An observational study in Heart Failure and Chronic Heart Failure, sponsored by NIRSense Inc.. Completed at 1 site in United States. Open to participants aged 18 Years to 85 Years. Per ClinicalTrials.gov, last updated 2026-10-14.
Sponsored by NIRSense Inc. · Observational
This prospective, single-center, observational pilot study evaluated an investigational wearable tissue oximeter (NIRSense Argus Oximetry System, also called Envello Core) in adult outpatients with chronic heart failure in New York Heart Association (NYHA) class I, II, or III at Jackson Heart Clinic in Jackson, Mississippi. During one routine clinic visit, participants wore three adhesive optical sensors, on the forearm, the thigh, and the sternum, while completing three standard tests: a blood pressure cuff occlusion of the arm (vascular occlusion test), a six-minute walk test, and a change from lying down to standing. The sensors use near-infrared spectroscopy to record changes in tissue oxygenation. The study compared tissue oxygenation responses across NYHA classes and with standard clinical measures (blood pressure, pulse rate, pulse oximetry, and walk distance). Participation added about 30 minutes to the visit, with no follow-up. Fifty participants were enrolled. No treatment decisions were based on the study device.
Background: Tissue oximeters use near-infrared spectroscopy (NIRS) to estimate tissue oxygenation noninvasively. NIRS tissue oximetry is used in surgery and intensive care, but low-burden wearable NIRS patches are recent, and their use in cardiovascular disease has not been assessed. Heart failure severity in outpatients is graded mainly by NYHA functional class, a clinical judgment. This pilot study examined whether tissue oxygenation measured by a wearable sensor during standardized tests relates to NYHA class.
Device: The NIRSense Argus Oximetry System (also called Envello Core) is an investigational, non-significant-risk, noninvasive wearable optical monitor. It consists of a reusable optical sensor with red and near-infrared light sources and detectors, a single-use medical-grade adhesive, and a display unit (tablet) that receives and stores the data. It measures relative tissue oxygenation by NIRS and, by photoplethysmography, pulse oximetry and pulse rate. The device has not been cleared or approved by the U.S. FDA. The study was conducted under the abbreviated investigational device exemption requirements for non-significant-risk devices.
Design: Single-center, prospective, observational study at an outpatient cardiology practice. Adults with heart failure in NYHA class I, II, or III were recruited from the clinic's patient population through flyers, staff approach, and phone contact at scheduling, and grouped by NYHA class. Each participant completed one visit. Three sensors were applied: on the dominant forearm over the wrist extensor muscles, vertically on the sternum, and vertically on the dominant thigh. Participants then completed three tests under clinical supervision. (1) Vascular occlusion test, performed twice: after a blood pressure measurement, a cuff on the upper arm was inflated to 50 mmHg above systolic pressure until forearm tissue oxygen saturation fell to 40% or for a maximum of 3 minutes, then released; the second test followed after tissue oxygenation had returned to baseline. (2) Six-minute walk test, with distance, breaks, and blood pressure before and after recorded. (3) Postural change: at least 5 minutes lying on an exam table with blood pressure recorded at 1-minute intervals for 3 minutes, then standing, with blood pressure recorded at 1-minute intervals for 3 minutes beginning after 1 minute of standing. Pulse oximetry and pulse rate were recorded with a standard pulse oximeter. There was no follow-up visit.
Data collected: Continuous sensor data from the three sites during all tests; date of birth, sex, height, weight, NYHA class, Fitzpatrick skin type, and medical history; blood pressure, pulse rate, pulse oximetry, and six-minute walk distance; adverse events, protocol deviations, and device deficiencies on the case report form.
Analysis: Sensor data were separated by test. Deoxygenation and reoxygenation slopes were extracted for the vascular occlusion and postural tests, and tissue oxygenation summary values for the walk test. Mean, median, and standard deviation were calculated for each NYHA class and each metric. Normality was assessed with Shapiro-Wilk tests. Correlations between sensor metrics and clinical measures were tested with Spearman or Pearson tests, and NYHA classes were compared with analysis of variance and Tukey tests, or Welch t-tests, as appropriate.
Enrollment: The protocol planned up to 200 participants. The sponsor closed enrollment after 50 participants, all of whom completed the visit. This record was registered after the study was completed.
5,801 studies on the registry are indexed under Heart Failure; 1,222 are open to participants now.
This study's enrollment of 50 is below the median of 200 across 1,719 observational studies indexed under Heart Failure.
Browse Heart Failure studies →NIRSense Inc. is the lead sponsor of 2 studies on the registry; 1 is open to participants now.
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Adults with previously diagnosed heart failure in New York Heart Association class I, II, or III, recruited from the existing patient population of an outpatient cardiology practice (Jackson Heart Clinic, Jackson, Mississippi) through clinic flyers, approach by clinic staff, and phone contact at scheduling.
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Exclusion Criteria:
Adults with heart failure classified as New York Heart Association class I at enrollment.
Device: Argus Oximetry System
Adults with heart failure classified as New York Heart Association class II at enrollment.
Device: Argus Oximetry System
Adults with heart failure classified as New York Heart Association class III at enrollment.
Device: Argus Oximetry System
Investigational wearable optical sensors using near-infrared spectroscopy and photoplethysmography to measure tissue oxygenation, pulse oximetry, and pulse rate. Three sensors are applied with a medical-grade adhesive to the dominant forearm, the sternum, and the dominant thigh and worn during a single clinic visit while the participant completes a vascular occlusion test (twice), a six-minute walk test, and a supine-to-standing postural test. Sensor data are collected for research only and are not used for treatment decisions.
Also known as: Envello Core, NIRSense Envello Core, NIRSense Sensor Patch, Argus Tissue Oximeter
Forearm tissue oxygenation kinetics during and after vascular occlusion, by NYHA class
Deoxygenation slope during cuff occlusion and reoxygenation slope after cuff release, measured by the NIRSense sensor on the dominant forearm and averaged over two vascular occlusion tests, compared across NYHA class I, II, and III. Hypothesis: slower reoxygenation after cuff release in participants with more severe heart failure.
Time frame: Day 1 (single study visit), from cuff inflation (up to 3 minutes of occlusion) through return to baseline after cuff release, for each of two tests
Rate and magnitude of tissue oxygenation decrease during a six-minute walk test, by NYHA class
Rate and overall magnitude of the decrease in tissue oxygenation measured by the NIRSense sensors on the forearm, thigh, and sternum during the walk, compared across NYHA class I, II, and III. Hypothesis: faster and greater decrease in participants with more severe heart failure.
Time frame: Day 1 (single study visit), during the six-minute walk test
Rate and magnitude of tissue oxygenation decrease on standing from a supine position, by NYHA class
Difference between supine and standing tissue oxygenation, and the rate of decrease on standing, measured by the NIRSense sensors on the forearm, thigh, and sternum, compared across NYHA class I, II, and III. Hypothesis: faster and greater decrease on standing in participants with more severe heart failure.
Time frame: Day 1 (single study visit), from 3 minutes before standing through the third blood pressure reading after standing
Correlation between sensor tissue oxygenation metrics and standard clinical measures
Spearman or Pearson correlation coefficients, within and across NYHA classes, between NIRSense tissue oxygenation metrics from each test and the standard measures recorded during the same test: blood pressure, pulse rate, and pulse oximetry for the vascular occlusion test; six-minute walk distance, blood pressure before and after the walk, pulse rate, and pulse oximetry for the walk test; supine-to-standing systolic blood pressure difference, pulse rate, and pulse oximetry for the postural test.
Time frame: Day 1 (single study visit), during the vascular occlusion, six-minute walk, and postural tests
Number of participants with adverse events and number of device deficiencies
Adverse events (including skin irritation at the adhesive site and events during the walk test such as dizziness or falls) and device deficiencies recorded on the case report form.
Time frame: Day 1, from sensor application through the end of the study visit
Plan to share: No — Individual participant data will not be shared. Study data are the confidential property of the sponsor under the Clinical Trial Agreement between NIRSense, Inc. and Jackson Heart Clinic.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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NIRSense Inc.