT (Ten Hospitals in the United Kingdom: two teaching hospitals, eight district general hospitals).
Inclusion: Over 18 years of age with a narrow complex tachycardia (QRS duration less than 0.12 seconds on ECG).
Unstable patients with systolic blood pressure less than 90mmHg
Patients with an indication for immediate cardioversion
Those in atrial fibrillation or flutter
Suspected atrial flutter requiring a trial of adenosine
Any contraindication to the Valsalva manoeuvre (aortic stenosis, recent MI, glaucoma, or retinopathy)
Inability to perform Valsalva, lie flat, or have legs lifted
Patients were to strain with a pressure of 40 mmHg sustained for 15 seconds by forced expiration. Immediately at the end of the strain, patients were laid flat and had their legs elevated by a staff member to 45 degrees for 15 seconds. Patients were then returned to a semi recumbent position for 45 seconds before their cardiac rhythm was reassessed by a three lead ECG.
Comparison: The standard Valsalva manoeuvre
Strain with a pressure of 40 mmHg sustained for 15 seconds by forced expiration. Patients remained semi recumbent at 45 degrees in a trolley and remained in this position for 60 seconds before reassessed for cardiac rhythm, initially by three lead ECG.
Primary: Return to sinus rhythm at one minute confirmed by ECG.
Secondary: Use of adenosine, use of any anti-arrhythmic, discharge home, length of stay in the emergency department and adverse events.
Author’s Conclusions:“In patients with supraventricular tachycardia, a modified Valsalva manoeuvre with leg elevation and supine positioning at the end of the strain should be considered as a routine first treatment, and can be taught to patients.”
Quality Checklist for Randomized Clinical Trials:
The study population included or focused on those in the ED. Yes
The patients were adequately randomized. Yes-by an independent statistician
The randomization process was concealed. Yes
The patients were analyzed in the groups to which they were randomized. Yes
The study patients were recruited consecutively (i.e. no selection bias). Yes
The patients in both groups were similar with respect to prognostic factors. Yes
All participants (patients, clinicians, outcome assessors) were unaware of group allocation. No-It was impossible to blind clinicians. Patients were blinded as we’ll discuss later. Statistical analysis was done by investigators blinded to treatment allocations.
All groups were treated equally except for the intervention. Yes
Follow-up was complete (i.e. at least 80% for both groups). Yes
All patient-important outcomes were considered. Yes
The treatment effect was large enough and precise enough to be clinically significant. Yes
Key Results: N=428 with mean age in the mid 50’s, approximately 40% being male and just less than half had a history of SVT.
The modified Valsalva manoeuvre resulted in an increased frequency of conversion out of SVT to a sinus rhythm, compared to the standard Valsalva manoeuvre. The primary outcome of return to sinus rhythm had an adjusted odds ratio (AOR) = 3.7 (95% CI: 3.3, 5.8, P<0.0001); NNT = 4 (95% CI: 3, 7)
Return to sinus rhythm at one minute: 43% vs. 17%, NNT = 4
Secondary Outcomes (modified vs. standard):
Less use of adenosine (50% vs. 69%): AOR=0.45 (95% CI: 0.30, 0.68; P=0.0002);
Less use of anti-arrhythmic treatment (57% vs. 80%): AOR=0.33 (95% CI: 0.21, 0.51; P<0.0001);
No difference discharge home (63% vs. 68%): AOR= 0.79 (95% CI: 0.51, 1.21; P<0.28);
No difference in time spend in the emergency department (2.82hrs vs. 2.83hrs): AOR=0.90 (95% CI: 0.75, 1.10; P=0.32)
No difference in adverse events (6% vs. 4%): AOR= 1.61 (95% CI: 0.63, 4.08; P<0.31);
This was a very well done, pragmatic study looking at a common problem. It provided a simple and cheap treatment option that was well tolerated and had impressive NNT of 4.
Dr. Robert Edmonds
Blinding: As mentioned in the checklist section, it was not possible to blind the patient or the treating physician to treatment group. The participants were not aware of which treatment was the “new” method so that should have help with blinding the patients. The investigators also had the analysis of the ECG blinded. An independent cardiologist who was masked to the treatment group allocation retrospectively assessed the ECGs. They even had an independent eletrophysiologist also blinded to treatment group assignment arbitrate any disagreements with the treating physician’s ECG interpretation.
Comment on author’s conclusion compared to SGEM Conclusion: We agree with the authors that a modified Valsalva manoeuvre should be tried first as routine care for stable SVT patients presenting to the emergency department and patients can be taught this technique.
SGEM Bottom Line: Try modifying the Valsalva manoeuvre to REVERT you next stable patient with SVT to a sinus rhythm.
Case Resolution: You have the patient perform a modified Valsalva manoeuvre, and after rehearsing what to do with the patient, she performs it with staff assistance and successfully converts out of SVT.
Clinical Application: This new information is enough to convince me to try the modified Valsalva manoeuvre for the next hemodynamically stable patient presenting with SVT.
What do I tell my patient? There is new and simple way that can slow your heart rate down to normal. It does not involve any drugs or electricity. It is successful in over 4 out of 10 patients. We have a short video for you to watch to show you how it’s done. After you have watched the video we can give it a try.
The Bottom Line Review:Postural modification to the standard Valsalva manoeuvre for emergency treatment of supraventricular tachycardias (REVERT) – A randomised controlled trial
Keener Kontest: Last weeks’ winner was Gerhard Dashi. He knew the Glenn Fry song The Heat is On was in the movie Beverly Hills Cop staring Eddie Murphy.
Listen to the SGEM for this weeks’ keener question. If you know the answer then send it to TheSGEM@gmail.com with “Keener” in the subject line. The 1st 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.