Q. What do you mean by QRS Changes?

The total amplitude of the QRS compared with exercise usually decreases near peak workload, as well as the T-wave amplitude, and there is a tendency towards right axis deviation. The QRS duration does not change significantly. If the stroke volume increases the T-wave may initially increase, which occurs early in exercise with moderate workloads. A decrease in R-wave is more likely to be seen immediately after the exercise period, however, rather than during it. When considering the QRS in the various leads during maximum exercise, there is a tendency towards a reduction in R-wave or S-wave amplitude; this is more marked in normal than in abnormal subjects. The decreased amplitude following a peak exercise period may be due to decrease in systolic and possibly diastolic volumes that often develop after peak cardiac output is attained.

This is termed the body effect, and found that left ventricular forces decreases stroke volume decrease and that right ventricular forces usually increase at the same time. In ischaemia, the systolic volume increases stroke volume decreases and the left ventricular R-waves any become taller.