Another Knowing What’s Right … From Left

I still do carotid sinus massage in patients with possible/probable supraventricular arrhythmias, rather than waiting for adenosine. Carotid sinus is especially effective in identifying atrial flutter in regular rapid tachycardias, sometimes with enough aberrancy to mimic ventricular tachycardia. The AV nodal block can be quite impressive (especially with A flutter) and scare the dickens out of anyone watching the monitor. I am amazed at how many trainees even in great institutions have never seen it done. I guess most clinicians prefer using adenosine, but carotid sinus massage is a safe, inexpensive way to increased vagal tone and decrease A-V conduction. The trick is to listen over both carotids to make sure there are no bruits or plaques that could dislodge emboli. Then press very firmly on the right carotid artery, just anterior to the sternocleidomastoid muscle, while watching the patient’s ECG. Sometimes you will get AV block rubbing on the right carotid sinus, but if not, definitely try the left. The right carotid sinus tends to control the sinus node rate, whereas the left carotid sinus has more control over AV conduction. At least that’s what happens in dogs and in some humans (1). So, when doing carotid sinus massage, try both the left and the right before you give up and spend money on adenosine.

1. Champagne, J, et. al. Differential effect of right and left carotid sinus massage: implications for sudden rate drop pacing algorithm. 2002 Jul;18(7):763–7. PMID: 12167966

This was also published on my Substack blog on 19 Sept 2023.