Short- and long-term reproducibility of cardiovascular tests of autonomic function in normal subjects.

Ten healthy normal subjects participated in a follow-up study in which the reproducibility of noninvasive cardiovascular autonomic function testing was studied. The tests used were the Valsalva manoeuvre, deep and quiet breathing, standing upright and isometric handgrip exercise. These tests were performed six times within a 2-year period. The reproducibility of these autonomic function tests within a day was evaluated in a separate study involving nine healthy subjects. In this study the tests were performed three times between 08.00 and 15.00. The results indicate that indices based on R-R interval ratios during testing were highly reproducible; that the indices remain reproducible over a 2-year follow up period and that reproducibility within a day was similar to that within longer time periods. The reproducibility of pressor responses to isometric exercise was poor. It is concluded that indices based on R-R ratios are suitable for use in follow up studies of autonomic function.