Impact of Hypoxia on Resting and Exertional Right Ventricular Performance

NCT ID: NCT05272514

Last Updated: 2023-05-09

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Total Enrollment

10 participants

Study Classification

OBSERVATIONAL

Study Start Date

2022-04-15

Study Completion Date

2022-12-15

Brief Summary

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The purpose of this study is to better understand how hypoxia (low oxygen) affects resting and exertional right ventricular function in healthy individuals.

Detailed Description

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The right ventricle plays a critical role in exercise. As workload increases with exercise, the right ventricle augments contractility and lusitropy (diastolic relaxation) to accommodate increased venous return (preload) and pulmonary arterial pressure (afterload). Using gold-standard pressure-volume analysis, the investigators have shown that impairments in right ventricular function limit functional capacity among individuals with cardiovascular disease, heart failure and pulmonary hypertension. In addition, the investigators have characterized right ventricular function during exercise in the healthy heart using these techniques. Hypoxia increases pulmonary arterial pressure via hypoxic pulmonary vasoconstriction. By increasing right ventricular afterload, hypoxia may compromise exercise capacity. However, data regarding the impact of hypoxia on right ventricular performance are lacking.

This is a human physiology study of resting and exertional right ventricular function under control (normoxic) and hypoxic conditions. The investigators will use pressure-volume analysis in conjunction with Swan-Ganz catheterization and echocardiography to assess right ventricular performance in healthy individuals at rest and during exercise in normoxia and hypoxia. The study protocol consists of three visits.

* Visit 1: Non-invasive symptom-limited cardiopulmonary exercise test under normoxic conditions (FiO2= 0.21).
* Visit 2: Non-invasive symptom-limited cardiopulmonary exercise test under hypoxic conditions (FiO2=0.12).
* Visit 3: Invasive resting and exertional hemodynamic assessment under normoxic and hypoxic conditions

In Visits 1 and 2, heart rate/rhythm, oxygen saturation, blood pressure, gas exchange parameters (oxygen uptake \[VO2\], carbon dioxide production \[VCO2\], and minute ventilation), and rated perceived exertion will be monitored. Cardiopulmonary exercise testing (CPET) will be performed on an upright cycle ergometer with workload starting at 0 Watts and increasing every 2 minutes until volitional exhaustion with maximum workload at 8-12 minutes. The order of Visits 1 and 2 will be randomized to reduce the potential for bias from a learning/ordering effect.

In Visit 3, the same non-invasive measurements will be obtained. Additionally, right heart catheterization with Swan-Ganz catheter and conductance catheter placement will be performed. This will provide gold-standard hemodynamic and pressure-volume loop analysis to measure outcomes of right ventricular contractility, lusitropy (diastolic relaxation), afterload, and ventricular-arterial coupling. First, participants will complete submaximal exercise at FiO2=0.21. Submaximal exercise will include 5 minutes at 50% of baseline maximal oxygen uptake (VO2max achieved during Visit 1). After 20 minutes' rest, hemodynamic measurements will be obtained at rest at FiO2 0.21, 0.17, 0.15 and 0.12 to characterize the impact of progressive hypoxia on resting right ventricular hemodynamics. Participants will then perform submaximal exercise (50% VO2 max from hypoxic baseline at Visit 2) at FiO2 0.12. Thereafter, participants will complete a symptom-limited CPET at FiO2 0.12 with monitoring of invasive hemodynamics.

Conditions

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Ventricular Dysfunction, Right Hypoxia

Study Design

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Observational Model Type

OTHER

Study Time Perspective

PROSPECTIVE

Study Groups

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Healthy individuals

10 healthy individuals will be recruited.

Hypoxia

Intervention Type OTHER

Individuals will be exposed to varying levels of hypoxia according to the protocol detailed above.

Interventions

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Hypoxia

Individuals will be exposed to varying levels of hypoxia according to the protocol detailed above.

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* Age 18 - 60
* For women, premenopausal status

Exclusion Criteria

* Active cardiovascular or pulmonary disease (e.g. hypertension, coronary artery disease, cardiomyopathy, arrhythmia, valvular abnormalities, diabetes, peripheral vascular disease, tobacco use, chronic obstructive pulmonary disease, asthma, interstitial lung disease, restrictive lung disease, or pulmonary hypertension)
* Use of cardiac- or pulmonary-related medications
* Prior history of high altitude pulmonary edema or high altitude cerebral edema
* Body mass index \< 18.5 or \> 30
* Anemia
* Iron deficiency
* Iron supplementation (oral or intravenous) in the preceding 60 days
* Systemic anticoagulation or aspirin use that cannot be temporarily held for the study
* Pregnancy
* Non-cardiopulmonary disorders that adversely influence exercise ability (e.g. arthritis or peripheral vascular disease)
* Dedicated athletic training (defined here as spending \>9 hours per week in vigorous physical activity \[≥6 mets\])
* Regular high-altitude exercise (defined here as engaging in vigorous physical activity \[≥1 hour at ≥6 mets\] at ≥8,000 ft for \>2 days per week over the preceding 4 weeks)
* Residence at ≥8,000 ft for 3 or more consecutive nights in the preceding 30 days
Minimum Eligible Age

18 Years

Maximum Eligible Age

60 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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University of Colorado, Denver

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Locations

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University of Colorado Anschutz Medical Campus

Aurora, Colorado, United States

Site Status

Countries

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United States

References

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Smith TG, Balanos GM, Croft QP, Talbot NP, Dorrington KL, Ratcliffe PJ, Robbins PA. The increase in pulmonary arterial pressure caused by hypoxia depends on iron status. J Physiol. 2008 Dec 15;586(24):5999-6005. doi: 10.1113/jphysiol.2008.160960. Epub 2008 Oct 27.

Reference Type BACKGROUND
PMID: 18955380 (View on PubMed)

Smith TG, Talbot NP, Privat C, Rivera-Ch M, Nickol AH, Ratcliffe PJ, Dorrington KL, Leon-Velarde F, Robbins PA. Effects of iron supplementation and depletion on hypoxic pulmonary hypertension: two randomized controlled trials. JAMA. 2009 Oct 7;302(13):1444-50. doi: 10.1001/jama.2009.1404.

Reference Type BACKGROUND
PMID: 19809026 (View on PubMed)

Cornwell WK, Tran T, Cerbin L, Coe G, Muralidhar A, Hunter K, Altman N, Ambardekar AV, Tompkins C, Zipse M, Schulte M, O'Gean K, Ostertag M, Hoffman J, Pal JD, Lawley JS, Levine BD, Wolfel E, Kohrt WM, Buttrick P. New insights into resting and exertional right ventricular performance in the healthy heart through real-time pressure-volume analysis. J Physiol. 2020 Jul;598(13):2575-2587. doi: 10.1113/JP279759. Epub 2020 May 18.

Reference Type BACKGROUND
PMID: 32347547 (View on PubMed)

Cornwell WK 3rd, Baggish AL, Bhatta YKD, Brosnan MJ, Dehnert C, Guseh JS, Hammer D, Levine BD, Parati G, Wolfel EE; American Heart Association Exercise, Cardiac Rehabilitation, and Secondary Prevention Committee of the Council on Clinical Cardiology; and Council on Arteriosclerosis, Thrombosis and Vascular Biology. Clinical Implications for Exercise at Altitude Among Individuals With Cardiovascular Disease: A Scientific Statement From the American Heart Association. J Am Heart Assoc. 2021 Oct 5;10(19):e023225. doi: 10.1161/JAHA.121.023225. Epub 2021 Sep 9.

Reference Type BACKGROUND
PMID: 34496612 (View on PubMed)

Forbes LM, Bull TM, Lahm T, Lawley JS, Hunter K, Levine BD, Lovering A, Roach RC, Subudhi AW, Cornwell WK 3rd. Right Ventricular Response to Acute Hypoxia among Healthy Humans. Am J Respir Crit Care Med. 2023 Aug 1;208(3):333-336. doi: 10.1164/rccm.202303-0599LE. No abstract available.

Reference Type DERIVED
PMID: 37311248 (View on PubMed)

Other Identifiers

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21-4354

Identifier Type: -

Identifier Source: org_study_id

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