Patient Care and Preparation
Preparation decides the tracing
Everything that determines whether a tracing is interpretable happens before the first complex is recorded. Confirm identity with two identifiers, verify the order, explain the procedure, and secure privacy and modesty - anxiety raises heart rate and muscle artifact. Position the patient supine with the head slightly elevated, arms resting at the sides rather than on the abdomen, legs uncrossed, and coach quiet breathing during the recording.
Skin preparation is the biggest lever on artifact: clip (do not shave) excessive hair, cleanse with alcohol or an abrasive pad, allow it to dry, and place electrodes on clean dry skin over bone rather than muscle. Standard placement: V1 fourth intercostal space at the right sternal border, V2 fourth ICS at the left sternal border, V4 fifth ICS midclavicular, V3 midway between V2 and V4, V5 and V6 at the V4 level in the anterior and midaxillary lines.
Traps: arm-lead reversal (LA/RA) makes P, QRS and T negative in lead I and inverts aVR - check that lead I is upright in sinus rhythm before blaming an arrhythmia. V1/V2 placed one interspace too high produce rSR' patterns and pseudo-infarct Q waves. Wandering baseline usually means poor prep or a loose electrode, not pathology. Tremor mimics flutter and fibrillation; have the patient relax the arms and re-record.
For any exercise or pharmacologic test, the same preparation plus equipment checks and a known defibrillator/crash cart location are mandatory.