SVT smartwatch (210 bpm) ?

A 33-year-old patient presents with palpitations, with a tachycardia recorded on a smartwatch at 220 beats per minute. An electrophysiological study is proposed.
During the study, programmed atrial stimulation is performed from CS 9–10, with decremental pacing at 600 ms, followed by an extra-stimulus at 360 ms.

We observe that the AH interval prolongs to 270 ms, and then…

When we decrease the S2 to 350 ms, we observe an AH jump, with the AH interval increasing to 320 ms.

A 1:1 tachycardia is induced, with a VA interval of –20 ms, which is consistent with a slow–fast AVNRT.

 

Unfortunately, we were unable to perform additional manoeuvres because the tachycardia terminated immediately each time.

 

In the end, we proceeded with ablation of the slow pathway.