Slide 1: You’re working nights…The nurse calls you in a panic that the patient’s telemetry is alarming “asystole.” [Tele strip] The patient is sleeping comfortably. You take a look at the strip. What’s going on?
Slide 2: There’s no QRS after those p’s…Do you need to gear up for an emergent transvenous pacemaker placement?
Slide 3: Notice the p-p intervals… As well as the p-r intervals… [Tele strip showing increasing intervals] They increase with each beat!
Slide 4: This is increased vagal tone or vagotonia. Increasing p-p interval = slowing at the SA node. Increasing p-r interval = slowing at the AV node. Simultaneous slowing at both nodes suggests an external stimulus. If there’s a block at only one of the two, that is more suggestive of conduction disease. You wake the patient up, his tele looks normal. No emergency pacing required!
Tags: asystole, AV node, cardiology, electrophysiology, p-p interval, p-r interval, SA node, telemetry, vagal tone