Testing of a Valsalva Assist Device (VAD) to assess effects on heart rate and strain pressures achieved compared to a standard manometer in healthy volunteers performing standard and modified Valsalva manoeuvres.

Abstract

Background Supraventricular tachycardia (SVT) is a relatively common condition causing palpitations, which, if not treated, can have serious adverse effects. SVT can initially be treated with a Valsalva manoeuvre (VM) (an exhalation against resistance, similar to blowing up a balloon), which induces a vagal response (drop in heart rate), terminating SVT in 5-54%. The VM’s efficacy is variable and there is debate as to the best way of generating the strain in practice and in which posture the VM should be carried out. A purpose-built device (Valsalva Assist Device (VAD)) has been proposed to improve this. We aimed to compare vagal responses of the supine and modified posture VMs using the VAD and standardised manometer.

Methods We performed a repeated measures randomised trial of four VMs (two supine VM and two modified VMs) in healthy adult volunteers with strains delivered using a manometer or VAD. Changes in heart rate were compared between the techniques. The pressure and duration of VM strains achieved with the VAD and manometer and adverse events were recorded and compared. The trial was registered with ClinicalTrials.gov (NCT03298880) and approved by the University of Exeter Medical School Ethics Committee.

Results 75 healthy participants aged 19-55 were recruited over three months. A mixed-effects linear regression was completed showing the modified VM had a significant drop of 7.7 bpm compared to the supine VM (p<0.001, CI 5.6 to 9.8). The VAD produced similar strain pressures but slightly shorter duration strains compared to the manometer.

Conclusions Modified VM was associated with a greater drop in heart rate than a supine VM. The VAD can be used to safely generate the recommended VM strain with equivalent pressure to the manometer but may require modification to enable the recommended duration of strain and full effect to be achieved.