Sympathetic nerve traffic and blood pressure changes after bilateral renal denervation in resistant hypertension: a time-integrated analysis.

BACKGROUND: Renal denervation reduces blood pressure (BP) and sympathetic drive in experimental animal models, but the effect of this intervention on sympathetic activity in patients with treatment-resistant hypertension is still unclear. METHODS: In an incident series of 29 patients with treatment-resistant hypertension, we performed serial measurements (n = 123) of muscle sympathetic nerve activity (MSNA, microneurography) and standardized BP measurements. Data were analysed by mixed linear modelling (MLM) and by regression analysis of time-integrated changes of both MSNA and synchronous, standardized (in-lab) BP measurements. RESULTS: Bilateral renal denervation was accompanied by a marked reduction in MSNA (P = 0.01 by MLM), which was parallelled by a reduction in systolic (from 175 ± 14 to 156 ± 16 mmHg) and, to a lesser extent, in diastolic (from 96 ± 12 to 87 ± 6 mmHg) BP over time. Neither systolic nor diastolic BP associated to a significant extent with corrected MSNA (MSNAC) in the MLM analysis (systolic BP versus MSNAC: ß = -0.08, P = 0.08; diastolic BP versus MSNAC: ß = -0.007, P = 0.75). However, the study of time-integrated changes in MSNA and BP showed a robust association between proportional changes in MSNA over time and simultaneous changes in systolic and diastolic BP (ß = 0.61, P < 0.001 and ß = 0.37 P < 0.05). CONCLUSIONS: Time-integrated changes in MSNAC and BP after bilateral renal denervation document a close link between the sympathetic activity and BP responses to this procedure. These findings further strengthen the relevance of the sympathetic nervous system both in the pathophysiology of resistant hypertension and in the BP-lowering effect of the procedure.

Baroreflex Activation Therapy in Congestive Heart Failure: Novel Findings and Future Insights.

Congestive heart failure is characterized by hemodynamic and non-hemodynamic abnormalities, the latter including an activation of the sympathetic influences to the heart and peripheral circulation coupled with an impairment of baroreceptor control of autonomic function. Evidence has been provided that both these alterations are hallmark features of the disease with a specific relevance for the disease progression as well as for the development of life-threatening cardiac arrhythmias. In addition, a number of studies have documented in heart failure the adverse prognostic role of the sympathetic and baroreflex alterations, which both are regarded as major independent determinants of cardiovascular morbidity and mortality. This represents the pathophysiological and clinical background for the use of carotid baroreceptor activation therapy in the treatment of congestive heart failure. Promising data collected in experimental animal models of heart failure have supported the recent performance of pilot small-scale clinical studies, aimed at providing initial information in this area. The results of these studies demonstrated the clinical safety and efficacy of the intervention which has been tested in large-scale clinical studies. The present paper will critically review the background and main results of the published studies designed at defining the clinical impact of baroreflex activation therapy in congestive heart failure patients. Emphasis will be given to the strengths and limitations of such studies, which represent the background for the ongoing clinical trials testing the long-term effects of the device in heart failure patients.

Role of ambulatory blood pressure monitoring in resistant hypertension.

Ambulatory blood pressure monitoring has gained growing popularity in the diagnosis and treatment of essential hypertension for several reasons, such as the lack of the so-called white-coat effect, the greater reproducibility as compared with clinic blood pressure, the ability to provide information on blood pressure phenomena of prognostic value and the closer relationship with the risk of cardiovascular morbidity and mortality. All the above-mentioned main features of ambulatory blood pressure monitoring are also true for resistant hypertension. In addition, however, in resistant hypertension, blood pressure monitoring allows one to precisely define the diagnosis of this clinical condition, by excluding the presence of white-coat hypertension, which is responsible for a consistent number of "false" resistant hypertensive cases. The approach also allows one to define the patterns of blood pressure variability in this clinical condition, as well as its relationships with target organ damage. Finally, it allows one to assess the effects of therapeutic interventions, such as renal nerves ablation, aimed at improving blood pressure control in this hypertensive state. The present paper will critically review the main features of ambulatory blood pressure monitoring in resistant hypertension, with particular emphasis on the diagnosis and treatment of this high-risk hypertensive state.

The Pamela study: main findings and perspectives.

PAMELA (Pressioni Arteriose Monitorate E Loro Associazioni) is an epidemiological study, originally designed to determine the normality of home and ambulatory blood pressure values. The study was performed on 3,200 subjects, aged 25 to 74 years, randomly selected from the general population of Monza (Milan, Italy). In the study context we performed clinical, home and ambulatory blood pressure measurements, echocardiographic assessment of cardiac structure and function as well as laboratory examinations (glucose and lipids). Personal and family histories were collected. The same procedures were repeated 10 years later. During a 12-year follow-up, the incident cardiovascular events were validated. Cardiovascular and all-cause fatal events were collected for a 16-year follow-up. This article will review the main results of the PAMELA study, with particular emphasis on (1) the prognostic value of the different blood pressure measurements, (2) the relationships between metabolic variables and blood pressure and (3) the clinical relevance and prognostic importance of left ventricular mass values and alterations.

Comparative effects of nebivolol and metoprolol on red cell distribution width and neutrophil/lymphocyte ratio in patients with newly diagnosed essential hypertension.

High level of circulating red cell distribution width (RDW) and neutrophil/lymphocyte (N/L) ratio may reflect ongoing vascular inflammation and play an important role in pathophysiology of hypertension. We evaluate the effects of nebivolol and metoprolol on the RDW and N/L in new essential hypertensive patients. After baseline assessment, 72 patients were randomly allocated to 5 mg/d of nebivolol (n = 37, 20 men) or 100 mg/d of metoprolol (n = 35, 18 men) and treated for 6 months. Blood pressure (BP), heart rate (HR), RDW, and N/L were measured before and after treatment. BP significantly decreased with both drugs (P < 0.001). Analog reduction was observed for resting HRs (P < 0.001), but metoprolol caused greater HR fall as compared with nebivolol (P < 0.001). After 6 months of treatment, nebivolol significantly lowered not only RDW but also the total white blood cell and N/L (P < 0.001, P = 0.023, P = 0.017, respectively). No changes were observed in metoprolol group. Percent decrease in RDW was found to be significantly higher in nebivolol than in the metoprolol group (P = 0.001) and remained also after correction for confounders (P = 0.012). Nebivolol improved RDW and N/L to a greater extent than metoprolol in patients with hypertension. These favorable effects may participate, together with the BP reduction, at the favorable properties of the drug in hypertension.

Differential patterns of regional neuroadrenergic cardiovascular drive in acromegalic disease.

It has been shown that acromegaly is characterized by an autonomic imbalance and by marked sympathoinhibition. However, there is no information available as to whether adrenergic inhibition is confined to selected vascular districts or, rather, is generalized. We examined 17 newly diagnosed active acromegalic patients without hyperprolactinaemia, pituitary hormone deficiencies, obstructive sleep apnoea and cardiac hypertrophy and 14 healthy subjects matched for age, sex and body mass index. For each subject, we collected information regarding anthropometric parameters and echocardiography, and collected plasma samples to investigate anterior pituitary function, glucose and lipid metabolism and plasma leptin levels. Beat-to-beat mean arterial pressure, heart rate and efferent post-ganglionic muscle and skin sympathetic nerve traffic (MSNA and SSNA, respectively; determined by microneurography) were measured. Both MSNA and SSNA were recorded in a randomized sequence over two 30 min periods. Measurements also included evaluation of SSNA responses to emotional stimulus. In addition to significant reductions in plasma leptin levels, acromegalic patients had markedly decreased MSNA compared with the healthy controls. There were no significant differences in SSNA between the two groups, either under basal conditions or in responses to arousal stimuli. There was a significant and direct correlation between MSNA and plasma leptin levels, but not between plasma leptin and SSNA. These data provide the first evidence that the sympathetic inhibition characterizing the early phase of acromegaly is not generalized to the entire cardiovascular system.

Impact of blood glucose variability on carotid artery intima media thickness and distensibility in type 1 diabetes mellitus.

AIMS: Diabetes mellitus is characterized by structural and functional alterations of the large- and medium-size arteries. Whether blood glucose variability, i.e. the glycemic oscillations occurring during the 24-h period, represents a risk factor for vascular alterations additional to and independent on HbA1c in type 1 diabetes mellitus is still undefined. The present study was carried out with the aim at investigating the impact of different measures of blood glucose variability on arterial structure and function. We studied 17 non-complicated type 1 diabetic patients (11 males, six females) with an age of 40.8 ± 7.6 years (mean ± SD). In each patient, 24-h glucose profile was obtained by continuous glucose monitoring system and glucose variability was expressed as mean ± SD of 24-h blood glucose levels, mean amplitude of glycemic excursions and postprandial hyperglycemic spikes. Arterial structure and function was measured as carotid IMT and stiffness. MAJOR FINDINGS: The different approaches to assessing blood glucose variability well correlated between and with HbA1c. Carotid IMT and stiffness showed significant correlations with age, blood pressure, heart rate and daily insulin intake but a non- significant correlation with blood glucose variability. PRINCIPAL CONCLUSION: Thus, in type 1 diabetes mellitus, measures of glycemic variability are useful in predicting both actual and long-lasting glycemic control. In absence of diabetes-related complications and of any intima-media thickness alterations, the major predictors of arterial distensibility are represented by traditional risk factors beside glycemic 24-h control.

Novel antihypertensive therapies: renal sympathetic nerve ablation and carotid baroreceptor stimulation.

Therapeutic interventions aimed at reducing high blood pressure still encompass a number of difficulties and limitations. This is the case particularly in resistant hypertension, i.e. a condition characterized by a very high cardiovascular risk. Carotid baroreceptor stimulation and renal sympathetic nerves ablation represent new approaches in the treatment of this condition. This paper will provide a comparison of the effects of the two procedures, highlighting their effects on blood pressure, metabolic profile, target organ damage, safety and tolerability profile.

Total cardiovascular risk, blood pressure variability and adrenergic overdrive in hypertension: evidence, mechanisms and clinical implications.

In hypertensive patients the risk of developing cardiovascular events and complications depends not only on the magnitude of the blood pressure elevation, but also, and to a consistent extent, on the presence of associated cardiovascular risk factors, concomitant disease and target organ damage. Recent findings suggest that also sympathetic overdrive and alterations in blood pressure variability (which are detected in hypertension) may participate at the increased cardiovascular risk of the patients with high blood pressure. This review will discuss the evidence collected over the past few years on the relationships between sympathetic activation and blood pressure variability and their impact on cardiovascular risk profile.

Left ventricular diastolic dysfunction in newly diagnosed untreated hypertensive patients.

Essential hypertension is characterized by a left ventricular dysfunction. However, the majority of the studies performed so far investigated patients under drug treatment and/or with concomitant diseases, such as obesity, diabetes, metabolic syndrome or coronary heart disease, which per se may affect diastolic function independently on the blood pressure elevation. The present study aimed at investigating left ventricular diastolic function in untreated, uncomplicated and newly diagnosed hypertensive patients by employing both routine echo-Doppler and pulse tissue-Doppler technique. Data were collected in 86 middle-aged essential hypertensive patients and in 18 sex-matched normotensive controls. At the echo-Doppler approach, about half of the hypertensive patients displayed a diastolic dysfunction (n = 44, E/A: 0.79 ± 0.02). They showed body mass index values slightly greater than hypertensive patients without diastolic dysfunction but superimposable blood pressure values and metabolic variables. When assessed via the pulse tissue-Doppler approach, patients with a reduced E/A displayed an Em/Am ratio significantly lower than patients without diastolic dysfunction and control subjects. This was the case when the data were related to the lateral and septal mitral annulus or averaged together. Furthermore, whereas myocardial systolic peak velocity (Sm) was lower in hypertensive patients than in control subjects, no significant between-groups difference in E/Em ratio was observed. Differently from the data obtained via the echo-Doppler approach, the tissue-Doppler method in patients without diastolic dysfunction showed a significant higher deceleration and isovolumetric relaxation times, with a lower Em velocity compared with the normotensive subjects. At the stepwise multiple regression analysis E/A ratio and E'/A' values were related with left ventricular mass index and body mass index after correction for age. These data provide evidence that diastolic dysfunction is of frequent detection in the earlier uncomplicated phases of the disease and that tissue Doppler detects an initial impairment of left ventricular relaxation in the patients in which at echo Doppler is still normal.

Blood pressure control and cardiovascular risk profile in hypertensive patients from central and eastern European countries: results of the BP-CARE study.

AIMS: Limited information is available on office and ambulatory blood pressure (BP) control as well as on cardiovascular (CV) risk profile in treated hypertensive patients living in central and eastern European countries. METHODS AND RESULTS: In 2008, a survey on 7860 treated hypertensive patients followed by non-specialist or specialist physicians was carried out in nine central and eastern European countries (Albania, Belarus, Bosnia, Czech Republic, Latvia, Romania, Serbia, Slovakia, and Ukraine). Cardiovascular risk assessment was based on personal history, clinic BP values, as well as target organ damage evaluation. Patients had a mean (±SD) age of 60.1 ± 11 years, and the majority of them (83.5%) were followed by specialists. Average clinic BP was 149.3 ± 17/88.8 ± 11 mmHg. About 70% of patients displayed a very high-risk profile. Electrocardiogram was performed in 99% of patients, echocardiography in 65%, carotid ultrasound in 24%, fundoscopy in 68%, and search for microalbuminuria in 10%. Ambulatory BP monitoring was performed in about one-fifth of the recruited patients. Despite the widespread use of combination treatment (87% of the patients), office BP control (<140/90 mmHg) was achieved in 27.1% only, the corresponding control rate for ambulatory BP (<130/80 mmHg) being 35.7%. Blood pressure control was (i) variable among different countries, (ii) worse for systolic than for diastolic BP, (iii) slightly better in patients followed by specialists than by non-specialists, (iv) unrelated to patients' age, and (v) more unsatisfactory in high-risk hypertensives and in patients with coronary heart disease, stroke, or renal failure. CONCLUSION: These data provide evidence that in central and eastern European countries office and ambulatory BP control are unsatisfactory, particularly in patients at very high CV risk, and not differ from that seen in Western Europe. They also show that assessment of subclinical organ damage is quite common, except for microalbuminuria, and that combination drug treatment is frequently used.

Sympathetic activation in cardiovascular and renal disease.

Given the importance of adrenergic neural functioning in cardiovascular control, the hypothesis that an elevation in sympathetic drive represents a key pathophysiological feature of diseases characterized by an impairment in cardiac or renal function has been long considered. However, modern approaches to directly quantify sympathetic nerve firing in humans have only been possible in the last 2 decades to provide objective documentation for the hypothesis. This paper will review the evidence that conditions such as essential hypertension, congestive heart failure and metabolic syndrome are all accompanied by an increased sympathetic drive, which is likely in all of them to play a pathogenetic role. It will then offer examples showing that sympathetic influences are directly involved in the progression of organ damage associated with these conditions. Finally, evidence will be presented that a maximum degree of sympathetic activation can be seen in end-stage renal failure, in which a relationship between sympathetic activation and clinical outcome has been documented. This has therapeutic implications, which involve the need to use treatments that oppose rather than enhance sympathetic neural activation.

Prevalence of cardiovascular risk factors in an unselected italian population. Results of the Cardiolab Project 2004-2008.

OBJECTIVE: Screening and educational campaigns on cardiovascular (CV) risk factors are important for primary and secondary prevention of CV disease. The CardioLab project is an observational cross-sectional study aimed at determining the prevalence of CV risk factors in a large unselected sample of the Italian population leaving in northern, central and southern Italy. METHODS AND RESULTS: Data collection included family and clinical history, anthropometric data, blood pressure, blood glucose and total cholesterol values. Individual CV risk profile was assessed throughout by the risk charts of both the Progetto Cuore and the Score Project. In 36,161 participants (56.3% men) with a mean age of 60 years a complete assessment of the above mentioned variables was obtained. 44.4% of the screened subjects was overweight, while approximately 20% of the population displayed an obese state with a body mass index >30 kg/m2. Alterations in blood glucose levels indicating the presence of glucose intolerance were identified in 11.5% of the population while 9.3% displayed overt diabetes. 36.1% and 42.3% had elevated total cholesterol levels (> 200 mg/dl) and blood pressure values (> or = 140/90 mmHg), respectively. New diagnosis of diabetes, hypercholesterolaemia and hypertension was obtained in 5.3%, 23.6% and 19.6%, respectively. Global assessment of the CV risk showed that approximately 12.6% of the population is at a high risk of CV events over a 10-year period. CONCLUSIONS: This large-scale observational study provides important information on the CV risk profile of an unselected Italian population and underlines the need for a more aggressive identification and appropriate correction of CV risk factors.

Sympathetic activation in congestive heart failure: reproducibility of neuroadrenergic markers.

OBJECTIVE: To assess the reproducibility of the two markers of adrenergic drive, venous plasma norepinephrine (NE) and efferent postganglionic muscle sympathetic nerve activity (MSNA), in reflecting the sympathetic activation characterizing congestive heart failure (CHF). METHODS AND MEASUREMENTS: In 19 CHF male normotensive patients (mean age: 53.0+/-2.1 years, NYHA classes II and III, left ventricular ejection fraction 35.9+/-2.9%), blood pressure (BP, Finapres), heart rate (EKG), plasma NE (HPLC assay) and MSNA (microneurography, peroneal nerve) were measured in two experimental sessions separated by a week interval. At each session, three NE samples were obtained and NE reproducibility between sessions was assessed by considering single NE samples or averaging 2-3 samples. RESULTS: While MSNA values showed a highly significant correlation between sessions (r=0.85, P<0.001), NE values based on a single blood sample evaluation did not correlate with each other (r=0.41, P=NS). NE correlation coefficients improved and achieved statistical significance when average data from 2 and 3 blood samples were examined (r=0.54 and r=0.57, P<0.02 for both). CONCLUSIONS: In CHF, MSNA displays a better reproducibility pattern than plasma NE. The reproducibility of the NE approach, however, can be improved by performing the assay on multiple blood samples.

Multicenter Randomized Double-Blind Comparison of Nebivolol plus HCTZ and Irbesartan plus HCTZ in the Treatment of Isolated Systolic Hypertension in Elderly Patients: Results of the NEHIS Study.

INTRODUCTION: The present study was aimed at comparing the antihypertensive efficacy, tolerability, and side effects profile of nebivolol/hydrochlorothiazide (NH) vs irbesartan/hydrochlorothiazide (IH) combination in elderly patients with isolated systolic hypertension (ISH). METHODS: 124 ISH patients aged 69.1 ± 5.1 years (mean ± SD) were enrolled by 13 general practitioners in Netherlands and Belgium and randomized in a double-blind fashion to receive either NH (5/12.5 mg day, n = 62) or IH (150/12.5 mg day, n = 62) for a 12-week period. The primary efficacy endpoint of the study was the comparison of the two combinations in terms of sitting office systolic blood pressure (BP) reduction after 12 weeks of treatment. In addition ambulatory BP, 24-h BP variability, tolerability, and safety profile were also investigated. RESULTS: 122 patients were included in the intention-to-treat analysis. After 12 weeks of treatment the reduction of systolic BP with NH was significantly greater than IH (-25.8 ± 12 vs -21.2 ± 14 mm Hg, P < 0.03). Diastolic BP reduction was significantly greater with NH after 4 and 8 weeks of treatment but similar at the end of the study (or after 12 weeks). In contrast, the magnitude of the 24-h, daytime, and nighttime systolic and diastolic BP reduction was almost similar in the two groups, while heart rate reduction induced by NH was significantly (P < 0.001) greater during the 24-h, daytime, and nighttime period than that induced by IH. NH caused a reduction in 24-h BP variability significantly greater than IH (standard deviation -4.4 ± 2.7 vs -2.2 ± 5.1 mm Hg, P < 0.02, variation coefficient -2.0 ± 2.6 vs -0.3 ± 3.4%, P < 0.01). Both treatment regimens were well tolerated. CONCLUSIONS: These data provide evidence that NH reduces office BP more than IH but has similar effects on 24-h BP. NH reduces 24-h systolic and diastolic BP variability more than IH, suggesting a greater protective effect on a variable known to adversely affect prognosis. TRIAL REGISTRATION: EU clinical Trials Register identifier, 2010-023104-28. FUNDING: Menarini International Operations Luxembourg.

Effects of chronic carotid baroreceptor activation on arterial stiffness in severe heart failure.

BACKGROUND: Heart failure with reduced ejection fraction (HFrEF) is characterized by activation of the sympathetic nervous system and increased arterial stiffness, leading to an impaired ventricular-vascular coupling. Baroreflex activation therapy (BAT) has been shown to reduce muscle sympathetic nerve activity (MSNA) and improve clinical status of patients with HFrEF. The purpose of this investigation was to determine the effects of BAT on arterial stiffness in HFrEF. METHODS AND RESULTS: MSNA, clinical variables, and parameters of central blood pressure (BP) and arterial stiffness were collected in 18 NYHA Class III HFrEF patients, nine receiving BAT and nine continuing with optimal medical management alone. Patients were followed for 3 months, with measurements at that time compared to baseline evaluation. Baseline characteristics of the groups were well matched. At 3 months, BAT did not improve central BP and arterial stiffness despite a significant amelioration of MSNA, NYHA class, Minnesota living with heart failure questionnaire score, number of heart failure medications and six-minute walking distance. The control group exhibited no significant changes in all the measured variables. CONCLUSIONS: Despite significant reductions in MSNA and clinical improvement, BAT does not appear to chronically modify arterial stiffness within this HFrEF cohort. Additional study is required to determine if this result applies to the HFrEF population as a whole.

Differential effects of enalapril-felodipine versus enalapril-lercanidipine combination drug treatment on sympathetic nerve traffic and metabolic profile in obesity-related hypertension.

Scanty information is available on the effects of combination drug treatment based on an ACE inhibitor and a calcium channel blocker on the neurometabolic alterations characterizing obesity-related hypertension (OHT). After 2-week run-in with enalapril (20 mg), 36 OHTs were randomized according to a double-blind crossover design to a combination therapy with either lercanidipine 10 mg (L) or felodipine extended release 5 mg (F), each lasting 8 weeks. Measurements included clinic and ambulatory blood pressure (BP) and heart rate, homeostasis model assessment index, plasma norepinephrine, and muscle sympathetic nerve activity. Patients with uncontrolled BP were then uptitrated to 20 mg/d (L) and 10 mg/d (F) combined with enalapril 20 mg, respectively, for further 8 weeks. For similar BP reductions, enalapril-lercanidipine (EL) caused norepinephrine and MSNA increases significantly less pronounced than those seen with enalapril-felodipine, the lesser sympathoexcitation observed with EL being coupled with a significant improvement in homeostasis model assessment index. This was the case also when L and F were uptitrated in the combination. In OHT, at variance from enalapril-felodipine, EL combination is almost entirely devoid of any major sympathoexcitatory effect and is associated with an improvement in insulin sensitivity.

New-onset left atrial enlargement in a general population.

AIM: Increased left atrium diameter (LAD) is associated with elevated risk of cardiovascular morbidity and mortality. We evaluated new-onset left atrium enlargement (LAE) and their correlates over a 10-year period in participants of the general population enrolled in the Pressioni Monitorate e Loro Associazioni study. METHODS: The study included 1045 participants with normal LAD at baseline evaluation having a readable echocardiogram at the end of follow-up. Cut-points for abnormal LAD were derived from reference values recommended by American Society of Echocardiography. RESULTS: Over a 10-year period, 123 participants (11.8%) progressed to LAE. The incidence of new-onset LAE increased significantly from the lowest to the highest tertile of baseline office, home and 24-h blood pressure (BP); BMI; fasting blood glucose and left ventricular mass index (LVMI). In multivariate analysis, baseline LAD [odds ratio (OR) 3.18, confidence interval (CI) 2.26-4.47, P < 0.001], female sex (OR 3.68, CI 2.20-6.18, P < 0.001), office SBP (OR 1.36, CI 1.08-1.70, P = 0.008), BMI (OR 1.35, CI 1.07-1.69, P = 0.01 and LVMI (OR 1.29, CI 1.01-1.64, P = 0.04) emerged as key correlates of new-onset LAE. CONCLUSION: The study shows that in the population, long-term changes from normal LAD to LAE are independently driven by several risk factors such as the female sex and an increased baseline LAD, BMI, LVMI and BP, with no predictive superiority of home and ambulatory versus office values. Preventing BP elevations, overweight/obesity and left ventricular hypertrophy may thus all be important for LAE prevention.

Blood pressure responses to renal denervation precede and are independent of the sympathetic and baroreflex effects.

It is still largely unknown whether the neuroadrenergic responses to renal denervation (RD) are involved in its blood pressure (BP)-lowering effects and represent predictors of the BP responses to RD. In 15 treated true resistant hypertensives, we measured before and 15 days, 1, 3, and 6 months after RD clinic, ambulatory and beat-to-beat BP. Measurements included muscle sympathetic nerve traffic (MSNA), spontaneous baroreflex-MSNA sensitivity, and various humoral and metabolic variables. Twelve treated hypertensives served as controls. BP, which was unaffected 15 days after RD, showed a significant decrease during the remaining follow-up period. MSNA and baroreflex did not change at 15-day and 1-month follow-up and showed, respectively, a decrease and a specular increase at 3 and 6 months after RD. No relationship, however, was detected between baseline MSNA and baroreflex, MSNA changes and BP changes. At the 6-month follow-up, the MSNA reduction was similar for magnitude in patients displaying a BP reduction greater or lower the median value. Similarly, the BP reduction detected 6 months after RD was similar in patients displaying a MSNA reduction greater or lower median value. No significant BP and MSNA changes were detected in the control group. Thus, the BP reduction associated with RD seems to precede the MSNA changes and not to display a temporal, qualitative, and quantitative relationship with the MSNA and baroreflex effects. Given the small sample size of the present study further investigations are warranted to confirm the present findings.

Neuroadrenergic disarray in pseudo-resistant and resistant hypertension.

Several studies have investigated the behavior of sympathetic cardiovascular drive in essential hypertension, providing conclusive evidence of the adrenergic activation characterizing this condition. These studies have also shown the importance of neuroadrenergic overdrive in the development and progression of the hypertensive state as well as in the pathogenesis of hypertension-related end-organ damage. The information available on the sympathetic nervous system's behavior in 'pseudo-resistant' and 'true resistant' hypertension is much more scarce. This paper will review the available knowledge on this issue by examining the data collected via indirect and direct approaches to investigate adrenergic function in resistant hypertension as well as the effects of pharmacological and non-pharmacological interventions.