ISSN: 2578-4633
Authors: Mittal SR* and Mittal G
Electrocardiographic changes on standing from supine position and subsequent hyperventilation were studied in 100 persons. Changes were correlated with any evidence of myocardial ischemia during stress and/or recovery phase of treadmill stress testing. 15 individuals showed electrocardiographic changes on standing from supine position. Increase in heart rate of more than 30 beats per minute without a fall of more than 20 mm Hg in systolic blood pressure was seen in three cases. Two of them developed ischemic changes during exercise. Decrease in R wave amplitude in leads V2 to V6 was seen in one individual who developed ischemic changes during exercise. New inversion of T waves in leads V2 to V4 in a case with pre-existing RBBB and inverted T wave becoming positive in lead V2 were also associated with electrocardiographic evidence of myocardial ischemia during exercise testing. Mild change in QRS axis, decrease in R wave amplitude in leads II, III, aVF and/or V3 to V5 , ST segment depression of less than 1 mm and decrease in amplitude or inversion of T waves in leads II, III, aVF and V1 to V6 did not have any correlation with evidence of myocardial ischemia during exercise. Fourteen persons showed new electrocardiographic changes during hyperventilation after standing. Three cases had decrease in heart rate. All the three had evidence of myocardial ischemia during treadmill testing. Increase in amplitude of R wave in lead V4, normalization of pre-excitation with unmasking of old myocardial infarction and ST segment depression of more than 2 mm in inferior and lateral precordial leads with ST segment elevation in lead aVR were also associated with development of ECG evidence of myocardial ischemia during treadmill testing. Decrease in R wave amplitude in leads II, III, aVF and/or V4 - V6 , ST segment depression of less than 1mm in inferior or lateral precordial leads and inversion of T waves did not have any significant correlation with development of electrocardiographic signs of myocardial ischemia during treadmill stress test.
Keywords: Electrocardiography; Exercise Electrocardiography; Hyperventilation; Postural Changes; ST-Segment; T Wave; Treadmill Test
