Blunted Nighttime Sympathetic Nervous System Response to Stress Among Thai Men with Positive Family History of Sudden Unexplained Nocturnal Death Syndrome

Abstract

Sudden unexplained nocturnal death syndrome (SUNDS) is prominent among northeast Thai men. This study tests the hypothesis that Thai men with positive family history of SUNDS display abnormal diurnal, autonomic nervous system responses to stress. Healthy northeast Thai men (20-49 years old) lived in the same rural area were divided into two groups based on their positive (PF) or negative family (NF1) history of SUNDS. A second control included Thai men with an NF history of SUNDS from a non-endemic area (NF2). All data were collected at 4:00-6:00 AM (nighttime) and 4:00-6:00 PM (daytime). All three groups displayed nighttime decreases in mean arterial pressure, heart rate, and blood glucose. Furthermore, all subjects displayed similar glucose tolerance and electrolyte balance. The tachycardic responses to a four-minute step test were similar among groups in the daytime, but the nighttime responses were significantly blunted in the PF group compared to either control group (about 20 bpm less). Tachycardic responses to a cold pressor test tended to decrease more during the nighttime in the PF compared to NF1 and NF2 groups, but the difference was not significant. Arterial pressure responses to the exercise were similar among the three groups during the nighttime, whereas in the NF2, daytime mean arterial pressures increased more than those in the other groups. The present data suggest that Thai men with a PF history of SUNDS display blunted sympathetic nervous system responses to stress during the nighttime, a potential factor that may trigger cardiac arrhythmias and contribute to SUNDS.

Heart rate turbulence measurements in patients with dipper and non-dipper hypertension: the effects of autonomic functions

“…The patients with non-dipper hypertension showed more significant autonomic dysfunction, increased peripheral resistance and myocardial hypertrophy, myocardial repolarization abnormalities, myocardial ischemia, and infarction [10,[29][30][31][32][33][34][35]. Due to these factors, sudden cardiac death risk may increase in patients with non-dipper hypertension [36][37][38]. Some studies have highlighted abnormalities in heart rate turbulence measurements in these patients [39].…”

“…Some studies have highlighted abnormalities in heart rate turbulence measurements in these patients [39]. Owing to close associations between the autonomic activity and heart rate turbulence measures, heart rate turbulence abnormalities may depend on autonomic dysfunction [35][36][37][38][39]. Therefore, the evaluation of HRT and HRV measurements together becomes more important.…”

Impact of Dietary Factors on Brugada Syndrome and Long QT Syndrome

“…The majority of sudden cardiac deaths seem to occur from 4 am to 6 am, so in a period of nocturnal sleep in which cortisol concentration tends to be lower than in other periods of the day [ 29 ]. This observation suggests a role for abnormal sympathetic activity, which has been observed in a SUNDS cohort (sudden unexplained death during nocturnal sleep), and SUNDS is still considered to share common genetic causes with BrS [ 30 , 31 ].…”

Racial Disparities in Ion Channelopathies and Inherited Cardiovascular Diseases Associated With Sudden Cardiac Death

“…BrS is inherited via autosomal dominant transmission and prevalent in southeast Asian populations. 51 Although the SCN5A gene has been implicated in 20% to 30% of BrS cases, it is doubtful that a monogenic mutation is responsible for its phenotypic manifestations. The genetic abnormality uniquely involves the epicardial aspect of the right ventricular outflow tract.…”