1
|
Möller FN, Fan JL, Futral JE, Hodgman CF, Kayser B, Lovering AT. Cardiopulmonary haemodynamics in Tibetans and Han Chinese during rest and exercise. J Physiol 2024; 602:3893-3907. [PMID: 38924564 DOI: 10.1113/jp286303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 05/22/2024] [Indexed: 06/28/2024] Open
Abstract
During sea-level exercise, blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) in humans without a patent foramen ovale (PFO) is negatively correlated with pulmonary pressure. Yet, it is unknown whether the superior exercise capacity of Tibetans well adapted to living at high altitude is the result of lower pulmonary pressure during exercise in hypoxia, and whether their cardiopulmonary characteristics are significantly different from lowland natives of comparable ancestry (e.g. Han Chinese). We found a 47% PFO prevalence in male Tibetans (n = 19) and Han Chinese (n = 19) participants. In participants without a PFO (n = 10 each group), we measured heart structure and function at rest and peak oxygen uptake (V ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ ), peak power output (W ̇ p e a k ${{\dot{W}}_{peak}}$ ), pulmonary artery systolic pressure (PASP), blood flow through IPAVA and cardiac output (Q ̇ T ${{\dot{Q}}_{\mathrm{T}}} $ ) at rest and during recumbent cycle ergometer exercise at 760 Torr (SL) and at 410 Torr (ALT) barometric pressure in a pressure chamber. Tibetans achieved a higherW peak ${W}_{\textit{peak}}$ than Han, and a higherV ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ at ALT without differences in heart rate, stroke volume orQ ̇ T ${{\dot{Q}}_{\mathrm{T}}} $ . Blood flow through IPAVA was generally similar between groups. Increases in PASP and total pulmonary resistance at ALT were comparable between the groups. There were no differences in the slopes of PASP plotted as a function ofQ ̇ T ${{\dot{Q}}_{\mathrm{T}}} $ during exercise. In those without PFO, our data indicate that the superior aerobic exercise capacity of Tibetans over Han Chinese is independent of cardiopulmonary features and more probably linked to differences in local muscular oxygen extraction. KEY POINTS: Patent foramen ovale (PFO) prevalence was 47% in Tibetans and Han Chinese living at 2 275 m. Subjects with PFO were excluded from exercise studies. Compared to Han Chinese, Tibetans had a higher peak workload with acute compression to sea level barometric pressure (SL) and acute decompression to 5000 m altitude (ALT). Comprehensive cardiac structure and function at rest were not significantly different between Han Chinese and Tibetans. Tibetans and Han had similar blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) during exercise at SL. Peak pulmonary artery systolic pressure (PASP) and total pulmonary resistance were different between SL and ALT, with significantly increased PASP for Han compared to Tibetans at ALT. No differences were observed between groups at acute SL and ALT.
Collapse
Affiliation(s)
- Fabian N Möller
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Boston, MA, USA
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
- German Sport University Cologne, Institute for Professional Sport Education and Qualification, Cologne, Germany
| | - Jui-Lin Fan
- Department of Physiology, Manaaki Manawa - The Centre for Heart Research, University of Auckland, Faculty of Medical and Health Sciences, Auckland, New Zealand
| | - Joel E Futral
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
- Oregon Heart & Vascular Institute, Springfield, Oregon, USA
| | - Charles F Hodgman
- Department of Health and Human Performance, University of Houston, Houston, TX, USA
| | - Bengt Kayser
- University of Lausanne, Institute of Sports Sciences, Lausanne, Switzerland
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| |
Collapse
|
2
|
Boulet LM, Vermeulen TD, Cotton PD, Foster GE. Influence of blood Po 2 on the stability of agitated saline contrast. J Appl Physiol (1985) 2020; 129:1341-1347. [PMID: 33054656 DOI: 10.1152/japplphysiol.00488.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The utility of transthoracic saline contrast echocardiography (TTSCE) to assess blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) in humans is limited due to the potential destabilizing effects of the gas concentration gradients established in varied blood-gas environments. This study assessed the specific effect of a hyperoxic and mixed venous blood-gas environment on the stability of saline contrast. We hypothesized that the rate of contrast mass lost in hyperoxic blood would be similar to mixed venous due to the establishment of equal and opposing gas gradients (O2, N2, CO2) created when the partial pressure of dissolved gases is manipulated. Using an in vitro model of the pulmonary circulation perfused with defibrinated sheep blood and a membrane oxygenator to control blood gases, we assessed the percent contrast conserved (an index of contrast stability) between inflow and outflow sites at multiple flow rates (1.8, 2.8, 4.3, and 6.8 L/min) in a hyperoxic (Po2: 646 ± 16 mmHg; Pco2: 0 ± 0 mmHg) and a mixed venous blood gas condition (Po2: 35 ± 3 mmHg; Pco2: 40 ± 0 mmHg). We found significant contrast decay with time in both conditions, with slightly higher contrast conservation in the hyperoxia trials (64 ± 32%) versus the mixed venous trials (55 ± 21%). These findings suggest that contrast stability is not likely a factor affecting the interpretation of TTSCE performed in healthy humans breathing hyperoxia and lends support to the existence of a local O2-dependent mechanism contributing to the regulation of Q̇IPAVA.NEW & NOTEWORTHY Hyperoxic blood has a small stabilizing effect on agitated saline contrast compared with mixed venous blood, lending support to studies that show the reversal of exercise-induced blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) with hyperoxia. These data support the possible presence of a local O2-dependent regulatory mechanism within the pulmonary vasculature that may play a role in Q̇IPAVA regulation.
Collapse
Affiliation(s)
- Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Paul D Cotton
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| |
Collapse
|
3
|
Foster GE. Measuring blood flow through intrapulmonary and intracardiac shunts: a technical labyrinth. J Physiol 2019; 597:5315-5316. [PMID: 31529499 DOI: 10.1113/jp278820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 09/16/2019] [Indexed: 11/08/2022] Open
Affiliation(s)
- Glen E Foster
- Centre for Heart, Lung, and Vascular Health. School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
| |
Collapse
|
5
|
Petrassi FA, Davis JT, Beasley KM, Evero O, Elliott JE, Goodman RD, Futral JE, Subudhi A, Solano-Altamirano JM, Goldman S, Roach RC, Lovering AT. AltitudeOmics: effect of reduced barometric pressure on detection of intrapulmonary shunt, pulmonary gas exchange efficiency, and total pulmonary resistance. J Appl Physiol (1985) 2018; 124:1363-1376. [PMID: 29357511 PMCID: PMC6008081 DOI: 10.1152/japplphysiol.00474.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 12/06/2017] [Accepted: 12/10/2017] [Indexed: 11/22/2022] Open
Abstract
Blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA) occurs in healthy humans at rest and during exercise when breathing hypoxic gas mixtures at sea level and may be a source of right-to-left shunt. However, at high altitudes, QIPAVA is reduced compared with sea level, as detected using transthoracic saline contrast echocardiography (TTSCE). It remains unknown whether the reduction in QIPAVA (i.e., lower bubble scores) at high altitude is due to a reduction in bubble stability resulting from the lower barometric pressure (PB) or represents an actual reduction in QIPAVA. To this end, QIPAVA, pulmonary artery systolic pressure (PASP), cardiac output (QT), and the alveolar-to-arterial oxygen difference (AaDO2) were assessed at rest and during exercise (70-190 W) in the field (5,260 m) and in the laboratory (1,668 m) during four conditions: normobaric normoxia (NN; [Formula: see text] = 121 mmHg, PB = 625 mmHg; n = 8), normobaric hypoxia (NH; [Formula: see text] = 76 mmHg, PB = 625 mmHg; n = 7), hypobaric normoxia (HN; [Formula: see text] = 121 mmHg, PB = 410 mmHg; n = 8), and hypobaric hypoxia (HH; [Formula: see text] = 75 mmHg, PB = 410 mmHg; n = 7). We hypothesized QIPAVA would be reduced during exercise in isooxic hypobaria compared with normobaria and that the AaDO2 would be reduced in isooxic hypobaria compared with normobaria. Bubble scores were greater in normobaric conditions, but the AaDO2 was similar in both isooxic hypobaria and normobaria. Total pulmonary resistance (PASP/QT) was elevated in HN and HH. Using mathematical modeling, we found no effect of hypobaria on bubble dissolution time within the pulmonary transit times under consideration (<5 s). Consequently, our data suggest an effect of hypobaria alone on pulmonary blood flow. NEW & NOTEWORTHY Blood flow through intrapulmonary arteriovenous anastomoses, detected by transthoracic saline contrast echocardiography, was reduced during exercise in acute hypobaria compared with normobaria, independent of oxygen tension, whereas pulmonary gas exchange efficiency was unaffected. Modeling the effect(s) of reduced air density on contrast bubble lifetime did not result in a significantly reduced contrast stability. Interestingly, total pulmonary resistance was increased by hypobaria, independent of oxygen tension, suggesting that pulmonary blood flow may be changed by hypobaria.
Collapse
Affiliation(s)
- Frank A Petrassi
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - James T Davis
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Kara M Beasley
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Oghenero Evero
- Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus , Denver, Colorado
| | - Jonathan E Elliott
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Randall D Goodman
- Oregon Heart and Vascular Institute, Echocardiography, Springfield, Oregon
| | - Joel E Futral
- Oregon Heart and Vascular Institute, Echocardiography, Springfield, Oregon
| | - Andrew Subudhi
- Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus , Denver, Colorado
| | | | - Saul Goldman
- Department of Chemistry, University of Guelph , Guelph, Ontario , Canada
| | - Robert C Roach
- Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus , Denver, Colorado
| | - Andrew T Lovering
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| |
Collapse
|
6
|
O'Halloran KD. High adventure shunts old notions of pulmonary vascular control during hypoxic exercise: contrasting views that might just burst your bubble! Exp Physiol 2017; 102:617-618. [PMID: 28393420 DOI: 10.1113/ep086376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Ken D O'Halloran
- Department of Physiology, School of Medicine, University College Cork, Cork, Ireland
| |
Collapse
|