Slide 1: You’re working in the ED and get handed the following EKG. [EKG] First thing’s first: what do you call this rhythm?
Slide 2: Let’s review: pacemaking 101. Who sets the beat? We have three pacemaking loci, each with a characteristic speed: SA node – 60-100 bpm, AV node: 40-60 bpm, ventricle: 20-40 bpm. [Diagram of heart shows SA node, AV node, Bundle of His, Left bundle branch, Right bundle branch, Purkinje fibers]
Slide 3: When the AV node is the source of an ectopic beat, we call it a junctional escape rhythm.
Slide 4: Let’s review: Junctional escape rhythms. The Ddx: It all boils down to decreased atrial activity: sinus bradycardia or sinus arrest, high-grade AV blocks, iatrogenic, or hyperkalemia. The EKG findings: narrow QRS complex, HR measuring 40-60 bpm, no preceding P waves.
Slide 5: Back to the strip. [EKG shows narrow QRS (<120ms), absent P waves, bonus: retrograde p waves] -> dx demystified: junctional escape rhythm
Tags: absent p waves, AV node, bundle of his, cardiology, high-grade AV block, hyperkalemia, iatrogenic, junctional escape rhythm, narrow QRS, pacemaking, purkinje fibers, retrograde p waves, SA node, sinus arrest, sinus bradycardia, ventricle