A sensitive indicator of myocardial damage, the ST segment is normally flat or isoelectric. A depressed ST segment may result from cardiac glycosides, myocardial ischemia, or a subendocardial infarction. An elevated ST segment suggests myocardial infarction.

Continuous ST-segment monitoring is helpful for patients with acute coronary syndromes and for those who have received thrombolytic therapy or have undergone coronary angioplasty or cardiac surgery.¹ ST-segment monitoring allows early detection of reocclusion. It’s also useful for patients who have had previous episodes of cardiac ischemia without chest pain, for those who have difficulty distinguishing cardiac pain from pain associated with other sources, and for those who have difficulty communicating. It gives the doctor the ability to identify and reverse ischemia by starting early interventions.²

Because ischemia typically occurs in only one portion of the heart muscle, not all electrocardiogram (ECG) leads detect it. Select the most appropriate lead by examining ECG tracings obtained during an ischemic episode. The leads showing ischemia are the same leads to use for ST-segment monitoring.

ST-segment monitoring isn’t useful for patients with left or right bundle-branch block or ventricular paced rhythm or for those who are very restless.²