Intraoperative continuous ECG monitoring is being set up for a patient with known coronary artery disease undergoing major bowel surgery. Which single bipolar lead configuration is most sensitive for detecting left ventricular anterior wall ischaemia?

• A Lead I
• B Lead II
• C Lead III
• D CM5 ✓

Explanation

The modified chest lead CM5 places the right arm electrode on the manubrium and the left arm electrode at the V5 position, with lead I selected on the monitor. It aligns with the V5 vector over the anterolateral left ventricle and detects roughly 90% of intraoperative ischaemic ST segment events. Lead II is preferred for detecting inferior wall ischaemia and arrhythmias because its axis parallels atrial depolarisation, making P waves prominent, but it misses most anterior wall events.

Reference: Morgan and Mikhail's Clinical Anesthesiology, 5th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.