Active compression garment prevents tilt-induced orthostatic tachycardia in humans.

Compression garments are used by patients with lower extremity edema to help regulate fluid distribution and to prevent orthostatic symptoms. Current compression stockings are often reported as uncomfortable and adherence is poor. The current study was conducted to assess the efficacy of a novel active compression garment on healthy individuals undergoing 60-degree head-up tilts for 10 min to induce venous pooling and subsequent physiological responses. During tilts while garments were on, participants' absolute change in heart rate relative to baseline was lower (16.7 ± 8.7 BPM) compared to control (20.9 ± 11.47 BPM, P = 0.002). There were no differences in changes in mean arterial blood pressure between conditions (P = 0.303). One participant had a pre-syncopal event which occurred during a tilt without garments. This participant did not experience pre-syncopal symptoms with the garments on. All together, these data suggest that a novel active compression garment is capable of blunting increases in heart rate during head-up tilt. While untested thus far in patient populations, these garments may prove efficacious in preventing orthostatic intolerance.

Orthostatic heart rate responses after prolonged space flights.

Orthostatic tachycardia (POTS) can occur after space flights. We determined orthostatic heart rate responses in 18 cosmonauts before and 3-5 days after long-term space missions. Cosmonauts undergoing a cardiovascular training program in space experienced only moderate POTS after their return to earth. Cardiovascular countermeasures may have attenuated POTS. Another possible interpretation is that cardiovascular deconditioning is not sufficient to elicit full blown POTS in the absence of additional genetic or environmental factors.