Atrial distension in humans during microgravity induced by parabolic flights.
The hypothesis was tested that human cardiac filling pressures increase and the left atrium is distended during 20-s periods of microgravity (microG) created by parabolic flights, compared with values of the 1-G supine position. Left atrial diameter (n = 8, echocardiography) increased significantly during microG from 26.8 +/- 1.2 to 30.4 +/- 0.7 mm (P < 0.05). Simultaneously, central venous pressure (CVP; n = 6, transducer-tipped catheter) decreased from 5.8 +/- 1.5 to 4.5 +/- 1.1 mmHg (P < 0.05), and esophageal pressure (EP; n = 6) decreased from 1.5 +/- 1.6 to -4.1 +/- 1.7 mmHg (P < 0.05). Thus transmural CVP (TCVP = CVP - EP; n = 4) increased during microG from 6.1 +/- 3. 2 to 10.4 +/- 2.7 mmHg (P < 0.05). It is concluded that short periods of microG during parabolic flights induce an increase in TCVP and left atrial diameter in humans, compared with the results obtained in the 1-G horizontal supine position, despite a decrease in CVP.
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Danish Aerospace Medical Centre of Research and Clinic of Aviation Medicine, Rigshospitalet 7522, DK-2200 Copenhagen, Denmark.
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D000328:Adult; D016275:Atrial Function; D002496:Central Venous Pressure / Q000502:physiology; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000033:anatomy & histology / Q000502:physiology*; D006325:Heart Atria / Q000033:anatomy & histology; D006801:Humans; D008297:Male; D008875:Middle Aged; D014893:Weightlessness / Q000009:adverse effects*; D018474:Weightlessness Simulation