Effect of mental stress on R wave amplitude of the electrocardiogram in young healthy male subjects.

The electrocardiographic effects of mental arithmetic stress were studied in 19 young, healthy male subjects. Blood pressure was measured by the cuff method before and during mental stress and electrocardiogram (V5) was monitored and recorded continuously throughout the study using a computerized ECG monitoring system. Heart rate increased from 65.8 +/- 7.0 (mean +/- standard deviation) to 76.7 +/- 9.9 beats/min (p less than 0.001). Systolic blood pressure rose from 122.7 +/- 9.6 to 129.1 +/- 11.7 mmHg (p less than 0.05), diastolic blood pressure from 76.2 +/- 8.8 to 83.0 +/0 11.0 mmHg (p less than 0.001), and mean blood pressure from 91.7 +/- 7.9 to 98.5 +/- 10.1 mmHg (p less than 0.001). These changes were all statistically significant. R wave amplitude decreased significantly from 18.6 +/- 6.9 to 17.0 +/- 6.5 mm for the group (p less than 0.001). No changes in the ST segment were observed; ST depression decreased from 0.56 +/- 0.47 to 0.54 +/- 0.43 mm (N.S.) and ST slope from 0.87 +/- 0.59 to 0.77 +/- 0.63 mm/sec (N.S.). Thus it is apparent that mental stress reduced R wave amplitude without causing ST segment changes in young, healthy subjects. The mechanism and clinical implications are discussed.