OBJECTIVES: We sought to evaluate whether changes in resting baroreflex control of heart rate are a distinctive feature of healthy subjects with a history of syncope prone to a positive tilt-test response. BACKGROUND: The mechanisms involved in the pathogenesis of vasovagal syncope (VVS) are still poorly understood; in particular, the contribution of arterial baroreflex control of heart rate is matter of discussion. METHODS: A passive tilt-table test was performed in 312 consecutive, otherwise healthy subjects (age 36 +/- 15 years) with unexplained syncope and 100 control subjects. At baseline, spontaneous baroreflex sensitivity (BRS; ms/mm Hg) and the baroreflex effectiveness index (BEI) were assessed using the sequence method. RESULTS: The study population showed normal baroreflex function. Tilt-induced VVS in 94 subjects who were younger than both the tilt-negative and control subjects (30 +/- 14, 38 +/- 15, and 37 +/- 14 years, respectively; p = 0.00005) showed greater BRS (17.4 +/- 9.8, 13.2 +/- 7.9, and 12.8 +/- 8.2 ms/mm Hg, respectively; p = 0.0001), but had a similar BEI (0.59 +/- 0.18, 0.56 +/- 0.19, and 0.58 +/- 0.2, respectively; p = NS). On Cox multivariate analysis, the occurrence of VVS during tilt was inversely related to age (hazard ratio 0.97; p = 0.0004) and directly related to the BRS slope of sequences, implying a baroreceptor deactivation (hazard ratio 1.05; p = 0.02), but not of sequences characterized by arterial baroreceptor stimulation. CONCLUSIONS: Subjects with tilt-induced VVS showed greater resting BRS but had a normal BEI. The enhanced reflex tachycardic response to arterial baroreceptor deactivation at rest may represent a characteristic feature of subjects prone to tilt-induced VVS.
OBJECTIVES: We sought to evaluate whether changes in resting baroreflex control of heart rate are a distinctive feature of healthy subjects with a history of syncope prone to a positive tilt-test response. BACKGROUND: The mechanisms involved in the pathogenesis of vasovagal syncope (VVS) are still poorly understood; in particular, the contribution of arterial baroreflex control of heart rate is matter of discussion. METHODS: A passive tilt-table test was performed in 312 consecutive, otherwise healthy subjects (age 36 +/- 15 years) with unexplained syncope and 100 control subjects. At baseline, spontaneous baroreflex sensitivity (BRS; ms/mm Hg) and the baroreflex effectiveness index (BEI) were assessed using the sequence method. RESULTS: The study population showed normal baroreflex function. Tilt-induced VVS in 94 subjects who were younger than both the tilt-negative and control subjects (30 +/- 14, 38 +/- 15, and 37 +/- 14 years, respectively; p = 0.00005) showed greater BRS (17.4 +/- 9.8, 13.2 +/- 7.9, and 12.8 +/- 8.2 ms/mm Hg, respectively; p = 0.0001), but had a similar BEI (0.59 +/- 0.18, 0.56 +/- 0.19, and 0.58 +/- 0.2, respectively; p = NS). On Cox multivariate analysis, the occurrence of VVS during tilt was inversely related to age (hazard ratio 0.97; p = 0.0004) and directly related to the BRS slope of sequences, implying a baroreceptor deactivation (hazard ratio 1.05; p = 0.02), but not of sequences characterized by arterial baroreceptor stimulation. CONCLUSIONS: Subjects with tilt-induced VVS showed greater resting BRS but had a normal BEI. The enhanced reflex tachycardic response to arterial baroreceptor deactivation at rest may represent a characteristic feature of subjects prone to tilt-induced VVS.
Authors: Mohammad S Alnoor; Holly K Varner; Ian J Butler; Jeremy E Lankford; Liang Zhu; Mohammed T Numan Journal: Pediatr Cardiol Date: 2022-01-28 Impact factor: 1.655
Authors: Tobia Zanotto; Thomas H Mercer; Marietta L van der Linden; Jamie P Traynor; Colin J Petrie; Arthur Doyle; Karen Chalmers; Nicola Allan; Jonathan Price; Hadi Oun; Ilona Shilliday; Pelagia Koufaki Journal: PLoS One Date: 2018-12-06 Impact factor: 3.240
Authors: Tobia Zanotto; Thomas H Mercer; Marietta L van der Linden; Robert Rush; Jamie P Traynor; Colin J Petrie; Arthur Doyle; Karen Chalmers; Nicola Allan; Ilona Shilliday; Pelagia Koufaki Journal: BMC Nephrol Date: 2020-03-14 Impact factor: 2.388
Authors: Kwang Jin Chun; Hye Ran Yim; Jungwae Park; Seung Jung Park; Kyoung Min Park; Young Keun On; June Soo Kim Journal: Yonsei Med J Date: 2016-03 Impact factor: 2.759