Although the Appelboam et al. (2015) study was conducted in hospital emergency department settings, there is no reason to assume that the modified Valsalva manoeuvre would not be both effective and safe for SVT reversion in general practice settings, as long as precautions are taken (see Contraindications and Precautions).
For patients who do not revert to sinus rhythm with the modified Valsalva manoeuvre, vagal tone can be increased by other techniques, including carotid sinus massage (CSM).
Carotid sinus massage is less effective than the Valsava manoeuvre and has around 1% risk of neurological complications, although these are usually transient. In addition to the same cardiovascular contraindications and precautions as for the modified Valsava manoeuvre, CSM is contraindicated in patients with carotid bruits or recent transient ischaemic attack (TIA) or stroke. As with the modified Valsalva manoeuvre, electrocardiogram (ECG) and heart rate should be monitored.
To perform CSM, the patient is placed in the supine position. Either the right or the left carotid sinus is gently massaged for at least five but no longer than 10 seconds, with care to avoid carotid artery trauma or occlusion. (The carotid sinus is located inferior to the angle of the mandible at the level of the thyroid cartilage, at the site of the arterial impulse.) If there is no reversion, CSM can be performed on the other side, after a 1–2 minute delay.