- HPI: Elderly septic patient
- Key ECG: If ever you see a bizarre appearance for 2 of the 3 standard limb leads (ie, leads I,II,III) — with the 3rd standard limb lead looking relatively (if not completely) appropriate — Think Artifact! Since lead II is the only normal lead in this ECG, the left arm electrode must be the affected electrode. Indeed, the patients dialysis fistula was on the left arm and was pulsating with each heart beat, moving the electrode and causing artifact. Since the cause of the Pulse-Tap Artifact is contact of one of the limb lead electrodes with a pulsating artery below it — the bizarre deflection that you suspect is artifact will have a fixed relationship to neighboring QRS complexes. You can prove the “culprit extremity” cause of artifact by demonstrating that artifact deflections are no longer present after repositioning the limb lead electrodes.
- Link to full case @ Dr. Smith’s ECG Blog: 2022-12-05