Subject(s)
Hypertension , Humans , Blood Pressure/physiology , Japan , Hypertension/physiopathology , Prognosis , Obesity/complications , Biomarkers , PhenotypeABSTRACT
Background Discerning the mechanisms driving orthostatic symptoms in human beings remains challenging. Therefore, we developed a novel approach combining cardiac and cerebral real-time magnetic resonance imaging, beat-to-beat physiological monitoring, and orthostatic stress testing through lower-body negative pressure (LBNP). We conducted a proof-of-concept study in a patient with severe orthostatic hypotension. Methods and Results We included a 46-year-old man with pure autonomic failure. Without and during -30 mmHg LBNP, we obtained 3T real-time magnetic resonance imaging of the cardiac short axis and quantitative flow measurements in the pulmonary trunk and middle cerebral artery. Blood pressure was 118/74 mmHg during supine rest and 58/35 mmHg with LBNP. With LBNP, left ventricular stroke volume decreased by 44.6%, absolute middle cerebral artery flow by 37.6%, and pulmonary trunk flow by 40%. Conclusions Combination of real-time magnetic resonance imaging, LBNP, and continuous blood pressure monitoring provides a promising new approach to study orthostatic intolerance mechanisms in human beings.
Subject(s)
Orthostatic Intolerance , Male , Humans , Middle Aged , Lower Body Negative Pressure , Blood Pressure/physiology , Stroke Volume , Magnetic Resonance ImagingABSTRACT
Background: Pulse wave velocity (PWV) independently predicts cardiovascular risk. Easy to use single-cuff oscillometric methods are utilized in clinical practice to estimate PWV. We applied the approach in master athletes to assess possible beneficial effects of lifelong exercise on vascular health. Furthermore, we compared single-cuff measurements with a two-cuff method in another cohort. Methods: We obtained single-cuff upper arm oscillometric measurements thrice in 129 master athletes aged 35-86 years and estimated PWV using the ArcSolver algorithm. We applied the same method in 24 healthy persons aged 24-55 years participating in a head down tilt bedrest study. In the latter group, we also obtained direct PWV measurements using a thigh cuff. Results: Estimated pulse velocity very highly correlated with age (R2 = 0.90) in master athletes. Estimated PWV values were located on the same regression line like values obtained in participants of the head down tilt bed rest study. The modest correlation between estimated and measured PWV (R² 0.40; p<0.05) was attenuated after adjusting for age; the mean difference between PWV measurements was 1 m/s. Conclusions: Estimated PWV mainly reflects the entered age rather than true vascular properties and, therefore, failed detecting beneficial effects of lifelong exercise. Funding: The AGBRESA-Study was funded by the German Aerospace Center (DLR), the European Space Agency (ESA, contract number 4000113871/15/NL/PG), and the National Aeronautics and Space Administration (NASA, contract number 80JSC018P0078). FH received funding by the DLR and the German Federal Ministry of Economy and Technology, BMWi (50WB1816). SM, JT and JJ were supported by the Austrian Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation, and Technology, BMK (SPACE4ALL Project, FFG No. 866761).
