We have located links that may give you full text access.
CLINICAL TRIAL
JOURNAL ARTICLE
Prolonged latency in the baroreflex mediated vascular resistance response in subjects with postural related syncope.
In addition to the gain, the delay of the baroreflex response plays an important role in the maintenance of cardiovascular system stability. Additionally when postural changes induce sudden drops in blood pressure, a delayed response may fail to maintain sufficient cerebral perfusion pressure. We tested the hypothesis that the delay of the carotid baroreceptor reflex is impaired in subjects with poor orthostatic tolerance. An orthostatic test with 60 degrees head-up tilt, and progressive lower-body negative pressure was performed on 27 patients with histories of unexplained syncope and 13 control subjects. The test was stopped at the onset of presyncope and time to presyncope was taken as a measure of orthostatic tolerance. Twelve patients had normal tolerance and thirteen patients had low tolerance. We measured beat-to-beat blood pressure (Finapres) and brachial artery blood flow velocity (Doppler ultrasonography). Before the test, we determined the response of forearm vascular resistance (mean arterial pressure/mean brachial artery velocity) to loading/unloading of carotid baroreceptors by the application of neck suction/pressure (-/+30 mmHg) to a chamber fitted overlying the carotid sinus. We measured the gain in the response (maximum percentage change from baseline value in vascular resistance divided by the neck collar pressure) and the latency in the response (delay of the maximum change in vascular resistance after neck-collar stimulation). Results are reported as means +/- SEM. In the three groups, there were no differences in the sensitivity of the vascular resistance response after baroreceptor loading/unloading. Following baroreceptor unloading, the latency of the response was 14.0+/-1.3 seconds in early fainters, 9.3+/-0.7 seconds in normal patients and 10.1+/-1.2 seconds in controls. The latency in blood pressure rise was 11.1+/-1.3 seconds in early fainters, 7.9+/-0.9 seconds in normal patients and 7.2+/-1.0 seconds in controls. The results following baroreceptor loading were more scattered. The early fainters still had a tendency to show prolonged latency. These results suggest that the delay in the baroreflex response plays an important role in postural related syncope.
Full text links
Related Resources
Trending Papers
Challenges in Septic Shock: From New Hemodynamics to Blood Purification Therapies.Journal of Personalized Medicine 2024 Februrary 4
Molecular Targets of Novel Therapeutics for Diabetic Kidney Disease: A New Era of Nephroprotection.International Journal of Molecular Sciences 2024 April 4
Perioperative echocardiographic strain analysis: what anesthesiologists should know.Canadian Journal of Anaesthesia 2024 April 11
The 'Ten Commandments' for the 2023 European Society of Cardiology guidelines for the management of endocarditis.European Heart Journal 2024 April 18
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app