Autonomic and hemodynamic origins of pre-hypertension: central role of heredity

The relationship between glycemic variability and blood pressure variability in normoglycemic normotensive individuals

BACKGROUND AND AIM

Glycemic fluctuations around a mean glucose level, referred as glycemic variability and blood pressure variability (BPV) are considered as independent risk factors for cardiovascular diseases, all-cause mortality, and cardiovascular disease-mortality. With this background in mind, we aimed to investigate the association between glycemic variability and BPV and their association in normoglycemic and normotensive individuals.

MATERIALS AND METHOD

Twenty-seven normotensive normoglycemic individuals were recruited. Twenty-four hour Holter devices were utilized to measure ambulatory blood pressure (BP) while continuous glucose monitoring (CGM) devices were applied to measure glycemic variability simultaneously to the subjects. These devices were kept on for 48 h. For BP recordings, daytime, nighttime, and 24-h BP determinations, their mean and SD were calculated. From CGM measurements, mean blood glucose (MBG), SD of blood glucose, the mean amplitude of glycemic excursions (MAGE), the mean of daily differences (MODD), coefficient of variation (correction of variability for the MBG), and daytime and nighttime blood glucose were determined.

RESULTS

The mean age of the subjects was 23.8 ± 2.7 years and 66% were women (18/27). In the correlation analysis between glycemic variability parameters and BPV parameters, SD of 24-h SBP was correlated with the SD of MBG (r = 0.52, P = 0.006), MAGE (r = 0.49, P = 0.009), and MODD (r = 0.46, P = 0.015). SD of daytime SBP was correlated with, MAGE (r = 0.42, P = 0.03) and MODD (r = 0.43, P = 0.02).

CONCLUSION

We report correlation between glycemic variability and BPV variables in normoglycemic and normotensive healthy individuals.

Relationship of Age With the Hemodynamic Parameters in Individuals With Elevated Blood Pressure

BACKGROUND

Age is known to be associated with the prevalence and pathophysiology of hypertension. However, there is little information on whether age stands as a good proxy for the specific hemodynamic profile of an individual with elevated blood pressure (BP), which could be important in the selection of therapy.

DESIGN

This is a cross-sectional study.

SETTING

People who underwent a noninvasive, hemodynamic assessment using impedance cardiography at 51 sites of iKang Health Checkup Centers throughout China between January 2012 and October 2018.

PARTICIPANTS

We included 116,851 individuals, aged 20 to 80 years.

MAIN OUTCOMES AND MEASURES

Relationship between age and hemodynamic parameters (cardiac index, systemic vascular resistance index [SVRI]), among individuals with elevated BP (systolic BP ≥130 mm Hg or diastolic BP ≥80 mm Hg).

RESULTS

Final study population included 45,082 individuals with elevated BP: 29,194 men and 15,888 women with a mean (±SD) age of 48 (±13) and 54 (±12) years, respectively. Cardiac index was negatively associated with age with an adjusted, per decade decrease of 0.17 (95% confidence interval [CI] = 0.17-0.18) L/min/m² in men and 0.24 (95% CI = 0.23-0.25) L/min/m² in women. SVRI was positively associated with age with an adjusted, per-decade increase of 174.2 (95% CI = 168.8-179.7) dynes·s·cm^-5 ·m² in men and 214.1 (95% CI = 204.3-223.8) dynes·s·cm^-5 ·m² in women. However, there was substantial overlap in the distribution of these parameters across different age groups in both sexes.

CONCLUSIONS

In this large study, we observed that cardiac index decreased and SVRI increased with age among individuals with elevated BP. Even though there was a general trend with age, we observed heterogeneity within age strata, suggesting that age alone is inadequate to indicate the hemodynamic profile for an individual. J Am Geriatr Soc 68:1520-1528, 2020.

Effects of combined histamine H1 and H2 receptor blockade on hemodynamic responses to dynamic exercise in males with high-normal blood pressure

While postexercise hypotension is associated with histamine H₁ and H₂ receptor-mediated postexercise vasodilation, effects of histaminergic vasodilation on blood pressure (BP) in response to dynamic exercise are not known. Thus, in 20 recreationally active male participants (10 normotensive and 10 with high-normal BP) we examined the effects of histamine H₁ and H₂ receptor blockade on cardiac output (CO), mean atrial pressure (MAP), aortic stiffness (AoStiff), and total vascular conductance (TVC) at rest and during progressive cycling exercise. Compared with the normotensive group, MAP, CO, and AoStiff were higher in the high-normal group before and after the blockade at rest, while TVC was similar. At the 40% workload, the blockade significantly increased MAP in both groups, while no difference was found in the TVC. CO was higher in the high-normal group than the normotensive group in both conditions. At the 60% workload, the blockade substantially increased MAP and decreased TVC in the normotensive group, while there were no changes in the high-normal group. A similar CO response pattern was observed at the 60% workload. These findings suggest that the mechanism eliciting an exaggerated BP response to exercise in the high-normal group may be partially due to the inability of histamine receptors. Novelty Males with high-normal BP had an exaggerated BP response to exercise. The overactive BP response is known due to an increase in peripheral vasoconstriction. Increase in peripheral vasoconstriction is partially due to inability of histamine receptors.

Sympathoexcitation and impaired arterial baroreflex sensitivity are linked to vascular inflammation in individuals with elevated resting blood pressure

Elevated Resting Blood Pressure (ERBP) in the prehypertensive range is associated with increased risk of hypertension and cardiovascular disease, the mechanisms of which remain unclear. Prior studies have suggested that ERBP may be associated with overactivation and dysregulation of the sympathetic nervous system (SNS). We hypothesized that compared to normotensives (≤120/80 mmHg), ERBP (120/80-139/89 mmHg) has higher SNS activity, impaired arterial baroreflex sensitivity (BRS), and increased vascular inflammation. Twenty-nine participants were studied: 16 otherwise healthy individuals with ERBP (blood pressure (BP) 130 ± 2/85 ± 2 mmHg) and 13 matched normotensive controls (mean BP 114 ± 2/73 ± 2 mmHg). We measured muscle sympathetic nerve activity (MSNA), beat-to-beat BP, and continuous electrocardiogram at rest and during arterial BRS testing via the modified Oxford technique. Blood was analyzed for the following biomarkers of vascular inflammation: lipoprotein-associated phospholipase A2 (Lp-PLA2), E-selectin, and intercellular adhesion molecule 1 (ICAM-1). Resting MSNA burst frequency (22 ± 2 vs. 16 ± 2 bursts/min, P = 0.036) and burst incidence (36 ± 3 vs. 25 ± 3 bursts/100 heart beats, P = 0.025) were higher in ERBP compared to controls. Cardiovagal BRS was blunted in ERBP compared to controls (13 ± 2 vs. 20 ± 3 msec/mmHg, P = 0.032), while there was no difference in sympathetic BRS between groups. Lp-PLA2 (169 ± 8 vs. 142 ± 9 nmol/min/mL, P = 0.020) and E-selectin (6.89 ± 0.6 vs. 4.45 ± 0.51 ng/mL, P = 0.004) were higher in ERBP versus controls. E-selectin (r = 0.501, P = 0.011) and ICAM-1 (r = 0.481, P = 0.015) were positively correlated with MSNA, while E-selectin was negatively correlated with cardiovagal BRS (r = -0.427, P = 0.030). These findings demonstrate that individuals with ERBP have SNS overactivity and impaired arterial BRS that are linked to biomarkers of vascular inflammation.

A new common functional coding variant at the DDC gene change renal enzyme activity and modify renal dopamine function

The intra-renal dopamine (DA) system is highly expressed in the proximal tubule and contributes to Na+ and blood pressure homeostasis, as well as to the development of nephropathy. In the kidney, the enzyme DOPA Decarboxylase (DDC) originating from the circulation. We used a twin/family study design, followed by polymorphism association analysis at DDC locus to elucidate heritable influences on renal DA production. Dense single nucleotide polymorphism (SNP) genotyping across the DDC locus on chromosome 7p12 was analyzed by re-sequencing guided by trait-associated genetic markers to discover the responsible genetic variation. We also characterized kinetics of the expressed DDC mutant enzyme. Systematic polymorphism screening across the 15-Exon DDC locus revealed a single coding variant in Exon-14 that was associated with DA excretion and multiple other renal traits indicating pleiotropy. When expressed and characterized in eukaryotic cells, the 462Gln variant displayed lower Vmax (maximal rate of product formation by an enzyme) (21.3 versus 44.9 nmol/min/mg) and lower Km (substrate concentration at which half-maximal product formation is achieved by an enzyme.)(36.2 versus 46.8 μM) than the wild-type (Arg462) allele. The highly heritable DA excretion trait is substantially influenced by a previously uncharacterized common coding variant (Arg462Gln) at the DDC gene that affects multiple renal tubular and glomerular traits, and predicts accelerated functional decline in chronic kidney disease.

Autonomic Cardiovascular Dysregulation at Rest and During Stress in Chronically Low Blood Pressure

Abstract. Chronic low blood pressure (hypotension) is accompanied by symptoms such as fatigue, reduced drive, faintness, dizziness, cold limbs, and concentration difficulties. The study explored the involvement of aberrances in autonomic cardiovascular control in the origin of this condition. In 40 hypotensive and 40 normotensive subjects, impedance cardiography, electrocardiography, and continuous blood pressure recordings were performed at rest and during stress induced by mental calculation. Parameters of cardiac sympathetic control (i.e., stroke volume, cardiac output, pre-ejection period, total peripheral resistance), parasympathetic control (i.e., heart rate variability), and baroreflex function (i.e., baroreflex sensitivity) were obtained. The hypotensive group exhibited markedly lower stroke volume, heart rate, and cardiac output, as well as higher pre-ejection period and baroreflex sensitivity than the control group. Hypotension was furthermore associated with a smaller blood pressure response during stress. No group differences arose in total peripheral resistance and heart rate variability. While reduced beta-adrenergic myocardial drive seems to constitute the principal feature of the autonomic impairment that characterizes chronic hypotension, baroreflex-related mechanisms may also contribute to this state. Insufficient organ perfusion due to reduced cardiac output and deficient cardiovascular adjustment to situational requirements may be involved in the manifestation of bodily and mental symptoms.

Elevated resting blood pressure augments autonomic imbalance in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is characterized by increased sympathetic nervous system (SNS) activity, blunted parasympathetic nervous system (PNS) activity, and impaired baroreflex sensitivity (BRS), which contribute to accelerated cardiovascular disease. Patients with PTSD also have chronic stress-related elevations in resting blood pressure (BP), often in the prehypertensive range; yet, it is unclear if elevated resting blood pressure (ERBP) augments these autonomic derangements in PTSD. We hypothesized that compared with normotensive PTSD (N-PTSD), those with ERBP (E-PTSD) have further increased SNS, decreased PNS activity, and impaired BRS at rest and exaggerated SNS reactivity, PNS withdrawal, and pressor responses during stress. In 16 E-PTSD and 17 matched N-PTSD, we measured continuous BP, ECG, muscle sympathetic nerve activity (MSNA), and heart rate variability (HRV) markers reflecting cardiac PNS activity [standard deviation of R-R intervals (SDNN), root mean square of differences in successive R-R intervals (RMSSD), and high frequency power (HF)] during 5 min of rest and 3 min of mental arithmetic. Resting MSNA ( P = 0.943), sympathetic BRS ( P = 0.189), and cardiovagal BRS ( P = 0.332) were similar between groups. However, baseline SDNN (56 ± 6 vs. 78 ± 8 ms, P = 0.019), RMSSD (39 ± 6 vs. 63 ± 9 ms, P = 0.018), and HF (378 ± 103 vs. 693 ± 92 ms², P = 0.015) were lower in E-PTSD versus N-PTSD. During mental stress, the systolic blood pressure response ( P = 0.011) was augmented in E-PTSD. Although MSNA reactivity was not different ( P > 0.05), the E-PTSD group had an exaggerated reduction in HRV during mental stress ( P < 0.05). PTSD with ERBP have attenuated resting cardiac PNS activity, coupled with exaggerated BP reactivity and PNS withdrawal during stress.

Sympathetic nerves and hypertension in stress, sleep apnea, and caregiving

PURPOSE OF REVIEW

The sympathetic nervous system (SNS) mediates short-term increases in blood pressure. Evidence that psychosocial stress leads to chronic hypertension is mixed. The SNS activation found in obstructive sleep apnea (OSA), caregiving for a severely demented spouse, and obesity more specifically address whether SNS activation might lead to the metabolic syndrome and hypertension.

RECENT FINDINGS

Obesity is associated with both increased SNS electrical activity and plasma norepinephrine. This is partly because of frequent OSA among the obese, but OSA does not fully explain SNS activation in obesity. Large stresses activate adrenal epinephrine release, but both animal and human studies indicate that epinephrine decreases aspects of the metabolic syndrome. On the other hand, norepinephrine is chronically elevated in OSA and among markedly stressed caregivers, and they have an increased incidence of hypertension. This is most striking in OSA, which causes a nocturnal diuresis. Hypertensive patients with OSA are resistant to the antihypertensive effects of diuretics, but respond to drugs that block SNS activity and the effects of renin.

SUMMARY

The SNS may mediate chronic blood pressure increases in response to specific stresses and alter responses to therapy. Evidence linking psychosocial stress to hypertension is mixed.

Autonomic and Vascular Control in Prehypertensive Subjects with a Family History of Arterial Hypertension

BACKGROUND

Individuals with a family history of systemic arterial hypertension (FHSAH) and / or prehypertension have a higher risk of developing this pathology.

OBJECTIVE

To evaluate the autonomic and vascular functions of prehypertensive patients with FHSAH.

METHODS

Twenty-five young volunteers with FHSAH, 14 normotensive and 11 prehypertensive subjects were submitted to vascular function evaluation by forearm vascular conductance(VC) during resting and reactive hyperemia (Hokanson®) and cardiac and peripheral autonomic modulation, quantified, respectively, by spectral analysis of heart rate (ECG) and systolic blood pressure (SBP) (FinometerPRO®). The transfer function analysis was used to measure the gain and response time of baroreflex. The statistical significance adopted was p ≤ 0.05.

RESULTS

Pre-hypertensive individuals, in relation to normotensive individuals, have higher VC both at rest (3.48 ± 1.26 vs. 2.67 ± 0.72 units, p = 0.05) and peak reactive hyperemia (25, 02 ± 8.18 vs. 18.66 ± 6.07 units, p = 0.04). The indices of cardiac autonomic modulation were similar between the groups. However, in the peripheral autonomic modulation, greater variability was observed in prehypertensive patients compared to normotensive individuals (9.4 [4.9-12.7] vs. 18.3 [14.8-26.7] mmHg2; p < 0.01) and higher spectral components of very low (6.9 [2.0-11.1] vs. 13.5 [10.7-22.4] mmHg2, p = 0.01) and low frequencies (1.7 [1.0-3.0] vs. 3.0 [2.0-4.0] mmHg2, p = 0.04) of SBP. Additionally, we observed a lower gain of baroreflex control in prehypertensive patients compared to normotensive patients (12.16 ± 4.18 vs. 18.23 ± 7.11 ms/mmHg, p = 0.03), but similar delay time (-1.55 ± 0.66 vs. -1.58 ± 0.72 s, p = 0.90).

CONCLUSION

Prehypertensive patients with FHSAH have autonomic dysfunction and increased vascular conductance when compared to normotensive patients with the same risk factor.

Randomised, double-blind, placebo-controlled, assessment of the efficacy and safety of dietary supplements in prehypertension

We aimed to evaluate efficacy and tolerability of a protocol including lifestyle modifications and a novel combination of dietary supplements in prehypertension. A prospective, double-blind, randomised, placebo-controlled trial was conducted in 176 subjects (103 men, aged 52±10 years), with blood pressure (BP) of 130-139 mm Hg systolic and/or 85-89 mm Hg diastolic entered. After a single-blind run-in period, participants were randomised to twice daily placebo (n=88) or a commercially available combination pill (n=88). Primary endpoints were the differences in clinic BP between the two groups at the end of the trial. Secondary endpoints included intragroup differences in clinic BP during the study period and response rates (that is, BP <130/85 mm Hg or a BP reduction >5 mm Hg on week 12). Baseline characteristics were similar among the treatment groups. At 12 weeks, the supplement group had lower systolic BP (124±9 versus 132±7 mm Hg, P<0.0001) and similar diastolic BP (81±8 versus 82±7 mm Hg, P=0.382) compared to the placebo group. With respect to baseline measures, changes in BP with supplements were statistically significant for systolic (-9.3±4.2 mm Hg, P<0.0001) and diastolic values (-4.2±3.6 mm Hg, P<0.0001). Changes versus baseline in systolic and diastolic BP, conversely, were not different on placebo. The overall response rate at week 12 was significantly greater with supplements than placebo (58% (51 of 88) and 25% (22 of 88), respectively, P<0.0001). This randomised trial shows that combination of supplements with BP-lowering effect is an effective additional treatment to conventional lifestyle modifications for a better control of systolic BP in prehypertension.

Polyphenols: a Promising Nutritional Approach to Prevent or Reduce the Progression of Prehypertension

Diet plays a crucial role in maintaining healthy blood pressure. Functional foods are increasingly popular among health-conscious consumers to reduce cardiovascular risk factors and improve vascular health. In particular, dietary polyphenols represent an extraordinary inventory of structurally different compounds that may represent promising candidate chemical entities to prevent or delay the onset of hypertension. In recent years, it has been recognized that prehypertension may be a predictor of clinical hypertension and consequently of cardiovascular risk. Moreover, prehypertension status is associated with increased levels of several inflammatory markers and it is also characterized by structural changes, including endothelial dysfunction and arteriolar hypertrophy. Despite the low bioavailability of polyphenols and the lack of clinical data from nutritional intervention studies, the antihypertensive role of polyphenols to control blood pressure and reduce inflammation and endothelial dysfunction has been subject of recent debate. The purpose of this article is to discuss the potential benefits of dietary polyphenols as a promising and effective nutritional strategy for the management of prehypertension.

[Why is it important to achieve the goals of treatment of hypertension…. About a case that began as ischemic stroke]

Systemic arterial hypertension (SAH) is one of the most common conditions seen in primary care of cardiovascular disease and whose consequences; depending on the "target organ" affecting produce ischemic heart disease, cerebral vascular disease or chronic kidney disease. In the pathogenesis of HAS are several physiopathological mechanisms involved; of which currently, to name the most important and frequent play a role in increasing adrenaline levels, the renin-angiotensin-aldosterone system and recently, much the participation of insulin resistance and hyperinsulinemia mentioned. These processes lead to an imbalance between the sympathetic and parasympathetic tone, coupled with hypersensitivity sodium trigger one of the pathophysiologic mechanisms of hypertension. SAH is currently defined as finding numbers of older blood pressure 140/90mm Hg. This is one of the diseases that most affect the world population prevalences found in age and gender groups 45 to 55% in men between 45 and 70 years and 45 to 65% in women of the same age group. In 2013 most recent clinical guidelines for treatment and the recommended goals, which has managed to reduce its complications and mortality were published; among which include vascular diseases such as ischemic heart and brain and kidney. In this paper a case that exemplifies the secondary complications in late diagnosis, damage to "target organ" by long-term exposure and inadequate compliance with therapeutic goals discussed.

Effects of Anxiety and Depression on Arterial Elasticity of Subjects With Suboptimal Physical Health

BACKGROUND

The authors investigated the effects of suboptimal health status (SHS; high-normal blood pressure, blood glucose, and blood lipids) on arterial elasticity in subjects with or without anxiety or depression.

HYPOTHESIS

Suboptimal physical health status and anxiety or depression increase the risk of cardiovascular diseases.

METHODS

This was a cross-sectional, observational, multicenter study. Among 1520 subjects who underwent physical examination between May 2009 and December 2012 in Beijing and Chongqing, China, 955 were included. All subjects completed anxiety and depression questionnaires. Systemic vascular compliance (SVC), systemic vascular resistance, and brachial artery distensibility (BAD) were measured during arterial elasticity evaluation.

RESULTS

Of 955 participants, 633 were classified as having SHS and 322 were classified as healthy. Systemic vascular compliance and BAD were worse in SHS subjects than in healthy subjects (SVC: 1.23 ± 0.22 vs 1.29 ± 0.25 mL/mm Hg; BAD: 6.26 ± 1.32 vs 6.61 ± 1.24%/mm Hg, respectively; both P < 0.05). Of 955 subjects, 37.7% and 43.9% had anxiety and depression, respectively. Systemic vascular compliance and BAD in SHS subjects with concomitant anxiety or depression were significantly lower than in SHS subjects without anxiety or depression (SVC: 1.22 ± 0.23 vs 1.23 ± 0.20 mL/mm Hg; BAD: 6.10 ± 1.36 vs 6.33 ± 1.20 %/mm Hg, respectively; both P < 0.05) and even lower than in healthy subjects.

CONCLUSIONS

Though anxiety and depression had less impact on arterial elasticity in a healthy population, they may be involved in pathogenesis of vascular damage in the population with SHS.

Resistive and pulsatile arterial hemodynamics and cardiovascular events: the Multiethnic Study of Atherosclerosis

Background

Arterial blood pressure is dependent on interactions between the heart and arteries. Resistive and pulsatile components of arterial load can be assessed by systemic vascular resistance (SVR, a microvascular property) and the ratio of stroke volume to pulse pressure (a surrogate of total arterial compliance, TAC), respectively. The relationship between arterial function and cardiovascular events in populations without cardiovascular disease is unknown.

Methods and Results

We studied 4806 adults enrolled in the Multi‐Ethnic Study of Atherosclerosis who were free of clinical cardiovascular disease at baseline. SVR and stroke volume/pulse pressure (SV/PP) were derived by sphygmomanometry and magnetic resonance imaging. The relationship between these measures of arterial function and incident cardiovascular events was assessed using Cox regression. With a mean follow‐up of 7.5 years, cardiovascular events occurred in 358 participants (7.4%). There was no relationship between SVR and subsequent cardiovascular events. However, increased stroke volume/pulse pressure was associated with reduced event rate in unadjusted (hazard ratio=0.67, 95% CI=0.58 to 0.77, P<0.001) and analyses that adjusted for multiple confounders (HR=0.75; 95% CI=0.62 to 0.90; P<0.001).

Conclusions

Greater total arterial compliance, manifest by higher stroke volume/pulse pressure is associated with a reduced incidence of subsequent CVE. In contrast, SVR was not independently associated with CVE in subjects free of overt cardiovascular disease at baseline. These findings support the concept that alternations in the large conduit vessels, rather than changes in microvascular resistance, are primarily related to incident cardiovascular disease.

Cardiovascular responsiveness to sympathoexcitatory stress in subjects with and without mild hypertension

PURPOSE

This study compared blood pressure, heart rate variability (HRV) and forearm blood flow, at rest and in response to sympathoexcitatory stressors between normotensive and mildly hypertensive participants.

METHODS

Participants aged 30-79 years with normal blood pressure (n = 49) or mild hypertension (n = 17), with no history of taking antihypertensive medication, were recruited. Participants completed a cold pressor test (CPT) followed by an ischaemic handgrip test (IHGT). Blood pressure, HRV, forearm blood flow and vascular resistance were measured at rest and in response to each test.

RESULTS

The CPT and IHGT evoked greater increases in mean arterial blood pressure in hypertensive participants (CPT: 10 ± 2 mmHg, IHGT: 9 ± 1 mmHg) compared with normotensive participants (CPT: 5 ± 1 mmHg, IHGT: 3 ± 1 mmHg; P < 0.05). Resting high frequency power, which is a parameter of HRV associated with parasympathetic cardiac modulation, was lower in hypertensive participants (hypertensive: 31.73 ± 4.07 nu; normotensive: 42.08 ± 2.22 nu; P = 0.026) and was negatively correlated with systolic blood pressure (r = -0.272, P = 0.03) and mean arterial pressure across all participants (r = -0.258, P < 0.05). There were no differences in HRV or forearm blood flow responses to the CPT or IHGT between groups.

CONCLUSION

This study demonstrated that sympathoexcitatory stress evoked by the CPT and IHGT induces an augmented blood pressure response in individuals with mild hypertension, which supports the notion that autonomic dysfunction is likely to contribute to the pathogenesis of hypertension. It remains to be determined whether the hypertensive response is mediated through alterations in cardiac activity, peripheral vascular resistance or both.

Delayed heart rate recovery is strongly associated with early and late-stage prehypertension during exercise stress testing

BACKGROUND

Heart rate recovery (HRR) has been shown to predict cardiovascular disease mortality. HRR is delayed in hypertension, but its association with prehypertension (PHT) has not been well studied.

METHODS

The study population consisted of 683 asymptomatic individuals (90% men, aged 47±7.9 years). HRR was defined as peak heart rate minus heart rate after a 2-minute rest. PHT was categorized into stage I (systolic blood pressure (SBP) 120-129mm Hg or diastolic BP (DBP) 80-84mm Hg) or stage II (SBP 130-139mm Hg or DBP 85-89mm Hg). Logistic regression was used to generate odds ratios (ORs) for the relationship between HRR and PHT.

RESULTS

The mean HRR was lower in the PHT groups than in those who were normotensive (60 bpm and 58 bpm in stages I and II PHT vs. 65 bpm in normal BP; P <0.01). Persons with PHT were more likely to be in the lowest quartile of HRR compared with those with normal BP (adjusted OR, 3.80 and 95% confidence interval [CI], 1.06, 13.56 for stage II PHT and adjusted OR, 3.01 and 95% CI 1.05, 8.66 for stage I PHT). In a fully adjusted model, HRR was still significantly associated with both stages of PHT.

CONCLUSION

Among asymptomatic patients undergoing stress testing, delayed HRR was independently associated with early and late stages of PHT. Further studies are needed to determine the usefulness of measuring HRR in the prevention and management of hypertension.

A validation of estimated total peripheral resistance using twin data

Chronically elevated total peripheral resistance (TPR) is a suspected contributor to the greater rates of hypertension in African Americans. Previous research suggests that over 50% of the variability in measures of vascular resistance may be attributable to genetic effects and genetic effects may play an even greater role in variability of TPR in African Americans. We have previously demonstrated the coherence of a simple equation-based estimate of total peripheral resistance (TPRest) with TPR obtained via a validated method (Hill et al, 2013). We sought further validation by estimating heritability for this measure. Using quantitative genetic analysis, heritabilites were calculated for TPRest during both a resting baseline and orthostasis in a population-based sample of African American mono- and dizygotic twins (mean age = 49.82 ± 14.62). Estimated heritability was greater for males (h2 = .40) both at rest and during orthostasis, compared to all other groups. This value is consistent with previously published point estimates of heritability. Collectively, these findings provide additional support for the validity of TPRest as a practical alternative for deriving additional hemodynamic data from archival sources.

Molecular sources of residual cardiovascular risk, clinical signals, and innovative solutions: relationship with subclinical disease, undertreatment, and poor adherence: implications of new evidence upon optimizing cardiovascular patient outcomes

Residual risk, the ongoing appreciable risk of major cardiovascular events (MCVE) in statin-treated patients who have achieved evidence-based lipid goals, remains a concern among cardiologists. Factors that contribute to this continuing risk are atherogenic non-low-density lipoprotein (LDL) particles and atherogenic processes unrelated to LDL cholesterol, including other risk factors, the inherent properties of statin drugs, and patient characteristics, ie, genetics and behaviors. In addition, providers, health care systems, the community, public policies, and the environment play a role. Major statin studies suggest an average 28% reduction in LDL cholesterol and a 31% reduction in relative risk, leaving a residual risk of about 69%. Incomplete reductions in risk, and failure to improve conditions that create risk, may result in ongoing progression of atherosclerosis, with new and recurring lesions in original and distant culprit sites, remodeling, arrhythmias, rehospitalizations, invasive procedures, and terminal disability. As a result, identification of additional agents to reduce residual risk, particularly administered together with statin drugs, has been an ongoing quest. The current model of atherosclerosis involves many steps during which disease may progress independently of guideline-defined elevations in LDL cholesterol. Differences in genetic responsiveness to statin therapy, differences in ability of the endothelium to regenerate and repair, and differences in susceptibility to nonlipid risk factors, such as tobacco smoking, hypertension, and molecular changes associated with obesity and diabetes, may all create residual risk. A large number of inflammatory and metabolic processes may also provide eventual therapeutic targets to lower residual risk. Classically, epidemiologic and other evidence suggested that raising high-density lipoprotein (HDL) cholesterol would be cardioprotective. When LDL cholesterol is aggressively lowered to targets, low HDL cholesterol levels are still inversely related to MCVE. The efflux capacity, or ability to relocate cholesterol out of macrophages, is believed to be a major antiatherogenic mechanism responsible for reduction in MCVE mediated in part by healthy HDL. HDL cholesterol is a complex molecule with antioxidative, anti-inflammatory, anti-thrombotic, antiplatelet, and vasodilatory properties, among which is protection of LDL from oxidation. HDL-associated paraoxonase-1 has a major effect on endothelial function. Further, HDL promotes endothelial repair and progenitor cell health, and supports production of nitric oxide. HDL from patients with cardiovascular disease, diabetes, and autoimmune disease may fail to protect or even become proinflammatory or pro-oxidant. Mendelian randomization and other clinical studies in which raising HDL cholesterol has not been beneficial suggest that high plasma levels do not necessarily reduce cardiovascular risk. These data, coupled with extensive preclinical information about the functional heterogeneity of HDL, challenge the "HDL hypothesis", ie, raising HDL cholesterol per se will reduce MCVE. After the equivocal AIM-HIGH (Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides: Impact on Global Health Outcomes) study and withdrawal of two major cholesteryl ester transfer protein compounds, one for off-target adverse effects and the other for lack of efficacy, development continues for two other agents, ie, anacetrapib and evacetrapib, both of which lower LDL cholesterol substantially. The negative but controversial HPS2-THRIVE (the Heart Protection Study 2-Treatment of HDL to Reduce the Incidence of Vascular Events) trial casts further doubt on the HDL cholesterol hypothesis. The growing impression that HDL functionality, rather than abundance, is clinically important is supported by experimental evidence highlighting the conditional pleiotropic actions of HDL. Non-HDL cholesterol reflects the cholesterol in all atherogenic particles containing apolipoprotein B, and has outperformed LDL cholesterol as a lipid marker of cardiovascular risk and future mortality. In addition to including a measure of residual risk, the advantages of using non-HDL cholesterol as a primary lipid target are now compelling. Reinterpretation of data from the Treating to New Targets study suggests that better control of smoking, body weight, hypertension, and diabetes will help lower residual risk. Although much improved, control of risk factors other than LDL cholesterol currently remains inadequate due to shortfalls in compliance with guidelines and poor patient adherence. More efficient and greater use of proven simple therapies, such as aspirin, beta-blockers, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, combined with statin therapy, may be more fruitful in improving outcomes than using other complex therapies. Comprehensive, intensive, multimechanistic, global, and national programs using primordial, primary, and secondary prevention to lower the total level of cardiovascular risk are necessary.

Genetic variation at the delta-sarcoglycan (SGCD) locus elevates heritable sympathetic nerve activity in human twin pairs

The Syrian Cardiomyopathic Hamster (BIO-14.6/53.58 strains) model of cardiac failure, resulting from naturally occurring deletion at the SGCD (delta-sarcoglycan) locus, displays widespread disturbances in catecholamine metabolism. Rare Mendelian myopathy disorders of human SGCD occur, although common naturally occurring SGCD genetic variation has not been evaluated for effects on human norepinephrine (NE) secretion. This study investigated the effect of SGCD genetic variation on control of NE secretion in healthy twin pairs. Genetic associations profiled SNPs across the SGCD locus. Trait heritability (h(2)) and genetic covariance (pleiotropy; shared h(2)) were evaluated. Sympathochromaffin exocytosis in vivo was probed in plasma by both catecholamines and Chromogranin B (CHGB). Plasma NE is substantially heritable (p = 3.19E-16, at 65.2 ± 5.0% of trait variance), sharing significant (p < 0.05) genetic determination with circulating and urinary catecholamines, CHGB, eGFR, and several cardio-metabolic traits. Participants with higher pNE showed significant (p < 0.05) differences in several traits, including increased BP and hypertension risk factors. Peak SGCD variant rs1835919 predicted elevated systemic vascular compliance, without changes in specifically myocardial traits. We used a chimeric-regulated secretory pathway photoprotein (CHGA-EAP) to evaluate the effect of SGCD on the exocytotic pathway in transfected PC12 cells; in transfected cells, expression of SGCD augmented CHGA trafficking into the exocytotic regulated secretory pathway. Thus, our investigation determined human NE secretion to be a highly heritable trait, influenced by common genetic variation within the SGCD locus. Circulating NE aggregates with BP and hypertension risk factors. In addition, coordinate NE and CHGB elevation by rs1835919 implicates exocytosis as the mechanism of release.

Nebivolol monotherapy in younger adults (younger than 55 years) with hypertension: a randomized, placebo-controlled trial

Nebivolol, a vasodilatory β1-blocker, may be well suited for the hemodynamics of the younger hypertensive patient. In this 8-week trial, 18- to 54-year-olds with a diastolic blood pressure (DBP) of 95 mm Hg to 109 mm Hg who completed a 4-week placebo-only phase were randomized to receive nebivolol (5 mg/d, titrated to 10-20 mg/d based on achievement of blood pressure <140/90 mm Hg [n=427]) or placebo (n=214). Primary and secondary efficacy parameters were changes in trough seated DBP and systolic blood pressure (SBP), respectively. Safety parameters included adverse events (AEs). The baseline mean age was 45.3 years; SBP/DBP, 154/100 mm Hg; and heart rate, 78 beats per minute. Completion rates were 91.3% (nebivolol) and 88.3% (placebo). At endpoint, there was a significant effect of nebivolol over placebo for DBP (-11.8 mm Hg vs -5.5 mm Hg, P<.001) and SBP (-13.7 mm Hg vs -5.5 mm Hg, P<.001). Total AE rates were 34.7% (nebivolol) and 32.2% (placebo). Nebivolol monotherapy is efficacious and well tolerated in adults younger than 55 years of age with increased DBP.

Central hemodynamics in prehypertension: effect of the β-adrenergic antagonist nebivolol

The aim of the current study was to characterize the effects of the novel β-adrenergic antagonist nebivolol on central aortic blood pressures, arterial properties, and nitroxidergic activity in individuals with prehypertension. Prehypertension is emerging as a major risk factor for several adverse cardiovascular consequences. Increased pulse wave velocity, aortic augmentation index, and aortic blood pressures have been linked with augmented risk of cardiovascular disease and mortality. While the effects of antihypertensive drugs on these parameters in hypertensive patients have been studied, there are limited data so far in prehypertension. Fifty individuals with prehypertension were randomized to either nebivolol (5 mg per day) or placebo in a double-blind clinical trial. Patients underwent measurement of pulse wave velocity as well as aortic blood pressure and aortic augmentation index via pulse wave analysis at baseline and 8 weeks. Patients also had blood and urine biochemistries done at each visit. Nebivolol achieved significant reductions in central aortic systolic (P=.011), diastolic (P=.009), and mean arterial blood pressure (P=.002). Pulse wave velocity trended toward improvement but did not achieve significance (P=.088). Nitric oxide production, measured as urinary nitrite/nitrite excretion, also rose substantially in the nebivolol group (by approximately 60%, P=.030). Central blood pressures can be effectively lowered by β-blockade while patients are still in the prehypertension phase, and the effects may be coupled to improve nitric oxide release by the drug.