Arterial baroreflex function in older adults with neurocardiogenic syncope

Abstract

Clin Invest Med 2009; 32 (3): E191-E198. AbstractPurpose: Neurocardiogenic syncope (formerly vasovagal) accounts for large numbers of falls in older adults and the mechanisms are poorly understood. This study examined the differences in baseline arterial baroreflex function in older adults with and without a neruocardiovascular response to orthostatic stress. Methods: Subjects were divided into two groups based on the presence (TT+ group) or absence (TT-group) of a neurocardiovascular response to upright tilting (70 degree head-up tilt for 10 minutes after 400 micrograms of sublingual nitroglycerin). A neurocardiovascular response was defined as presyncopal symptoms (lightheadedness) in association with at least a 30 mm Hg decrease in blood pressure. Before being divided into groups, baroreflex function was assessed using the spontaneous baroreflex method (baroreflex sensitivity, BRS). This method involves the analysis of "spontaneous" swings in blood pressure and heart rate that are mediated by the arterial baroreflexes. Results: 42 older adults (mean age 70.3±0.7 yr) were recruited, of which 18 were in the TT+ and 24 were in the TT-group. At baseline, the TT+ group demonstrated increased arterial baroreflex sensitivity in response to negative blood pressure sequences only (BRSdown, 11.2±1.9 vs. 7.3±1.0 ms/mm Hg, P=0.011). During tilt, the TT+ group demonstrated a much larger decrease in overall arterial baroreflex sensitivity than the TT-group (-6.8±1.2 vs. -3.2±0.9 ms/mm Hg, P=0.012). There was a negative correlation between BRSdown and length of tilt table test (r=-0.329, P=0.041) in the TT+ subjects. Conclusion: Older adults with neurocardiogenic syncope have exaggerated arterial baroreflex sensitivity at baseline.

Hemodynamic parameters and baroreflex sensitivity during head‐up tilt test in patients with neurally mediated syncope

“…Changes in baroreflex sensitivity (BRS) reflecting cardiovascular autonomic function have been suggested to be the primary mechanism for NMS . Several studies on the relationship between increased, decreased, or resetting of BRS and the development of NMS have been reported due to different methods of measuring BRS, diverse definitions of the head‐up tilt test (HUT) period, and various HUT protocols with or without drug administration. Administration of drugs such as nitroglycerin or isoproterenol to increase the diagnostic yield of HUT might be related to their effects of potent vasodilation on the alteration of HUT outcomes.…”

Intra-strain variations of baroreflex sensitivity in young Wistar-Kyoto rats

“…3 Over the past 20 years, it has been reported that arterial baroreflex function is related to the prognosis of acute cardiovascular infarction, arrhythmias, heart failure and stroke in humans. [3][4][5][6][7] Clinical observations indicate that patients with lower baroreflex sensitivity exhibit shorter survival times with these diseases. Arterial baroreflex function plays an important role in the pathogenesis and prognosis of hypertension, atherosclerosis, aconitine-induced arrhythmia and LPSinduced shock.…”

Caracterização da modulação autonômica cardiovascular nas posições supina e vertical, usando-se a manobra postural passiva, em pacientes com história clínica de síncope neurocardiogênica e indivíduos saudáveis

“…Resultados semelhantes também foram encontrados nos estudos de outros autores (FREITAS et al, 1999;SUZUKI et al, 2003;MADDEN and LOCKHART, 2009;LAGI et al, 2011) promoveu numa fase inicial, após a mudança postural, uma resposta hipotensora (PICCIRILLO et al, 2004).…”

“…Por outro lado, nesse contexto, vários outros mecanismos fisiopatológicos, particularmente os que se referem aos mecanismos de gatilho da SINC, ainda precisam ser intensamente investigados, em razão das discordâncias relatadas por diferentes autores na literatura (MOSQUEDA-GARCIA et al, 1997;ALBONI, et al, 2001;SHELDON et al, 2006;VAN DIJK and SHELDON 2008;Sheldon et al, 2010;SHELDON, 2013, VALLEJO et al, 2015. Por outro lado, nos pacientes com história sugestiva de SINC, diferentes relatos na literatura têm documentado que o padrão de respostas das variáveis cardiovasculares ao Tilt-test, entre o momento da mudança postural (horizontal à vertical) e o aparecimento da síncope ou pré-sincope, mostra-se muito heterogênio, tanto quando expresso em valores médios, como em variabilidade de pressão arterial e frequência cardíaca; além disso, a metodologia mais adequada a ser usada na aplicação do Tilt-test ainda não é consensual (FREITAS et al, 1999;PICCIRILLO et al, 2004;MADDEN and LOCKHART, 2009;DUPLYAKOV et al, 2011;FORLEO et al, 2013;MEREU et al, 2013;SHINOHARA et al, 2014). A investigação sobre este último aspecto assume grande importância, porque pode permitir ou não a possibilidade de prever-se a ocorrência de síncope no…”

“…Entretanto, outros autores relataram em seus estudos que a sensibilidade barorreflexa permanece inalterada até momentos anteriores a síncope ou há aumento do ganho barorreflexo nos indivíduos com SINC (FREITAS et al, 1999;MADDEN and LOCKHART, 2009 (JARDINE et al, 1998;BRIGNOLE et al, 2001;JULU et al, 2003;CHEN-SCARABELLI and SCARABELLI, 2004;ALBONI et al, 2007;MOYA et al, 2009;BRIGNOLE and HAMDAN, 2012;BARBIC et al, 2015); 3-em vários trabalhos sobre SINC os voluntários incluídos tomam medicações que podem influenciar nas respostas autonômicas na mudança postural (FOLINO et al, 2007). Também são fatores críticos, que influenciam a interpretação dos achados: 1-o tipo do protocolo experimental escolhido (velocidade da mudança postural súbita (igual ou maior a 10 segundos) ou progressiva, angulação da mesa na posição vertical; tempo de permanência do paciente na posição vertical; MPP isolada ou associada à fármacos (nitroglicerina, isoprenalina e adenosina) (MONTANO et al, 1994;KOCHIADAKIS et al, 1998;FREITAS et al, 1999;BARON-ESQUIVIAS et al, 2003;BARON-ESQUIVIAS and MARTINEZ-RUBIO, 2003;MOYA, 2009;MOYA et al, 2009;IACOVIELLO et al, 2010;DUPLYAKOV et al, 2011) CARDIOLOGY, 1996;LOMBARDI et al, 1996;KOCHIADAKIS et al, 1997;PORTA et al, 2001;STAUSS, 2003;LAUDE et al, 2004;MAESTRI et al, 2007;VOSS et al, 2009;MEREU et al, 2014) Idade (anos) Média ± DP 23,6 ± 12,4 27,2 ± 13,7 26,5 ± 3,4 0,11…”