Deceleration Capacity——A Novel Measure for Autonomic Nervous System in Patients with Vasovagal Syncope on Tilt-table Testing

• Published in: Journal of Huazhong University of Science and Technology. Medical sciences Vol. 37; no. 3; pp. 326 - 331
• Main Authors: Huang, Fen, Xu, Chun-fang, Deng, Xiao-yan, Zuo, Ping, Lin, Fan, Fan, Jing-jing, Xu, Wen-jia, Yang, Xiao-yun
• Format: Journal Article
• Language: English
• Published: Wuhan Huazhong University of Science and Technology 01.06.2017; Department of Cardiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
• Subjects: Adult; autonomic; Autonomic Nervous System - diagnostic imaging; Autonomic Nervous System - physiopathology; Blood Pressure - physiology; Bradycardia - complications; Bradycardia - diagnostic imaging; Bradycardia - physiopathology; Case-Control Studies; Deceleration; Echocardiography; Electrocardiography; Female; Heart - diagnostic imaging; Heart - physiopathology; Heart Rate - physiology; Hemodynamics - physiology; Holter; Humans; hypotension; Hypotension - complications; Hypotension - diagnostic imaging; Hypotension - physiopathology; Male; markedly; Medicine; Medicine & Public Health; Middle Aged; normalized; Posture - physiology; subgroups; sympathetic; syncope; Syncope, Vasovagal - complications; Syncope, Vasovagal - diagnostic imaging; Syncope, Vasovagal - physiopathology; Tilt-Table Test - statistics & numerical data; unexplained; Vagus Nerve - diagnostic imaging; Vagus Nerve - physiopathology; withdrawal; vasovagal syncope; head-up tilt-table testing; deceleration capacity; heart rate variability
• ISSN: 1672-0733; 1993-1352; 1993-1352
• DOI: 10.1007/s11596-017-1735-7

This study was to investigate the changes of autonomic nerve function and hemodynamics in patients with vasovagal syncope（VVS） during head-up tilt-table testing（HUT）. HUT was performed in 68 patients with unexplained syncope and 18 healthy subjects served as control group. According to whether bradycardia, hypotension or both took place during the onset of syncope, the patients were divided during the test into three subgroups： vasodepressor syncope（VD）, cardioinhibitory syncope（CI） and mixed syncope（MX） subgroups. Heart rate, blood pressure, heart rate variability（HRV）, and deceleration capacity（DC） were continuously analyzed during HUT. For all the subjects with positive responses, the normalized low frequency（LFn） and the LF/HF ratio markedly decreased whereas normalized high frequency（HFn） increased when syncope occurred. Syncopal period also caused more significant increase in the power of the DC in positive groups. These changes were more exaggerated compared to controls. All the patients were indicative of a sympathetic surge in the presence of withdrawal vagal activity before syncope and a sympathetic inhibition with a vagal predominance at the syncopal stage by the frequency-domain analysis of HRV. With the measurements of DC, a decreased vagal tone before syncope stage and a vagal activation at the syncopal stage were observed. The vagal tone was higher in subjects showing cardioinhibitory responses at the syncopal stage. DC may provide an alternative method to understand the autonomic profile of VVS patients.