[QRS axis shift in deep breathing]

We examined changes in mean QRS axis of electrocardiogram during the deep breathing test in outpatients with hypertension, ischemic heart disease, and/or diabetes mellitus. The mean age of all patients (n = 596; male 327, female 269) was 63.0 years (male 62.7 years, female 63.4 years). The average of the mean QRS axis in all patients was shifted to the right during deep inspiration. The changes in mean QRS axis during deep breathing test were more than 60 degrees in 27 patients (4%) (mean age: 70.0 years), 30-59 degrees in 118 patients (20%) (mean age: 65.5 years), and 0-29 degrees in 451 patients (76%) (mean age: 61.9 years). These results suggest that the changes in mean QRS axis during deep breathing are greater in the aged patients.