Anterior wall myocardial infarction and 50 Hz interference

Anterior wall myocardial infarction and 50 Hz interference

Anterior wall myocardial infarction with QS complexes and ST segment elevation in V1 to V6. T wave inversions are seen in inferior leads. Prominent negative P waves in V1 indicate possibility of left ventricular dysfunction secondary to extensive myocardial infarction. 50 Hz interference, also known as line voltage interference or AC interference, is seen in the standard leads, maximum in lead II.

This an enlarged view showing the AC interference. It can usually be avoided by recording with ECG machine disconnected from power supply and running on battery. Sometimes electrical connections to a motorised bed and monitoring leads may have to be removed in ICU patients.