NASVAL-SVT: Nasal Swab Versus Modified Valsalva for Supraventricular Tachycardia (NASVAL-SVT)

A Randomized Controlled Trial Comparing Nasal Swab and Modified Valsalva Maneuver for the Treatment of Supraventricular Tachycardia

Supraventricular tachycardia (SVT) is a common heart rhythm disorder seen in emergency departments, causing a rapid heartbeat (typically 150-250 beats per minute). The current best non-drug treatment, the modified Valsalva maneuver (mVM), successfully restores normal rhythm in about 43% of cases. When these maneuvers fail, intravenous adenosine is used, which, while effective, can cause brief but distressing side effects such as chest tightness, shortness of breath, and intense anxiety.

During the COVID-19 pandemic, some patients briefly fainted during nasal swab collection. This happens because inserting a swab into the back of the nasal cavity (nasopharynx) stimulates the trigeminal nerve, which then activates the vagus nerve and slows the heart - a phenomenon called the trigeminocardiac (or nasocardiac) reflex. One published case report described a patient whose SVT was terminated within 10 seconds using a nasal swab.

This study compares the nasal swab technique with the modified Valsalva maneuver in patients presenting to the emergency department with SVT. Patients are randomly assigned to one of two groups. The primary outcome is whether a normal heart rhythm is restored within 1 minute of the procedure. Patient comfort and satisfaction are also measured.

The study is conducted in two phases. The first (pilot) phase (30 patients per group) will assess whether the study can be successfully conducted and collect data to finalize the required sample size. The second (main) phase will use the pilot phase's actual data to determine the final number of participants needed.

Study Overview

• Status: Recruiting
• Conditions: Supraventricular Tachycardia; Paroxysmal Supraventricular Tachycardia; Atrioventricular Nodal Reentry Tachycardia; Vagal Maneuver
• Intervention / Treatment: Procedure: Nasopharyngeal Swab Insertion; Procedure: Modified Valsalva Maneuver (REVERT Protocol)

Detailed Description

BACKGROUND:

Supraventricular tachycardia (SVT) encompasses re-entrant arrhythmias dependent on the atrioventricular node, including atrioventricular nodal re-entry tachycardia (AVNRT) and atrioventricular re-entry tachycardia (AVRT). Vagal maneuvers increase parasympathetic tone via the vagus nerve, slowing atrioventricular conduction and terminating these re-entrant circuits. The modified Valsalva maneuver (REVERT protocol) achieves termination in approximately 43% of cases, making it the most effective non-pharmacological approach currently available.

The trigeminocardiac reflex (TCR), also termed the nasocardiac reflex, involves mechanical stimulation of the nasal mucosa and nasopharynx activating the trigeminal nerve (V1/V2 branches) → pterygopalatine ganglion → trigeminal nucleus → dorsal vagal nucleus → cardiac inhibitory parasympathetic output → bradycardia. This reflex has been documented in nasoendoscopy studies (observed in approximately 30% of patients) and was reported to cause syncope during COVID-19 nasopharyngeal swab collection. Hooker and Liebman (2023) reported SVT termination within 10 seconds of nasal swab insertion in a patient refractory to other vagal maneuvers and adenosine. Cinpolat et al. (2025) reported a mean 28% decrease in heart rate and 22% decrease in systolic blood pressure during nasopharyngeal swab procedures, explicitly suggesting SVT as a potential application.

STUDY DESIGN:

Two-phase prospective single-center randomized controlled superiority trial.

• Phase 1 (pilot): 30 participants per arm (n=60 total). Primary aim: feasibility assessment.
• Phase 2 (main): Sample size recalculated from actual pilot-phase conversion rates.

RANDOMIZATION: Computer-generated blocked randomization (block sizes 4 and 6, randomly mixed) stratified by SVT subtype (probable AVNRT / probable AVRT / indeterminate). Allocation concealment using sequentially numbered, sealed, opaque envelopes.

BLINDING: Open-label for participants and care providers; outcome assessor (30-minute satisfaction survey) and statistician are blinded.

INTERVENTIONS:

• Arm 1 (Nasal Swab): Standard nasopharyngeal swab inserted through the right nostril, parallel to the nasal septum, to the nasopharyngeal vault. Held for 10 seconds with gentle rotation, then withdrawn. Patient in 45-degree semi-recumbent position.
• Arm 2 (mVM/REVERT): Forced expiration for 15 seconds into 10 mL syringe barrel, immediately followed by rapid supine repositioning and 45-degree passive leg elevation for 15 seconds.

OUTCOMES: Primary: sinus rhythm conversion at 1 minute (T=60 seconds post-procedure). Secondary: conversion at 3 and 5 minutes; rescue adenosine requirement; procedural discomfort (VAS 0-10); treatment satisfaction (5-point Likert); re-preference; SVT recurrence at 24 hours and 30 days; adverse event profile.

STATISTICAL ANALYSIS: Chi-square or Fisher's exact test for the primary outcome. Results reported as absolute risk difference with 95% CI. Intention-to-treat analysis as the primary; per-protocol analysis as a sensitivity analysis. Benjamini-Hochberg correction for secondary outcomes. Multiple imputation (MICE) for missing data between 5-20%.

SAFETY STOPPING RULES: Immediate procedure termination and rescue therapy for hemodynamic deterioration, arrhythmia worsening, patient request, or serious adverse event. Pilot phase safety stopping rule: ≥3 serious adverse events in either group triggers protocol review.

PILOT FEASIBILITY GO/NO-GO CRITERIA:

• Monthly enrollment rate: ≥5 patients/month
• Protocol adherence rate: ≥85%
• Missing data rate: ≤10%
• 30-day follow-up completion: ≥70%

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Emir Ünal; Phone Number: +905327766010; Email: emirunal@gmail.com

Study Locations

• Turkey (Türkiye)
  • Pendik
    • Istanbul, Pendik, Turkey (Türkiye), 34899
      • Recruiting
      • Marmara University Pendik Training and Research Hospital
      • Contact: Emir Ünal; Phone Number: 05327766010; Email: emirunal@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 18 years or older
• Electrocardiographically confirmed supraventricular tachycardia (SVT): narrow QRS complex (≤120 ms), regular rhythm, rapid ventricular rate, documented on 12-lead ECG or continuous cardiac monitoring
• Hemodynamic stability, defined as ALL of the following simultaneously present:
• Systolic blood pressure ≥90 mmHg
• Diastolic blood pressure ≥60 mmHg
• Alert and oriented mental status (GCS 15)
• No signs of acute end-organ dysfunction
• Ability and willingness to provide written informed consent

Exclusion Criteria:

• Age younger than 18 years
• Pregnancy (known or suspected)
• Inability to confirm SVT diagnosis by ECG criteria
• Delta wave or pre-excitation pattern on ECG (Wolff-Parkinson-White syndrome or asymptomatic pre-excitation) - due to risk of ventricular fibrillation with vagal maneuvers
• Wide QRS tachycardia (QRS ≥120 ms) where ventricular tachycardia cannot be excluded
• Absolute contraindication to modified Valsalva maneuver (inability to assume supine position or passive leg elevation)
• Contraindication to nasal swab (nasal surgery within 30 days, active epistaxis, visible nasal polyp or mass)
• Hemodynamic instability requiring immediate synchronized cardioversion
• Prior enrollment in this study (re-presentation with SVT)
• Refusal to participate

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Nasal Swab Group; Nasopharyngeal swab insertion per standardized protocol	Procedure: Nasopharyngeal Swab Insertion; A standard nasopharyngeal swab (approximately 15 cm flexible nylon-tipped swab, sterile) is inserted through the right nostril (left if anatomically impeded), directed parallel to the nasal septum along the nasal floor (posteriorly, not superiorly), and advanced until mild resistance is felt at the nasopharyngeal vault. The swab is held in this position for 10 seconds with optional gentle rotation, then slowly withdrawn. The procedure is performed with the patient in a 45-degree semi-recumbent position under continuous cardiac monitoring (ECG, SpO2, NIBP). T=0 is defined as the moment the swab is fully withdrawn. The procedure is performed once; failure leads to rescue therapy (intravenous adenosine) without a second attempt.
Active Comparator: Modified Valsalva Group; Modified Valsalva maneuver per REVERT protocol	Procedure: Modified Valsalva Maneuver (REVERT Protocol); The modified Valsalva maneuver is performed per the REVERT protocol. The patient, seated at 45 degrees, performs a forced expiration for 15 seconds into the barrel of a 10 mL syringe (aiming to push the plunger back, targeting an expiratory pressure of≥40 mmHg). Immediately upon completion, the patient is rapidly repositioned supine, and both legs are passively elevated to 45 degrees for 15 seconds, then returned to the semi-recumbent position. Total maneuver duration is approximately 30 seconds. T=0 is defined as the moment the patient returns to the semi-recumbent position. The procedure is performed once; failure leads to rescue therapy (intravenous adenosine) without a second attempt.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sinus Rhythm Conversion Rate at 1 Minute	Proportion of participants who convert to sinus rhythm within 1 minute of procedure completion (T=60 seconds), as assessed by continuous 12-lead ECG monitoring. T=0 is defined as the moment the intervention is completed (swab withdrawn / patient returned to semi-recumbent position after leg raise). Rhythm is independently verified by two investigators reviewing the ECG rhythm strip recording. Conversion is defined as a dichotomous outcome: yes (sinus rhythm confirmed at T=60 seconds) or no.	1 minute after procedure completion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sinus Rhythm Conversion Rate at 5 Minutes	Proportion of participants who convert to sinus rhythm within 5 minutes of procedure completion, assessed by continuous ECG monitoring.	5 minutes after procedure completion
Adverse Events Profile	Incidence and nature of adverse events including but not limited to epistaxis, vasovagal syncope, significant bradycardia (heart rate <40 bpm), hypotension, and respiratory distress, documented on a structured adverse event checklist.	During procedure and up to 30 minutes after procedure completion

Collaborators and Investigators

• Sponsor: Marmara University Pendik Training and Research Hospital

Publications and helpful links

General Publications

• Appelboam A, Reuben A, Mann C, Gagg J, Ewings P, Barton A, Lobban T, Dayer M, Vickery J, Benger J; REVERT trial collaborators. Postural modification to the standard Valsalva manoeuvre for emergency treatment of supraventricular tachycardias (REVERT): a randomised controlled trial. Lancet. 2015 Oct 31;386(10005):1747-53. doi: 10.1016/S0140-6736(15)61485-4. Epub 2015 Aug 24.
• Hooker EA, Liebman JS. Termination of paroxysmal supraventricular tachycardia by intranasal swab insertion. Am J Emerg Med. 2023 Oct;72:222.e3-222.e4. doi: 10.1016/j.ajem.2023.08.002. Epub 2023 Aug 2.
• Koskinen A, Tolvi M, Jauhiainen M, Kekalainen E, Laulajainen-Hongisto A, Lamminmaki S. Complications of COVID-19 Nasopharyngeal Swab Test. JAMA Otolaryngol Head Neck Surg. 2021 Jul 1;147(7):672-674. doi: 10.1001/jamaoto.2021.0715.
• Betlejewski S, Betlejewski A, Burduk D, Owczarek A. [Nasal-cardiac reflex]. Otolaryngol Pol. 2003;57(5):613-8. Polish.
• Boux I, Tomasello R, Grisoni L, Pulvermuller F. Brain signatures predict communicative function of speech production in interaction. Cortex. 2021 Feb;135:127-145. doi: 10.1016/j.cortex.2020.11.008. Epub 2020 Dec 2.
• Cinpolat R. Nasocardiac reflex-induced resolution of persistent hiccups via intranasal swab stimulation: A case report. Am J Emerg Med. 2025 Jun;92:253.e3-253.e4. doi: 10.1016/j.ajem.2025.04.003. Epub 2025 Apr 2.
• Case LK, Madian N, McCall MV, Bradson ML, Liljencrantz J, Goldstein B, Alasha VJ, Zimmerman MS. Abeta-CT Affective Touch: Touch Pleasantness Ratings for Gentle Stroking and Deep Pressure Exhibit Dependence on A-Fibers. eNeuro. 2023 May 26;10(5):ENEURO.0504-22.2023. doi: 10.1523/ENEURO.0504-22.2023. Print 2023 May.

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2026
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: May 23, 2026
• First Submitted That Met QC Criteria: May 23, 2026
• First Posted (Actual): June 1, 2026

Study Record Updates

• Last Update Posted (Actual): June 1, 2026
• Last Update Submitted That Met QC Criteria: May 23, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: emergency department; nasal swab; SVT; Valsalva maneuver; nasocardiac reflex; trigeminocardiac reflex; REVERT
• Additional Relevant MeSH Terms: Cardiac Conduction System Disease; Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Disease Attributes; Arrhythmias, Cardiac; Tachycardia, Reciprocating; Tachycardia; Pathological Conditions, Signs and Symptoms; Emergencies; Tachycardia, Ventricular; Tachycardia, Supraventricular; Tachycardia, Atrioventricular Nodal Reentry
• Other Study ID Numbers: 09.2025.299

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Yes, individual participant de-identified data (including the data dictionary and statistical analysis plan) will be shared. Data will be available beginning 12 months after primary publication to researchers who provide a methodologically sound proposal. Requests should be directed to the corresponding author (emirunal@gmail.com).
• IPD Sharing Time Frame: Beginning 12 months after primary publication, with no specified end date.
• IPD Sharing Access Criteria: Researchers who provide a methodologically sound proposal to achieve aims in the approved protocol. Requests must be directed to the corresponding author (emirunal@gmail.com). Data will be shared via secure data transfer after signing a data use agreement.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No