Hypertension in Blacks: Individualized Therapy Based on Renin/Aldosterone Phenotyping

Triple Antihypertensive Medication Prediction Score After Intracerebral Hemorrhage (the TRICH Score)

BACKGROUND AND OBJECTIVES

Poor long-term blood pressure (BP) control due to undertreatment of hypertension is not uncommon after intracerebral hemorrhage (ICH). It heightens the risk of ICH recurrence and subsequent stroke, which is the highest within the first year. Promptly achieving BP targets would significantly reduce these risks. To accomplish this, upfront triple antihypertensive medications could be prescribed soon after ICH because many ICH survivors require ≥3 antihypertensives. However, not all would suit this approach, particularly those with cerebral amyloid angiopathy (CAA), where elevated admission BP may be due to acute hypertensive response rather than underlying hypertension. In addition, overtreatment and excessive BP lowering would cause more side effects and have been associated with increased mortality in older patients. Hence, to facilitate individualized treatment, we aimed to develop a score (TRICH) to predict the need for ≥3 antihypertensives at 3 months after ICH.

METHODS

We developed the score using data from the University of Hong Kong prospective ICH registry (2011-2022) and validated it in 3 hospitals (2020-2022) locally. Consecutive patients with spontaneous ICH who survived >90 days and had follow-up BP 3 months after ICH were included. Predictors for needing ≥3 antihypertensive medications at 3 months were identified using multivariate logistic regression, and the score was created using the β-coefficients.

RESULTS

The TRICH score was developed from 462 patients (mean age 66.6 ± 14.3 years, 60% male) and validated in 203 patients (mean age 66.3 ± 14.6 years, 62% male). The 9-point score (age younger than 60 years = 1, male = 1, ischemic heart disease = 1, admission estimated glomerular filtration rate <60 mL/min/1.73 m2 = 2, admission systolic BP 190-230 mm Hg = 2 while >230 mm Hg = 4) has a c-statistic (95% CI) of 0.79 (0.75-0.83) in the development cohort and 0.76 (0.69-0.82) in validation. A dichotomized score (≥3 points) predicted the need for ≥3 antihypertensives with 0.73 (95% CI 0.67-0.80) sensitivity and 0.76 (95% CI 0.70-0.81) specificity. The score performed better in patients with untreated/uncontrolled hypertension before ICH than in controlled patients (c-statistic [95% CI] 0.81 [0.77-0.86] vs 0.74 [0.69-0.80], p = 0.037) but showed no difference between patients with CAA and non-CAA patients.

DISCUSSION

The TRICH score identifies patients with ICH who need ≥3 antihypertensive medications 3 months after ICH with good discrimination ability. It may guide upfront triple antihypertensive prescription, but further research is warranted, particularly in non-Han Chinese populations.

Racial and regional differences in efficacy of sodium-glucose cotransporter 2 inhibitors on cardiorenal outcomes: A systematic review and meta-analysis

BACKGROUND

To investigate the efficacy of SGLT2 inhibitors on multiple cardiorenal outcomes across different racial/ethnic groups and regions.

METHODS

We searched PubMed, Cochrane Library, Web of Science, and Embase databases in April 2024 for a systematic review and meta-analysis. Owing to inconsistencies in the reporting of the racial/ethnic and regional demographics, participants were grouped into three racial groups (Asian, Black, and White) and four regional (Asia, Central/South America, Europe, North America) groups. We compared the efficacy of SGLT2 inhibitors among these racial/ethnic and regional groups by calculating the ratio of hazard ratios (RHR). We evaluated the composite of cardiovascular death or hospitalization for heart failure (HHF), cardiovascular death, HHF, all-cause death, major adverse cardiac events, and cardiorenal composite outcomes.

RESULTS

We included 14 randomized placebo-controlled trials with 94,445 participants. Across the three racial/ethnic groups, SGLT2 inhibitors showed comparable efficacy. Compared with White patients, the efficacy of SGLT2 inhibitors on HHF was more pronounced in Black patients (RHR, 0.64; 95 % confidence interval [CI], 0.44-0.94), and a numerically lower risk was associated with Asian patients (RHR, 0.62; 95 % CI, 0.38-1.01). A consistent reduction in cardiovascular events with SGLT2 inhibitors was observed across all regions, while the efficacy of SGLT2 inhibitors on HHF was more pronounced in Asia than in other regions (RHR, 0.52; 95 % CI, 0.33-0.81).

CONCLUSIONS

SGLT2 inhibitors showed generally consistent efficacy across various racial/ethnic and regional groups, with some differences noted in specific populations. Ensuring adequate representation of diverse populations in clinical trials would be key to addressing healthcare disparities.

Advancements in the research of the structure, function, and disease-related roles of ARMC5

The armadillo repeat containing 5 (ARMC5) gene is part of a family of protein-coding genes that are rich in armadillo repeat sequences, are ubiquitously present in eukaryotes, and mediate interactions between proteins, playing roles in various cellular processes. Current research has demonstrated that reduced expression or absence of the ARMC5 gene in various tumor tissues can lead to uncontrolled cell proliferation, thereby inducing a range of diseases. The ARMC5 gene was initially extensively studied in the context of bilateral macronodular adrenocortical disease (BMAD), with harmful pathogenic variants in ARMC5 identified in approximately 50% of BMAD patients. With advancing research, scientists have discovered that ARMC5 pathogenic variants may also have potential effects on other diseases and could be associated with increased susceptibility to certain cancers. This review aims to present the latest research progress on how the ARMC5 gene plays its role in tumors. It outlines the basic structure of ARMC5 and the regions where it functions, as well as the diseases currently proven to be associated with ARMC5. Moreover, some evidence suggests its relation to embryonic development and the regulation of immune system activity. In conclusion, the ARMC5 gene is a crucial focal point in genetic and medical research. Understanding its function and regulation is of great importance for the development of new therapeutic strategies related to diseases associated with its pathogenic variants.

Sociodemographic modifiers of effects of statin initiation on dementia incidence: An emulated trial design in a large health care member population with 10+ years of follow-up

INTRODUCTION

Mixed evidence on how statin use affects risk of Alzheimer's disease and related dementias (ADRD) may reflect heterogeneity across sociodemographic factors. Few studies have sufficient power to evaluate effect modifiers.

METHODS

Kaiser Permanente Northern California (KPNC) members (n = 705,061; n = 202,937 with sociodemographic surveys) who initiated statins from 2001 to 2010 were matched on age and low-density lipoprotein cholesterol (LDL-C) with non-initiators and followed through 2020 for incident ADRD. Inverse probability-weighted Cox proportional hazards models were used to evaluate effect modification by age, gender, race/ethnicity, education, marital status, income, and immigrant generation.

RESULTS

Statin initiation (vs non-initiation) was not associated with ADRD incidence in any of the 32 subgroups (p > .05). Hazard ratios ranged from 0.964 (95% CI: 0.923 to 1.006) among Asian-identified participants to 1.122 (95% CI: 0.995 to 1.265) in the highest income category.

DISCUSSION

Sociodemographic heterogeneity appears to have little to no influence on the relationship between statin initiation and dementia.

HIGHLIGHTS

The study includes a large and diverse cohort from Kaiser Permanente (N = 705,061). An emulated trial design of statin initiation on dementia incidence was used. Effect modification by sociodemographic factors was assessed. There were no significant Alzheimer's disease and related dementias (ADRD) risk differences in 32 sociodemographic subgroups (p > 0.05).

Unraveling trends and disparities in acute myocardial infarction-related mortality among adult cancer patients: A nationwide CDC-WONDER analysis (1999-2020)

Background

Cancer patients are at an increased risk for the incidence and complications of acute myocardial infarction (AMI) due to shared risk factors and treatment-related adverse effects. Mortality trends for AMI-related deaths in adult cancer patients in the U.S. remain unexplored.

Methodology

This study used CDC WONDER data for death certificates from 1999 to 2020, identifying U.S. adults (≥25 years) with cancer (ICD-10: C00-D49) who died of AMI (ICD-10: I21) as the underlying cause. Age-adjusted mortality rates (AAMRs) and annual percent changes (APCs) were calculated and stratified by gender, age, race, and geographic location.

Results

Between 1999 and 2020, there were 109,462 AMI-related deaths in adult cancer patients. The AAMR decreased from 4.3 per 100,000 in 1999 to 1.4 in 2020. A significant decline occurred from 1999 to 2015 (APC: 6.65; 95 % CI: 6.95 to -6.40; p < 0.001), followed by a stable trend from 2015 to 2020 (APC: 1.36; 95 % CI: 2.69 to 0.91; p = 0.152). Men had higher AAMRs than women (3.5 vs. 1.5). AAMRs were highest in older adults (10.5) compared to middle-aged (0.7) and young adults (0.1). Racial disparities showed the highest AAMRs in non-Hispanic (NH) Black patients (2.7), followed by NH Whites (2.4), NH American Indian/Alaska Native (1.6), Hispanic/Latino (1.3), and NH Asian/Pacific Islander (1.1). Non-metropolitan areas had higher AAMRs than metropolitan areas (2.8 vs. 2.2).

Conclusions

This analysis highlights a significant decline in AMI-related mortality among cancer patients in the U.S., with persistent disparities by gender, age, race and geographical location.

Salt sensitivity of blood pressure: mechanisms and sex-specific differences

Salt sensitivity of blood pressure (SSBP) is an independent risk factor for cardiovascular disease in individuals with or without hypertension. However, the mechanisms and management of SSBP remain unclear, mainly because the diagnosis of this condition relies on salt loading-depletion protocols that are not feasible in the clinic. The prevalence of hypertension is lower in premenopausal women than in men, but this sex-specific difference is reversed after menopause. Whether excessive SSBP in women at any age contributes to this reversal is unknown, but many clinical studies that have rigorously assessed for SSBP using salt loading-depletion protocols have confirmed that SSBP is more prevalent in women than in men, including during premenopausal age. In this Review, we discuss sex-specific mechanisms of SSBP. We describe sex-related differences in renal transporters, hypertensive pregnancy, SSBP in autoimmune disorders and mitogen-activated protein kinase signalling pathways, and highlight limitations and lessons learned from Dahl salt-sensitive rat models.

Increased Anion Exchanger-1 (Band 3) on the Red Blood Cell Membrane Accelerates Scavenging of Nitric Oxide Metabolites and Predisposes Hypertension Risks

The erythrocyte membrane is highly specialized with ∼1 million anion exchanger-1 (AE1) per cell for rapid membrane permeation of HCO3-(aq), as most blood CO2(g) is carried in this hydrated anionic form. People with the GP.Mur blood type have more AE1 on their erythrocyte membrane, and they excrete CO2(g) more efficiently. Unexpectedly, GP.Mur/increased AE1 is also associated with higher blood pressure (BP). To solve this, we knocked the human GYP.Mur gene into C57BL/6J mice at 3'-UTR of GYPA to generate GPMur knock-in (KI) mice. KI of human GYP.Mur increased murine AE1 expression on the red blood cells (RBC). GPMur KI mice were naturally hypertensive, with normal kidney functions and lipid profiles. Blood NO3- [the stable nitric oxide (NO) reservoir] was significantly lower in the GPMur mice. GPMur KI also accelerated AE1-mediated NO2- influx into the RBCs and intraerythrocytic NO2-/NO processing. From tests with different categories of antihypertensives, hypertension in GPMur mice responded best to direct arterial vasodilator hydralazine, suggesting that vasodilator deficiency is the leading cause of "GPMur/AE1-triggered hypertension." In conclusion, we showed that GPMur/increased AE1 predisposed hypertension risks. Mechanistically, higher AE1 expression increased RBC membrane permeability for NO2- and consequently accelerated erythroid NO2-/NO metabolism; this is associated with lower NO bioavailability and higher BP. As hypertension affects a quarter of the world population and GP.Mur is a common Southeast Asian (SEA) blood type, this work may serve as a primer for "GPMur (biomarker)-based" therapeutic development for hypertension.

Shifting paradigms in primary aldosteronism: reconsideration of screening strategy via integrating pathophysiological insights

Several decades have passed since the description of the first patient with primary aldosteronism (PA). PA was initially classified in two main forms: aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA). However, the pathogenesis of PA has now been shown to be far more complex. For this reason, the traditional classification needs to be updated. Given the recent advancements in our understanding of PA pathogenesis, we should reevaluate how frequent PA cases are, beginning with the reconstruction of the screening strategy. Recent studies consistently indicated that PA has been identified in 22% of patients with resistant hypertension and 11% even in normotensives. The frequency is influenced by the screening strategy and should be based on understanding the pathogenesis of PA. Progress has been made to promote our understanding of the pathogenesis of PA by the findings of aldosterone driver mutations, which have been found in normotensives and hypertensives. In addition, much clinical evidence has been accumulated to indicate that there is a spectrum in PA pathogenesis. In this review, we will summarize the recent progress in aldosterone measurement methods based on LC-MS/MS and the current screening strategy. Then, we will discuss the progress of our understanding of PA, focusing on aldosterone driver mutations and the natural history of PA. Finally, we will discuss the optimal strategy to improve screening rate and case detection.

Temporal trends in cardiovascular mortality among patients with hematological malignancies: a 20-year perspective

BACKGROUND

We present an analysis of cardiovascular-related deaths specific to hematological cancer patients in the United States from 1999 to 2020, examining trends in relation to age, gender, and type of hematological cancer.

RESEARCH DESIGN AND METHODS

Utilizing the Multiple Cause of Death databases, our research included 88,146 decedents with cardiovascular primary cause of death and with hematologic disease. We determined the percentage of cardiovascular deaths associated with each disease category. Furthermore, we developed age-adjusted mortality rates, categorizing them based on sex, age, race, Latino origin, and the type of hematological cancer.

RESULTS

Between 1999 and 2020, there was a decreasing temporal trend in overall cardiovascular mortality for lymphoma, leukemia and multiple myeloma (-38.8% -31.8% & -29.4%). The most common cardiovascular mortality cause in the hematological malignancy population was ischemic heart disease, followed by cerebrovascular disease (53.4%, 20.2%). African American, Asian, and White patients showed decreasing for overall CV death for all hematological malignancies, with African American subgroups showing the lowest mortality reduction over time (AAMR: -26.8%, -41.2%, -33.3%). However, hypertension mortality increased for most racial groups.

CONCLUSIONS

Over the last 2 decades, the rate of cardiovascular mortality amongst patients with underlying hematological malignancy has decreased.

Regional Differences in the Epidemiology of Heart Failure

Heart failure (HF) epidemiology, patient characteristics, and clinical outcomes exhibit substantial regional variations, reflecting diverse etiologies and health system capacities. This review comprehensively analyses these variations, drawing on data from recent global registries and clinical trials. Our review indicates that ischemic and hypertensive heart diseases are prevalent globally but differ in dominance depending on the region. Notably, regions such as Africa and Latin America show higher instances of HF from hypertensive heart disease and Chagas cardiomyopathy, respectively. Moreover, disparities in age and comorbidity profiles across regions highlight younger populations with HF in lower-income countries compared to older populations in high-income regions. This review also highlights the global disparity in guideline-directed medical and device therapy, underscoring significant underuse in lower-income regions. These insights emphasize the need for targeted HF management strategies considering regional clinical and demographic characteristics to enhance global HF care and outcomes.

Effects of SGLT2 Inhibitors on Cardiac Mechanics in Hispanic and Black Diabetic Patients

Background: Clinical trials demonstrating improved cardiovascular outcomes with SGLT2 inhibitors have often had limited representation from Black and Hispanic populations. While the mechanisms of action are not well known, ethnicity- or gender-based receptor physiology may render SGLT2 inhibitors a better agent in certain populations over others. Methods: A medical records query yielded diabetic patients initiated on SGLT2 inhibitors between 2013 and 2020. Patients with coronary artery disease, cardiac arrhythmias, and heart failure were excluded. Transthoracic echocardiographic studies (TTE) before and after starting SGLT2 inhibitors were analyzed, and post-processing left ventricular global longitudinal strain (LV GLS) analysis was also performed on each echocardiographic study. Univariate outliers and patients with missing data were excluded. Results: Among 94 patients with TTE (mean age 60.7 years; 68% Hispanics, 22.3% Blacks; median follow up of 7 months), there were significant improvements in the mean LV GLS (-15.3 vs. -16.5; p = 0.01), LV mass (LVM) (198.4 ± 59.6 g vs. 187.05 ± 50.6 g; p = 0.04), and LV mass index (LVMI) (100.6 ± 26.6 g/m2 vs. 94.3 ± 25.4 g/m2; p = 0.03) before and after initiating SGLT2 inhibitors but no significant change in the ratio (MV E/E') of peak early diastolic mitral flow velocity (E) and spectral pulsed-wave Doppler-derived early diastolic velocity from the septal mitral annulus (E') (12.5 ± 5.7 vs. 12.7 ± 4.8; p = 0.38). Changes in HbA1c (r2 = 0.82; p = 0.026), LVM (r2 = 0.20; p = 0.04), and LVMI (r2 = 0.20; p = 0.04) were found to be independently associated with changes in values of LV GLS on follow-up echocardiograms, when compared to the pre-medication LV GLS number. Conclusion: Non-White diabetic patients receiving SGLT2 inhibitors against a backdrop of other cardioprotective medications demonstrate significant improvements in LV remodeling and LV GLS, driven in part by an improvement in glycemic control. Large, prospective studies are needed to explore the differences in the therapeutic actions of SGLT2 inhibitors among different populations.

Risk of Major Adverse Cardiovascular Events After Emergency Department Visits for Hypertensive Urgency

BACKGROUND

Chronic hypertension is an established long-term risk factor for major adverse cardiovascular events (MACEs). However, little is known about short-term MACE risk after hypertensive urgency, defined as an episode of acute severe hypertension without evidence of target-organ damage. We sought to evaluate the short-term risk of MACE after an emergency department (ED) visit for hypertensive urgency resulting in discharge to home.

METHODS

We performed a case-crossover study using deidentified administrative claims data. Our case periods were 1-week intervals from 0 to 12 weeks before hospitalization for MACE. We compared ED visits for hypertensive urgency during these case periods versus equivalent control periods 1 year earlier. Hypertensive urgency and MACE components were all ascertained using previously validated International Classification of Diseases, Tenth Revision Clinical Modification codes. We used McNemar test for matched data to calculate risk ratios.

RESULTS

Among 2 225 722 patients with MACE, 1 893 401 (85.1%) had a prior diagnosis of hypertension. There were 4644 (0.2%) patients who had at least 1 ED visit for hypertensive urgency during the 12 weeks preceding their MACE hospitalization. An ED visit for hypertensive urgency was significantly more common in the first week before MACE compared with the same chronological week 1 year earlier (risk ratio, 3.5 [95% CI, 2.9-4.2]). The association between hypertensive urgency and MACE decreased in magnitude with increasing temporal distance from MACE and was no longer significant by 11 weeks before MACE (risk ratio, 1.2 [95% CI, 0.99-1.6]).

CONCLUSIONS

ED visits for hypertensive urgency were associated with a substantially increased short-term risk of subsequent MACE.

Measurements of Abdominal Obesity are Associated with Metabolic Syndrome Severity Independent of Hypertensive Phenotype in White but not Black Young Adults

PURPOSE

This study sought to determine if metabolic syndrome severity (MetSindex) was differentially associated with abdominal obesity based on waist circumference (WC) site and the presentation of hypertensive phenotypes in a group of young White and Black adults.

METHODS

A total of 139 young adult (22.5 ± 3.3 years) non-Hispanic White (n = 73) and non-Hispanic Black (n = 66) males and females (M 53, 86 F) completed this cross-sectional evaluation. Participants had their WC measured at three distinct locations along the abdomen which were used to calculate waist-to-hip and waist-to-height ratios. Systolic (SBP) and diastolic blood pressure (DBP) were collected and used to calculate mean arterial pressure (MAP). In addition to traditional metabolic syndrome (MetS) risk factors, BP values were individually used to produce three separate MetSindex scores representing three specific hypertensive phenotypes (MetSSBP, MetSDBP, MetSMAP), and each of these were evaluated against each abdominal obesity estimate.

RESULTS

MetSDBP and MetSSBP were significantly higher than all other indices for females (all p ≤ 0.002) and males (all p < 0.001), respectively. MetSDBP was significantly higher than MetSMAP for White females (p = 0.039), and MetSSBP was significantly higher than MetSDBP and MetSMAP (both p < 0.001) for Black males. Standalone and joint estimates of abdominal obesity were uniquely associated with MetSindex across hypertensive phenotypes for White, but not Black males and females.

CONCLUSIONS

Specific hypertensive phenotypes may differentially determine MetSindex, but these estimates are not associated with abdominal obesity in young Black adults regardless of measurement location. Healthcare professionals should address this disparity by providing more comprehensive MetS screening procedures for young Black adults.

CLINICAL TRIALS REGISTRATION

NCT05885672.

Causes of Chronic Kidney Disease and Their Associations with Cardiovascular Risk and Disease in a Sub-Saharan Low-Income Population

Introduction

The causes of chronic kidney disease (CKD) in people living in Sub-Saharan Africa await identification. Also, whether cardiovascular risk and disease extent differ among patients with different CKD etiologies is uncertain.

Methods

In this prospective cross-sectional study, we examined the presumed causes of chronic kidney disease (CKD) and their relationships with cardiovascular risk and disease in 743 consecutive patients from a sub-Saharan low-income population.

Results

Hypertensive nephropathy (HNP) (60.2%), diabetic nephropathy (DNP) (24.4%), HIV associated CKD (20.0%) and glomerular disease (13.6%) comprised the major CKD etiologies upon enrolment at the hospital nephrology clinic. Pulse pressure was larger in patients with concurrent HNP and DNP than in those with HNP only (p<0.001). Pulse pressure and systolic blood pressure were larger in HNP or/and DNP patients than those with HIV associated CKD and glomerular disease (p=0.04 to <0.001). Cardiovascular disease was more prevalent in patients with HNP and concurrent HNP and DNP than those from other etiologic categories (p<0.05). HNP and DNP were associated with pulsatile pressures (pulse pressure and systolic blood pressure) independent of one another (p<0.01). In adjusted product of coefficient mediation analysis, mean arterial or distending pressure accounted fully for the potential impact of HNP on pulsatile pressures (103.9-115.7%) but not for that of DNP on the respective pressures (-2.0%-(-)7.5%).

Conclusion

HNP is by far the most prevalent presumed cause of CKD in this African population. Cardiovascular risk and disease differ markedly across CKD etiological categories.

Determinants of mortality in hypertensive patients admitted with COVID-19: a single-centre retrospective study at a tertiary hospital in South Africa

BACKGROUND

The Coronavirus Disease 2019 (COVID-19) pandemic has significantly impacted global health, with successive outbreaks leading to substantial morbidity and mortality. Hypertension, a leading cause of cardiovascular disease globally, has been identified as a critical comorbidity in patients with severe COVID-19, exacerbating the risk of adverse outcomes. This study aimed to elucidate the impact of hypertension on COVID-19 outcomes within the South African context.

METHODS

A retrospective analysis was conducted at King Edward VIII Hospital, KwaZulu-Natal, South Africa, encompassing patients aged 13 years and above admitted with laboratory-confirmed SARS-CoV-2 infection between June 2020 and December 2021. The study investigated the association between hypertension and COVID-19 outcomes, analysing demographic, clinical, and laboratory data. Statistical analysis involved univariate and multivariate logistic regression to identify predictors of mortality among the hypertensive cohort.

RESULTS

The study included 420 participants-encompassing 205 with hypertension. Hypertensive patients demonstrated significantly greater requirements for oxygen and steroid therapy (p < 0.001), as well as higher mortality rates (44.88%, p < 0.001)) compared to their non-hypertensive counterparts. Key findings demonstrated that a lower oxygen saturation (adjusted odds ratio (aOR) 0.934, p = 0.006), higher pulse pressure (aOR 1.046, p = 0.021), elevated CRP (aOR 1.007, p = 0.004) and the necessity for mechanical ventilation (aOR 5.165, p = 0.004) were independent risk factors for mortality in hypertensive COVID-19 patients. Notably, the study highlighted the pronounced impact of hypertension-mediated organ damage (HMOD) on patient outcomes, with ischemic heart disease being significantly associated with increased mortality (aOR 8.712, p = 0.033).

CONCLUSION

Hypertension significantly exacerbates the severity and mortality risk of COVID-19 in the South African setting, underscoring the need for early identification and targeted management of hypertensive patients. This study contributes to the understanding of the interplay between hypertension and COVID-19 outcomes, emphasising the importance of considering comorbidities in the management and treatment strategies for COVID-19. Enhanced pandemic preparedness and healthcare resource allocation are crucial to mitigate the compounded risk presented by these concurrent health crises.

Analysis of the combined effect of rs699 and rs5051 on angiotensinogen expression and hypertension

Background

Hypertension (HTN) involves genetic variability in the renin-angiotensin system and influences antihypertensive response. We previously reported that angiotensinogen (AGT) messenger RNA (mRNA) is endogenously bound by miR-122-5p and rs699 A > G decreases reporter mRNA in the microRNA functional-assay PASSPORT-seq. The AGT promoter variant rs5051 C > T is in linkage disequilibrium (LD) with rs699 A > G and increases AGT transcription. The independent effect of these variants is understudied due to their LD therefore we aimed to test the hypothesis that increased AGT by rs5051 C > T counterbalances AGT decreased by rs699 A > G, and when these variants occur independently, it translates to HTN-related phenotypes.

Methods

We used in silico, in vitro, in vivo, and retrospective models to test this hypothesis.

Results

In silico, rs699 A > G is predicted to increase miR-122-5p binding affinity by 3%. Mir-eCLIP results show rs699 is 40-45 nucleotides from the strongest microRNA-binding site in the AGT mRNA. Unexpectedly, rs699 A > G increases AGT mRNA in an AGT-plasmid-cDNA HepG2 expression model. Genotype-Tissue Expression (GTEx) and UK Biobank analyses demonstrate liver AGT expression and HTN phenotypes are not different when rs699 A > G occurs independently from rs5051 C > T. However, GTEx and the in vitro experiments suggest rs699 A > G confers cell-type-specific effects on AGT mRNA abundance, and suggest paracrine renal renin-angiotensin-system perturbations could mediate the rs699 A > G associations with HTN.

Conclusions

We found that rs5051 C > T and rs699 A > G significantly associate with systolic blood pressure in Black participants in the UK Biobank, demonstrating a fourfold larger effect than in White participants. Further studies are warranted to determine if altered antihypertensive response in Black individuals might be due to rs5051 C > T or rs699 A > G. Studies like this will help clinicians move beyond the use of race as a surrogate for genotype.

Pathophysiology of primary hypertension in children and adolescents

The progress in research on the physiology of the cardiovascular system made in the last 100 years allowed for the development of the pathogenesis not only of secondary forms of hypertension but also of primary hypertension. The main determinants of blood pressure are described by the relationship between stroke volume, heart rate, peripheral resistance, and arterial stiffness. The theories developed by Guyton and Folkow describe the importance of the volume factor and total peripheral resistance. However, none of them fully presents the pathogenesis of essential hypertension. The multifactorial model of primary hypertension pathogenesis developed by Irving Page in the 1940s, called Page's mosaic, covers most of the pathophysiological phenomena observed in essential hypertension. The most important pathophysiological phenomena included in Page's mosaic form a network of interconnected "nodes". New discoveries both from experimental and clinical studies made in recent decades have allowed the original Page mosaic to be modified and the addition of new pathophysiological nodes. Most of the clinical studies confirming the validity of the multifactorial pathogenesis of primary hypertension concern adults. However, hypertension develops in childhood and is even perinatally programmed. Therefore, the next nodes in Page's mosaic should be age and perinatal factors. This article presents data from pediatric clinical trials describing the most important pathophysiological processes associated with the development of essential hypertension in children and adolescents.

Characteristics of heart failure with a preserved ejection fraction in black South African patients

Background

Heart failure with a preserved ejection fraction (HFpEF) is common in the elderly (≥75 years) and associated with arterial stiffness. The mean age of HFpEF presentation is lower (40-55 years) in sub-Saharan Africa. No clinical study has been conducted on HFpEF in identifying and characterising this phenotype at a younger age, moreover in a South African black population where the risk of HFpEF is two times higher than in other ethnic groups. This study investigated the characteristics of HFpEF in a black South African population, the biochemical markers that predict HFpEF and cardiac structural changes in this HF phenotype.

Methods

Sixty-six participants with HFpEF and 213 controls were enrolled. All participants gave informed consent and completed a standardised questionnaire. Echocardiographic, anthropometric, central haemodynamic measurements, pulse wave velocity (PWV) and biomarker analysis were done.

Results

The mean age of HFpEF participants was 54.88 ± 13.51 years. Most of the participants (76 %) were between 20 and 64 years, while only 24 % were older. HFpEF participants were hypertensive, and more obese with increased incidence of alcohol consumption. PWV was increased in HFpEF (9.97 ± 2.78 m/s) when compared to participants without HFpEF (6.11 ± 2.18 m/s), p < 0.0001. There were no significant associations between central haemodynamic parameters, N-terminal pro B-type natriuretic peptide (NT-proBNP) (p = 0.9746), and galectin-3 (p = 0.2166). NT-proBNP, but not galectin-3, was associated with left ventricular hypertrophy (p = 0.0002) and left atrial diameter (p = 0.0005).

Conclusion

HFpEF in South Africa is predominant in obese young to middle-age individuals with arterial stiffness and who consume alcohol regularly. NT-proBNP could be used to diagnose HFpEF, however, should be interpreted with caution in populations with a high prevalence of obesity.

Low Cortisone as a Novel Predictor of the Low-Renin Phenotype

A large proportion of patients with low-renin hypertension (LRH) correspond to primary aldosteronism (PA). However, some of these subjects have low to normal aldosterone. Since low renin is driven by excessive mineralocorticoids or glucocorticoids acting on mineralocorticoid receptors (MRs), we hypothesize that a low-cortisone condition, associated classically with 11βHSD2 deficiency, is a proxy of chronic MR activation by cortisol, which can also lead to low renin, elevated blood pressure, and renal and vascular alterations.

Objective

To evaluate low cortisone as a predictor of low renin activity and its association with parameters of kidney and vascular damage.

Methods

A cross-sectional study was carried out in 206 adult subjects. The subjects were classified according to low plasma renin activity (<1 ng/mL × hours) and low cortisone (<25th percentile).

Results

Plasma renin activity was associated with aldosterone (r = 0.36; P < .001) and cortisone (r = 0.22; P = .001). A binary logistic regression analysis showed that serum cortisone per ug/dL increase predicted the low-renin phenotype (OR 0.4, 95% CI 0.21-0.78). The receiver operating characteristic curves for cortisone showed an area under the curve of 0.6 to discriminate subjects with low renin activity from controls. The low-cortisone subjects showed higher albuminuria and PAI-1 and lower sodium excretion. The association study also showed that urinary cortisone was correlated with blood pressure and serum potassium (P < .05).

Conclusion

This is the first study showing that low cortisone is a predictor of a low-renin condition. Low cortisone also predicted surrogate markers of vascular and renal damage. Since the aldosterone to renin ratio is used in the screening of PA, low cortisone values should be considered additionally to avoid false positives in the aldosterone-renin ratio calculation.

Genetic Factors Contributing to the Pathogenesis of Essential Hypertension in Two African Populations

The African continent has the highest prevalence of hypertension globally, with South Africa reporting the highest prevalence in Southern Africa. While the influence of genetic variability in the pathogenesis of hypertension is well described internationally, limited reports are available for African populations. This study aimed to assess the association of genetic variants and essential hypertension in a cohort of two ethnic South African population groups. Two hundred and seventy-seven hypertensive and one hundred and seventy-six normotensive individuals were genotyped for 78 variants. Genotyping was performed using the Illumina GoldenGate Assay and allele-specific polymerase chain reaction. The association of variants was assessed using the Fisher Exact test under the additive and allelic genetic models, while multivariate logistic regression was used to predict the development of hypertension. Five variants (CYP11B2 rs179998, AGT rs5051 and rs699, AGTR1 rs5186, and ACE rs4646994) were significantly associated with essential hypertension in the cohort under study. Furthermore, AGTR1 rs5186 and AGT rs699 were identified as risk factors for the development of hypertension in both ethnic groups. In two ethnic South African populations, an association was observed between renin-angiotensin-aldosterone system (RAAS)-related genes and the development of hypertension.

Multifocal, Asymmetric Bilateral Primary Aldosteronism Cannot be Excluded by Strong Adrenal Vein Sampling Lateralization: An International Retrospective Cohort Study

BACKGROUND

Primary aldosteronism (PA) has been broadly dichotomized into unilateral and bilateral forms. Adrenal vein sampling (AVS) lateralization indices (LI) ≥2 to 4 are the standard-of-care to recommend unilateral adrenalectomy for presumed unilateral PA. We aimed to assess the rates and characteristics of residual PA after AVS-guided adrenalectomy.

METHODS

We conducted an international, retrospective, cohort study of patients with PA from 7 referral centers who underwent unilateral adrenalectomy based on LI≥4 on baseline and/or cosyntropin-stimulated AVS. Aldosterone synthase (CYP11B2) immunohistochemistry and next generation sequencing were performed on available formalin-fixed paraffin-embedded adrenal tissue.

RESULTS

The cohort included 283 patients who underwent AVS-guided adrenalectomy, followed for a median of 326 days postoperatively. Lack of PA cure was observed in 16% of consecutive patients, and in 22 patients with lateralized PA on both baseline and cosyntropin-stimulated AVS. Among patients with residual PA postoperatively, 73% had multiple CYP11B2 positive areas within the resected adrenal tissue (versus 23% in those cured), wherein CACNA1D mutations were most prevalent (63% versus 33% in those cured). In adjusted regression models, independent predictors of postoperative residual PA included Black versus White race (odds ratio, 5.10 [95% CI, 1.45-17.86]), AVS lateralization only at baseline (odds ratio, 8.93 [95% CI 3.00-26.32] versus both at baseline and after cosyntropin stimulation), and CT-AVS disagreement (odds ratio, 2.75 [95% CI, 1.20-6.31]).

CONCLUSIONS

Multifocal, asymmetrical bilateral PA is relatively common, and it cannot be excluded by robust AVS lateralization. Long-term postoperative monitoring should be routinely pursued, to identify residual PA and afford timely initiation of targeted medical therapy.

Evaluation of a Best-Practice Advisory for Primary Aldosteronism Screening

Importance

Primary aldosteronism (PA) is a common cause of secondary hypertension and an independent risk factor for cardiovascular morbidity and mortality. Fewer than 2% to 4% of patients at risk are evaluated for PA.

Objective

To develop and evaluate an electronic health record best-practice advisory (BPA) that assists with PA screening.

Design, Setting, and Participants

This prospective quality improvement study was conducted at academic center outpatient clinics. Data analysis was performed between February and June 2023 and included adults with hypertension and at least 1 of the following: 4 or more current antihypertensive medications; hypokalemia; age younger than 35 years; or adrenal nodule(s). Patients previously tested for PA were excluded.

Exposure

A noninterruptive BPA was developed to trigger for PA screening candidates seen in outpatient setting by clinicians who treat hypertension. The BPA included an order set for PA screening and a link to results interpretation guidance.

Main Outcomes and Measures

(1) The number of PA screening candidates identified by the BPA between October 1, 2021, and December 31, 2022; (2) the rates of PA screening; and (3) the BPA use patterns, stratified by physician specialty were assessed.

Results

Over 15 months, the BPA identified 14 603 unique candidates (mean [SD] age, 65.5 [16.9] years; 7300 women [49.9%]; 371 [2.5%] Asian, 2383 [16.3%] Black, and 11 225 [76.9%] White individuals) for PA screening, including 7028 (48.1%) with treatment-resistant hypertension, 6351 (43.5%) with hypokalemia, 1537 (10.5%) younger than 35 years, and 445 (3.1%) with adrenal nodule(s). In total, 2040 patients (14.0%) received orders for PA screening. Of these, 1439 patients (70.5%) completed the recommended screening within the system, and 250 (17.4%) had positive screening results. Most screening orders were placed by internists (40.0%) and family medicine physicians (28.1%). Family practitioners (80.3%) and internists (68.9%) placed most orders via the embedded order set, while specialists placed most orders (83.0%-95.4%) outside the BPA. Patients who received screening were younger and included more women and Black patients than those not screened. The likelihood of screening was higher among patients with obesity and dyslipidemia and lower in those with chronic kidney disease and established cardiovascular complications.

Conclusions and Relevance

The study results suggest that noninterruptive BPAs are potentially promising PA screening-assistance tools, particularly among primary care physicians. Combined with artificial intelligence algorithms that optimize the detection yield, refined BPAs may contribute to personalized hypertension care.

Efficacy of beta-blockers on blood pressure control and morbidity and mortality endpoints in hypertensives of African ancestry: an individual patient data meta-analysis

Introduction

Compared with first-line antihypertensives, beta-blockers (BB) have been reported to lower the central aortic blood pressure suboptimally and are associated with increased stroke risk. This observation has not been investigated in hypertensives of African ancestry. We hypothesised that an individual patient data meta-analysis (IPD-MA) on the efficacy of second- or third-generation beta-blockers (STGBBs) in hypertensives of African descent may provide new insights.

Methods

A single-stage IPD-MA analysed the efficacy of STGBB in lowering the mean arterial blood pressure and reducing the composite outcomes: cardiovascular death, stroke, and myocardial infarction.

Results

A total of 11,860 participants from four randomised control trials were included in the analysis. Second- or third-generation beta-blockers reduced the mean arterial pressure by 1.75 mmHg [95% confidence interval (CI):1.16-2.33; P < 0.001] in all participants included in the analysis, and by 1.93 mmHg (95% CI: 0.86-3.00; P < 0.001) in hypertensive Africans. In patients with established cardiovascular disease, where the benefits of BB therapy are well established, STGBBs were associated with an adjusted odds ratio of 1.33 (95% CI: 1.06-1.65; P = 0.015) of the composite outcome, most likely due to confounding. Similarly, the risk of total myocardial infarction was 1.76 times higher (95% CI: 1.15-2.68; P = 0.008) in hypertensives of African ancestry on STGBBs.

Conclusion

The STGBBs reduced the mean arterial pressure comparably to other antihypertensives, and they were not associated with an increased risk of stroke.

The Self-Fulfilling Process of Clinical Race Correction: The Case of Eighth Joint National Committee Recommendations

There is growing attention to how unfounded beliefs about biological differences between racial groups affect biomedical research and health care, in part, through race adjustment in clinical tools. We develop a case study of the Eighth Joint National Committee (JNC 8)'s 2014 Evidence-Based Guideline for the Management of High Blood Pressure in Adults, which recommends a distinct initial hypertension treatment for Black versus nonblack patients. We analyze the historical context, study design, and racialized findings of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) that informed development of the guideline. We argue that ALLHAT's racialized outcomes emanated from a poor and artificial study design and analysis weakened by implicit assumptions about race as biological. We show that the acceptance and utilization of ALLHAT for race correction arises from its historical context within the "inclusion-and-difference paradigm" and its indication of the inefficacy of angiotensin-converting-enzyme inhibitors for Black patients, which follows from the enduring, yet, refuted slavery hypertension hypothesis. We demonstrate that the JNC 8 guideline displays the self-fulfilling process of racial reasoning: presuppositions about racial differences inform the design and interpretation of research, which then conceptually reinforce ideas about racial differences leading to differential medical treatment. We advocate for the abolition of race adjustment and the integration of structural competency, biocritical inquiry, and race-conscious medicine into biomedical research and clinical medicine to disrupt the use of race as a proxy for ancestry, environment, and social treatment and to address the genuine determinants of racialized disparities in hypertension.

Management of hypertensive crisis: British and Irish Hypertension Society Position document

Patients with hypertensive emergencies, malignant hypertension and acute severe hypertension are managed heterogeneously in clinical practice. Initiating anti-hypertensive therapy and setting BP goal in acute settings requires important considerations which differ slightly across various diagnoses and clinical contexts. This position paper by British and Irish Hypertension Society, aims to provide clinicians a framework for diagnosing, evaluating, and managing patients with hypertensive crisis, based on the critical appraisal of available evidence and expert opinion.

Assessment of Adverse Childhood Experiences in the South Bronx on the Risk of Developing Chronic Disease as Adults

Background Adverse childhood experiences (ACEs) have a negative impact on health outcomes. Using a cross-sectional study design, our objective was to identify the prevalence of ACEs among residents of South Bronx and the increased relationship between such childhood stressors and the prevalence of both chronic disease and modifiable high-risk behavior in adulthood. Methods We recruited patients from a hospital-based, adult primary care clinic in the metropolitan area of the South Bronx. A prospectively designed, observational study recruited patients in a consecutive fashion to conduct a cross-sectional survey between September 2017 and January 2018. The demographic representation comprises a low socioeconomic sector of urban New York City, with low education and immigrant population. A modified ACE questionnaire that included nine ACE categories (Physical Abuse, Sexual Abuse, Household Substance Abuse, Separation from Parents, Incarcerated Household Member, Parental Separation/Divorce, and Bullying) in addition to questions on demographics, high-risk behavior, and diagnosis of chronic disease. Our primary objective was to gather the incidence of ACEs organized by domains. Secondary objectives were to demonstrate any expected increase (as odds ratios (ORs)) in chronic disease or maladaptive social habits when compared to patients with no ACEs within the cohort. The OR for the associations was calculated with logistic regression. Individual logistic regression models for each chronic disease, high-risk behavior, and demographics were used to measure the exposure response of the nine ACE categories.  Results A total of 454 patients completed the survey. The average age was 53.1±14.2 years, and females were 49% of the sample. Hispanics were at 61% followed by Blacks at 34%. Participants reported high-risk behavior at 24%, had a high prevalence of chronic illness (82%), and had ACE events at 70%. We found a significant relationship between ACE events and having a chronic disease diagnosis and engagement in high-risk behavior with higher odds of reporting chronic illnesses among participants with exposure to childhood stressors (OR 1.26, 95% confidence interval 1.1-1.5, p=0.002). Of the nine ACE categories, many were independently associated with one or more chronic diseases in adulthood. Conclusion According to our survey data, ACE events in our patient population were more prevalent (30% with four or more exposures), higher than the proposed average of one out of six Americans with four or more exposures nationally according to national statistics. These childhood stressors appeared to have a strong association with the development of high-risk behavior and chronic illnesses.

Elevated blood pressure among adolescents in sub-Saharan Africa: a systematic review and meta-analysis

BACKGROUND

More people from sub-Saharan Africa aged between 20 years and 60 years are affected by end-organ damage due to underlying hypertension than people in high-income countries. However, there is a paucity of data on the pattern of elevated blood pressure among adolescents aged 10-19 years in sub-Saharan Africa. We aimed to provide pooled estimates of high blood pressure prevalence and mean levels in adolescents aged 10-19 years across sub-Saharan Africa.

METHODS

In this systematic review and meta-analysis, we searched PubMed, Google Scholar, African Index Medicus, and Embase to identify studies published from Jan 1, 2010, to Dec 31, 2021. To be included, primary studies had to be observational studies of adolescents aged 10-19 years residing in sub-Saharan African countries reporting the pooled prevalence of elevated blood pressure or with enough data to compute these estimates. We excluded studies on non-systemic hypertension, in African people not living in sub-Saharan Africa, with participant selection based on the presence of hypertension, and with adult cohorts in which we could not disaggregate data for adolescents. We independently extracted relevant data from individual studies using a standard data extraction form. We used a random-effects model to estimate the pooled prevalence of elevated blood pressure and mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) levels overall and on a sex-specific basis. This study is registered with PROSPERO (CRD42022297948).

FINDINGS

We identified 2559 studies, and assessed 81 full-text studies for eligibility, of which 36 studies comprising 37 926 participants aged 10-19 years from ten (20%) of 49 sub-Saharan African countries were eligible. A pooled sample of 29 696 adolescents informed meta-analyses of elevated blood pressure and 27 155 adolescents informed meta-analyses of mean blood pressure. Sex data were available from 26 818 adolescents (14 369 [53·6%] were female and 12 449 [46·4%] were male) for the prevalence of elevated blood pressure and 23 777 adolescents (12 864 [54·1%] were female and 10 913 [45·9%] were male) for mean blood pressure. Study quality was high, with no low-quality studies. The reported prevalence of elevated blood pressure ranged from 4 (0·2%) of 1727 to 1755 (25·1%) of 6980 (pooled prevalence 9·9%, 95% CI 7·3-12·5; I?=99·2%, p_{heterogeneity}<0·0001). Mean SBP was 111 mm Hg (95% CI 108-114) and mean DBP was 68 mm Hg (66-70). 13·4% (95% CI 12·9-13·9; p_{heterogeneity}<0·0001) of male participants had elevated blood pressure compared with 11·9% (11·3-12·4; p_{heterogeneity}<0·0001) of female participants (odds ratio 1·04, 95% CI 0·81-1·34; p_{heterogeneity}<0·0001).

INTERPRETATION

To our knowledge, this systematic review and meta-analysis is the first systematic synthesis of blood pressure data specifically derived from adolescents in sub-Saharan Africa. Although many low-income countries were not represented in our study, our findings suggest that approximately one in ten adolescents have elevated blood pressure across sub-Saharan Africa. Accordingly, there is an urgent need to improve preventive heart-health programmes in the region.

FUNDING

None.

Managing patients with sex-, race-, or ethnicity-based cardiovascular health inequities

ABSTRACT

Cardiovascular health inequities are experienced among cisgender women, gender minorities, Black and Indigenous people, and people with lower socioeconomic status. Early identification and treatment of patients at risk for disparate and adverse cardiac health outcomes are essential.

Analysis of the Combined Effect of rs699 and rs5051 on Angiotensinogen Expression and Hypertension

Hypertension (HTN) involves genetic variability in the renin-angiotensin system and characterizing this variability will help advance precision antihypertensive treatments. We previously reported that angiotensinogen (AGT) mRNA is endogenously bound by mir-122-5p and that rs699 A>G significantly decreases reporter mRNA in the functional mirSNP assay PASSPORT-seq. The AGT promoter variant rs5051 C>T is in linkage disequilibrium (LD) with rs699 A>G and increases AGT transcription. We hypothesized that the increased AGT by rs5051 C>T counterbalances AGT decrease by rs699 A>G, and when these variants occur independently, would translate to HTN-related phenotypes. The independent effect of each of these variants is understudied due to their LD, therefore, we used in silico, in vitro, in vivo, and retrospective clinical and biobank analyses to assess HTN and AGT expression phenotypes where rs699 A>G occurs independently from rs5051 C>T. In silico, rs699 A>G is predicted to increase mir-122-5p binding strength by 3%. Mir-eCLIP assay results show that rs699 is 40-45 nucleotides from the strongest microRNA binding site in the AGT mRNA. Unexpectedly, rs699 A>G increases AGT mRNA in a plasmid cDNA HepG2 expression model. GTEx and UK Biobank analyses demonstrate that liver AGT expression and HTN phenotypes were not different when rs699 A>G occurs independently from rs5051 C>T, allowing us to reject the original hypothesis. However, both GTEx and our in vitro experiments suggest rs699 A>G confers cell-type specific effects on AGT mRNA abundance. We found that rs5051 C>T and rs699 A>G significantly associate with systolic blood pressure in Black participants in the UK Biobank, demonstrating a 4-fold larger effect than in White participants. Further studies are warranted to determine if the altered antihypertensive response in Black individuals might be due to rs5051 C>T or rs699 A>G. Studies like this will help clinicians move beyond the use of race as a surrogate for genotype.

Addressing global disparities in blood pressure control: perspectives of the International Society of Hypertension

Raised blood pressure (BP) is the leading cause of preventable death in the world. Yet, its global prevalence is increasing, and it remains poorly detected, treated, and controlled in both high- and low-resource settings. From the perspective of members of the International Society of Hypertension based in all regions, we reflect on the past, present, and future of hypertension care, highlighting key challenges and opportunities, which are often region-specific. We report that most countries failed to show sufficient improvements in BP control rates over the past three decades, with greater improvements mainly seen in some high-income countries, also reflected in substantial reductions in the burden of cardiovascular disease and deaths. Globally, there are significant inequities and disparities based on resources, sociodemographic environment, and race with subsequent disproportionate hypertension-related outcomes. Additional unique challenges in specific regions include conflict, wars, migration, unemployment, rapid urbanization, extremely limited funding, pollution, COVID-19-related restrictions and inequalities, obesity, and excessive salt and alcohol intake. Immediate action is needed to address suboptimal hypertension care and related disparities on a global scale. We propose a Global Hypertension Care Taskforce including multiple stakeholders and societies to identify and implement actions in reducing inequities, addressing social, commercial, and environmental determinants, and strengthening health systems implement a well-designed customized quality-of-care improvement framework.

Racial disparities in characteristics and outcomes of patients undergoing mitral transcatheter edge-to-edge repair

Background

There are scarce data regarding the post-mitral transcatheter edge-to-edger repair (TEER) course in different racial groups.

Objective

To assess the impact of race on outcomes following TEER for mitral regurgitation (MR).

Methods

This is a single-center, retrospective analysis of consecutive TEER procedures performed during 2013-2020. The primary outcome was the composite of all-cause mortality or heart failure (HF) hospitalizations along the first postprocedural year. Secondary outcomes included individual components of the primary outcome, New York Heart Association (NYHA) class, MR grade, and left ventricular mass index (LVMi).

Results

Out of 964 cases, 751 (77.9%), 88 (9.1%), 68 (7.1%), and 57 (5.9%) were whites, blacks, Asians, and Hispanics, respectively. At baseline, non-whites and blacks were younger and more likely be female, based in lower socioeconomic areas, not fully insured, diagnosed with functional MR, and affected by biventricular dysfunction. Intra-procedurally, more devices were implanted in blacks. At 1-year, non-whites (vs. whites) and blacks (vs. non-blacks or whites) experienced higher cumulative incidence of the primary outcome (32.9% vs. 22.5%, p = 0.002 and 38.6% vs. 23.4% or 22.5%, p = 0.002 or p = 0.001, respectively), which were accounted for by hospitalizations in the functional MR sub-cohort (n = 494). NYHA class improved less among blacks with functional MR. MR severity and LVMi equally regressed in all groups. White race (HR 0.62, 95% CI 0.39-0.99, p = 0.047) and black race (HR 2.07, 95% CI 1.28-3.35, p = 0.003) were independently associated with the primary outcome in functional MR patients only.

Conclusion

Mitral TEER patients of different racial backgrounds exhibit major differences in baseline characteristics. Among those with functional MR, non-whites and blacks also experience a less favorable 1-year clinical outcome.

Call to action: Understanding the differences in the use of SGLT-2 inhibitors and GLP-1 receptor agonists

Cardiovascular disease remains one of the most prominent global health problems and has been demonstrated to disproportionally affect certain communities. Despite an increasing collective effort to improve health inequalities, a multitude of disparities continue to affect cardiovascular outcomes. Among the most prominent disparities within cardiovascular disease prevention are with the use and distribution of sodium-glucose cotransporter-2 (SGLT-2) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists. Several landmark trials have demonstrated the efficacy of these novel agents, not only in cardiovascular disease prevention among those with diabetes, but also in heart failure and chronic kidney disease. However, the use of these agents remains limited by disparities in certain racial/ethnic, sex, and socioeconomic groups. This review works to highlight and understand these differences on the use and prescribing patterns of pivotal agents in cardiovascular disease prevention, SGLT-2 inhibitors and GLP-1 agonists. Our aim is to enrich understanding and to inspire efforts to end disparities in cardiovascular morbidity and mortality due to race, sex and income inequality.

Measuring copeptin, a surrogate for vasopressin in patients with hypertension - Can it identify those who are volume Responsive?

BACKGROUND

Among hypertensive patients, plasma renin activity is lower and the response to diuretic monotherapy greater in volume responsive hypertensive patients. We hypothesized that hormones influencing extracellular volume such as vasopressin / antidiuretic hormone (ADH) might permit the development of a simple test to identify those with volume-related hypertension. Such a test might be of particular benefit to the Black population which is purported to have a higher incidence of volume-related and responsive hypertension. Thus, using copeptin, a surrogate marker for ADH, we studied if there were differences in this hormone between those with and without volume responsive hypertension.

METHODS

Serum copeptin was measured in biobanked blood samples from the Genetic Epidemiology of Responses to Antihypertensives (GERA) I study and analyzed with other variables from the study dataset.

RESULTS

There was no relationship between PRA and copeptin values nor could the response in blood pressure be predicted by the copeptin values. However, baseline copeptin levels were higher in Black than in White subjects (7.5 pmol/L vs 5.4 pmol/L, P < 0.001) while plasma sodium and calculated plasma osmolality were slightly lower in keeping with the concept that Black subjects have more volume-related hypertension. In addition, after hydrochlorothiazide (HCTZ), copeptin was significantly lower in Black (6.2 pmol/L, P = 0.004) but unchanged in White subjects (5.2 pmol/L, P = 0.901) and there were also changes in sodium.

CONCLUSION

The current study suggests differences in ADH physiology between hypertensive Black and White patients. However, the use of copeptin to identify volume responsive patients could not be confirmed.

Genetic heterogeneity in cardiovascular disease across ancestries: Insights for mechanisms and therapeutic intervention

Cardiovascular diseases (CVDs) are complex in their aetiology, arising due to a combination of genetics, lifestyle and environmental factors. By nature of this complexity, different CVDs vary in their molecular mechanisms, clinical presentation and progression. Although extensive efforts are being made to develop novel therapeutics for CVDs, genetic heterogeneity is often overlooked in the development process. By considering molecular mechanisms at an individual and ancestral level, a richer understanding of the influence of environmental and lifestyle factors can be gained and more refined therapeutic interventions can be developed. It is therefore expedient to understand the molecular and clinical heterogeneity in CVDs that exists across different populations. In this review, we highlight how the mechanisms underlying CVDs vary across diverse population ancestry groups due to genetic heterogeneity. We then discuss how such genetic heterogeneity is being leveraged to inform therapeutic interventions and personalised medicine, highlighting examples across the CVD spectrum. Finally, we present an overview of how polygenic risk scores and Mendelian randomisation can foster more robust insight into disease mechanisms and therapeutic intervention in diverse populations. Fulfilment of the vision of precision medicine requires more exhaustive leveraging of the genetic variability across diverse ancestry populations to improve our understanding of disease onset, progression and response to therapeutic intervention.

Precision Medicine in Diabetes

Tailoring treatment or management to groups of individuals based on specific clinical, molecular, and genomic features is the concept of precision medicine. Diabetes is highly heterogenous with respect to clinical manifestations, disease progression, development of complications, and drug response. The current practice for drug treatment is largely based on evidence from clinical trials that report average effects. However, around half of patients with type 2 diabetes do not achieve glycaemic targets despite having a high level of adherence and there are substantial differences in the incidence of adverse outcomes. Therefore, there is a need to identify predictive markers that can inform differential drug responses at the point of prescribing. Recent advances in molecular genetics and increased availability of real-world and randomised trial data have started to increase our understanding of disease heterogeneity and its impact on potential treatments for specific groups. Leveraging information from simple clinical features (age, sex, BMI, ethnicity, and co-prescribed medications) and genomic markers has a potential to identify sub-groups who are likely to benefit from a given drug with minimal adverse effects. In this chapter, we will discuss the state of current evidence in the discovery of clinical and genetic markers that have the potential to optimise drug treatment in type 2 diabetes.

Race-related population attributable fraction of preventable risk factors of dementia: A Latino population-based study

Background

Risk factors for dementia have distinct frequency and impact in relation to race. Our aim was to identify differences in modifiable risk factors of dementia related to races and estimate their population attributable fraction (PAF).

Methods

An epidemiological cohort was used to estimate the prevalence of 10 modifiable risk factors for dementia among five races-White, Black, Brown, Asian, and Indigenous. Sample weighting was used to estimate the prevalence and PAF of each risk factor in each race.

Results

A total of 9070 individuals were included. Overall adjusted PAF was the lowest in Indigenous (38.9%), and Asian individuals (41.2%). Race-related prevalence of individual risk factors was widely variable in our population, but hearing loss was the most important contributor to the overall PAF in all races.

Conclusions

Public policies aiming to reduce preventable risk factors for dementia should take into consideration the race of the target populations.

HIGHLIGHTS

Preventable risk factors for dementia vary according to race.Hearing loss presented the highest prevalence among all races studied.Indigenous and Asian individuals presented the lowest population attributable fractions.Black and Brown individuals were more vulnerable to social determinants.

Towards the multileveled and processual conceptualisation of racialised individuals in biomedical research

In this paper, we discuss the processes of racialisation on the example of biomedical research. We argue that applying the concept of racialisation in biomedical research can be much more precise, informative and suitable than currently used categories, such as race and ethnicity. For this purpose, we construct a model of the different processes affecting and co-shaping the racialisation of an individual, and consider these in relation to biomedical research, particularly to studies on hypertension. We finish with a discussion on the potential application of our proposition to institutional guidelines on the use of racial categories in biomedical research.

Role of Renin-Angiotensin-Aldosterone System and Cortisol in Endometriosis: A Preliminary Report

Endometriosis is a chronic inflammatory disease associated with pelvic pain, infertility, and increased cardiovascular risk. Recent studies suggest a possible role of aldosterone as a pro-inflammatory hormone in the pathogenesis of the disease. Cortisol is also an important mediator of stress reaction, but its role is controversial in endometriosis. The aim of this study was to evaluate aldosterone and cortisol levels and blood pressure values in women with endometriosis. We measured blood pressure, plasma aldosterone, renin, cortisol, and dehydroepiandrosterone sulfate (DHEAS) in 20 women with untreated minimal or mild pelvic endometriosis compared with 20 healthy controls matched for age and body mass index. Aldosterone values were similar in the two groups, while renin was significantly lower and the aldosterone to renin ratio was significantly higher in patients with endometriosis than in controls. Systolic blood pressure was in the normal range, but significantly higher in patients with endometriosis. Morning plasma cortisol was normal, but significantly lower in patients with endometriosis compared with controls, while DHEAS to cortisol ratio was similar in the two groups. These preliminary results are evidence of increased biological aldosterone activity and dysregulation of the hypothalamic-pituitary-adrenal axis in early stages of endometriosis. These alterations could play a role in disease development, suggesting new therapeutic targets for aldosterone receptor blockers.

Optimization of respiratory-gated auricular vagus afferent nerve stimulation for the modulation of blood pressure in hypertension

Background

The objective of this pilot study was to identify frequency-dependent effects of respiratory-gated auricular vagus afferent nerve stimulation (RAVANS) on the regulation of blood pressure and heart rate variability in hypertensive subjects and examine potential differential effects by sex/gender or race.

Methods

Twenty hypertensive subjects (54.55 ± 6.23 years of age; 12 females and 8 males) were included in a within-person experimental design and underwent five stimulation sessions where they received RAVANS at different frequencies (i.e., 2 Hz, 10 Hz, 25 Hz, 100 Hz, or sham stimulation) in a randomized order. EKG and continuous blood pressure signals were collected during a 10-min baseline, 30-min stimulation, and 10-min post-stimulation periods. Generalized estimating equations (GEE) adjusted for baseline measures were used to evaluate frequency-dependent effects of RAVANS on heart rate, high frequency power, and blood pressure measures, including analyses stratified by sex and race.

Results

Administration of RAVANS at 100 Hz had significant overall effects on the reduction of heart rate (β = -2.03, p = 0.002). It was also associated with a significant reduction of diastolic (β = -1.90, p = 0.01) and mean arterial blood pressure (β = -2.23, p = 0.002) in Black hypertensive participants and heart rate in female subjects (β = -2.83, p = 0.01) during the post-stimulation period when compared to sham.

Conclusion

Respiratory-gated auricular vagus afferent nerve stimulation exhibits frequency-dependent rapid effects on the modulation of heart rate and blood pressure in hypertensive patients that may further differ by race and sex. Our findings highlight the need for the development of optimized stimulation protocols that achieve the greatest effects on the modulation of physiological and clinical outcomes in this population.

Resistance to Antihypertensive Drugs: Is Gut Microbiota the Missing Link?

Microbiota colonization begins at birth and continuously reshapes throughout the course of our lives, resulting in tremendous interindividual heterogeneity. Given that the gut microbiome, similar to the liver, houses many categories of catalytic enzymes, there is significant value in understanding drug-bacteria interactions. The discovery of this link could enhance the therapeutic value of drugs that would otherwise have a limited or perhaps detrimental effect on patients. Resistant hypertension is one such subset of the hypertensive population that poorly responds to antihypertensive medications, resulting in an increased risk for chronic cardiovascular illnesses and its debilitating effects that ultimately have a detrimental impact on patient quality of life. We recently demonstrated that the gut microbiota is involved in the metabolism of antihypertensive drugs and thus contributes to the pathophysiology of resistant hypertension. Due to a lack of knowledge of the mechanisms, novel therapeutic approaches that account for the gut microbiota may allow for better therapeutic outcomes in resistant hypertension. Therefore, the purpose of this review is to summarize our current, albeit limited, understanding of how the gut microbiota may possess particular enzymatic activities that influence the efficacy of antihypertensive drugs.

Identification of a Gut Commensal That Compromises the Blood Pressure-Lowering Effect of Ester Angiotensin-Converting Enzyme Inhibitors

Background:

Despite the availability of various classes of antihypertensive medications, a large proportion of hypertensive individuals remain resistant to treatments. The reason for what contributes to low efficacy of antihypertensive medications in these individuals is elusive. The knowledge that gut microbiota is involved in pathophysiology of hypertension and drug metabolism led us to hypothesize that gut microbiota catabolize antihypertensive medications and compromised their blood pressure (BP)-lowering effects.

Methods and Results:

To test this hypothesis, we examined the BP responses to a representative ACE (angiotensin-converting enzyme) inhibitor quinapril in spontaneously hypertensive rats (SHR) with or without antibiotics. BP-lowering effect of quinapril was more pronounced in the SHR+antibiotics, indicating that gut microbiota of SHR lowered the antihypertensive effect of quinapril. Depletion of gut microbiota in the SHR+antibiotics was associated with decreased gut microbial catabolism of quinapril as well as significant reduction in the bacterial genus Coprococcus. C. comes, an anaerobic species of Coprococcus, harbored esterase activity and catabolized the ester quinapril in vitro. Co-administration of quinapril with C. comes reduced the antihypertensive effect of quinapril in the SHR. Importantly, C. comes selectively reduced the antihypertensive effects of ester ramipril but not nonester lisinopril.

Conclusions:

Our study revealed a previously unrecognized mechanism by which human commensal C. comes catabolizes ester ACE inhibitors in the gut and lowers its antihypertensive effect.

Primary Aldosteronism Screening Rates Differ with Sex, Race, and Comorbidities

Background

Primary aldosteronism (PA) is a common but under‐recognized cause of secondary hypertension. Data directly comparing screening rates across single and overlapping indications are lacking.

Methods and Results

We conducted a retrospective review of adults with hypertension seen in outpatient clinics at a tertiary referral academic center between January 1, 2017, and June 30, 2020. We included patients with hypertension plus at least one of the following: resistant hypertension; age<35 years; obstructive sleep apnea; hypokalemia; or an adrenal mass. We excluded patients with adrenal insufficiency, severe renal disease, or heart failure, and renovascular hypertension. Of 203 535 patients with hypertension, 86044 (42.3%) met at least 1 PA screening criterion, and of these, 2898 (3.4%) were screened for PA. Screening occurred in 2.7% of patients with resistant hypertension; 4.2% of those with obstructive sleep apnea; 5.1% of those <35 years; 10.0% of those with hypokalemia; and 47.3% of patients with an adrenal mass. Screening rates were higher in patients with multiple risk factors: 16.8% for ≥3, 5.7% for 2, and 2.5% for 1 criterion. Multiple logistic regression showed that the odds of PA screening were higher in patients with hypokalemia: odds ratio (95% CI): 3.0 (2.7–3.3); women: 1.3 (1.2–1.4); Black versus White: 1.5 (1.4–1.7); those with obstructive sleep apnea, chronic renal disease, stroke, and dyslipidemia.

Conclusions

Consideration for PA is given in a small subset of at‐risk patients, and typically after comorbidities have developed.

Roles of Angiotensin III in the brain and periphery

Angiotensin (Ang) III, a biologically active peptide of the renin angiotensin system (RAS) is predominantly known for its central effects on blood pressure. Our understanding of the RAS has evolved from the simplified, classical RAS, a hormonal system regulating blood pressure to a complex system affecting numerous biological processes. Ang II, the main RAS peptide has been widely studied, and its deleterious effects when overexpressed is well-documented. However, other components of the RAS such as Ang III are not well studied. This review examines the molecular and biological actions of Ang III and provides insight into Ang III's potential role in metabolic diseases.

Do nurses document all discussions of patient problems and nursing interventions in the electronic health record? A pilot study in home healthcare

Objective

To assess the overlap of information between electronic health record (EHR) and patient–nurse verbal communication in home healthcare (HHC).

Methods

Patient–nurse verbal communications during home visits were recorded between February 16, 2021 and September 2, 2021 with patients being served in an organization located in the Northeast United States. Twenty-two audio recordings for 15 patients were transcribed. To compare overlap of information, manual annotations of problems and interventions were made on transcriptions as well as information from EHR including structured data and clinical notes corresponding to HHC visits.

Results

About 30% (1534/5118) of utterances (ie, spoken language preceding/following silence or a change of speaker) were identified as including problems or interventions. A total of 216 problems and 492 interventions were identified through verbal communication among all the patients in the study. Approximately 50.5% of the problems and 20.8% of the interventions discussed during the verbal communication were not documented in the EHR. Preliminary results showed that statistical differences between racial groups were observed in a comparison of problems and interventions.

Discussion

This study was the first to investigate the extent that problems and interventions were mentioned in patient–nurse verbal communication during HHC visits and whether this information was documented in EHR. Our analysis identified gaps in information overlap and possible racial disparities.

Conclusion

Our results highlight the value of analyzing communications between HHC patients and nurses. Future studies should explore ways to capture information in verbal communication using automated speech recognition.

Salt sensitivity of blood pressure in childhood and adolescence

Although moderation of sodium intake is recommended population-wide, it remains uncertain who benefits from salt restriction. Salt sensitivity refers to changes in blood pressure in response to sodium intake and may occur with or without hypertension. Unfortunately, there is no practical way to assess salt sensitivity in daily practice. Assessment of salt sensitivity even in research studies is challenging with varying protocols utilized which may contribute to differing results. Building on studies in animals and adults, risk factors and conditions associated with salt sensitivity have been identified in the pediatric and young adult populations. This review presents the limited evidence linking obesity, low birth weight, diabetes, chronic kidney disease, and race/ethnicity with salt sensitivity in children, adolescents, and young adults. The impact of stress on sodium handling is also reviewed. The influence of age on the timing of introduction of dietary salt restriction and the long-term influence of salt sensitivity on risk for hypertension are considered. Lastly, interventions other than salt restriction that may improve salt sensitivity and may inform recommendations to families are reviewed.

Blood Pressure Control Among Non-Hispanic Black Adults Is Lower Than Non-Hispanic White Adults Despite Similar Treatment With Antihypertensive Medication: NHANES 2013-2018

BACKGROUND

Controlled blood pressure can prevent or reduce adverse health outcomes. Social and structural determinants may contribute to the disparity that despite equivalent proportions on antihypertensive medication, non-Hispanic Black (Black) adults have lower blood pressure control and more cardiovascular events than non-Hispanic White (White) adults.

METHODS

Data from 2013 to 2018 National Health and Nutrition Examination Survey were pooled to assess control among Black and White adults by antihypertensive medication use and selected characteristics using the 2017 American College of Cardiology/American Heart Association (ACC/AHA) Blood Pressure Guideline definition (systolic blood pressure <130 mm Hg and diastolic blood pressure <80 mm Hg) among 4,739 adults.

RESULTS

Among those treated with antihypertensive medication, an estimated 34.9% of Black and 45.0% of White adults had controlled blood pressure. Control was lower for Black and White adults among most subgroups of age, sex, education, insurance status, usual source of care, and poverty-income ratio. Black adults had higher use of diuretics (28.5%-Black adults vs. 23.5%-White adults) and calcium channel blockers (24.2%-Black adults vs. 14.7%-White adults) compared with White adults. Control among Black adults was lower than White adults across all medication classes including diuretics (36.1%-Black adults vs. 47.3%-White adults), calcium channel blockers (30.2%-Black adults vs. 40.1%-White adults), and number of medication classes used.

CONCLUSIONS

Suboptimal blood pressure control rates and disparities warrant increased efforts to improve control, which could include addressing social and structural determinants along with emphasizing implementation of the 2017 ACC/AHA Blood Pressure Guideline into clinical practice.

Reduced blood pressure in sickle cell disease is associated with decreased angiotensin converting enzyme (ACE) activity and is not modulated by ACE inhibition

Background

Sickle cell disease (SCD) incurs vaso-occlusive episodes and organ damage, including nephropathy. Despite displaying characteristics of vascular dysfunction, SCD patients tend to present relatively lower systemic blood pressure (BP), via an unknown mechanism. We investigated associations between BP and renin-angiotensin-system (RAS) components in SCD and determined whether an inhibitor of angiotensin converting enzyme (ACE; often used to slow SCD glomerulopathy) further modulates BP and RAS components in a murine model of SCD.

Methods

BP was compared in human subjects and mice with/without SCD. Plasma angiotensin II, ACE and renin were measured by immunoassay. BP was reevaluated after treating mice with enalapril (25 mg/kg, 5x/week) for 5 weeks; plasma and organs were stored for angiotensin II and ACE activity measurement, and quantitative real-time PCR.

Results

Diastolic BP and systolic BP were significantly lower in patients and mice with SCD, respectively, compared to controls. Reduced BP was associated with increased plasma renin and markers of kidney damage (mice) in SCD, as well as significantly decreased plasma ACE concentrations and ACE enzyme activity. As expected, enalapril administration lowered BP, plasma angiotensin II and organ ACE activity in control mice. In contrast, enalapril did not further reduce BP or organ ACE activity in SCD mice; however, plasma angiotensin II and renin levels were found to be significantly higher in enalapril-treated SCD mice than those of treated control mice.

Conclusion

Relative hypotension was confirmed in a murine model of SCD, in association with decreased ACE concentrations in both human and murine disease. Given that ACE inhibition has an accepted role in decreasing BP, further studies should investigate mechanisms by which ACE depletion, via both Ang II-dependent and alternative pathways, could contribute to reduce BP in SCD and understand how ACE inhibition confers Ang II-independent benefits on kidney function in SCD.

Interventions Incorporating Therapeutic Alliance to Improve Medication Adherence in Black Patients with Diabetes, Hypertension and Kidney Disease: A Systematic Review

BACKGROUND

Black Americans have a disproportionately increased risk of diabetes, hypertension, and kidney disease, and higher associated morbidity, mortality, and hospitalization rates than their White peers. Structural racism amplifies these disparities, and negatively impacts self-care including medication adherence, critical to chronic disease management. Systematic evidence of successful interventions to improve medication adherence in Black patients with diabetes, hypertension, and kidney disease is lacking. Knowledge of the impact of therapeutic alliance, ie, the unique relationship between patients and providers, which optimizes outcomes especially for minority populations, is unclear. The role and application of behavioral theories in successful development of medication adherence interventions specific to this context also remains unclear.

OBJECTIVE

To evaluate the existing evidence on the salience of a therapeutic alliance in effective interventions to improve medication adherence in Black patients with diabetes, hypertension, or kidney disease.

DATA SOURCES

Medline (via PubMed), EMBASE (OvidSP), Cumulative Index of Nursing and Allied Health Literature (CINAHL) (EBSCOhost), and PsycINFO (ProQuest) databases.

REVIEW METHODS

Only randomized clinical trials and pre/post intervention studies published in English between 2009 and 2022 with a proportion of Black patients greater than 25% were included. Narrative synthesis was done.

RESULTS

Eleven intervention studies met the study criteria and eight of those studies had all-Black samples. Medication adherence outcome measures were heterogenous. Five out of six studies which effectively improved medication adherence, incorporated therapeutic alliance. Seven studies informed by behavioral theories led to significant improvement in medication adherence.

DISCUSSION/CONCLUSION

Study findings suggest that therapeutic alliance-based interventions are effective in improving medication adherence in Black patients with diabetes and hypertension. Further research to test the efficacy of therapeutic alliance-based interventions to improve medication adherence in Black patients should ideally incorporate cultural adaptation, theoretical framework, face-to-face delivery mode, and convenient locations.

Independent relationships between renal mechanisms and systemic flow, but not resistance to flow in primary hypertension in Africa

AIMS

Whether renal mechanisms of hypertension primarily translate into increases in systemic vascular resistance (SVR) in all populations is uncertain. We determined whether renal mechanisms associate with either increases in SVR (and impedance to flow) or systemic flow in a community of African ancestry.

METHOD

In a South African community sampled across the full adult age range (n = 546), we assessed stroke volume (SV), peak aortic flow (Q), SVR, characteristic impedance (Zc) and total arterial compliance (TAC) from velocity and diameter measurements in the outflow tract (echocardiography) and central arterial pressures. Renal changes were determined from creatinine clearance (glomerular filtration rate, GFR) and fractional Na+ excretion (FeNa+) (derived from 24-h urine collections).

RESULTS

Independent of confounders (including MAP and pressures generated by the product of Q and Zc), SV (and hence cardiac output) (P < 0.0001) and Q (P < 0.01), but not SVR, Zc or TAC (P = 0.09-0.20) were independently associated with decreases in both GFR (index of nephron number) and FeNa+. Through an interactive effect (P < 0.0001), the impact of GFR on SV or Q was strongly determined by FeNa+ and vice versa. The relationship between the GFR-FeNa+ interaction and either SV or Q was noted in those above or below 50 years of age, although neither GFR, FeNa+ nor the interaction were independently associated with SVR, Zc or TAC at any age.

CONCLUSION

Across the full adult lifespan, in groups of African ancestry, renal mechanisms of hypertension translate into increases in systemic flow rather than into resistance or impedance to flow.