Study of How Heart Rate Affects Blood Flow in the Brain Using Electrophysiology in Patients Scheduled for Heart Procedures

What this Trial Is About

Researchers are studying the relationship between heart rate and blood flow in the middle cerebral artery MCA, aiming to better understand how heart rate affects cerebral blood flow velocity. This is particularly relevant for conditions like postural tachycardia syndrome POTS, where patients experience chronic symptoms such as dizziness and fainting due to possible changes in cerebral blood flow. The study focuses on the hemodynamic factors influencing MCA blood flow using patients already scheduled for elective electrophysiological studies. The study involves temporarily pacing the heart at controlled rates using a catheter placed in the right atrium during an electrophysiology procedure. Participants will undergo pacing at four different heart rates100, 120, 150, and 171 beats per minutefor one minute each, with rest periods in between. Heart rate, blood pressure, and MCA cerebral blood flow velocity will be continuously monitored using skin electrodes, finger cuffs, and transcranial Doppler ultrasound. Data on stroke volume, cardiac output, and vascular resistance will be collected to analyze their relationship with cerebral blood flow. Participants will be monitored while lying down during the procedure, which adds about 10 to 15 minutes to their planned electrophysiology study. Assessments include continuous heart rate and blood pressure monitoring, Doppler ultrasound to measure blood flow velocity, and recording of cardiac function parameters. The main measurement is the change in MCA cerebral blood flow velocity in response to pacing at 150 beats per minute compared to baseline. Safety and hemodynamic responses will be observed during and after pacing, with the clinical procedure continuing as planned afterward.

Assessment of the Relationship Between Cerebral Blood Flow and Heart Rate