Vasodepressor syncope induced by lower body negative pressure: possible relevance to +Gz-stress training--a case...

We present a case report of vasodepressor syncope with brief sinus pause in a 26-year-old male subject following a graded lower body negative pressure (LBNP) challenge culminating at -70 mm Hg. Cessation of the LBNP protocol resulted in the return of heart rate and blood pressure activity to pre-challenge levels. Sinus arrest during central hypovolemic stress has been noted in the literature. Its potential in rare cases during exposure to high levels of LBNP should be noted as increasing numbers of investigators utilize presyncopal LBNP testing to assess the orthostatic responses of pilots and astronauts.