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

Summary

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.

Conditions

• Supraventricular Tachycardia
• Paroxysmal Supraventricular Tachycardia
• Atrioventricular Nodal Reentry Tachycardia
• Vagal Maneuver

Interventions

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 The swab is held in this position for 10 seconds with optional gentle rotation, then slowly withdrawn.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.

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.

Sponsors & Collaborators

• Marmara University Pendik Training and Research Hospital

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2026-05-01

Primary Completion

2027-05-31

Completion

2027-06-30

Countries

• Turkey (Türkiye)

Study Locations