Will placing arm leads on the shoulder instead of the wrist alter electrocardiogram (EKG) findings?

Impact of Placing Arm Leads on the Shoulder Instead of Wrist on ECG Findings

Yes, placing arm leads on the shoulder instead of the wrist will change ECG findings, particularly affecting ECG voltages and durations in the limb leads. 1

Changes in ECG Parameters When Using Shoulder Placement

• Electrode placement along the limbs can significantly affect ECG voltages and durations, with more pronounced effects observed in the limb leads 1
• Moving electrodes from the wrist to the shoulder causes:
  • Increased R wave amplitude in inferior leads (II, III, aVF) 2
  • Decreased R wave amplitude in lateral leads (I, aVL) 2
  • Rightward shift of P, QRS, and T wave axes 2

Clinical Significance of These Changes

• These alterations can potentially affect diagnostic criteria:
  • Inferior infarct patterns may disappear when electrodes are moved from standard positions to torso/shoulder positions 2
  • Over half of ECGs showing inferior infarct criteria in standard configuration had those criteria erased when electrodes were moved to torso positions 2
  • QRS axis shifts can occur, becoming more vertical when electrodes are placed on the shoulders 2

Standard Recommendations for Electrode Placement

• The American Heart Association recommends placement of limb lead electrodes on the arms and legs distal to the shoulders and hips 1, 3
• Historically, limb lead electrodes have been attached at the wrists and ankles with the patient in a supine position 1
• For cardiac monitoring (not diagnostic ECGs), electrodes are commonly placed on the torso to reduce motion artifact 1

Monitoring vs. Diagnostic ECG Considerations

• In bedside cardiac monitoring, limb electrodes are placed on the torso to reduce muscle artifact and avoid tethering the patient 1
• ECGs recorded with torso placement of limb electrodes cannot be considered equivalent to standard ECGs and should not be used interchangeably for serial comparison 3
• The practice of recording ECGs from the upper arm rather than the wrist to "reduce motion artifact" has become popular but alters ECG morphology 1

Common Pitfalls and Recommendations

• Placing electrodes on the shoulders rather than wrists may lead to:
  • Misdiagnosis of cardiac conditions due to altered ECG morphology 1, 2
  • False negatives for inferior myocardial infarction 2
  • Inaccurate assessment of left ventricular hypertrophy due to voltage changes 1
• If shoulder placement is necessary due to clinical circumstances:
  • Document the non-standard electrode placement on the ECG 3
  • Consider that diagnostic criteria derived from standard placement may not apply 1
  • Be cautious when comparing to previous ECGs taken with standard placement 3

Alternative Approaches

• For patients where standard placement is difficult, some research suggests that placing the right arm electrode on the torso and the left arm electrode on the upper arm may offer a compromise between reducing noise and maintaining fidelity to standard recordings 2
• When motion artifact is a concern but diagnostic accuracy is critical, consider using better skin preparation techniques rather than altering electrode positions 1