SGEM#67: Shock the Monkey Tonight (Valsalva Maneuver for SVT)

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Date: March 23, 2014

Case Scenario: Thirty-year-old woman presents for the first time with supraventricular tachycardia (SVT). You call the cardiologist after three unsuccessfully attempts to chemically convert her into sinus. The cardiologists asked you why you did not try the Valsalva maneuver (VM).

Question: Is the valsalva maneuver effective in converting supra ventricular tachycardia?

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 by the VM, drugs (adenosine, calcium channel blockers or beta-blockers) or electricity (synchronized cardioversion).

The VM is a non-invasive way to convert patients from SVT to sinus.It increases myocardial refractory period by increasing intrathoracic pressure thus stimulating baroreceptors in the aortic arch and carotid bodies Increases vagal tone (parasympathetic).

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 el 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. I almost picked the mammalian dive reflex as the keener question.

Article: Smith et al. Effectiveness of the Valsalva Manoeuvre for reversion of supraventricular tachycardia. Cochrane Database March 2013.

Population: 316 patients presenting with SVT from three randomized controlled trials from Singapore, England, and Taiwan. Two studies were done in a controlled arrhythmia lab setting after patients had ceased all medications. One study involved patients presenting undifferentiated to an emergency department with an episode of SVT.
 Intervention: Valsalva maneuver defined by posture [supine or supine with legs elevated], strain duration [15 to 30 seconds], and pressure [intraoral with range 30 to 50 mm Hg].
Comparison: Standard pharmacological therapy for cardioversion of SVT.
Outcome: The primary outcome was reversion of SVT to sinus rhythm. Side effects, cardiovascular effects and mortality associated with VM use for SVT were not reported in any of the studies.

Authors’ Conclusions: “We did not find sufficient evidence to support or refute the effectiveness of the Valsalva Maneuver for termination of SVT. Further research is needed and this should include a standardized approach to performance technique and methodology.”

Quality Checklist:

Clinically relevant question with an established criterion standard? Yes. The question is clinically relevant but unfocused in terms of exact presentation of SVT (varying etiologies, such as primary or recurrent or artificial i.e. induced).
Search detailed and exhaustive. Yes
The methodological quality of primary studies were assessed for common forms of bias? Yes. The authors assessed risk of bias using the Cochrane Handbook for Systematic Reviews of Intervention checklist to determine potential selection bias, performance bias, attrition bias, or detection bias. Most patients included were pre-selected, prepared and had lab-induced SVT.
Assessments of studies were reproducible? Yes
Was there low between-study heterogeneity. No. The studies were very heterogeneous, only one included emergency department patients, and 2/3 included induced SVT with prior exclusions of home medications.

Key Results: They found three randomized controlled trials of 316 patients presenting with SVT. Two studies were done in a controlled arrhythmia lab setting after patients had ceased all medications. One study involved patients presenting undifferentiated to an emergency department with an episode of SVT.

Primary Outcome: Conversion of SVT (results could not be pooled due to heterogeneity)
- Arrhythmia lab: 54.3% (19/35) and 45.9% (61/133)
- Emergency Department 19.4% (12/62).

BEEM Commentary: Only one of the included studies was on emergency department presentations of spontaneous SVT and not induced SVT (controlling for prior medications and co-morbidities). This grouped comparison is not applicable to the emergency medicine group and does not answer questions with respect to varying VM techniques. The patients with induced SVT in the lab, and who had prior medications held do not represent patients seen in the emergency department with spontaneous SVT or primary SVT. The authors recognize the fact the included review studies are limited in application to SVT presentations.

Bottom Line: There is no standardized methods to perform a VM to terminate uncomplicated SVT that are evidence based.

Clinical Application: VM is a viable technique that is poorly researched for the conversion of SVT and should not be considered essential to attempt prior to chemical cardioversion. It may work in up to 20% of presentations. What do I tell my patient: We can try a valsalva maneuver (pushing air out with your throat, mouth, and nose closed) with reasonable safety while preparing medications for a rapid heartbeat like you have to attempt to correct your palpitations. However, there is no evidence that pushing the air out will be effective and may only work approximately 1 out of every 5 attempts.

Keener Kontest: Last weeks winner was Luis Rubio. He knew that I was going to be away teaching at SweetBEEM this week.

Listen to this weeks podcast for the Keener Question. If you know what the answer send me an email to TheSGEM@gmail.com with keener in the subject line. The first person to correctly answer the keener question will receive a cool skeptical prize.