Orthostatic tolerance of normal Indians and those with suspected abnormal cardiovascular reflex status.

There were 143 healthy Indian males subjected to 70 degrees headup tilt (HUT) for 20 min on 166 occasions to evaluate their cardiovascular response. They responded with a significant rise in heart rate, diastolic pressure, and mean arterial pressure. Pulse pressure fell significantly. Heart rate and diastolic pressure during the tilt were significantly (p less than 0.05) and positively correlated to the height of the subjects. None of the subjects had syncope, which has been reported in normal individuals elsewhere. Of the 57 subjects with suspected abnormality of the cardiovascular reflex status, who were also investigated by the tilt test, 13 (22.8%) developed various degrees of orthostatic intolerance. Of these 13 subjects, 10 had had syncope in the past. In view of these observations, it is concluded that 70 degrees head-up tilt is an important clinicophysiological investigation in the assessment of subjects with a suspected abnormality of their cardiovascular reflex status.