The goal of this clinical trial is to compare two physical techniques for treating paroxysmal supraventricular tachycardia in adults. This condition causes a fast, regular heartbeat that starts and stops suddenly. Participants must be medically stable and have the condition confirmed by an electrocardiogram (ECG). The main question is: Does the reverse vagal maneuver restore normal heart rhythm more often than the modified Valsalva maneuver before rescue treatment is needed? Researchers randomly assign participants to one of the two maneuvers. Participants assigned to the modified Valsalva maneuver sit in a partly upright position. They blow into a 10-mL syringe for 15 seconds with enough force to move the plunger. They then lie flat while their legs are raised for 15 seconds. Participants assigned to the reverse vagal maneuver sit upright and breathe out normally. They then close their nose and mouth and try to breathe in forcefully for 15 seconds. All participants have an ECG before the maneuver and continuous heart rhythm monitoring. If normal rhythm is not restored, the assigned maneuver may be repeated up to three times. An ECG is recorded 45 seconds after each attempt. Participants receive standard rescue treatment if the assigned maneuver does not restore normal rhythm or if continuing becomes unsafe. Researchers also record first-attempt success, rescue medication, electrical cardioversion, return of the fast heartbeat, hospital disposition, unwanted effects, repeat emergency department visits, and catheter ablation during one year of follow-up.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
142
Participants were positioned semirecumbent with the stretcher head elevated to approximately 45° and instructed to blow into a 10-mL syringe for 15 seconds with sufficient force to move the plunger, aiming to generate approximately 40 mm Hg of expiratory pressure. Pressure was not measured using a manometer. Immediately afterward, participants were placed supine, and their legs were elevated to approximately 45°, without knee flexion, for 15 seconds. The maneuver could be repeated up to three times if sinus rhythm was not restored.
Participants performed the maneuver while seated. After exhaling normally without force, they occluded the nose and mouth and attempted forceful inspiration against the closed airway for 15 seconds. The supervising clinician verified airway occlusion and completion of the prescribed sequence and duration. The maneuver could be repeated up to three times if sinus rhythm was not restored.
Düzce University Faculty of Medicine Hospital, Department of Emergency Medicine
Düzce, Turkey (Türkiye)
ECG-Confirmed Conversion to Sinus Rhythm During the Assigned Maneuver Protocol
The primary outcome was ECG-confirmed conversion from PSVT to sinus rhythm following any of up to three permitted attempts of the assigned vagal maneuver and before initiation of rescue medication or electrical cardioversion. Conversion was determined using the standardized ECG assessment performed 45 seconds after completion of each attempt. Participants who remained in PSVT after completion or early discontinuation of the assigned maneuver protocol were classified as non-converters.
Time frame: At 45 seconds after the final performed assigned maneuver attempt, upon completion or early discontinuation of the protocol (maximum of 3 attempts) and before initiation of rescue therapy
Assigned Maneuver Attempt at ECG-Confirmed Conversion to Sinus Rhythm
Conversion was categorized as occurring after the first, second, or third assigned maneuver attempt, or as no conversion, based on ECG assessment 45 seconds after each attempt.
Time frame: At 45 seconds after each assigned maneuver attempt (attempts 1, 2, and 3), through completion of the assigned maneuver protocol and before initiation of rescue therapy
Number of Participants Receiving Rescue Medication During the Index Emergency Department Visit
Number of participants who received pharmacologic rescue treatment for persistent PSVT after failure or early discontinuation of the assigned maneuver protocol, or for recurrent PSVT after ECG-confirmed initial conversion during emergency department observation. Each participant was counted once, regardless of the number or type of rescue medications administered.
Time frame: From randomization until emergency department discharge or transfer to inpatient care, whichever occurred first, during the index visit (estimated assessment period: 4 hours)
Number of Participants Undergoing Electrical Cardioversion During the Index Emergency Department Visit
Number of participants who underwent electrical cardioversion for persistent or recurrent PSVT during the index emergency department visit. Electrical cardioversion could be performed after failure or early discontinuation of the assigned maneuver protocol, or earlier if clinically indicated because of hemodynamic instability, clinical deterioration, intolerable symptoms, or concern that another assigned maneuver attempt was unsafe. Each participant was counted once, regardless of the number of cardioversion attempts performed.
Time frame: From randomization until emergency department discharge or transfer to inpatient care, whichever occurred first, during the index visit (estimated assessment period: 4 hours).
Number of Participants With Recurrent PSVT During Emergency Department Observation
Number of randomized participants who experienced recurrence of PSVT after an initially successful ECG-confirmed conversion to sinus rhythm and before emergency department discharge or transfer to inpatient care during the index visit. Each participant was counted once, regardless of the number of recurrent PSVT episodes.
Time frame: From the initial ECG-confirmed conversion to sinus rhythm until emergency department discharge or transfer to inpatient care, whichever occurred first, assessed over an estimated period of 4 hours during the index visit.
Number of Participants in Each Emergency Department Disposition Category at the End of the Index Visit
Number of participants in each of three mutually exclusive emergency department disposition categories: discharge from the emergency department, admission to a hospital ward, or admission to an intensive care unit. Each participant was classified in one disposition category at the end of the index emergency department visit.
Time frame: At the end of the index emergency department visit, defined as emergency department discharge or transfer to a hospital ward or intensive care unit, assessed approximately 4 hours after randomization.
Repeat Emergency Department Presentation for PSVT
Repeat emergency department presentation for PSVT during follow-up.
Time frame: Up to 1 year after randomization
Catheter Ablation During Follow-up
Catheter ablation performed for PSVT after the index emergency department visit.
Time frame: Up to 1 year after randomization
Participants Experiencing Any Prespecified Adverse Event
This composite binary outcome indicated whether a participant experienced at least one prespecified adverse event during the assigned maneuver protocol or subsequent emergency department observation. Prespecified events included dizziness, nausea, dyspnea, presyncope, syncope, chest pain, hypotension, worsening arrhythmia, and other clinically important maneuver-related events. Each participant was counted once, regardless of the number or type of events experienced, and the outcome was reported as the number of participants with at least one event.
Time frame: From initiation of the first assigned maneuver attempt through completion of emergency department observation, an average of 4 hours after randomization
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