Determinants of Spontaneous Baroreflex Sensitivity in a Healthy Working Population (original) (raw)
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The first-degree relatives (FDRs) of persons with type 2 diabetes mellitus have been reported to have higher risk of developing insulin resistance and diabetes than the general population. 1,2 There are also reports of increased cardiovascular (CV) risks and prevalence of CV diseases in this high-risk population. The pathophysiologic mechanisms that predispose these high-risk subjects to CV risks have not been precisely elucidated. Recently we have reported the contribution of sympathovagal imbalance (SVI) to CV risks in FDRs of type 2 diabetics. 5 Previous reports indicate sex difference in pathophysiology, clinical characteristics, severity, and vulnerability to complication in diabetes. Our report suggests significant alteration in energy homeostasis and increased susceptibility to insulin resistance in male rats compared with female rats after ventromedial hypothalamus lesion obesity. 10 There are reports of sexual dimorphism in glucose metabolism, insulin sensitivity, and insulin resistance. There is also report of sex difference in CV risks, with men more susceptible to CV diseases. 14 It was reported that sex difference in incidence of CV disease background Although cardiovascular (CV) risks are reported in first-degree relatives (FDRs) of type 2 diabetics, effects of gender on sympathovagal imbalance (SVI) and CV risks in these subjects have not been investigated.
Hypertension, 2008
In adults, initial stages of hypertension are associated with elevated sympathetic drive and significant alterations in indirect autonomic markers. There is growing evidence that children in the highest-pressure percentiles will be more likely to develop hypertension in adulthood, although mechanisms are not understood. We assessed whether computer analysis of RR interval and arterial blood pressure variability could detect early autonomic alterations in childhood hypertension, as assessed by noninvasive time and frequency domain measures of baroreflex regulation. We studied 75 children, subdivided in 3 subgroups of similar age (9.7Ϯ0.2 years): control subjects, prehypertensive children (ie, children with arterial pressure values Ͼ90th and Ͻ95th percentile for age, gender, and height), and children in the hypertensive range (ie, Ͼ95th percentile; systolic arterial pressure: 97Ϯ3/57Ϯ2, 121Ϯ5/70Ϯ1, and 128Ϯ2/ 80Ϯ2 mm Hg, respectively). We observed that hypertensive children demonstrate a significant impairment of the baroreflex as compared with control subjects (index ␣: 20Ϯ2 and 40Ϯ4 ms/mm Hg; spontaneous baroreflex slope: 20Ϯ2 and 37Ϯ5; ms/mm Hg; PϽ0.05 in both cases) and reduced RR variance. A similar baroreflex impairment is also observed in children whose arterial pressure falls short of this limit, ie, in the prehypertensive range. In conclusion, hypertensive children display a marked baroreflex impairment. A similar baroreflex impairment is also observed in the prehypertensive state. Baroreflex assessment could furnish additional information in the clinical assessment of pediatric hypertension. (Hypertension. 2008;51:1289-1294.)
P.060 Baroreflex Sensitivity and the Quality of Blood Pressure Regulation
Artery Research, 2007
thickness (IMT) is a marker of early atherosclerosis that is correlated with traditional risk factors and is predictive of subsequent myocardial infarction and stroke. Furthermore, possible differences in the pathophysiology of common carotid artery IMT and femoral IMT might allow the exploration of differential gene regulation in specific vascular beds. Methods: The current data included 63 probands (mean age 44.83 AE 7.41) and 77 relatives (mean age 45.35 AE 8.14). from 63 families. B-mode carotid and femoral ultrasonography was used to definite mean IMT of commom carotid (CCA) and common femoral artery (CFA). Variance component methods were used to estimate heritability from the normalized deviates. Results: Variances explained by all final covariates (includes sex, age, blood pressure, smoking, total cholesterol, HDL cholesterol, triglicerides, diabetus status, body mass index) for mean CCA and mean CFA IMT were 0.393 and 0.394, respectively. Multivariable eadjusted heritability were 0.232 for mean CCA and 0.141 for mean CFA IMT (all P <0.005). Conclusion: These data suggest that genetic factors independent of traditional cardiovascular risk factors more influence to CCA IMT than to CFA IMT. Although we found that acquired risk factors contribute progressively to IMT. Future studies of genetic linkage and gene candidate association are warranted to identify specific genetic variants predisposing early symptoms of atherosclerosis in specific vascular beds.
Heart rate and pulse pressure amplification in hypertensive subjects
American Journal of Hypertension, 2003
Background: Although mean blood pressure (MBP) remains unmodified along the arterial tree, pulse pressure (PP) increases physiologically from the central to the peripheral arteries. Amplification of PP is known to be influenced by heart rate (HR), but the impact of this alteration has never been tested in patients with hypertension. Methods: A total of 712 hypertensive subjects, either treated or untreated, were divided into three classes of HR level. Carotid and brachial systolic blood pressure (SBP), carotid augmentation index, a marker of wave reflections, and carotid-brachial PP amplification were measured using applanation tonometry. Results: Independent of age, sex, and antihypertensive drugs, subjects with HR Ͼ80 beats/min were characterized, in comparison with those with lower HR, by reduced carotid SBP, PP, and augmentation index, resulting in a significant increase in PP amplification. In men but not in women, this pattern was associated with higher values of brachial SBP and DBP and by higher incidences of elevated glycemia and atherosclerotic alterations. In the male population, PP amplifications was, independent of HR, associated with the presence of  blocking agents (negative association) and elevated plasma glucose. Conclusions: Hypertensive men and women with high HR have significant PP amplifications, principally because of reduced central SBP and disturbed wave reflections. -blocking agents and plasma glucose independently alter PP amplification in men but not in women. Whether these opposite patterns influence the gender difference in cardiovascular risk should be prospectively studied.
A comparison of pharmacologic and spontaneous baroreflex methods in aging and hypertension
Journal of Hypertension, 2009
Background-Phenylephrine bolus injection is an established technique to measure baroreflex sensitivity (BRS). This study quantified the relationship between the phenylephrine method and noninvasive measures of BRS and examined the effects of aging and hypertension on BRS. We also examined whether heart rate variability (HRV) provides as much information as does BRS. Methods-BRS was determined by phenylephrine bolus (BRS phe), amyl nitrite inhalation (BRS amyl), Valsalva maneuver (BRS Vals) and by time (BRS (+)) and spectral domain analysis (BRS LFα , 004-015Hz) of spontaneous blood pressure and R-R interval changes over the 5-min time period. Results-The phenylephrine method significantly correlated with other methods (BRS LFα R=0.54, BRS (+) R=0.55, BRS Vals R=0.43 and BRS amyl R=0.39; P≤0.001). Each method underestimated the BRS phe by the factors 0.62, 0.64, 0.59 and 0.33, respectively; P value less than 0.001. Only BRS LFα was significantly different between normotensive and hypertensive patients in young [24.3 ±1.4 (n=40) vs. 12.2±2.3 (n=7)] and middle-aged [16.5±1.1 (n=71) vs. 10.8±1.1 (n=31) groups, respectively]. HRV in the high frequency band (0.15-0.40Hz) was significantly lower in young hypertensive patients than in normal controls (26±6.0 vs. 50±2.4, P<0.05). Conclusion-Although all methods correlated with the phenylephrine technique, none of them could be used interchangeably with that technique. BRS LFα detected the baroreflex loss of hypertension most clearly, and BRS amyl did not differ among groups.