Using Breathing Techniques to Ease Anxiety in ICU Patients Awaiting Heart Transplants

March 24, 2026 updated by: Rachel Cavallaro, Hartford HealthCare

Effectiveness of Heart Rate Variability in Reducing Anxiety in Pre-Heart Transplant Candidates in the ICU

The goal of this clinical trial is to learn whether a breathing-based relaxation technique called heart rate variability biofeedback (HRVB) can help reduce anxiety in adult patients who are in the intensive care unit (ICU) and waiting for a heart transplant. The main questions it aims to answer are:

Can HRVB reduce anxiety in patients awaiting heart transplantation in the ICU? Does HRVB help patients feel more in control of their emotions during this stressful time?

Participants will:

Complete a brief anxiety assessment before and after the intervention Participate in a guided HRVB session using a breathing device or app Learn how to use the technique on their own for future stress management

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This is a single-group clinical trial designed to evaluate the effectiveness of heart rate variability biofeedback (HRVB) in reducing anxiety among adult patients who are currently admitted to the intensive care unit (ICU) and awaiting heart transplantation. Patients in this population often experience elevated levels of psychological distress, including anxiety and panic symptoms, due to the uncertainty of their medical condition, the high-stress ICU environment, and the emotional burden of awaiting a life-saving procedure.

Heart rate variability (HRV) is a physiological marker of autonomic nervous system function and emotional regulation. HRVB is a non-invasive intervention that teaches individuals to regulate their breathing in a way that promotes optimal HRV. This technique has been shown in prior research to reduce anxiety and improve emotional resilience in various populations, but its application in critically ill transplant candidates remains underexplored.

Participants in this study will complete a baseline assessment of anxiety using validated self-report measures. They will then participate in a guided HRVB session, which includes paced breathing instruction and the use of a biofeedback device or app that provides real-time feedback on heart rate and breathing patterns. Following the session, participants will complete a post-intervention assessment to evaluate changes in anxiety levels. Participants will also be encouraged to continue practicing the technique independently as appropriate.

This study aims to assess the feasibility and immediate psychological benefits of HRVB in a high-acuity medical setting and to inform future research on integrative behavioral health interventions for transplant candidates.

Study Type

Interventional

Enrollment (Estimated)

60

Phase

  • Not Applicable

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria

  • any gender
  • any race/ethnicity
  • ≥18 years old with no upper limit
  • currently inpatient in the cardiac ICU, awaiting heart transplant
  • elevated anxiety symptoms as evidenced by cut scores on the Depression, Anxiety and Stress Scale (DASS-21) and the Cardiac Anxiety Questionnaire (CAQ) (Lovibond & Lovibond, 1995; Eifert et al., 2000).
  • proficiency in speaking, reading and writing in English Participants in this study must be proficient in English due to the language limitations of the study administrator. The intervention includes a teaching component that requires verbal instruction, psychoeducation, and interactive engagement, all of which will be conducted exclusively in English. At this time, the study administrator is only proficient in English and is unable to reliably deliver the intervention or assess participant understanding in other languages. To ensure consistency, accuracy, and fidelity of the intervention, as well as to maintain ethical standards in informed consent and participant comprehension, only English-speaking individuals will be eligible to participate.
  • able/willing to consent to participate Exclusion Criteria
  • <18 years of age
  • active psychosis or delirium
  • current neurological problems (e.g., stroke) at time of enrollment that would interfere with the ability to complete the practice
  • on a ventilator at time of enrollment
  • pregnancy
  • unable or unwilling to consent to participate

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Heart Rate Variability Biofeedback for Anxiety Reduction in ICU Heart Transplant Candidates"
Participants in this arm will receive a single-session heart rate variability biofeedback (HRVB) intervention while admitted to the intensive care unit (ICU) as candidates for heart transplantation. The intervention includes a guided breathing exercise using a biofeedback device or app that provides real-time feedback on heart rate and breathing patterns. A trained clinician will lead the session, which is designed to promote autonomic regulation and reduce anxiety. Participants will complete self-report anxiety assessments immediately before and after the session to evaluate changes in psychological distress. They will also receive brief instruction on how to continue using the breathing technique independently as appropriate.
Behavioral: Heart Rate Variability Biofeedback (HRVB)
Participants will receive a single-session heart rate variability biofeedback (HRVB) intervention while admitted to the intensive care unit (ICU) as candidates for heart transplantation. The intervention involves guided paced breathing using a biofeedback device or app that provides real-time feedback on heart rate and breathing patterns. A trained clinician will lead the session, which is designed to promote autonomic regulation and reduce anxiety. Participants will complete pre- and post-intervention self-report assessments to evaluate changes in anxiety levels. They will also receive brief instruction on how to continue using the breathing technique independently.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
DASS-21 Anxiety Scale (Depression Anxiety Stress Scales - 21-item short form)
Time Frame: Baseline (pre-intervention) and after 2 weeks (post-intervention)

Standardized self-report measure of anxiety Each item is scored 0-3. Each subscale (Depression, Anxiety, Stress) has 7 items → raw score 0-21, then multiplied by 2 to align with DASS-42 scoring.

Final score range per subscale: 0-42 (after multiplying) Higher scores = more severe symptoms.
Baseline (pre-intervention) and after 2 weeks (post-intervention)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Cardiac Anxiety Questionnaire
Time Frame: Baseline (pre-intervention) and after 2 weeks (post-intervention)
Standardized self-report measure of anxiety Contains 18 items, each rated on a 0-5 Likert scale (0 = never, 5 = always). Total score is the mean of all items. Minimum possible mean score: 0 Maximum possible mean score: 5 Higher CAQ scores = greater cardiac anxiety (worse outcome)
Baseline (pre-intervention) and after 2 weeks (post-intervention)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hartford HealthCare

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

March 1, 2026

Primary Completion (Estimated)

November 1, 2027

Study Completion (Estimated)

December 1, 2027

Study Registration Dates

First Submitted

October 1, 2025

First Submitted That Met QC Criteria

January 23, 2026

First Posted (Actual)

February 2, 2026

Study Record Updates

Last Update Posted (Actual)

March 27, 2026

Last Update Submitted That Met QC Criteria

March 24, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • HHC-2025-0188

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Only IPD used in the results publication

IPD Sharing Time Frame

Beginning 1 year after publication with no end date

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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