ST changes generally refer to an elevation or depression in the ST segment (see Normal Heart Beat) of the EKG complex. Both ST segment elevation and depression must be evaluated in conjunction with any patient symptoms with any treatment being directed at fixing the underlying problem.
The above is technically a sinus tachycardia with a rate of 107 beats per minute with ST depression of approximately 3 mm (3 small boxes). The arrow is pointing at the ST segment of the EKG. If you look at Normal Heart Rhythm, you will note that the ST segment is neither elevated or depressed which is referred to as being isoelectric. A thorough evaluation of ST changes requires the use of a 12 lead EKG. ST segment depression can suggest the presence of ischemia, or lack of blood flow to the heart muscle itself. Patients may complain of chest tightness, pressure or pain and/or lightheadedness or dizziness in these situations.
The above is a normal sinus rhythm with a rate of 68 beats per minute with ST elevation of 2 mm (2 small boxes). The arrow is pointing at the ST segment of the EKG. ST elevation in certain leads can be normal, so a thorough evaluation would require a 12 lead EKG and perhaps additional tests if the patient is symptomatic. Symptoms may include chest tightness, pressure or pain and/or lightheadedness or dizziness. ST segment elevation can suggest the presence of ischemia, or lack of blood flow to the heart muscle itself.