Every one has a physiologic response to upright tilt. Therefore a "negative
tilt test" is confusing. A normal response to upright tilt is shown. There is an increase in heart rate
on the order of 15 beats per minute during the first 10 minutes of orthostasis.
Heart rate continues to rise slowly thereafter. The upper limit for the heart
rate increase is 30 beats per minute during the first 10 minutes in adults and
somewhat greater in adolescents. systolic blood pressure often increases
slightly. There is a large increase in diastolic blood pressure so that the
pulse pressure is typically decreased. This goes along with a decrease in
cardiac stroke volume.