Performance Testing of the Modified Electrocardiogram Lead Placement

During general anesthesia for surgery, doctors use an electrocardiogram (ECG)-a simple heart monitor-to check for problems like poor blood flow to the heart or irregular heartbeats. Normally, ECG stickers (called electrodes) go on both shoulders and the left side of the belly, right outside the heart area, to get clear readings. But for shoulder surgery, these spots are in the way of the operation, so doctors often place them elsewhere, like on the breastbone instead of the shoulder. This can give fuzzy or wrong results, missing key changes in the patient's heart-good or bad-during surgery. To fix this and better watch heart health in shoulder surgery patients, this study tests different ECG sticker spots: the usual ones, the common backup (like on the breastbone), and a new idea-placing them near both temples. Researchers hope to find which setup gives the most accurate heart readings to keep patients safer.

Inclusion Criteria: * Adult male and female patients aged 19 to 65 years scheduled for surgery under general anesthesia. * Patients scheduled for surgery in areas that do not affect ECG electrode placement (e.g., abdomen, head, face, lower limbs). * Patients with normal or abnormal ST segment changes confirmed on preoperative ECG. Exclusion Criteria: * Patients who do not consent to the study. * Patients with implanted pacemakers. * Patients with a history of heart or lung surgery.