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Understanding Heart and Blood Vessel Interactions During Cardiac Unloading

This study is looking at how your heart and blood vessels work together when your blood pressure drops, a situation called cardiac unloading. Researchers want to understand how age and sex affect this interaction, especially since many older adults, particularly women, experience dizziness or fainting when standing up. Participants will undergo procedures involving a lower body negative pressure (LBNP) chamber, which gently reduces blood pressure in the lower body, sometimes combined with isometric handgrip exercise. The study aims to measure how well your heart and arteries respond to these changes by looking at arterial elastance (how stiff your arteries are), ventricular elastance (how well your heart muscle contracts), and their coupling ratio (how well they work together). This research could help us better understand and manage conditions like orthostatic intolerance (feeling dizzy when standing up).

Study design
This interventional study plans to enroll 64 healthy participants, divided into younger (18-35 years) and older (65+ years) age groups.
What's involved
Participants will be exposed to a lower body negative pressure chamber protocol, with or without isometric handgrip exercise, in stages lasting 5 minutes each.
Compensation
Not stated in the trial record.
Follow-up
Measurements will be taken at baseline and during each stage of the lower body negative pressure protocol.

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NCT06939153

Effects of Age, Sex and Isometric Exercise on Ventricular-Vascular Interactions During Cardiac Unloading

Recruiting
NAAges 18+Interventional
Tracy Baynard
~64 participants
Updated 2026-04-30 on ClinicalTrials.gov
What's tested:LBNPLBNP + Isometric handgrip exercise

At a glance

Recruiting sites
1 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Arterial elastance
Measured over "Baseline/pre-LBNP", "During each LBNP stage (-20 mmHg, -30 mmHg, -40 mmHg, -50 mmHg) in the last 2 minutes"
+4 more outcomes measured

Conditions

Orthostatic Intolerance

Explore related trials

Orthostatic Intolerance

Where it's being run

1 sites across 1 states
Massachusetts1

Who to contact

João L. Marôco, MS
[email protected]
7738933897
Email the study team

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Eligibility criteria

Inclusion

People aged 18-35 years or aged ≥ 65 years
Healthy without symptons of orthostatic intolerance (i.e., nausea, sweating, weakness, visual disturbance)
Seated systolic and/or diastolic BP \<140/90 mmHg;
Body mass index \<35 kg/m2
Recreationally active (≤ 2 days of structured physical activity)
Regular menstrual cycles in young females

Exclusion

People diagnosed with cardiovascular, diabetes, inflammatory or renal diseases and neurodegenerative-related dementia
Tobacco users
People prescribed with beta-blockers
Pregnant females
People unable to fit or get into the lower body negative pressure chamber

What this trial measures

  • Arterial elastance"Baseline/pre-LBNP", "During each LBNP stage (-20 mmHg, -30 mmHg, -40 mmHg, -50 mmHg) in the last 2 minutes"

    Arterial elastance reflective of lumped afterload will be non-invasively estimated as end-systolic pressure (obtained from tonometry) divided by stroke volume (obtained from echocardiography)

  • Ventricular elastance"Baseline/pre-LBNP", "During each LBNP stage (-20 mmHg, -30 mmHg, -40 mmHg, -50 mmHg) in the last 2 minutes"

    Ventricular elastance, reflective of ventricle contractility, will be non-invasively estimated as end-systolic pressure (obtained from tonometry) divided by end-systolic volume (obtained from echocardiography).

  • Ventricular-vascular coupling ratio"Baseline/pre-LBNP", "During each LBNP stage (-20 mmHg, -30 mmHg, -40 mmHg, -50 mmHg) in the last 2 minutes"

    The arterial-to-ventricular elastance ratio will be considered as an index describing cardiac energy and efficacy.

  • Wasted pressure effort"Baseline/pre-LBNP", "During each LBNP stage (-20 mmHg, -30 mmHg, -40 mmHg, -50 mmHg) in the last 2 minutes"

    Wasted pressure effort, a marker of pulsatile afterload, will be estimated from pressure-flow analyses

  • Brachial blood pressure"Baseline/pre-LBNP", "During each LBNP stage (-20 mmHg, -30 mmHg, -40 mmHg, -50 mmHg) in the last 2 minutes"

    Beat-to-beat BP will be recorded continuously using finger plethysmography and calibrated to reflect both brachial artery systolic and diastolic blood pressure