The normal cardioversion rates in SVT are less than 20%. However we perform this procedure before giving adenosine as it is benign, costs nothing and has no side effect profile. The reality however is that until now we have had poor reversion rates.
The classic approach is to have the patient ‘strain’, thus providing Valsalva. This can be done by having them blow into a blood pressure(BP) manometer and keep the BP up around 40mm Hg, or to use a 10cc syringe and ask the patient to blow the plunger out, so it moves.
In this new study in the Lancet, the REVERT Trial tried a slight modification with GREAT results.
This was a randomised controlled trial of 433 patients.
The patient whilst in a sitting position at 45 degrees, maintains Valsalva for 15 seconds. In their case they used the BP manometer, but a 10mL syringe can also be used.
The patients in the control group remained in the same position for the next minute and rhythm was reassessed.
The patients in the ‘treatment’ arm were then placed in the recumbent position and the legs were raised to 45 degrees, for 15 seconds. They were then be returned to the sitting position for one minute and assessed.
The reversion rate with this manoeuvre was 43% compared to 17% in the control group.
It is certainly a technique worth trying.
The patient performs the Valsalva manoeuvre for 15 seconds, whilst sitting at an angle of about 45 degrees. The head of the bed is then dropped, whilst the legs are lifted to an angle of 45 degrees.
The legs are held up for 15 seconds. The patient is then returned to the sitting position and given 1 minute before the rhythm is assessed.
Images taken from accompanying video to the article - www.thelancet.com Published online August 25, 2015 http://dx.doi.org/10.1016/S0140-6736(15)61485-4