The Modified Valsalva Maneuver: Head Down, Legs Up

Background: Supraventricular tachycardia (SVT) is not an uncommon presentation to the emergency department. A common first-line therapy for hemodynamically stable SVT is the standard Valsalva maneuver (sVm) but it has a low success rate (5-20%). After failed conversion to normal sinus rhythm with sVm, patients who remain in SVT, the next step is typically to receive intravenous adenosine; it briefly stops all conduction through the AV node causing a sense of doom in patients.

The modified Valsalva maneuver (mVm) has been shown to have a higher success rate in converting hemodynamically stable SVT to normal sinus rhythm (NSR) when compared to sVm (REVERT trial). MVm works by increasing venous return and vagal stimulation by laying patients supine and elevating their legs and has been shown to be a simple, safe and cost effective method. There have now been several RCTs since the publication of the 2015 REVERT trial showing a similar success rate of converting patients to NSR with the mVm in comparison to sVm, however they have not been pooled into a meta-analysis until now.

Article: Abdulhamid AS et al. Modified Valsalva Versus Standard Valsalva for Cardioversion of Supraventricular Tachycardia: Systematic Review and Meta-Analysis. International Journal of Arrhythmia 2021. [Link is HERE]

Clinical Question: Is the modified Valsalva maneuver (mVm) more successful than the standard Valsalva maneuver (sVm) at converting SVT to normal sinus rhythm?

What They Did:

Systematic review and meta‐analysis searching Medline/PubMed, Ovid, Web of Science, and Cochrane Central Register of Controlled trials.
Only randomized controlled trials (RCTs) that compared the mVm to the sVm in treating SVT were included

Outcomes:

Primary: Termination of SVT within 1 minute
Secondary:
- Need for emergency abortive antiarrhythmic medication
- Reported adverse events related to either of the valsalva maneuvers
- Time spent in the ED

Trial Characteristics:

Literature yielded 875 articles
- 4 articles (Published between 2015 to 2019) were included in the review that met all inclusion criteria
- 787 total participants
  - sVm = 394 participants
  - mVm = 393 participants
  - Mean age = 44.3 to 61years

Critical Findings:

- Primary Outcomes
  - Termination of SVT in 1 minute
    - mVm more effective in restoring NSR than sVm (RR=2.54, CI 1.98–3.24, P<0.001)
  - Comparison of Return to Sinus Rhythm in 1 min between mVM and sVM
    - Appelboam 2015
      - mVm: 93/214 (43.5%)
      - sVm: 37/214 (17.3%)
    - Cobacioglu 2017
      - mVm: 12/28 (42.9%)
      - sVm: 3/28 (10.7%)
    - Ceylan 2019
      - mVm: 12/32 (37.5%)
      - sVm: 4/33 (12.1%)
    - Chen 2019
      - mVm: 55/119 (46.2%)
      - sVm: 19/119 (16.0%)
    - Pooled
      - mVm: 172/393 (43.8%)
      - sVm: 63/394 (16.0%)
      - NNT = 3.6

Secondary Outcomes

- Need for Emergency Abortive Antiarrhythmic Medication (Reported in 3 studies)
  - mVm: 191/361 (52.9%)
  - sVm: 280/361 (77.6%)
  - RR 0.68; 95% CI 0.61 to 0.76; p < 0.001
- Reported Adverse Events Related to Either of the Valsalva Maneuvers (Reported in 3 studies)
  - mVm: 17/361 (4.7%)
  - sVm: 11/361 (3.0%)
  - RR 1.53; 95% CI 0.73 to 3.23; p = not statistically significant
- No statistically significant difference in time spent in the ED between groups

Strengths

Only randomized controlled trials were included
Broad search of literature with 875 articles reviewed
Easily reproducible intervention
Meaningful outcomes selected
Largest study in the meta-analysis (55% weight of the primary outcome) had a low risk of bias
Conducted systematic review and meta-analysis according to a respecified protocol following PRISMA guidelines

Limitations

Small sample size for a meta-analysis
No pediatric patient data
No subgroup analysis
Hospital admission is a subjective outcome. A study with pre-determined admission criteria would be needed to answer this question

Discussion

MVm is highly effort dependent and could be one of the reasons variability in success rates is seen in the literature. Anecdotally, I have found coaching patients prior to starting the procedure the importance of effort and the steps of the procedure to help improve success rates
Blowing into an empty 10cc syringe, can result in an intrathoracic pressure equivalent of 40mmHg and is more widely available than an aneroid manometer
The passive leg raise at the end of the mVm will help increase preload which in turn increases cardiac output causing a higher vagal response and potentially a higher success rate in conversion to NSR
Of note in the Chen et al study a 90 degree leg raise was used instead of a 45 degree leg raise. This resulted in a higher conversion rate than the other three studies
Few things in American medicine are simple, cost zero dollars, are well tolerated and have zero serious adverse events. This study reiterates and solidifies the fact that the mVm is the go to treatment for patients with hemodynamically stable SVT.
Performing mVm could decrease hospital resource utilization because if successful, does not require an IV line, pad placement or even hospitalization. During pandemic times when all hospital beds and equipment are in short supply this treatment can be invaluable

Authors Conclusion:

“Our review found MVM to be more effective than SVM in terminating SVT. This should encourage broader adoption of the MVM as a first-line vagal maneuver in subjects presenting with SVT in the emergency room.”

Clinical Take Home Point

In patients with hemodynamically stable SVT the modified Valsalva maneuver should be the first line treatment as it is more effective than standard treatment in converting patients to NSR. It is simple, costs nothing, has similar adverse events, and similar time spent in the ED as standard Valsalva maneuver.

References:

Abdulhamid AS et al. Modified Valsalva Versus Standard Valsalva for Cardioversion of Supraventricular Tachycardia: Systematic Review and Meta-Analysis. International Journal of Arrhythmia 2021. [Link is HERE]

For More Thoughts on This Topic Checkout:

REBEL EM: The REVERT Trial – A Modified Valsalva Maneuver to Convert SVT
REBEL EM: Another RCT of the Modified Valsalva Maneuver

Post Peer Reviewed By: Salim R. Rezaie, MD (Twitter: @srrezaie)
Post Cover Photo By: Mark Ramzy, DO (Twitter: @MRamzyDO)

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