Plain-English translation of NCT03446326 on ClinicalTrials.gov ↗ · Source last updated · Translation generated · How we translate trials
This study doesn't follow the usual testing phases — it may be an observational study or a different type of research.
Researchers want to understand why pacemakers don't always prevent fainting in people with vasovagal syncope, even though faster heart rates should theoretically pump more blood. This study uses your existing pacemaker to safely test your heart's performance at different speeds — from 50 to 130 beats per minute — to measure how much blood your heart actually pumps at each rate.
Doctors have used pacemakers to treat recurrent fainting, but they often don't work as expected. This study aims to solve that puzzle by measuring exactly what happens to your heart's pumping ability when its speed increases, which could lead to better treatments.
You likely qualify if…
You likely don't qualify if…
You'll visit the lab for one session where researchers use your pacemaker to gradually increase your heart rate through nine different speeds while lying flat on a table. Between each speed change, they'll recalibrate a finger blood pressure cuff to measure how much blood your heart is pumping. After the final test while lying down, you'll rest for 10 minutes, then be tilted upright at a steep angle (nearly standing) and the whole process repeats to see if your heart performs differently when you're upright.
AI-generated summary from trial data · Jul 16, 2026 · Not medical advice
Canada
Enrollment target
~25 participants
Started
January 2018
Primary completion
January 2027
Age range
18 Years – 70 Years
Last updated on clinicaltrials.gov in May 2026.
Reach out to the team running this trial. Response times vary — some teams are faster than others.
Central contact
Satish R Raj, MD MSCI
University of Calgary
Tell us you're interested and we'll help connect you with the research team. We'll walk you through what to expect first — no email needed to get started.