Hypertension is a common but frequently overlooked adverse effect of erythropoietin (EPO) therapy. Underreporting of hypertension with EPO is likely due to either more aggressively managing ...hypertension through the prescription of antihypertensive drugs or closer attention to dry weight. The purpose and focus of this review is to critically evaluate the mechanisms of EPO-induced hypertension. Preclinical data are considered first, followed by clinical data where available. Mediated by a variety of molecules, there is an imbalance in the vascular tone favoring net vasoconstriction that mediates EPO-induced hypertension. Animal studies show the primary importance of chronic kidney disease in the genesis of EPO-induced hypertension. Preclinical studies show deranged regulation of the nitric oxide, endothelins and porstanoids and the sympathoadrenal and renin-angiotensin pathways as causes of EPO-induced hypertension. Human studies suggest that EPO administration is also associated with increased responsiveness to catecholamines and angiotensin II on vascular tissue; in addition, hypoxia-induced vasodilation may be impaired in those with EPO-induced hypertension. There is little evidence for EPO as a direct vasoconstrictor or its effect on blood viscosity as a mechanism of EPO-induced hypertension. EPO-induced hypertension, at least in part, appears to be independent of an increase in hemoglobin, because experiments show that hemoglobin may be increased by EPO without an increase in blood pressure (BP) by simply treating the animals with EPO-binding protein and that treatment with EPO in the setting of iron deficiency may not increase hemoglobin but may still increase BP. However, experimental data are not consistent across studies and better mechanistic designs are needed, especially in patients with chronic kidney disease, to dissect the precise mechanism of EPO-induced hypertension. Animal studies suggest that hypoxia-inducible factor stablizers may induce hypertension by provoking calcification and augmenting chronic intermittent hypoxia as occurs in sleep apnea. Others show that there may be an antihypertensive effect via kidney repair. Whether these drugs will alter the risk of hypertension compared with EPO remains to be seen.
Blood pressure measured before and after dialysis does not agree well with those recorded outside the dialysis unit. Whether recordings obtained outside the dialysis unit are of greater prognostic ...value than blood pressure obtained just before and after dialysis remains incompletely understood. Among 326 patients on long-term hemodialysis, blood pressure was self-measured at home for 1 week, over an interdialytic interval by ambulatory recording and before and after dialysis over 2 weeks. Over a mean follow-up of 32 (SD 20) months, 102 patients died (31%), yielding a crude mortality rate of 118/1000 patient years. Systolic but not diastolic blood pressure was found to be of prognostic importance. Adjusted and unadjusted multivariate analyses showed increasing quartiles of ambulatory and home systolic blood pressure to be associated with all-cause mortality (adjusted hazard ratios for increasing quartiles of ambulatory2.51, 3.43, 2.62; and for home blood pressure2.15, 1.7, 1.44). Mortality was lowest when home systolic blood pressure was between 120 to 130 mm Hg and ambulatory systolic blood pressure was between 110 to 120 mm Hg. Blood pressure recorded before and after dialysis was not statistically significant (P=0.17 for predialysis, and P=0.997 for postdialysis) in predicting mortality. Out-of-dialysis unit blood pressure measurement provided superior prognostic information compared to blood pressure within the dialysis unit (likelihood ratio test, P<0.05). Out-of-dialysis unit blood pressure among hemodialysis patients is prognostically more informative than that recorded just before and after dialysis. Therefore, the management of hypertension among these patients should focus on blood pressure recordings outside the dialysis unit.
Background
Cardiovascular morbidity and mortality was reduced by 25% when blood pressure (BP) was targeted to 120 mm Hg systolic compared with 140 mm Hg systolic in Systolic Blood Pressure ...Intervention Trial (SPRINT); however, BP was measured using a research technique. SPRINT specified 5 minutes of seated rest in a quiet room followed by 3 oscillometric measurements without an observer in the room. The relationship of this research‐grade methodology to routine BP measurements is not known.
Methods and Results
Among 275 people with chronic kidney disease who had BP <140/90 mm Hg when they came to the clinic, we measured BP as in SPRINT and recorded BP on the same day without specification of seated rest. Compared with routine measurement, the research‐grade systolic BP was 12.7 mm Hg lower with wide limits of agreement (−46.1 to 20.7 mm Hg). Research grade systolic BP was 7.9 mm Hg lower than daytime ambulatory systolic BP and had wide agreement limits (−33.2 to 17.4 mm Hg). Whereas the routine, research‐grade, and daytime ambulatory systolic BP were all related to echocardiographic left ventricular hypertrophy, the strength of the relationship between research‐grade and daytime ambulatory systolic BP to left ventricular hypertrophy was similar and stronger than the strength of the relationship between routine systolic BP and left ventricular hypertrophy.
Conclusions
Taken together, these results suggest that translation of the SPRINT results will require measurement of BP as performed in that trial. Instead of an algebraic manipulation of routine clinic measurements, the SPRINT methodology of BP measurement would be needed at minimum if implementation of the SPRINT results were to be deployed in the population at large.
In this double-blind trial, patients with chronic kidney disease and type 2 diabetes were randomly assigned to receive the nonsteroidal, selective mineralocorticoid receptor antagonist finerenone or ...placebo. Treatment with finerenone resulted in lower risks of chronic kidney disease outcomes and cardiovascular outcomes than placebo.
Mean arterial pressure has been used in clinical trials in nephrology to randomly assign and treat patients, yet the pulsatile component of BP is recognized to influence outcomes in older people. I ...examined the unique contributions of systolic (SBP) and diastolic BP (DBP) on the risk for ESRD and death in patients with chronic kidney disease (CKD).
A single-center, prospective cohort study was conducted of 218 veterans with CKD (22% black, 4% women, mean age 68 yr, clinic BP 154.1 +/- 25.1/85.2 +/- 13.9 mmHg, 48% with diabetes).
During follow-up of up to 7 yr, 63 patients had ESRD and 102 patients died. Compared with those with controlled SBP (<130 mmHg), patients with moderate control (130 to 149 mmHg) had hazard ratio of 3.87 and those with poor control hazard ratio of 9.09 for ESRD. DBP had no direct ability to predict ESRD. For all-cause mortality, a J-shaped relationship was seen for SBP and an inverse relationship was seen for DBP. Considered jointly in the Cox model, a higher SBP and lower DBP improved the prediction of all-cause mortality compared with either BP component alone. The presence of J curve was especially pronounced in patients with advanced CKD, absence of clinical proteinuria, or age >65 yr.
In older patients with CKD, SBP predicts ESRD and a higher SBP and lower DBP predicts all-cause mortality. Lower BP of <110/70 mmHg is a marker of higher mortality in older individuals with advanced CKD.
Although the endocrine effects of vitamin D are widely recognized, somewhat less appreciated is that vitamin D may serve paracrine functions through local activation by 1-alpha-hydroxylase and thus ...maintain immunity, vascular function, cardiomyocyte health, and abrogate inflammation and insulin resistance. In the kidney, vitamin D may be important for maintaining podocyte health, preventing epithelial-to-mesenchymal transformation, and suppressing renin gene expression and inflammation. Replacement with pharmacologic dosages of vitamin D receptor agonists (VDRA) in animal models of kidney disease consistently show reduction in albuminuria, abrogation of glomerulosclerosis, glomerulomegaly, and glomerular inflammation, effects that may be independent of BP and parathyroid hormone, but the effects of VDRA in preventing tubulointerstitial fibrosis and preventing the progression of kidney failure in these animal models are less clear. Emerging evidence in patients with chronic kidney disease (CKD) show that vitamin D can reduce proteinuria or albuminuria even in the presence of angiotensin-converting enzyme inhibition. In addition to reducing proteinuria, VDRA may reduce insulin resistance, BP, and inflammation and preserve podocyte loss providing biologic plausibility to the notion that the use of VDRA may be associated with salubrious outcomes in patients with diabetic nephropathy. Patients with CKD have a very high prevalence of deficiency of 25-hydroxyvitamin D. Whether pharmacologic dosages of vitamin D instead of VDRA in patients with CKD can overcome the paracrine and endocrine functions of this vitamin remains unknown. To demonstrate the putative benefits of native vitamin D and VDRA among patients with CKD, randomized, controlled trials are needed.
Abstract
This review covers the last 80 years of remarkable progress in the development of mineralocorticoid receptor (MR) antagonists (MRAs) from synthesis of the first mineralocorticoid to trials ...of nonsteroidal MRAs. The MR is a nuclear receptor expressed in many tissues/cell types including the kidney, heart, immune cells, and fibroblasts. The MR directly affects target gene expression—primarily fluid, electrolyte and haemodynamic homeostasis, and also, but less appreciated, tissue remodelling. Pathophysiological overactivation of the MR leads to inflammation and fibrosis in cardiorenal disease. We discuss the mechanisms of action of nonsteroidal MRAs and how they differ from steroidal MRAs. Nonsteroidal MRAs have demonstrated important differences in their distribution, binding mode to the MR and subsequent gene expression. For example, the novel nonsteroidal MRA finerenone has a balanced distribution between the heart and kidney compared with spironolactone, which is preferentially concentrated in the kidneys. Compared with eplerenone, equinatriuretic doses of finerenone show more potent anti-inflammatory and anti-fibrotic effects on the kidney in rodent models. Overall, nonsteroidal MRAs appear to demonstrate a better benefit–risk ratio than steroidal MRAs, where risk is measured as the propensity for hyperkalaemia. Among patients with Type 2 diabetes, several Phase II studies of finerenone show promising results, supporting benefits on the heart and kidneys. Furthermore, finerenone significantly reduced the combined primary endpoint (chronic kidney disease progression, kidney failure, or kidney death) vs. placebo when added to the standard of care in a large Phase III trial.
The epidemiology of hypertension among hemodialysis (HD) patients is difficult to describe accurately because of difficulties in the assessment of blood pressure (BP).
Using 44-hour interdialytic ...ambulatory BP measurements, we describe the epidemiology of hypertension in a cohort of 369 patients. To seek correlates of hypertension control, antihypertensive agents were withdrawn among patients with controlled hypertension and ambulatory BP monitoring was repeated.
Hypertension (defined as an average ambulatory systolic BP ≥135 mm Hg or diastolic BP ≥85 mm Hg, or the use of antihypertensive medications) was prevalent in 82% of the patients and independently associated with epoetin use, lower body mass index and fewer years on dialysis. Although 89% of the patients were being treated, hypertension was controlled adequately in only 38%. Poor control was independently associated with greater antihypertensive drug use. Inferior vena cava (IVC) diameter in expiration was associated with increased risk of poorly controlled hypertension both in cross-sectional analysis and after withdrawal of antihypertensive drugs.
Interdialytic hypertension is highly prevalent and difficult to control among HD patients. End-expiration IVC diameter is associated with poor control of hypertension in cross-sectional analyses as well as after washout of antihypertensive drugs. Among HD patients, an attractive target for improving hypertension control appears to be the reduction of extracellular fluid volume.
CKD is common and frequently complicated with hypertension both predialysis and in ESKD. As a major modifiable risk factor for cardiovascular disease in this high-risk population, treatment of ...hypertension in CKD is important. We review the mechanisms and indications for the major classes of antihypertensive drugs, including angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers,
-adrenergic blocking agents, dihydropyridine calcium channel blockers, thiazide diuretics, loop diuretics, mineralocorticoid receptor blockers, direct vasodilators, and centrally acting
-agonists. Recent evidence suggests that
-adrenergic blocking agents may have a greater role in patients on dialysis and that thiazide diuretics may have a greater role in patients with advanced CKD. We conclude with sharing our general prescribing algorithm for both patients with predialysis CKD and patients with ESKD on dialysis.
PURPOSE OF REVIEWCircadian variation is commonly seen in healthy people; aberration in these biological rhythms is an early sign of disease. Impaired circadian variation of blood pressure (BP) has ...been shown to be associated with greater target organ damage and with an elevated risk of cardiovascular events independent of the BP load. The purpose of this review is to examine the physiology of circadian BP variation and propose a tripartite model that explains the regulation of circadian BP.
RECENT FINDINGSThe time-keeper in mammals resides centrally in the suprachiasmatic nucleus. Apart from this central clock, molecular clocks exist in most peripheral tissues including vascular tissue and the kidney. These molecular clocks regulate sodium balance, sympathetic function and vascular tone. A physiological model is proposed that integrates our understanding of molecular clocks in mice with the circadian BP variation among humans. The master regulator in this proposed model is the sleep–activity cycle. The equivalents of peripheral clocks are endothelial and adrenergic functions. Thus, in the proposed model, the variation in circadian BP is dependent upon three major factorsphysical activity, autonomic function, and sodium sensitivity.
SUMMARYThe integrated consideration of physical activity, autonomic function, and sodium sensitivity appears to explain the physiology of circadian BP variation and the pathophysiology of disrupted BP rhythms in various conditions and disease states. Our understanding of molecular clocks in mice may help to explain the provenance of blunted circadian BP variation even among astronauts.
PDF
