Although she's postmenopausal, she's not on hormone replacement therapy. You learn that her only regular exercise is housework and that her father died of a heart attack at age 50. Diabetes mellitus is a strong predictor of heart disease in women, doubling the risk of CAD and quadrupling the risk of heart failure. Because ECG changes reflect decreases in the oxygen supply to the myocardium, Mrs. Allen's 12-lead ECG results will give you more insight into her condition. Look for changes in the ST segment and T wave indicative of myocardial ischemia, injury, or infarction.
Ischemia occurs when coronary artery vasospasm decreases oxygen supply to the myocardium.
It's usually a reversible, transient event that's corrected when the blood and oxygen supply to the myocardium is restored. If prolonged, however, ischemia leads to injury. Contiguous ECG leads reflect electrical activity in the same area of the myocardium. Keep in mind, however, that the T wave is normally inverted in aVR and sometimes in leads III and V1. If these changes continue despite treatment, the physician may order a stress thallium test to diagnose the perfusion defect.