Cardiopulmonary Baroreflex Control of Renal Sympathetic Nerve Activity Is Impaired in Dogs With Left Ventricular Dysfunction.

BACKGROUND: Activation of neurohormonal systems contributes to the progression of heart failure (HF). The mechanism(s) whereby these systems become activated is(are) not fully explained. We determined whether vagal cardiopulmonary baroreflex control of renal sympathetic nerve activity is abnormal in dogs with left ventricular (LV) dysfunction in the absence of clinical HF, and the relationship of abnormalities in baroreflexes to the development of the neurohumoral excitatory state. METHODS: LV end-systolic and end-diastolic dimensions (echocardiography), arterial baroreflex sensitivity (slope of ΔRR/Δsystolic BP during phenylephrine or nitroglycerin bolus), and neurohumoral profiles (plasma norepinephrine, renin activity, and arginine vasopressin) were measured serially in conscious dogs (n=24) with progressive LV dysfunction due to rapid ventricular pacing. LV dimensions were used to define groups with mild, moderate, and marked LV dilatation (LVD; increase in LV end-diastolic volume <15%, 15-30%, and >30% of control, respectively). Changes in renal nerve activity (RNA) were recorded in response to increases in pulmonary capillary wedge pressure (PCWP) induced by volume infusion in anesthetized, sinoaortic-denervated dogs. RESULTS: Cardiopulmonary baroreflex sensitivity (slope of %ΔRNA/ΔPCWP) for mild LVD (-17.8%/mmHg) was the same as controls (-17.7%/mmHg). However, the slopes of moderate (-5.8%/mmHg) and severe LVD (-1.9%/mmHg) were decreased significantly compared with controls (P < .05). Arterial baroreflex sensitivity was preserved at all stages of LVD. Plasma norepinephrine, renin activity, and arginine vasopressin remained unchanged after 4, 7, and 11 days of pacing. CONCLUSIONS: Vagal cardiopulmonary baroreflex control of renal sympathetic nerve activity is blunted early in the development of LVD. These abnormalities precede neurohumoral excitation and abnormal arterial baroreflexes and become apparent when LV end-diastolic volume starts to increase.

Use of Diuretics in the Treatment of Heart Failure in Older Adults.

Diuretics are the most commonly prescribed class of drugs in patients with heart failure, and in the short term they remain the most effective treatment for relief from fluid congestion. This article reviews the mode of action of the various diuretic classes and the physiologic adaptations that follow and sets up the basis for their use in the treatment of volume-retaining states, particularly as applies to the elderly. In addition, the article reviews the common side effects related to diuretics.

Assessment and management of hypertension in transplant patients.

Hypertension in renal transplant recipients is common and ranges from 50% to 80% in adult recipients and from 47% to 82% in pediatric recipients. Cardiovascular morbidity and mortality and shortened allograft survival are important consequences of inadequate control of hypertension. In this review, we examine the epidemiology, pathophysiology, and management considerations of post-transplant hypertension. Donor and recipient factors, acute and chronic allograft injury, and immunosuppressive medications may each explain some of the pathophysiology of post-transplant hypertension. As observed in other patient cohorts, renal artery stenosis and adrenal causes of hypertension may be important contributing factors. Notably, BP treatment goals for renal transplant recipients remain an enigma because there are no adequate randomized controlled trials to support a benefit from targeting lower BP levels on graft and patient survival. The potential for drug-drug interactions and altered pharmacokinetics and pharmacodynamics of the different antihypertensive medications need to be carefully considered. To date, no specific antihypertensive medications have been shown to be more effective than others at improving either patient or graft survival. Identifying the underlying pathophysiology and subsequent individualization of treatment goals are important for improving long-term patient and graft outcomes in these patients.

Not just chlorthalidone: evidence-based, single tablet, diuretic alternatives to hydrochlorothiazide for hypertension.

Accounting for 15 % of deaths worldwide, hypertension is often treated with hydrochlorothiazide (HCTZ) (50 million prescriptions annually). HCTZ has a <24-h duration of action, is less potent than chlorthalidone and all major antihypertensive drug classes, and is inferior to four antihypertensive drugs for cardiovascular event (CVE) reduction. If there were alternative diuretics, why prescribe HCTZ? Chlorthalidone is often offered as an alternative to HCTZ, but has limited pharmaceutical formulations. However, there are seven evidence-based, single-tablet, alternative diuretics. For reducing CVE, the following are superior to their comparators: chlorthalidone versus four antihypertensives in multiple hypertensive populations; indapamide versus placebo in elderly Chinese (and versus enalapril for left ventricular hypertrophy), triamterene-HCTZ versus placebo in elderly Europeans, amiloride-HCTZ versus three antihypertensives, and indapamide-perindopril versus placebo in three populations. Additionally, chlorthalidone-azilsartan and spironolactone-HCTZ are potent combinations The aldosterone antagonist component of the latter combination has been shown to reduce total mortality by 30 % in heart failure. Five of these seven have multiple dose formulations. Six cost $4-$77 monthly. In conclusion, based on both scientific and practical grounds, new prescriptions for HCTZ are rarely justified.

Cardiovascular burden associated with uremic toxins in patients with chronic kidney disease.

BACKGROUND: Retention of uremic toxins in patients with chronic kidney disease (CKD) negatively affects multiple organ systems, including the cardiovascular system, resulting in significant morbidity and mortality. Alleviation of the adverse effects of uremic toxins is an important priority in the management of CKD. SCOPE: This review focuses on the evidence for the influence of uremic toxins on cardiovascular morbidity and mortality among patients with CKD and slowly developing uremia. The cardiovascular effects of acute kidney injury and rapidly developing azotemia are beyond the scope of this review and will not be discussed. Data on potential treatment options aimed at ameliorating the toxic effects of uremic toxins are summarized. FINDINGS: Uremic toxins are associated with significant cardiovascular morbidity and mortality in patients with CKD. While a number of preclinical studies have detailed these effects, clinical studies directly evaluating cardiovascular outcomes consequent to the presence of uremic toxins have only recently become available. CONCLUSION: Uremic toxins play an important role in the progression of cardiovascular disease in patients with CKD. Further studies are needed to better characterize the impact of these compounds on cardiovascular outcomes. Beneficial treatments are currently available that, in preliminary studies, appear to neutralize some of the adverse effects of uremic toxins. Large randomized clinical trials are needed to further determine the utility of these varied therapeutic agents.

Mineralocorticoid receptor antagonists for heart failure with reduced ejection fraction: integrating evidence into clinical practice.

Mineralocorticoid receptor antagonists (MRAs) improve survival and reduce morbidity in patients with heart failure, reduced ejection fraction (HF-REF), and mild-to-severe symptoms, and in patients with left ventricular systolic dysfunction and heart failure after acute myocardial infarction. These clinical benefits are observed in addition to those of angiotensin converting enzyme inhibitors or angiotensin receptor blockers and beta-blockers. The morbidity and mortality benefits of MRAs may be mediated by several proposed actions, including antifibrotic mechanisms that slow heart failure progression, prevent or reverse cardiac remodelling, or reduce arrhythmogenesis. Both eplerenone and spironolactone have demonstrated survival benefits in individual clinical trials. Pharmacologic differences exist between the drugs, which may be relevant for therapeutic decision making in individual patients. Although serious hyperkalaemia events were reported in the major MRA clinical trials, these risks can be mitigated through appropriate patient selection, dose selection, patient education, monitoring, and follow-up. When used appropriately, MRAs significantly improve outcomes across the spectrum of patients with HF-REF.

Therapeutic perspectives in hypertension: novel means for renin-angiotensin-aldosterone system modulation and emerging device-based approaches.

The conventional antihypertensive therapies including renin-angiotensin-aldosterone system antagonists (converting enzyme inhibitors, receptor blockers, renin inhibitors, and mineralocorticoid receptor blockers), diuretics, ß-blockers, and calcium channel blockers are variably successful in achieving the challenging target blood pressure values in hypertensive patients. Difficult to treat hypertension is still a commonly observed problem world-wide. A number of drugs are considered to be used as novel therapies for hypertension. Renalase supplementation, vasopeptidase inhibitors, endothelin antagonists, and especially aldosterone antagonists (aldosterone synthase inhibitors and novel selective mineralocorticoid receptor blockers) are considered an option in resistant hypertension. In addition, the aldosterone antagonists as well as (pro)renin receptor blockers or AT(2) receptor agonists might attenuate end-organ damage. This array of medications has now been complemented by a number of new approaches of non-pharmacological strategies including vaccination, genomic interference, controlled breathing, baroreflex activation, and probably most successfully renal denervation techniques. However, the progress on innovative therapies seems to be slow and the problem of resistant hypertension and proper blood pressure control appears to be still persisting. Therefore the regimens of currently available drugs are being fine-tuned, resulting in the establishment of several novel fixed-dose combinations including triple combinations with the aim to facilitate proper blood pressure control. It remains an exciting question which approach will confer the best blood pressure control and risk reduction in this tricky disease.

Drug dosing consideration in patients with acute and chronic kidney disease-a clinical update from Kidney Disease: Improving Global Outcomes (KDIGO).

Drug dosage adjustment for patients with acute or chronic kidney disease is an accepted standard of practice. The challenge is how to accurately estimate a patient's kidney function in both acute and chronic kidney disease and determine the influence of renal replacement therapies on drug disposition. Kidney Disease: Improving Global Outcomes (KDIGO) held a conference to investigate these issues and propose recommendations for practitioners, researchers, and those involved in the drug development and regulatory arenas. The conference attendees discussed the major challenges facing drug dosage adjustment for patients with kidney disease. In particular, although glomerular filtration rate is the metric used to guide dose adjustment, kidney disease does affect nonrenal clearances, and this is not adequately considered in most pharmacokinetic studies. There are also inadequate studies in patients receiving all forms of renal replacement therapy and in the pediatric population. The conference generated 37 recommendations for clinical practice, 32 recommendations for future research directions, and 24 recommendations for regulatory agencies (US Food and Drug Administration and European Medicines Agency) to enhance the quality of pharmacokinetic and pharmacodynamic information available to clinicians. The KDIGO Conference highlighted the gaps and focused on crafting paths to the future that will stimulate research and improve the global outcomes of patients with acute and chronic kidney disease.

What is the role of aldosterone excess in resistant hypertension and how should it be investigated and treated?

Resistant hypertension has evolved as an important global health care problem. Primary aldosteronism is one of several potentially reversible causes of resistant hypertension. Primary aldosteronism can be effectively treated, when recognized, with a mineralocorticoid receptor antagonist, such as spironolactone and eplerenone. Each of these compounds can reduce blood pressure as monotherapy or when given with a range of other antihypertensive drug classes. These compounds have distinctive pharmacokinetic and pharmacodynamic patterns that require some forethought in their use before they are prescribed. However, as the use of mineralocorticoid-blocking agents has gradually increased, the hazards inherent to use of such drugs has become more apparent. Whereas the endocrine side effects of spironolactone are in most cases little more than a cosmetic annoyance, the potassium-sparing effects of both spironolactone and eplerenone can prove fatal if sufficient degrees of hyperkalemia develop. However, for most patients the risk of developing hyperkalemia in and of itself should not discourage the prudent clinician from bringing these compounds into play. Hyperkalemia should always be considered as a likelihood in any patient receiving one or the other of these medications. As such, steps should be taken to lessen the likelihood of it occurring if therapy is being contemplated with agents in this class.

Curcumin prevents cardiac remodeling secondary to chronic renal failure through deactivation of hypertrophic signaling in rats.

The prevalence of left ventricular hypertrophy (LVH) is frequent in patients with end-stage renal disease following chronic renal failure (CRF). We investigated the therapeutic efficacy of curcumin, the principal curcuminoid of the Indian curry spice turmeric, in attenuation of LVH and sought to delineate the associated signaling pathways in blunting the hypertrophic response in nephrectomized rats. Adult Sprague-Dawley rats underwent nephrectomy (Nx) by removal of 5/6 of the kidneys. Four groups were studied for 7 wk: 1) control (sham), 2) Nx, 3) Nx + curcumin (150 mg/kg bid), and 4) Nx + enalapril (15 mg/kg bid) as positive control. Subtotal nephrectomy caused renal dysfunction, as evidenced by a gradual increase in proteinuria and elevation in blood urea nitrogen and plasma creatinine. Nx rats showed a significant hypertrophic response and increased diameter of inferior vena cava at inspiration, which was inhibited by treatment with curcumin or enalapril. Moreover, the Nx rats demonstrated changes in the signaling molecules critically involved in the hypertrophic response. These include increased glycogen synthase kinase-3ß phosphorylation, ß-catenin expression, calcineurin, phosphorylated (p) nuclear factor of activated T cells, pERK, and p-cAMP-dependent kinase. Both curcumin and enalapril variably but effectively deactivated these pathways. Curcumin attenuates cardiac hypertrophy and remodeling in nephrectomized rats through deactivation of multiple hypertrophic signaling pathways. Considering the safety of curcumin, these studies should facilitate future clinical trials in suppressing hypertrophy in patients with CRF.

The evolution of renin-angiotensin blockade: angiotensin-converting enzyme inhibitors as the starting point.

The renin-angiotensin system has been a target in the treatment of hypertension for close to three decades. Several medication classes that block specific aspects of this system have emerged as useful therapies, including angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and, most recently, direct renin inhibitors. There has been a natural history to the development of each of these three drug classes, starting with their use as antihypertensive agents; thereafter, in each case they have been employed as end-organ protective agents. To date, there has been scant evidence to favor angiotensin receptor blockers or direct renin inhibitors over angiotensin-converting enzyme inhibitors in treating hypertension or in affording end-organ protection; thus, angiotensin-converting enzyme inhibitors remain the standard of care when renin-angiotensin system blockade is warranted.

Can focused US with a diagnostic US contrast agent favorably affect renal function?

Focused ultrasonography (US) with simultaneous administration of a US microbubble contrast agent was used to transiently increase the glomerular filtration rate while altering the sieving properties of glomeruli in normal rabbits. In its current form, this process has very limited application potential to states of abnormal renal function.

Fibrate therapy and renal function.

Fibrates are a class of lipid-lowering medications primarily used as second-line agents behind statins. The adverse-effect profile of fibrates has been marked by a puzzling yet reversible rise in serum creatinine values with their use. It is not known whether this finding represents a true change in renal function. One proposed explanation for this phenomenon is that fibrates increase the production of creatinine, in which case a rise in serum creatinine values would not represent a true deterioration in renal function. An alternative theory is that fibrates reduce the production of vasodilatory prostaglandins, which would lead to a true change in renal function in patients who experience a rise in serum creatinine values. Routine serum creatinine monitoring is advisable in fibrate-treated patients, particularly in those with preexisting renal disease. A 30% increase in serum creatinine values in the absence of other causes of serum creatinine change warrants discontinuation of fibrate therapy. Serum creatinine values can take several weeks to return to their baseline values following discontinuation of a fibrate.

A guide to the management of blood pressure in the diabetic hypertensive patient.

Diabetes mellitus and hypertension frequently coexist in patients with the insulin resistance syndrome (IRS). Patients with both diabetes and hypertension typically have widespread endothelial dysfunction, increased oxidative stress, an activated sympathoadrenal system, and an elevated systemic burden of inflammatory mediators. Patients with diabetes and hypertension also have concomitant mixed dyslipidemia and obesity with significant frequency, and are at high risk for the development of macro- and microvascular disease, congestive heart failure, and nephropathy. Current data suggest that ACE inhibitors or angiotensin receptor blockers with or without a diuretic are important, if not preferred, initial therapies for the patient with diabetes and hypertension. Other drug classes such as combined alpha-/beta-adrenoceptor antagonists, dihydropyridine calcium channel antagonists (CCAs), and peripheral alpha-adrenoceptor antagonists are also useful therapeutic options in these patients. In order to optimally reduce the risk for cardiovascular events in the patient with diabetes and hypertension, optimal BP control should be coupled with comprehensive lifestyle modification and aggressive management of dyslipidemia and hyperglycemia.

Does the benefit from treating to lower blood pressure targets vary with age? A systematic review and meta-analysis.

BACKGROUND: Recommendations differ regarding how blood pressure targets should vary with age. Crucial to this controversy is whether treatment benefit varies with age. METHODS: Systematic searches were conducted for trials randomizing treatment in intensive arms to the recommended SBP targets: 120-140 mmHg. Head-to-head meta-analyses and meta-regression were conducted. RESULTS: Sixteen trials met criteria. Relative to higher targets, lower targets reduced cardiovascular events, but treatment benefit differed significantly among trials due to patient age. Treatment significantly benefited older patients (mean age 77, SD = 72-81), relative risk (RR) = 0.77 (0.61,0.97), P = 0.025, but not younger patients (mean age 61, SD = 53-70), RR = 0.90 (0.78,1.03), P = 0.121, even though the latter had much greater statistical power. The (RR in 80 year olds)/(RR in 55 year olds) = 0.68 (0.47,0.97), P = 0.036. Though statistically nonsignificant, corresponding trends for more specific outcomes favored older patients: Coronary artery disease 0.80, stroke 0.85, heart failure 0.54, and total mortality 0.76. For adverse effects this trend was 0.86 (0.33,2.26). The number needed to treat to lower targets to prevent one cardiovascular event over 10 years in eight populations declined with age by 94%+. CONCLUSION: In these novel results, for both RR and absolute risk, treating to SBPs of 120-140 mmHg versus higher targets benefited older patients more than younger patients without an age-related increase in the RR for adverse effects. Nonetheless, because all clinical trials excluded the most frail older patients, clinicians must consider individual patient characteristics such as frailty, autonomy, and cognitive ability when choosing blood pressure targets.

Do pleiotropic effects of antihypertensive medications exist or is it all about the blood pressure?

Examination of the large-scale drug-versus-drug trials suggests that the initial drug choice is of token importance and that better blood pressure control is the primary determinant of superior outcomes. In pooled analyses, the achieved blood pressure is similar for older and less expensive drugs, such as thiazide-type diuretics, and for newer and more costly agents, such as angiotensin-converting enzyme inhibitors, -angiotensin-receptor blockers, and calcium-channel blockers. If blood pressure--independent differences favoring one antihypertensive drug class over another truly exist, they have been singularly difficult to uncover with any consistency. Considering that multidrug therapy is required in the majority of patients with hypertension, the debate as to which drug class is best to start with is moot, in that the clinician is now more called upon to decide the best combinations of drugs and not the best monotherapy.

Pharmacologic considerations in the positioning of beta-blockers in antihypertensive therapy.

Beta-blockers have been used to treat hypertension for decades, either as monotherapy or combined with other antihypertensive agents, primarily diuretics, often as fixed-dose combination products. Although beta-blockers can lower blood pressure in most patients, outcomes data with these drugs have been disappointing and their value for patients without "compelling indications" has been questioned recently. The early beta-blockers had significant pharmacologic shortcomings; however, later-generation beta-blockers have distinctive and presumably better pharmacologic profiles. The most recently introduced drugs, the vasodilating beta-blockers carvedilol and nebivolol, are now being broadly evaluated as to their efficacy and tolerability in clinical practice.