Recruiting

Cardiac Output

Sponsor:

University of Calgary

Code:

NCT03446326

Conditions

Vasovagal Syncope

Eligibility Criteria

Sex: All

Age: 18 - 70

Healthy Volunteers: Not accepted

Interventions

Pacing

Study Details

Brief summary:

The investigators will seek to determine the effects of different heart rates on both stroke volume and cardiac output using non-invasive hemodynamic assessments. In order to safely manipulate the HR, the investigators will study patients with permanent pacemakers in whom heart rate manipulation can be done in a safe and non-invasive manner.

Conditions

Vasovagal Syncope

Study ID

NCT03446326

Start date

Jan 1, 2018

Status verified date

Apr, 2026

Completion date

Jan 1, 2028

Anticipated

Primary completion date

Jan 1, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 70

Healthy Volunteers: Not accepted

Inclusion Criteria:

  • Age 18-70 years (inclusive)
  • Implanted permanent pacemaker or implanted defibrillator capable of atrial and ventricular pacing
  • LV ejection fraction >50%

Exclusion Criteria:

  • Unable or unwilling to provide informed consent
  • Clinical need for a cardiac resynchronization device

Study Design

Enrollment

25 participants

Anticipated

Intervention Model

Single group

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Stroke volume and cardiac output

Pacing runs will occur at the following rates:

  • 50 beats per minute (bpm)
  • 60 bpm
  • 70 bpm
  • 80 bpm
  • 90 bpm
  • 100 bpm
  • 110 bpm
  • 120 bpm
  • 130 bpm

The finger blood pressure cuff will be calibrated between pacing runs.

Following the final pacing run while supine, the patient will be given 10 minutes to rest prior to the upright portion of the study. They will then be strapped into the table (so they will not fall) and then they will be tilted up to >70 degrees (almost standing up). They will stand for \~10 minutes prior to commencing the next pacing trains.

Interventions

Pacing

Assess the non-invasively determined stroke volume and cardiac output response at different paced heart rates in patients with a cardiac pacemaker or implanted defibrillator with preserved ejection fractions (LVEF≥50%)

Primary outcome measure

  • Change in cardiac output while atrial pacing at lower and higher rates while supine [ Time Frame: 1 day ]

Central Contacts and Locations

Central contacts

Satish R Raj, MD MSCI

4032106152satish.raj@ucalgary.ca

Locations

University of Calgary

Recruiting

Calgary, Alberta, Canada, T2N 4Z6

Contacts

Satish R Raj, MD, MSCI

403-210-6152autonomic.research@ucalgary.ca

Robert S Sheldon, MD, PhD

403-220-8191autonomic.research@ucalgary.ca

More Information

Sponsor

University of Calgary

Last update posted

May 5, 2026

Last verified

Apr, 2026

Keywords

  • pacemaker
  • stroke volume
  • cardiac output
  • heart rate

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by University of Calgary on 2026-05-05.