Healthy Aging Research | www.har-journal.com Brinth et al. 2014 | 3:6 1 Carotid sinus syndrome and cardiovagal regulation in elderly patients with suspected syncope-related falls Louise Brinth 1,2* , Tabassam Latif 2 , Kirsten Pors 2 , Andreas Kjær 3 , Jesper Mehlsen 1,2 1 Department of Clinical Physiology & Nuclear Medicine, Frederiksberg Hospital, Frederiksberg, Denmark 2 Coordinating Research Center, Frederiksberg Hospital, Frederiksberg, Denmark 3 Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Rigshospital and University of Copenhagen, Copenhagen, Denmark Abstract Background: Falls and syncope in the elderly may be caused by hypersensitivity in the high-pressure baroreflex control - carotid sinus syndrome (CSS). The pathophysiological process causing CSS remains poorly understood. Methods: We studied the hemodynamic response to carotid sinus massage (CSM) and compared this to other measurements of autonomic cardiovascular control in patients suspected of syncope-related falls. One hundred patients (≥80 years-old) referred to our syncope unit due to recurrent falls or possible syncope participated. CSM was performed in the supine and head-up tilted (HUT) positions. A hypersensitive response was defined by current guidelines. Results: In the supine position, heart rate (HR) and systolic blood pressure (SBP) decreased during CSM on the right side by 17.0 +/- 15.2 min -1 and 32.5 +/- 25.5 mmHg, and on the left side by 12.8 +/- 14.3 min -1 and 22.7 +/- 20.7 mmHg, respectively. Changes in SBP were greater in the head-up tilted position (right side; p=0.029, left side; p=0.007). Hypersensitive responses were elicited in 45 patients. We found orthostatic hypotension (OH) (r=-0.275, p=0.015), not CSS, to be inversely correlated to low frequency HR variability during HUT. Conclusions: The hemodynamic response to CSM has a well-defined pattern and differs both with respect to the stimulus site and patient position. We suggest that CSS is not a distinct pathophysiological process or disease entity but rather an acquired cardiovascular instability due to age-related degeneration and following mismatch between different components of cardiovascular regulation. Citation: Brinth L, Latif T, Pors K, Kjær A, Mehlsen J (2014) Carotid sinus syndrome and cardiovagal regulation in elderly patients with suspected syncope-related falls. Healthy Aging Research 3:6. doi:10.12715/har.2014.3.6 Received: August 1, 2014; Accepted: November 12, 2014; Published: November 26, 2014 Copyright: © 2014 Brinth et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Competing interests: The authors have declared that no competing interests exist. * Email: louisebrinth@live.dk Introduction Falls are the most common cause of accidents in older people and lead to substantial morbidity and mortality [1]. A common cause of falls in the elderly is syncope and, as such, the 10-year incidence is almost 25% in people over 70 years-old [2]. As syncope is often associated with retrograde amnesia [3], syncope- related falls are presumably under-reported. Falls in the elderly due to syncope may be caused by hypersensitivity of the high-pressure baroreflex control of heart rate (HR) and blood pressure (BP) (carotid sinus hypersensitivity, CSH) and lead to carotid sinus syndrome (CSS), a condition in which the hypersensitive baroreflexes are accompanied by recurrent symptoms of dizziness, light-headedness or syncope.