Resistant hypertension

Risk factors of postoperative delirium following spine surgery: A meta-analysis of 50 cohort studies with 1.1 million participants

Objectives

Postoperative delirium (POD) is considered to be a common complication of spine surgery. Although many studies have reported the risk factors associated with POD, the results remain unclear. Therefore, we performed a meta-analysis to identify risk factors for POD among patients following spinal surgery.

Methods

We systematically searched the PubMed, Embase and the Cochrane Library for relevant articles published from 2006 to February 1, 2023 that reported risk factors associated with the incidence of POD among patients undergoing spinal surgery. The Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines were followed, and random effects models were used to estimate pooled odds ratio (OR) estimates with 95 % confidence intervals (CIs) for each factor. The evidence from observational studies was classified according to Egger's P value, total sample size, and heterogeneity between studies.

Results

Of 11,329 citations screened, 50 cohort studies involving 1,182,719 participants met the inclusion criteria. High-quality evidence indicated that POD was associated with hypertension, diabetes mellitus, cardiovascular disease, pulmonary disease, older age (>65 years), patients experiencing substance use disorder (take drug ≥1 month), cerebrovascular disease, kidney disease, neurological disorder, parkinsonism, cervical surgery, surgical site infection, postoperative fever, postoperative urinary tract infection, and admission to the intensive care unit (ICU). Moderate-quality evidence indicated that POD was associated with depression, American Society of Anesthesiologists (ASA) fitness grade (>II), blood transfusion, abnormal potassium, electrolyte disorder, length of stay, inability to ambulate and intravenous fluid volume.

Conclusions

Conspicuous risk factors for POD were mainly patient- and surgery-related. These findings help clinicians identify high-risk patients with POD following spinal surgery and recognize the importance of early intervention.

Left ventricular myocardial strain responding to chronic pressure overload in patients with resistant hypertension evaluated by feature-tracking CMR

OBJECTIVES

The study aimed to investigate the alterations of myocardial deformation responding to long-standing pressure overload and the effects of focal myocardial fibrosis using feature-tracking cardiac magnetic resonance (FT-CMR) in patients with resistant hypertension (RH).

METHODS

Consecutive RH patients were prospectively recruited and underwent CMR at a single institution. FT-CMR analyses based on cine images were applied to measure left ventricular (LV) peak systolic global longitudinal (GLS), radial (GRS), and circumferential strain (GCS). Functional and morphological CMR variables, and late gadolinium enhancement (LGE) imaging were also obtained.

RESULTS

A total of 50 RH patients (63 ± 12 years, 32 men) and 18 normotensive controls (57 ± 8 years, 12 men) were studied. RH patients had a higher average systolic blood pressure than controls (166 ± 21 mmHg vs. 116 ± 8 mmHg, p < 0.001) with the intake of 5 ± 1 antihypertensive drugs. RH patients showed increased LV mass index (78 ± 15 g/m2 vs. 61 ± 9 g/m2, p < 0.001), decreased GLS (- 16 ± 3% vs. - 19 ± 2%, p = 0.001) and GRS (41 ± 12% vs. 48 ± 8%, p = 0.037), and GCS was reduced by trend (- 17 ± 4% vs. - 19 ± 4%, p = 0.078). Twenty-one (42%) RH patients demonstrated a LV focal myocardial fibrosis (LGE +). LGE + RH patients had higher LV mass index (85 ± 14 g/m2 vs. 73 ± 15 g/m2, p = 0.007) and attenuated GRS (37 ± 12% vs. 44 ± 12%, p = 0.048) compared to LGE - RH patients, whereas GLS (p = 0.146) and GCS (p = 0.961) were similar.

CONCLUSION

Attenuation of LV GLS and GRS, and GCS decline by tendency, might be adaptative changes responding to chronic pressure overload. There is a high incidence of focal myocardial fibrosis in RH patients, which is associated with reduced LV GRS.

CLINICAL RELEVANCE STATEMENT

Feature-tracking CMR-derived myocardial strain offers insights into the influence of long-standing pressure overload and of a myocardial fibrotic process on cardiac deformation in patients with resistant hypertension.

KEY POINTS

• Variations of left ventricular strain are attributable to the degree of myocardial impairment in resistant hypertensive patients. • Focal myocardial fibrosis of the left ventricle is associated with attenuated global radial strain. • Feature-tracking CMR provides additional information on the attenuation of myocardial deformation responding to long-standing high blood pressure.

Beyond Conventional Control: Insights Into Drug-Resistant Hypertension

It is believed that 9-18% of patients with hypertension have resistant hypertension, a serious medical disease. The increased cardiovascular risk associated with this illness demands appropriate diagnosis and treatment. It is necessary to conduct an in-depth investigation of the various etiologies, indicators of risk, and multiple disorders of resistant hypertension. This is crucial in order to establish the diagnosis and make the best decisions regarding therapy. Treatment should also take lifestyle changes into account in addition to medicinal and interventional therapy. When there is a suspicion of resistant hypertension, examining the medications used to treat the hypertensive patient after ruling out pseudo hypertension, improper blood pressure monitoring and control, and the white-coat effect are necessary. Resistant hypertension, according to a specific definition, is a condition that cannot be treated with more than two antihypertensive drugs, including a diuretic. An effective multidrug therapy for the treatment of resistant hypertension includes angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, beta-blockers, diuretics, long-acting calcium channel blockers, and mineralocorticoid receptor antagonists. However, alternative, cutting-edge treatments, such as renal denervation or baroreflex activation, could develop a brand-new avenue for decreasing blood pressure. These new surgical interventions might prove out to be of immense importance in coming times. Secondary causes of resistant hypertension, such as obstructive sleep apnea, coronary artery diseases, nephropathy, or endocrinal diseases, must be checked out in order to make an accurate diagnosis of this illness. This review article briefly summarizes the epidemiology, risk factors, causes, pathogenesis, diagnosis, and treatment approaches that may help with the long-term management of resistant hypertension.

Renal Innervation in Resistant Hypertension: A Review of Pathophysiology and Renal Denervation as Potential Treatment

Background

Advances in treatment and increased awareness have improved the prognosis for many patients with hypertension (HTN). Resistant hypertension (RH) refers to a subset of hypertensive individuals who fail to achieve a desired blood pressure (BP) despite concurrent use of 3 different classes antihypertensive agents, one being a diuretic, and proper lifestyle changes. The prevalence and prognosis of RH are unclear owing to its heterogeneous etiologies, risk factors, and secondary comorbidities. Previous research has provided evidence that increased renal sympathetic nerve activity (RSNA) within the renal artery contributes to RH development. Renal denervation (RDN) is a procedure that attempts to ameliorate the effects of heightened RSNA via ablation renal sympathetic fibers. BP reductions associated with RDN may be attributed to decreased norepinephrine spillover, restoration of natriuresis, increasing renal blood flow, and lowering plasma renin activity. Early clinical trials perpetuated positive results, and enthusiasm grew exponentially. However, recent clinical trials have called into question RDN's efficacy. Numerous limitations must be addressed to discern the true effectiveness of RDN as a therapeutic option for RH.

Objective

We aimed to review the current understanding of RH, the anatomy of renal arteries, physiology of RH on renal arteries, anatomical pathways of the sympathetic involved in RH, RDN as a treatment option, and all relevant clinical trials treating RH with RDN.

Methods

We piloted a MEDLINE^® database search of literature extending from 1980 to 2017, with emphasis on the previous five years, combining keywords such as “resistant hypertension” and 
“renal denervation.”

Conclusion

A plethora of information is available regarding heightened RSNA leading to RH. RDN as a possible treatment option has shown a range of results. Reconciling RDN's true efficacy requires future trials to increased sites of nerve ablation, standardized protocol, increased anatomical understanding per individual basis, stricter guidelines regarding study design, increased operator experience, and integrating the use of a multielectrode catheter.

Resistant hypertension in elderly: a clinical manifestation of heart failure with preserved ejection fraction? retrospective single-center analysis

Background: Resistant hypertension (RHT) is defined as high blood pressure despite three antihypertensive medications one being a diuretic. RHT is a common clinical problem and as a subgroup has not been studied widely. The present study has investigated patient demographics and if the RHT might be a clinical presentation of heart failure with preserved ejection fraction (HFPEF) in elderly. Method: The outpatient data between January and June 2015 of Izmir Kemalpasa State hospital's hypertension specialty clinic has been reviewed retrospectively. The patients with pseudo-RHT are excluded. Among 957 patients, 68 patients have been identified as true RHT with a left ventricle ejection fraction ≥50%. HFPEF is defined according to the latest guideline. Instead of a common cut-off level for NT-proBNP, age and gender-related cut-off levels have been used. Results: The mean age was 63.24 ± 12.05 years. Among 68 patients, 49 were female. While only 3 patients in younger group (8.8%) had elevated levels of NT-proBNP, 22 of older RHT patients (64.7%) had high levels. NT-proBNP levels were disproportionally high in elderly (p < 0.001) and high levels in RHT patients were related to a larger left atrial diameter (p < 0.001). Conclusion: The underlying mechanism might be different in RHT according to age. Hypervolemia might be the key factor in older RHT patients but not in younger patients. The current study suggests RHT in elderly can be a clinical presentation of HFPEF, and they should be investigated and treated accordingly. Because of single-center results and limited patients, further studies are needed.

SFE/SFHTA/AFCE Consensus on Primary Aldosteronism, part 2: First diagnostic steps

In patients with suspected primary aldosteronism (PA), the first diagnostic step, screening, must have high sensitivity and negative predictive value. The aldosterone-to-renin ratio (ARR) is used because it has higher sensitivity and lower variability than other measures (serum potassium, plasma aldosterone, urinary aldosterone). ARR is calculated from the plasma aldosterone (PA) and plasma renin activity (PRA) or direct plasma renin (DR) values. These measurements must be taken under standard conditions: in the morning, more than 2hours after awakening, in sitting position after 5 to 15minutes, with normal dietary salt intake, normal serum potassium level and without antihypertensive drugs significantly interfering with the renin-angiotensin-aldosterone system. To rule out ARR elevation due to very low renin values, ARR screening is applied only if aldosterone is>240pmol/l (90pg/ml); DR values<5mIU/l are assimilated to 5mIU/l and PRA values<0.2ng/ml/h to 0.2ng/ml/h. We propose threshold ARR values depending on the units used and a conversion factor (pg to mIU) for DR. If ARR exceeds threshold, PA should be suspected and exploration continued. If ARR is below threshold or if plasma aldosterone is<240pmol/l (90pg/ml) on two measurements, diagnosis of PA is excluded.

Prevalence and characteristics of resistant hypertension at primary clinics in Korea: a nationwide cross-sectional study

Background

Although resistant hypertension (RH) is known to be associated with higher rates of cardiovascular events than is non-RH, there are no reported data on the prevalence of RH in Korean patients. We evaluated the prevalence and characteristics of RH among hypertensive patients treated at primary clinics in Korea.

Methods

Between August 2010 and January 2011, 247 primary care physicians enrolled 3088 patients with essential hypertension. We acquired demographic and anthropometric data using a questionnaire, evaluated blood pressure, and conducted a variety of laboratory tests using serum and urine. RH was defined as systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg with the use of three antihypertensive agents of different classes, including a diuretic, or controlled hypertension with the use of four or more medications.

Results

We analyzed 3088 patients with hypertension, 48.3 % of whom were men. The mean age of patients was 64.3 ± 11.3 years and the prevalence of RH was 7.9 %. Patients with RH were more likely to be men, and to have higher waist circumference, increased blood levels of HbA1c, triglycerides, and serum creatinine, lower blood levels of high-density lipoprotein (HDL), and higher rates of current smoker, history of heart failure or coronary artery disease, and electrocardiographic left ventricular hypertrophy (LVH), than were patients with non-RH (all comparisons, P < 0.05). In the multivariate analysis, RH was shown to be significantly associated with the following conditions: presence of electrocardiographic LVH (odds ratio [OR] 2.23, 95 % confidence interval [CI] 1.34–3.71), current smoker (OR 1.75, 95 % CI 1.27–2.40), renal impairment (OR 1.65, 95 % CI 1.23–2.22), abdominal obesity (OR 1.60, 95 % CI 1.20–2.13), and cardiovascular diseases (OR 1.50, 95 % CI 1.04–2.17).

Conclusions

The prevalence of RH was relatively low at primary clinics in Korea compared with the prevalence reported in other countries. RH was associated with electrocardiographically confirmed LVH, renal impairment, current smoker, abdominal obesity, and cardiovascular diseases. These are the first reported data of RH in Korea. Our findings may be helpful in the early detection and thorough clinical management of patients with RH at primary clinics.

Haemodynamic Responses to Selective Vagal Nerve Stimulation under Enalapril Medication in Rats

Selective vagal nerve stimulation (sVNS) has been demonstrated to lower blood pressure (BP) in rats without causing major side effects. This method might be adapted for the treatment of therapy-resistant hypertension in patients. Converting enzyme inhibitors (CEIs) are among the first drugs that are administered for arterial hypertension and prominently reduce BP primarily by interacting with the renin-angiotensin system of the kidneys. Beyond the reduction of BP, CEI have a positive effect on the survival rate after myocardial infarction; they reduce the rates of stroke and improve the neurohormonal status in heart-failure patients. If sVNS might be introduced as a therapy against resistant hypertension, patients will at least partially stay on their CEI medication. It is therefore the aim of this study to investigate the influence of the CEI enalapril on the haemodynamic and respiratory effects of sVNS. In 10 male Wistar rats, a polyimide-based multichannel-cuff-electrode was placed around the vagal nerve bundle to selectively stimulate the aortic depressor nerve fibres. Stimulation parameters were adapted to the thresholds of the individual animals and included repetition frequencies between 30 and 50 Hz, amplitudes of 0.5 to 1.5 mA and pulse widths between 0.4 ms and 1.0 ms. BP responses were detected with a microtip transducer in the left carotid artery, and electrocardiography was recorded with subcutaneous electrodes. After intravenous administration of enalapril (2 mg/kg bodyweight), the animals’ mean arterial blood pressures (MAPs) decreased significantly, while the heart rates (HRs) were not significantly influenced. The effects of sVNS on BP and HR were attenuated by enalapril but were still present. We conclude that sVNS can lower the MAP during enalapril treatment without relevant side effects.

Clinical value of ambulatory blood pressure: Is it time to recommend for all patients with hypertension?

Hypertension is a very common disease, and office measurements of blood pressure are frequently inaccurate. Ambulatory Blood Pressure Monitoring (ABPM) offers a more accurate diagnosis, more detailed readings of average blood pressures, better blood pressure measurement during sleep, fewer false positives by detecting more white-coat hypertension, and fewer false negatives by detecting more masked hypertension. ABPM offers better management of clinical outcomes. For example, based on more accurate measurements of blood pressure variability, ABPM demonstrates that taking antihypertensive medication at night leads to better controlled nocturnal blood pressure, which translates into less end organ damage and fewer clinical complications of hypertension. For these reasons, albeit some shortcomings which were discussed, ABPM should be considered as a first-line tool for diagnosing and managing hypertension.

Intensive blood pressure control during the hyperacute phase of intracerebral hemorrhage in patients at risk for resistant hypertension: a retrospective cohort study

INTRODUCTION

There are limited data evaluating intensive systolic blood pressure (SBP) control during the hyperacute phase of intracerebral hemorrhage (ICH) in patients with multiple risk factors for resistant hypertension. We evaluated the feasibility and safety of this intervention in a primary population that includes patients with multiple risk factors for resistant hypertension.

MATERIALS AND METHODS

We conducted a retrospective analysis of ICH patients for which intensive SBP control (<140 mm Hg)- i.e. less than or equal to 140 was targeted. All patients possessed at least 2 risk factors that have been associated with resistant hypertension. Our primary objective was to determine the percentage of patients who achieved goal SBP within 1 hour of ICH diagnosis. Secondary objectives included identifying predictors of achieving goal SBP within 6 hours.

RESULTS

Goal SBP within 1 hour was achieved in 8.1% of patients. The total number of risk factors a patient possessed was found to negatively predict ability to achieve goal SBP. For each risk factor possessed, the odds of achieving goal SBP within 6 hours are reduced by 31% (odds ratio, 0.69 [95% confidence interval, 0.54-0.89]).

CONCLUSION

Intensive SBP control after ICH was difficult to achieve within 1 hour in those with risk factors for resistant hypertension. Patients' total risk factors were found to reduce the odds of achieving goal SBP within 6 hours.

Resistant hypertension and associated comorbidities in a veterans affairs population

Resistant hypertension (RH) is understudied and its reported prevalence varies with study populations. The authors sought to determine its prevalence and association with certain comorbid conditions in a Veterans Affairs population. This cross-sectional study utilized demographic and clinical data from 17,466 patients. Chi-square or t test was used for comparing groups with and without RH. Multivariate logistic regression analysis was used to determine independent associations. Overall, the prevalence of RH was 9%, and 13% of all hypertensive patients met criteria for RH. After adjusting for confounding variables, RH was significantly associated with older age (odds ratio [OR], 1.007), higher body mass index (OR, 1.04), Framingham score (OR, 1.14), and coexisting coronary artery disease, cerebrovascular accident/transient ischemic attack, peripheral vascular disease, congestive heart failure, chronic kidney disease, diabetes mellitus, erectile dysfunction, and metabolic syndrome (OR, 1.3, 1.32, 1.29, 2.88, 2.13, 1.2, 1.12, and 1.2, respectively; all P<.05). Our results indicate a complex interplay of certain comorbid conditions among patients with RH and suggest the need for multifaceted interventions in this high-risk population to prevent cardiovascular events.

Prevalence and predictors of resistant hypertension in a primary care setting: a cross-sectional study

Background

Patients with resistant hypertension are subjected to a higher risk of getting stroke, myocardial infarction, congestive heart failure and renal failure. However, the exact prevalence of resistant hypertension in treated hypertensive patients in Malaysia is not known. This paper examines the prevalence and determinants of resistant hypertension in a sample of hypertensive patients.

Methods

We examined the control of blood pressure in a randomly selected sample of patients with hypertension in a primary care clinic. Demographic data, blood pressure and anti-hypertensive drug use were captured from patient records at the end of 2007. Resistant hypertension is defined as failure to achieve target blood pressure of < 140/90 mmHg while on full doses of an appropriate three-drug regimen that includes a diuretic. Multivariate logistic regression was used for the analysis.

Results

A total of 1217 patients with hypertension were entered into the analysis. Mean age of the patients was 66.8 ± 9.7 years and 64.4% were female. More than half of the subjects (56.9%) had diabetes mellitus. Median BP was 130/80 mmHg. Overall prevalence of resistant hypertension was 8.8% (N = 107/1217). In multivariate logistic regression analysis, presence of chronic kidney disease is more likely to be associated with resistant hypertension (odds ratio [OR] 2.89, 95% confidence interval [CI] 1.56-5.35). On the other hand, increase per year of age is associated with lower odds of resistant hypertension in this population (OR 0.96, 95% CI 0.93-0.99).

Conclusions

Resistant hypertension is present in nearly one in ten hypertensive patients on treatment. Hypertensive patients who have underlying chronic kidney disease are associated with higher odds of having resistant hypertension. Hence, in managing patients with hypertension, primary care physicians should be more alert and identify patients with chronic kidney disease as such patients are more likely to develop resistant hypertension. By doing that, these patients can be treated more aggressively earlier in order to achieve blood pressure target and thus reduce cardiovascular events.

Regulation of renin secretion and arterial pressure during prolonged baroreflex activation: influence of salt intake

Chronic electric activation of the carotid baroreflex produces sustained reductions in sympathetic activity and arterial pressure and is currently being evaluated as antihypertensive therapy for patients with resistant hypertension. However, the influence of variations in salt intake on blood pressure lowering during baroreflex activation (BA) has not yet been determined. As the sensitivity of arterial pressure to salt intake is linked to the responsiveness of renin secretion, we determined steady-state levels of arterial pressure and neurohormonal responses in 6 dogs on low, normal, and high salt intakes (5, 40, 450 mmol/d, respectively) under control conditions and during a 7-day constant level of BA. Under control conditions, there was no difference in mean arterial pressure at low (92±1) and normal (92±2 mm Hg) sodium intakes, but pressure increased 9±2 mm Hg during high salt. Plasma renin activity (2.01±0.23, 0.93±0.20, 0.01±0.01 ng angiotensin I/mL/h) and plasma aldosterone (10.3±1.9, 3.5±0.5, 1.7±0.1 ng/dL) were inversely related to salt intake, whereas there were no changes in plasma norepinephrine. Although mean arterial pressure (19-22 mm Hg) and norepinephrine (20%-40%) were lower at all salt intakes during BA, neither the changes in pressure nor the absolute values for plasma renin activity or aldosterone in response to salt were different from control conditions. These findings demonstrate that suppression of sympathetic activity by BA lowers arterial pressure without increasing renin release and indicate that changes in sympathetic activity are not primary mediators of the effect of salt on renin secretion. Consequently, blood pressure lowering during BA is independent of salt intake.

The prevalence, incidence, prognosis, and associated conditions of resistant hypertension

Resistant hypertension is a relevant condition gaining special attention given its clinical and economic impact. Although the true prevalence is unknown, clinical trials and population-based studies have shown that it is a common clinical problem that likely will increase in incidence with an aging and more obese population. A complex interaction of various risk factors including lifestyle, associated conditions, and identifiable secondary causes can lead to uncontrolled hypertension. Important factors including improper blood pressure measuring technique, poor medication adherence, and the white coat phenomenon can lead to pseudoresistance, or a false impression of treatment resistance, which must be excluded. Patients with true resistant hypertension have a greater risk for developing adverse cardiovascular events compared with those with controlled blood pressure, leading to an unfavorable prognosis without adequate treatment. This article reviews the current understanding of the epidemiology of resistant hypertension.

[Patient adherence in antihypertensive treatment]

Hypertension is one of the most frequent chronic diseases as well as most important cardiovascular risk factors in developed countries. Blood pressure control to target levels can significantly decrease the risk for development of coronary artery disease, stroke, chronic renal disease and mortality. Adequately maintained blood pressure is very important in high risk patients. In the treatment of hypertension, life style therapy and drug treatment have essential roles. Further, patient adherence plays a significant part of the treatment, too. Importantly, about half of the patients only become adherent to antihypertensive therapy by the end of the first year treatment. Hence, non-adherence of patients is an important cause for resistant hypertension. Adherence is influenced by the complexity of drug regimen and characteristic of drug class, as well as age and gender of patients.

Characteristics of resistant hypertension in a large, ethnically diverse hypertension population of an integrated health system

OBJECTIVE

To evaluate the prevalence of and characterize resistant hypertension in a large representative population with successful hypertension management and reliable health information.

PATIENT AND METHODS

We performed a cross-sectional study using clinical encounter, laboratory, and administrative information from the Kaiser Permanente Southern California health system between January 1, 2006, and December 31, 2007. From individuals older than 17 years with hypertension, resistant hypertension was identified and prevalence was determined. Multivariable logistic regression was used to calculate odds ratios (ORs), with adjustments for demographic characteristics, clinical variables, and medication use.

RESULTS

Of 470,386 hypertensive individuals, 60,327 (12.8%) were identified as having resistant disease, representing 15.3% of those taking medications. Overall, 37,061 patients (7.9%) had uncontrolled hypertension while taking 3 or more medicines. The ORs (95% CIs) for resistant hypertension were greater for black race (1.68 [1.62-1.75]), older age (1.11 [1.10-1.11] for every 5-year increase), male sex (1.06 [1.03-1.10]), and obesity (1.46 [1.42-1.51]). Medication adherence rates were higher in those with resistant hypertension (93% vs 89.8%; P<.001). Chronic kidney disease (OR, 1.84; 95% CI, 1.78-1.90), diabetes mellitus (OR, 1.58; 95% CI, 1.53-1.63), and cardiovascular disease (OR, 1.34; 95% CI, 1.30-1.39) were also associated with higher risk of resistant hypertension.

CONCLUSION

In a more standardized hypertension treatment environment, we observed a rate of resistant hypertension comparable with that of previous studies using more fragmented data sources. Past observations have been limited due to nonrepresentative populations, reliability of the data, heterogeneity of the treatment environments, and less than ideal control rates. This cohort, which was established using an electronic medical record-based approach, has the potential to provide a better understanding of resistant hypertension and outcomes.

Definition, identification and treatment of resistant hypertension in chronic kidney disease patients

Resistant hypertension, the inability to achieve goal blood pressure despite the use of three or more appropriately dosed antihypertensive drugs (including a diuretic), remains a common clinical problem, especially in patients with chronic kidney disease (CKD). While the exact prevalence and prognosis of resistant hypertension in CKD patients remain unknown, resistant hypertension likely contributes significantly to increased cardiovascular risk and progression of kidney disease in this population. We review the identification and evaluation of patients with resistant hypertension, including the importance of 24-h ambulatory blood pressure monitoring in the identification of 'white-coat', 'masked' and 'non-dipper' hypertension, the latter of which has particular clinical and therapeutic importance in patients with resistant hypertension and CKD. We then discuss treatment strategies for resistant hypertension that target the pathophysiologic mechanisms underlying resistance to treatment, including persistent volume excess, incomplete renin-angiotensin-aldosterone system blockade and inadequate nocturnal blood pressure control. Finally, we propose a treatment algorithm for evaluation and treatment of resistant hypertension in patients with CKD.

Identifying patients with resistant hypertension and options for clinical management

In addition to the increasing prevalence of hypertension, the number of patients with treatment-resistant hypertension is also rising. It is important to identify these patients in order to improve the treatment outcomes and to screen for potential secondary causes. Clinical characteristics of patients with resistant hypertension include advanced age, male gender, obesity, high salt intake and alcohol consumption. Those with high baseline blood pressure, diabetes, chronic kidney disease or obstructive sleep apnea are also prone to developing resistant hypertension. Physicians should initiate close monitoring and aggressive treatment for those patients, as resistant hypertension is associated with a higher risk of cardiovascular morbidities, regardless of the control of blood pressure. However, treatment of resistant hypertension is currently a great challenge in clinical practice as all of these patients are already taking multiple antihypertensive medications, including the first-line treatments advocated in guidelines. In patients who have been presented multiple drugs, the room for further titration is often limited. Spironolactone has been demonstrated to be effective as an add-on therapy for patients with resistant hypertension. In addition to drug treatment, baroreceptor stimulation therapy and renal sympathetic denervation are promising new approaches in this group of patients. Further studies on the pathogenesis and the treatment of resistant hypertension would help to improve the outcome of this patient subgroup.

Effects of electrical stimulation of carotid baroreflex and renal denervation on atrial electrophysiology

INTRODUCTION

This study was designed to compare the effect of electrical baroreflex stimulation (BRS) at an intensity used in hypertensive patients and renal denervation (RDN) on atrial electrophysiology. BRS and RDN reduce blood pressure and global sympathetic drive in patients with resistant hypertension. Whereas RDN decreases sympathetic renal afferent nerve activity, leading to decreased central sympathetic drive, BRS modulates autonomic balance by activation of the baroreflex, resulting in both reduced sympathetic drive and increased vagal activation. Increased vagal tone potentially shortens atrial refractoriness resulting in a stabilization of reentry circuits perpetuating atrial fibrillation (AF).

METHODS AND RESULTS

In normotensive anesthetized pigs (n = 12), we compared the acute effect of BRS and RDN on blood pressure, atrial effective refractory period (AERP), and inducibility of AF. Electrical BRS was titrated to result in comparable heart rate and blood pressure reduction compared to irreversible RDN. BRS resulted in a rapid and pronounced shortening of AERP (from 162 ± 8 milliseconds to 117 ± 16 milliseconds, P = 0.001) associated with increased AF-inducibility from 0% to 82%. This shortening in AERP was completely reversible after stopping BRS. After administration of atropine, AF-inducibility during BRS was attenuated. Ventricular repolarization was not modulated by BRS. In RDN, AF was not inducible; however, it did not prevent BRS-induced shortening of AERP.

CONCLUSION

RDN and BRS resulting in comparable blood pressure and heart rate reductions differently influence atrial electrophysiology. Vagally mediated shortening of AERP, resulting in increased AF-inducibility, was observed with BRS but not with RDN.

Renal sympathetic denervation for the treatment of systemic hypertension

Systemic hypertension is a common cardiovascular problem that often cannot be fully treated with existing nonpharmacologic and pharmacologic measures. A catheter-based strategy which denervates the renal afferent and efferent autonomic nervous system has been developed for the treatment of drug-resistant hypertension. In early clinical trials, this procedure was shown to be both feasible and safe in reducing blood pressure in patients with uncontrolled hypertension receiving treatment with a minimum of 3 antihypertensive drugs. In addition, this procedure has been associated with decreased renin secretion, preservation of renal function, improved glucose tolerance, and a reduction in left ventricular hypertrophy. The long-term effects of this procedure (beyond 3 years) still need to be determined. A large 530-patient sham-controlled trial is now in progress.

Device therapy of resistant hypertension

It is well known that hypertension is an independent cardiovascular risk factor. Treatment of hypertension frequently includes administration of three or more drugs. Resistant hypertension is defined when blood pressure remains above target value despite full doses (the patient’s maximum tolerated dose) of antihypertensive medication consisting of at least three different classes of drugs including a diuretic. Pharmacological treatment of hypertension is often unsuccessful despite the increasing number of drug combinations. Uncontrolled hypertension, however, increases the cardiovascular risk. Device treatment of resistant hypertension is currently testing two major fields. One of them the stimulation of baroreceptors in the carotid sinus and the other is radiofrequency ablation of sympathetic nerve fibers around renal arteries to reduce blood pressure in drug resistant hypertension. Orv. Hetil., 2013, 154, 203–208.

Inducible nitric oxide synthase haplotype associated with hypertension and responsiveness to antihypertensive drug therapy

Hypertension is a multifactorial disorder associated with increased inducible nitric oxide synthase (iNOS) expression and activity. While genetic polymorphisms affect iNOS expression, it is not known whether iNOS gene polymorphisms affect the susceptibility to hypertension and the responses to antihypertensive therapy. This study aimed at assessing whether iNOS polymorphisms ((CCTTT)(n), g.-1026C>A, and g.2087G>A) and haplotypes are associated with hypertension and with responsiveness to drug therapy. We studied 115 well controlled hypertensive patients (HTN), 82 hypertensive patients resistant to optimized antihypertensive therapy (RHTN), and 113 normotensive healthy subjects (NT). Genotypings were carried out using real-time polymerase chain reaction (PCR) and PCR amplification followed by capillary electrophoresis. The software PHASE 2.1 was used to estimate the haplotype frequencies in each group. Variant genotypes (GA+AA) for the g.2087G>A polymorphism were more commonly found in hypertensive patients (HTN+RHTN) than in normotensives (P=0.016; OR=2.05). We found no associations between genotypes and responsiveness to therapy (P>0.05). The S-C-A haplotype was more commonly found in hypertensive patients (HTN+RHTN) than in normotensives (P=0.014; OR=6.07). Interestingly, this haplotype was more commonly found in the HTN group than in the RHTN group (P=0.012; OR=0.14). Our findings indicate that the g.2087G>A polymorphism in the iNOS gene affects the susceptibility to hypertension. Moreover, while the S-C-A haplotype is associated with hypertension, it is also associated with responsiveness to antihypertensive therapy.

New drugs, procedures, and devices for hypertension

Successful treatment of hypertension is difficult despite the availability of several classes of antihypertensive drug, and the value of strategies to combat the effect of adverse lifestyle behaviours on blood pressure. In this paper, we discuss two promising therapeutic alternatives for patients with resistant hypertension: novel drugs, including new pharmacological classes (such as vasopeptidase inhibitors and aldosterone synthase inhibitors) and new molecules from present pharmacological classes with additional properties in blood-pressure or metabolism pathways; and new procedures and devices, including stimulation of arterial baroreceptors and catheter-based renal denervation. Although several pharmacological targets have been discovered with promising preclinical results, the clinical development of novel antihypertensive drugs has been more difficult and less productive than expected. The effectiveness and safety of new devices and procedures should be carefully assessed in patients with resistant hypertension, thus leading to a new era of outcome trials and evidence-based guidelines.

Predictors of resistant hypertension in an unselected sample of an adult male population in Italy

Prevalence, incidence and predictors of resistant hypertension (RH), (defined as blood pressure persistently above goal in spite of the concurrent use of three antihypertensive agents of different classes) in the general population remain largely unknown. A complete database including anthropometric and biochemical data was collected in 1994-1995 (baseline examination) in 1,019 participants (mean age 51.8, range: 25-79 years) and again in 2002-2004 in 794 male participants of the Olivetti Heart Study (OHS) in southern Italy. The incidence of RH over the average follow-up time of 7.9 years was 4.8% (38/794) in the whole study population and 10.1% (31/307) among hypertensive participants. Basal blood pressure (systolic, diastolic or pulse pressure), cholesterol and urinary albumin/creatinine ratio (ACR) significantly predicted the risk of developing RH using a logistic regression model that also included age as covariates. If in the same model we added basal pharmacological treatment, the fractional excretion of sodium (FENa) also became a statistically significant predictor, and this last model explained nearly 25% of the risk of developing RH. In this unselected sample of an adult male population, ACR (an early marker of organ damage), an elevated FENa (a proxy for dietary sodium intake), cholesterol and a higher basal blood pressure level were independent predictors of RH.

Are sleep symptoms predictors of resistant hypertension in a population-based sample? Findings from the National Health and Nutritional Examination Survey

The aim of this study was to test the association of self-reported sleep symptoms to those identified with severe hypertension in a nationally representative sample of adults. Self-reported and study-measured health and sleep characteristics were collected by the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2008. Of 10,526 individuals with completed sleep surveys participating in the study, the authors identified 379 patients with severe hypertension defined as those treated with ≥ 3 antihypertensive medications including a diuretic; 110 of these had resistant hypertension (RHTN) despite therapy, while 269 were controlled for severe hypertension (CSHTN). Patients with RHTN were more likely to be married, less educated, smoke, and self-report unsatisfactory health and diabetes when compared with patients with CSHTN. Multivariate analyses showed that poorly controlled diabetes (glycated hemoglobin >7%) was the strongest predictor of RHTN (odds ratio, 3.0; 95% confidence interval, 1.2-7.9). Unsatisfactory health (odds ratio, 1.7; 95% confidence interval, 1.7-2.7) was also associated with RHTN. Poorly controlled diabetes and self-reported unsatisfactory heath showed significant association with RHTN. Contrary to expectations, there was no significant association between self-reported snoring/snorting and RHTN, when other factors were examined. The association between poorly controlled diabetes and RHTN warrants further emphasis on strict control of diabetes in these individuals.

M-atrial natriuretic peptide: a novel antihypertensive protein therapy

The natriuretic peptides, specifically atrial natriuretic peptide (ANP), are increasingly recognized to play a fundamental role in blood pressure (BP) regulation. This role in BP regulation reflects the pluripotent cardiorenal actions of ANP, which include diuresis, enhancement of renal blood flow and glomerular filtration rate, systemic vasodilatation, suppression of aldosterone, and inhibition of the sympathetic nervous system. These actions of ANP, in addition to recent human studies demonstrating an association of higher plasma ANP with lower risk of hypertension, support the development of an ANP-based therapy for hypertension. M-ANP is a novel ANP-based peptide that is resistant to proteolytic degradation and possesses greater BP-lowering, renal function-enhancing, and aldosterone-suppressing properties than native ANP. In an animal model of hypertension, M-ANP lowers BP via multiple mechanisms, including vasodilatation, diuresis, and inhibition of aldosterone. Importantly, M-ANP enhances both glomerular filtration rate and renal blood flow despite reductions in BP. The pluripotent BP-lowering actions and concomitant enhancement of renal function associated with M-ANP are highly attractive characteristics for an antihypertensive agent and underscore the therapeutic potential of M-ANP. M-ANP currently is heading into clinical testing, which may advance this novel strategy for human hypertension.

Functional VEGF haplotypes affect the susceptibility to hypertension

We examined whether vascular endothelial growth factor (VEGF) polymorphisms (C-2578A, G-1154A and G-634C) are associated with hypertension, response to antihypertensive therapy and nitric oxide (NO) formation. Substudy 1 compared the distribution of VEGF genotypes and haplotypes in 178 patients with arterial hypertension (100 whites and 78 blacks) and 186 healthy controls (115 whites and 71 blacks). Substudy 2 compared the distribution of VEGF markers in 82 patients with controlled hypertension, 89 patients with resistant hypertension and 101 normotensive (NT) patients. In substudy 3, plasma nitrite/nitrate (NOx) levels were determined (chemiluminescence assay) in 64 NT subjects and 48 hypertensive (HTN) subjects, and the distribution of VEGF markers was compared in subjects having low NOx with subjects having high NOx. Although the substudy 1 showed no differences in genotypes or allele distributions for the three VEGF polymorphisms between NT and HTN subjects, the 'C-A-G' haplotype was more common in white NT subjects than in the white HTN subjects, and the 'C-A-C' haplotype was more frequent in black and white HTN subjects than in black and white NT subjects. The substudy 2 showed similar results, with no differences between responsive and resistant HTN subjects. The substudy 3 showed that the 'C-A-G' haplotype, which had a protective effect against hypertension, was significantly more common in subjects with higher NOx concentrations than in subjects with lower NOx concentrations. VEGF haplotypes are associated with hypertension, and the haplotype associated with normotension was more common in subjects with increased NO formation, possibly offering a mechanistic clue for our findings.

Epidemiology of resistant hypertension

Resistant hypertension is an entity that has gained a lot of attention in recent years. The prevalence and prognosis of resistant hypertension have not yet been examined by proper population studies, but data from several sources suggest that this entity is not uncommon and is associated with an elevated risk of hypertensive complications. Moreover, several factors and conditions that can interfere with blood pressure control such as excess sodium intake, obesity, diabetes, older age, kidney disease, and certain identifiable causes of hypertension were shown to be common among patients with resistance to antihypertensive treatment. Importantly, the prevalence of several of these conditions has been increasing continuously during the past years, suggesting a future increase in the frequency of resistant hypertension. This article will discuss current knowledge and associated future implications relevant to the epidemiology of resistant hypertension.

Gene variation in resistant hypertension: multilocus analysis of the angiotensin 1-converting enzyme, angiotensinogen, and endothelial nitric oxide synthase genes

Resistant hypertension, a complex multifactorial hypertensive disease, is triggered by genetic and environmental factors and involves multiple physiological pathways. Single genetic variants may not reveal significant associations with resistant hypertension because their effects may be dependent on gene-gene or gene-environment interactions. We examined the interaction of angiotensin I-converting enzyme (ACE), angiotensinogen (AGT), and endothelial nitric oxide synthase (NOS3) polymorphisms with environmental factors (gender, age, body mass index, glycemia, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, estimated glomerular filtration rate, and urinary sodium excretion) in 70 resistant, 80 well-controlled hypertensive patients, and 70 normotensive controls. All subjects were genotyped for ACE insertion/deletion (rs1799752); AGT M235T (rs699), and NOS3 Glu298Asp (rs 1799983). Multifactorial associations were tested using two statistical methods: the traditional parametric method (adjusted logistic regression analysis) and gene-gene and gene-environment interactions evaluated by multifactor dimensionality reduction analyses. While adjusted logistic regression found no significant association between the studied polymorphisms and controlled or resistant hypertension, the multifactor dimensionality reduction analyses showed that carriers of the AGT 235T allele were at increased risk for resistant hypertension, especially if they were older than 50 years. The AGT 235T allele constituted an independent risk factor for resistant hypertension.

Common secondary causes of resistant hypertension and rational for treatment

Resistant hypertension is defined as uncontrolled blood pressure despite the use of three antihypertensive drugs, including a diuretic, in optimal doses. Treatment resistance can be attributed to poor adherence to antihypertensive drugs, excessive salt intake, physician inertia, inappropriate or inadequate medication, and secondary hypertension. Drug-induced hypertension, obstructive sleep apnoea, primary aldosteronism, and chronic kidney disease represent the most common secondary causes of resistant hypertension. Several drugs can induce or exacerbate pre-existing hypertension, with non-steroidal anti-inflammatory drugs being the most common due to their wide use. Obstructive sleep apnoea and primary aldosteronism are frequently encountered in patients with resistant hypertension and require expert management. Hypertension is commonly found in patients with chronic kidney disease and is frequently resistant to treatment, while the management of renovascular hypertension remains controversial. A step-by-step approach of patients with resistant hypertension is proposed at the end of this review paper.

Novel procedure- and device-based strategies in the management of systemic hypertension

Despite the considerable advances in the treatment of hypertension that have been made over the past few decades, adequate management and control of this condition remains poor, and efforts are ongoing to develop new strategies to improve related outcomes. Novel therapeutic approaches to the management of systemic hypertension fall into two major categories: (i) those that seek to improve blood pressure-lowering efficacy using new therapeutic strategies in addition to standard non-pharmacological and pharmacological approaches and (ii) novel ways to optimize and improve the efficacy and utility of existing therapies. Novel procedure- and device-based strategies to control hypertension include renal sympathetic denervation and baroreflex sensitization. These two techniques will be the focus of the present review.

Role of laparoscopic nephrectomy for refractory hypertension in poorly functioning kidneys

INTRODUCTION

Hypertension is a common medical problem mainly treated by effective antihypertensive drugs. Persistent hypertension can be difficult to manage and have detrimental effect on vital organs. Nephrectomy of poorly functioning kidneys may be indicated in a minority of such cases.

PATIENTS AND METHODS

We performed laparoscopic nephrectomy on 12 patients with refractory hypertension.

RESULTS

Eight had complete response, three had partial response and one had no response.

CONCLUSIONS

Laparoscopic nephrectomy has a role in carefully selected adult patients with refractory hypertension due to non-functioning kidney. Patients need to understand the surgical risks as well as the small risk of failure to treat hypertension.

Resistant hypertension workup and approach to treatment

Resistant hypertension is defined as blood pressure above the patient's goal despite the use of 3 or more antihypertensive agents from different classes at optimal doses, one of which should ideally be a diuretic. Evaluation of patients with resistive hypertension should first confirm that they have true resistant hypertension by ruling out or correcting factors associated with pseudoresistance such as white coat hypertension, suboptimal blood pressure measurement technique, poor adherence to prescribed medication, suboptimal dosing of antihypertensive agents or inappropriate combinations, the white coat effect, and clinical inertia. Management includes lifestyle and dietary modification, elimination of medications contributing to resistance, and evaluation of potential secondary causes of hypertension. Pharmacological treatment should be tailored to the patient's profile and focus on the causative pathway of resistance. Patients with uncontrolled hypertension despite receiving an optimal therapy are candidates for newer interventional therapies such as carotid baroreceptor stimulation and renal denervation.

RGS2 expression and aldosterone: renin ratio modulate response to drug therapy in hypertensive patients

OBJECTIVE

RGS2 (regulators of G-protein signalling) is a negative regulator of Galphaq protein signalling, which mediates the action of several vasoconstrictors. Low RGS2 expression increases G-protein-coupled signalling in hypertensive patients. The aim of the present study was to correlate RGS2 expression in peripheral blood mononuclear cells (PBMs) with response to antihypertensive therapy in never-treated patients with essential hypertension.

METHODS AND DESIGN

RGS2 expression was measured by real-time quantitative RT-PCR in peripheral blood mononuclear cells (PBMs) from 102 essential hypertensives. The diagnosis of essential hypertension was based on all clinically required tests, including the captopril suppression test. Antihypertensive treatment was given in accordance to international guidelines. End-point of the study was systolic blood pressure (BP) less than 140 mmHg and diastolic BP less than 90 mmHg with three or less different antihypertensive agents, which identified responders to treatment. Resistant hypertension was defined as the failure to control systolic and/or diastolic BP despite at least three different classes of antihypertensive agents, including a diuretic.

RESULTS

During follow-up, 85 (83%) patients reached the end point (responders). Resistant hypertensives (n = 17, 17%) were older, had higher baseline BP, plasma aldosterone and aldosterone: renin ratio (ARR) and lower plasma renin activity than patients who reached the end point. RGS2 was negatively correlated to systolic BP at enrollment and significantly lower in PBMs from resistant hypertensives in comparison with patients that reached BP goal. According to logistic regression analysis, high RGS2 expression was predictor of reaching BP goal, whereas high ARR after captopril, age and systolic pressure at enrolment were predictor of resistant hypertension.

CONCLUSION

RGS2 expression affects the response to antihypertensive treatment. Reduced RGS2 expression contributes to resistance to antihypertensive agents through poor negative feedback on the effects of aldosterone and of other vasoactive agents.

Urinary albumin excretion is associated with true resistant hypertension

Resistant (or refractory) hypertension (RH) is a clinical diagnosis based on blood pressure (BP) office measurements. About one third of subjects with suspected RH have indeed pseudo-resistant hypertension and 24-h ambulatory-blood pressure-monitoring aids to precisely identify them. Our aim was to determine those clinical, laboratory or echocardiographic variables that may be associated with subjects with sustained hypertension (namely true RH). We carried out a cross-sectional analysis of 143 patients consecutively enrolled with the clinical diagnosis of RH. All patients underwent clinical-demographic, laboratory evaluation, 2D-echocardiography and 24-h ambulatory-blood pressure-monitoring. Pseudo-resistant hypertension or white-coat RH was defined if office BP was > or =140 and/or 90 mm Hg and 24-h BP <130/80 mm Hg. One-hundred and three (72%) patients had true RH and 40 (28%) patients had white-coat RH. True RH patients had significantly higher diabetes prevalence and higher office-systolic blood pressure (SBP) levels. Regarding target organ damage, left ventricular mass index (LVMI) and 24-h urinary albumin excretion (UAE) were also higher in true RH after adjustment for possible confounders (P=0.031 and P=0.012, respectively). In a logistic regression analysis, only office-SBP (multivariate OR (95%CI): 1.030 (1.003-1.057), P=0.030) and UAE (multivariate OR (95% CI): 2.376 (1.225-4.608), P=0.010) were independently associated with true RH. We conclude that true resistant hypertension is associated with silent target organ damage, especially UAE. In patients with suspected RH, assessment of 24 h ambulatory BP is the most accurate way to detect a population with high risk for target-organ damage.

Clinical approach in treatment of resistant hypertension

Resistant hypertension, defined as failure to achieve target blood pressure despite the use of optimal or maximum doses of at least 3 agents, one of which is a diuretic, or requiring 4 or more medications to achieve blood pressure goal, is likely to affect up to 20% of all patients with hypertension. Apparent resistant hypertension may be caused by medication nonadherence, substances that either interfere with antihypertensive mediations or cause blood pressure elevation, and under- or inappropriate medication treatment. Certain patient characteristics are associated with the presence of resistant hypertension and include chronic kidney disease, diabetes, obesity, and presence of end-organ damage (microalbuminuria, retinopathy, left-ventricular hypertrophy). Secondary causes of resistant hypertension are not uncommon and include obstructive sleep apnea, chronic kidney disease, primary aldosteronism, renal artery stenosis, pheochromocytoma, and Cushing's disease. Initial medication management usually includes adding or increasing the dose of a diuretic, which is effective in lowering the blood pressure of a large number of patients with resistant hypertension. Additional management options include maximizing lifestyle modification, combination therapy of antihypertensive agents depending on individual patient characteristics, adding less-commonly used fourth- or fifth-line antihypertensive agents, and referral to a hypertension specialist.

Spironolactone and doxazosin treatment in patients with resistant hypertension

INTRODUCTION AND OBJECTIVES

The aim of this study was to evaluate the use of spironolactone and doxazosin as treatment for patients with resistant hypertension.

METHODS

This retrospective study involved 181 outpatients with resistant hypertension (defined as a failure of blood pressure [BP] control despite treatment with three drugs, one of which was a diuretic) who received additional spironolactone (n=88) or doxazosin (n=93).

RESULTS

Mean systolic BP in the spironolactone group fell by 28 mmHg (95% confidence interval [CI], 24-32 mmHg; P< .001) and mean diastolic BP fell by 12 mmHg (95% CI, 9-14 mmHg; P< .001). The corresponding falls in the doxazosin group were 16 mmHg (95% CI, 13-20 mmHg; P< .001) and 7 mmHg (95% CI, 5-9 mmHg; P< .001), respectively. The decrease was significantly greater with spironolactone for both systolic (P< .001) and diastolic (P=.003) pressures. At the end of follow-up, 30% of all patients had achieved BP control, with control being more frequent with spironolactone (39%) than doxazosin (23%; P=.02). Multivariate logistic regression analysis showed that the only factors that significantly influenced the achievement of BP control were diabetes (odds ratio=0.17; 95% CI, 0.08-0.39; P< .001) and baseline systolic BP <165 mmHg (odds ratio=2.56; 95% CI, 1.11-5.90; P=.03).

CONCLUSIONS

In patients with resistant hypertension, the addition of either spironolactone or doxazosin resulted in a significant decrease in BP, though the decrease appeared to be greater with spironolactone. The presence of diabetes complicated BP control.