Hyperacute Limb Leads

A woman in her 30s presented with chest pain for 6 hours, non-radiating, and not associated with any aggravating or relieving factors. On presenting to emergency services, her chest pain had subsided, and a 12-lead electrocardiogram (ECG) was done (Figure 1).

Figure 1.

12-lead ECG Showing Bizarre ST Elevation in leads I, II, aVR, aVL, and aVF.

The 12-lead ECG shows ST elevation in leads I, II, aVR, aVL, and aVF with ST flattening in V3–V6. Considering the asymptomatic status at the time of the ECG, a repeat ECG was taken few minutes later which showed complete resolution of the changes (Figure 2). The absence of reciprocal ST depression and elevation not pertaining to any coronary territory suggested an acute infarction. Serum electrolytes were normal. Analysing the ECG, the onset of elevation and large, bizarre t waves suggest the possibility of the artifact. The fixed coupling interval between QRS and the artifact suggests a cardiac cycle-related artifact. These changes were there in all limb leads except lead III which does not use the right upper limb, secondary to the pulse-tapping artifact effect of the right radial or ulnar artery (Figure 3). Coronary vasospasm can mimic pulse-tapping artifacts by causing sudden ST elevation and spontaneous resolution, but the patient remained chest pain free and troponin levels were also normal. Hence was not evaluated in our patient. Pulse-tapping artifact has been described often in patients with arteriovenous fistula and high-volume pulse but has been described in normal-volume people as well and warrants appropriate diagnosis to avoid unnecessary hospitalization.

Figure 2.

ECG Repeated after a while Showing Resolution of ST Changes.

Figure 3.

Illustration of Lead III Being Normal while Lead I and II Showing ST Elevation as Related to Pulse Tapping Artefact in the Right Upper limb.