CTEPH is an uncommon complication of COVID-19: UK national surveillance and observational screening cohort studies.

INTRODUCTION: Pulmonary embolism (PE) is a well-recognised complication of COVID-19 infection, and chronic thromboembolic pulmonary disease with and without pulmonary hypertension (CTEPD/CTEPH) are potential life-limiting consequences. At present the burden of CTEPD/CTEPH is unclear and optimal and cost-effective screening strategies yet to be established. METHODS: We evaluated the CTEPD/CTEPH referral rate to the UK national multidisciplinary team (MDT) during the 2017-2022 period to establish the national incidence of CTEPD/CTEPH potentially attributable to COVID-19-associated PE with historical comparator years. All individual cases of suspected CTEPH were reviewed by the MDT for evidence of associated COVID-19. In a separate multicentre cohort, the risk of developing CTEPH following hospitalisation with COVID-19 was calculated using simple clinical parameters at a median of 5 months post hospital discharge according to existing risk scores using symptoms, ECG and NT pro-BNP. RESULTS: By the second year of the pandemic, CTEPH diagnoses had returned to the pre-pandemic baseline (23.1 versus 27.8 cases per month, p=0.252). Of 334 confirmed CTEPD/CTEPH cases, 4 (1.2%) patients were identified to have CTEPH potentially associated with COVID-19 PE, and a further 3 (0.9%) CTEPD without PH. Of 1094 patients (mean age 58 years, 60.4% male) hospitalised with COVID-19 screened across the UK, 11 (1.0%) were at high risk of CTEPH at follow-up, none of whom had a diagnosis of CTEPH made at the national MDT. CONCLUSION: A-priori risk of developing CTEPH following COVID-19-related hospitalisation is low. Simple risk scoring is a potentially effective way of screening patients for further investigation.

Effects of potassium supplementation on plasma aldosterone: a systematic review and meta-analysis in humans.

OBJECTIVES: Effects of potassium supplementation on blood pressure (BP) may be offset by an increase in plasma aldosterone. The magnitude of potassium-dependent regulation of aldosterone secretion in humans is not fully characterized; it is not clear whether this is mediated by activation of the renin-angiotensin-aldosterone system (RAAS), as a result of a reduction in BP or other mechanisms. We performed a systematic review and meta-analysis of clinical trials assessing effects of potassium on plasma aldosterone and renin in adult individuals. METHODS: This was carried out in accordance with PRISMA guidelines. Three databases were searched: MEDLINE, EMBASE and CENTRAL. Titles were firstly screened by title and abstract for relevance before full-text articles were assessed for eligibility. The keywords used included "aldosterone", "potassium" and "RAAS". RESULTS: 6395 articles were retrieved and after title/abstract screening, 123 full-text articles were assessed for eligibility. Thirty-six met the prespecified inclusion/exclusion criteria (of which 18/36 also reported systolic BP). Potassium supplementation caused a significant decrease in systolic BP (mean difference [95% CI] -3.69 mmHg [-4.91, -2.46], P  < 0.001) and increase in serum potassium (+0.37 [0.23, 0.52] mmol/l, P  < 0.001). There was an increase in plasma aldosterone (standardized difference 0.426 [0.299, 0.553], P  < 0.001) but not in plasma renin activity. Meta-regression showed a significant positive correlation between change in plasma aldosterone and change in serum potassium ( P  < 0.001). CONCLUSIONS: Potassium supplementation increases plasma aldosterone concentrations, which correlates with the increase in serum potassium concentration which does not appear to be mediated by an increase in plasma renin activity.

Ethnicity differences in geometric remodelling and myocardial composition in hypertension unveiled by cardiovascular magnetic resonance.

AIMS: Hypertensive patients of African ancestry (Afr-a) have higher incidences of heart failure and worse clinical outcomes than hypertensive patients of European ancestry (Eu-a), yet the underlying mechanisms remain misunderstood. This study investigated right (RV) and left (LV) ventricular remodelling alongside myocardial tissue derangements between Afr-a and Eu-a hypertensives. METHODS AND RESULTS: 63 Afr-a and 47 Eu-a hypertensives underwent multi-parametric cardiovascular magnetic resonance. Biventricular volumes, mass, function, mass/end-diastolic volume (M/V) ratios, T2 and pre-/post-contrast T1 relaxation times, synthetic extracellular volume, and myocardial fibrosis (MF) were measured. 3D shape modelling was implemented to delineate ventricular geometry. LV and RV mass (indexed to body-surface-area) and M/V ratio were significantly greater in Afr-a than Eu-a hypertensives (67.1 ± 21.7 vs. 58.3 ± 16.7 g/m2, 12.6 ± 3.48 vs. 10.7 ± 2.71 g/m2, 0.79 ± 0.21 vs. 0.70 ± 0.14 g/mL, and 0.16 ± 0.04 vs. 0.13 ± 0.03 g/mL, respectively; P < 0.03). Afr-a patients showed greater basal interventricular septum thickness than Eu-a patients, influencing LV hypertrophy and RV cavity changes. This biventricular remodelling was associated with prolonged T2 relaxation time (47.0 ± 2.2 vs. 45.7 ± 2.2 ms, P = 0.005) and higher prevalence (23% vs. 4%, P = 0.001) and extent of MF [2.3 (0.6-14.3) vs. 1.6 (0.9-2.5) % LV mass, P = 0.008] in Afr-a patients. Multivariable linear regression showed that modifiable cardiovascular risk factors and greater end-diastolic volume, but not ethnicity, were independently associated with greater LV mass. CONCLUSION: Afr-a hypertensives had distinctive biventricular remodelling, including increased RV mass, septal thickening and myocardial tissue abnormalities compared with Eu-a hypertensives. From this study, modifiable cardiovascular risk factors and ventricular geometry, but not ethnicity, were independently associated with greater LV myocardial mass.

Serum metabolomics improves risk stratification for incident heart failure.

AIMS: Prediction and early detection of heart failure (HF) is crucial to mitigate its impact on quality of life, survival, and healthcare expenditure. Here, we explored the predictive value of serum metabolomics (168 metabolites detected by proton nuclear magnetic resonance [1H-NMR] spectroscopy) for incident HF. METHODS AND RESULTS: Leveraging data of 68 311 individuals and >0.8 million person-years of follow-up from the UK Biobank cohort, we (i) fitted per-metabolite Cox proportional hazards models to assess individual metabolite associations, and (ii) trained and validated elastic net models to predict incident HF using the serum metabolome. We benchmarked discriminative performance against a comprehensive, well-validated clinical risk score (Pooled Cohort Equations to Prevent HF [PCP-HF]). During a median follow-up of ≈12.3 years, several metabolites showed independent association with incident HF (90/168 adjusting for age and sex, 48/168 adjusting for PCP-HF). Performance-optimized risk models effectively retained key predictors representing highly correlated clusters (≈80% feature reduction). Adding metabolomics to PCP-HF improved predictive performance (Harrel's C: 0.768 vs. 0.755, ΔC = 0.013, [95% confidence interval [CI] 0.004-0.022], continuous net reclassification improvement [NRI]: 0.287 [95% CI 0.200-0.367], relative integrated discrimination improvement [IDI]: 17.47% [95% CI 9.463-27.825]). Models including age, sex and metabolomics performed almost as well as PCP-HF (Harrel's C: 0.745 vs. 0.755, ΔC = 0.010 [95% CI -0.004 to 0.027], continuous NRI: 0.097 [95% CI -0.025 to 0.217], relative IDI: 13.445% [95% CI -10.608 to 41.454]). Risk and survival stratification was improved by integrating metabolomics. CONCLUSION: Serum metabolomics improves incident HF risk prediction over PCP-HF. Scores based on age, sex and metabolomics exhibit similar predictive power to clinically-based models, potentially offering a cost-effective, standardizable, and scalable single-domain alternative.

'Legacy publication of a 2009 validation of the Riester Big Ben Square Desk aneroid device for blood pressure measurement according to the European Society of Hypertension International Protocol for validation of blood pressure measuring devices in adults (2002)'.

OBJECTIVE: To report a validation of the Riester Big Ben Square Desk Aneroid Sphygmomanometer according to the international protocol developed by the Working Group on Blood Pressure Monitoring of the European Society of Hypertension 2002 (ESH-IP 2002) in the interest of transparency. This legacy publication is intended to assure users that the device satisfied the requirements in place at that time. METHODS: Performance of the device was assessed by participants' age, sex, arm circumference and entry SBP/DBP. Validation was performed in 33 participants. The sphygmomanometer was assessed according to the ESH-IP, which defines zones of accuracy compared to the mercury standard as ≤5, ≤10, ≤15 mmHg or more. RESULTS: The mean (± SD) age was 50.5 ±â€…13.0 years, range 29-71 years, entry SBP 142.6 ±â€…23.7 mmHg, entry DBP 89.0 ±â€…17.8 mmHg. The device passed all the requirements listed and the validation protocol. The Riester Big Ben Square Desk aneroid sphygmomanometer slightly underestimated the observer-measured SBP, yet slightly overestimated DBP. The observer-device disagreement was -0.8 ±â€…6.4 mmHg SBP and +0.6 ±â€…4.0 mmHg DBP. CONCLUSION: These data show that the Riester Big Ben Square Desk aneroid sphygmomanometer fulfilled the ESH-IP 2002 requirements for the validation of BP monitors. It was on this basis that the British and Irish Hypertension Society recommended it for clinical use in the adult population.

The Effect of a Neuronal Nitric Oxide Synthase Inhibitor on Neurovascular Regulation in Humans.

BACKGROUND: Neurovascular coupling (NVC) is a key process in cerebral blood flow regulation. NVC ensures adequate brain perfusion to changes in local metabolic demands. Neuronal nitric oxide synthase (nNOS) is suspected to be involved in NVC; however, this has not been tested in humans. Our objective was to investigate the effects of nNOS inhibition on NVC in humans. METHODS: We performed a 3-visit partially randomized, double-blinded, placebo-controlled, crossover study in 12 healthy subjects. On each visit, subjects received an intravenous infusion of either S-methyl-L-thiocitrulline (a selective nNOS-inhibitor), 0.9% saline (placebo control), or phenylephrine (pressor control). The NVC assessment involved eliciting posterior circulation hyperemia through visual stimulation while measuring posterior and middle cerebral arteries blood velocity. RESULTS: nNOS inhibition blunted the rapidity of the NVC response versus pressor control, evidenced by a reduced initial rise in mean posterior cerebral artery velocity (-3.3% [-6.5, -0.01], P=0.049), and a reduced rate of increase (ie, acceleration) in posterior cerebral artery velocity (slope reduced -4.3% [-8.5, -0.1], P=0.045). The overall magnitude of posterior cerebral artery response relative to placebo control or pressor control was not affected. Changes in BP parameters were well-matched between the S-methyl-L-thiocitrulline and pressor control arms. CONCLUSIONS: Neuronal NOS plays a role in dynamic cerebral blood flow control in healthy adults, particularly the rapidity of the NVC response to visual stimulation. This work opens the way to further investigation of the role of nNOS in conditions of impaired NVC, potentially revealing a therapeutic target.

Lifestyle intervention in obese pregnancy and cardiac remodelling in 3-year olds: children of the UPBEAT RCT.

BACKGROUND/OBJECTIVES: Obesity in pregnancy has been associated with increased childhood cardiometabolic risk and reduced life expectancy. The UK UPBEAT multicentre randomised control trial was a lifestyle intervention of diet and physical activity in pregnant women with obesity. We hypothesised that the 3-year-old children of women with obesity would have heightened cardiovascular risk compared to children of normal BMI women, and that the UPBEAT intervention would mitigate this risk. SUBJECTS/METHODS: Children were recruited from one UPBEAT trial centre. Cardiovascular measures included blood pressure, echocardiographic assessment of cardiac function and dimensions, carotid intima-media thickness and heart rate variability (HRV) by electrocardiogram. RESULTS: Compared to offspring of normal BMI women (n = 51), children of women with obesity from the trial standard care arm (n = 39) had evidence of cardiac remodelling including increased interventricular septum (IVS; mean difference 0.04 cm; 95% CI: 0.018 to 0.067), posterior wall (PW; 0.03 cm; 0.006 to 0.062) and relative wall thicknesses (RWT; 0.03 cm; 0.01 to 0.05) following adjustment. Randomisation of women with obesity to the intervention arm (n = 31) prevented this cardiac remodelling (intervention effect; mean difference IVS -0.03 cm (-0.05 to -0.008); PW -0.03 cm (-0.05 to -0.01); RWT -0.02 cm (-0.04 to -0.005)). Children of women with obesity (standard care arm) compared to women of normal BMI also had elevated minimum heart rate (7 bpm; 1.41 to 13.34) evidence of early diastolic dysfunction (e prime) and increased sympathetic nerve activity index by HRV analysis. CONCLUSIONS: Maternal obesity was associated with left ventricular concentric remodelling in 3-year-old offspring. Absence of remodelling following the maternal intervention infers in utero origins of cardiac remodelling. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: The UPBEAT trial is registered with Current Controlled Trials, ISRCTN89971375.

Genetic-Guided Pharmacotherapy for Atrial Fibrillation: A Systematic and Critical Review of Economic Evaluations.

OBJECTIVES: This study aimed to examine the extent and quality of evidence from economic evaluations (EEs) of genetic-guided pharmacotherapy (PGx) for atrial fibrillation (AF) and to identify variables influential in changing base-case conclusions. METHODS: From systematic searches, we included EEs of existing PGx testing to guide pharmacotherapy for AF, without restrictions on population characteristics or language. Articles excluded were genetic tests used to guide device-based therapy or focused on animals. RESULTS: We found 18 EEs (46 comparisons), all model-based cost-utility analysis with or without cost-effectiveness analysis mostly from health system's perspectives, of PGx testing to determine coumadin/direct-acting anticoagulant (DOAC) dosing (14 of 18), to stratify patients into coumadin/DOACs (3 of 18), or to increase patients' adherence to coumadin (1 of 18) versus non-PGx. Most PGx to determine coumadin dosing found PGx more costly and more effective than standard or clinical coumadin dosing (19 of 24 comparisons) but less costly and less effective than standard DOAC dosing (14 of 14 comparisons). The remaining comparisons were too few to observe any trend. Of 61 variables influential in changing base-case conclusions, effectiveness of PGx testing was the most common (37%), accounted for in the models using time-based or medication-based approaches or relative risk. The cost of PGx testing has decreased and plateaued over time. CONCLUSIONS: EEs to date only partially inform decisions on selecting optimal PGx testing for AF, because most evidence focuses on PGx testing to determine coumadin dosing, but less on other purposes. Future EE may refer to the list of influential variables and the approaches used to account for the effect of PGx testing to inform data collection and study design.

Neuronal nitric oxide synthase regulates regional brain perfusion in healthy humans.

AIMS: Neuronal nitric oxide synthase (nNOS) is highly expressed within the cardiovascular and nervous systems. Studies in genetically modified mice suggest roles in brain blood flow regulation while dysfunctional nNOS signalling is implicated in cerebrovascular ischaemia and migraine. Previous human studies have investigated the effects of non-selective NOS inhibition but there has been no direct investigation of the role of nNOS in human cerebrovascular regulation. We hypothesized that inhibition of the tonic effects of nNOS would result in global or localized changes in cerebral blood flow (CBF), as well as changes in functional brain connectivity. METHODS AND RESULTS: We investigated the acute effects of a selective nNOS inhibitor, S-methyl-L-thiocitrulline (SMTC), on CBF and brain functional connectivity in healthy human volunteers (n = 19). We performed a randomized, placebo-controlled, crossover study with either intravenous SMTC or placebo, using magnetic resonance imaging protocols with arterial spin labelling and functional resting state neuroimaging. SMTC infusion induced an ∼4% decrease in resting global CBF [-2.3 (-0.3, -4.2) mL/100g/min, mean (95% confidence interval, CI), P = 0.02]. In a whole-brain voxel-wise factorial-design comparison of CBF maps, we identified a localized decrease in regional blood flow in the right hippocampus and parahippocampal gyrus following SMTC vs. placebo (2921 voxels; T = 7.0; x = 36; y = -32; z = -12; P < 0.001). This was accompanied by a decrease in functional connectivity to the left superior parietal lobule vs. placebo (484 voxels; T = 5.02; x = -14; y = -56; z = 74; P = 0.009). These analyses adjusted for the modest changes in mean arterial blood pressure induced by SMTC as compared to placebo [+8.7 mmHg (+1.8, +15.6), mean (95% CI), P = 0.009]. CONCLUSIONS: These data suggest a fundamental physiological role of nNOS in regulating regional CBF and functional connectivity in the human hippocampus. Our findings have relevance to the role of nNOS in the regulation of cerebral perfusion in health and disease.

Effect of diuretics on plasma aldosterone and potassium in primary hypertension: A systematic review and meta-analysis.

AIM: By contrast with drugs inhibiting the renin-angiotensin-aldosterone system (RAAS), diuretics stimulate renin release by the kidneys. Although plasma aldosterone (PA) is thought to be mainly regulated by RAAS activity, serum potassium has been shown to be an important factor in animal models and humans. Here we perform a systematic review and meta-analysis of randomised controlled trials (RCT) in hypertension investigating the effects of diuretic therapy on PA and the correlation of change in PA with that of potassium and blood pressure (BP). METHODS: Three databases were searched: MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL). Titles were first screened by title and abstract for relevance before full-text articles were assessed for eligibility according to a predefined inclusion/exclusion criteria. RESULTS: A total of 1139 articles were retrieved, of which 42 met the prespecified inclusion/exclusion criteria. The average standardised difference in mean PA was similar for all classes of diuretic: thiazide/thiazide-like 0.299 (95% confidence interval [CI] 0.150, 0.447), loop 0.927 (0.37, 1.49), MRA/potassium-sparing 0.265 (0.173, 0.357) and combination 0.466 (0.137, 0.796), Q = 6.33, P = .097. In subjects untreated with another antihypertensive, there was a significant relationship between change in PA and change in systolic BP but no relationship with the change in potassium. CONCLUSION: In RCTs of diuretic therapy in hypertension, there is an increase in PA with all classes of diuretic and no significant between-class heterogeneity. Change in PA is not related with potassium but correlates with the change in BP in subjects untreated with another antihypertensive medication.

Estimating pulse wave velocity from the radial pressure wave using machine learning algorithms.

One of the European gold standard measurement of vascular ageing, a risk factor for cardiovascular disease, is the carotid-femoral pulse wave velocity (cfPWV), which requires an experienced operator to measure pulse waves at two sites. In this work, two machine learning pipelines were proposed to estimate cfPWV from the peripheral pulse wave measured at a single site, the radial pressure wave measured by applanation tonometry. The study populations were the Twins UK cohort containing 3,082 subjects aged from 18 to 110 years, and a database containing 4,374 virtual subjects aged from 25 to 75 years. The first pipeline uses Gaussian process regression to estimate cfPWV from features extracted from the radial pressure wave using pulse wave analysis. The mean difference and upper and lower limits of agreement (LOA) of the estimation on the 924 hold-out test subjects from the Twins UK cohort were 0.2 m/s, and 3.75 m/s & -3.34 m/s, respectively. The second pipeline uses a recurrent neural network (RNN) to estimate cfPWV from the entire radial pressure wave. The mean difference and upper and lower LOA of the estimation on the 924 hold-out test subjects from the Twins UK cohort were 0.05 m/s, and 3.21 m/s & -3.11m/s, respectively. The percentage error of the RNN estimates on the virtual subjects increased by less than 2% when adding 20% of random noise to the pressure waveform. These results show the possibility of assessing the vascular ageing using a single peripheral pulse wave (e.g. the radial pressure wave), instead of cfPWV. The proposed code for the machine learning pipelines is available from the following online depository (https://github.com/WeiweiJin/Estimate-Cardiovascular-Risk-from-Pulse-Wave-Signal).

Genetic-guided pharmacotherapy for venous thromboembolism: a systematic and critical review of economic evaluations.

Despite the known contributions of genes, genetic-guided pharmacotherapy has not been routinely implemented for venous thromboembolism (VTE). To examine evidence on cost-effectiveness of genetic-guided pharmacotherapy for VTE, we searched six databases, websites of four HTA agencies and citations, with independent double-reviewers in screening, data extraction, and quality rating. The ten eligible studies, all model-based, examined heterogeneous interventions and comparators. Findings varied widely; testing was cost-saving in two base-cases, cost-effective in four, not cost-effective in three, dominated in one. Of 22 model variables that changed decisions about cost-effectiveness, effectiveness/relative effectiveness of the intervention was the most frequent, albeit of poor quality. Studies consistently lacked details on the provision of interventions and comparators as well as on model development and validation. Besides improving the reporting of interventions, comparators, and methodological details, future economic evaluations should examine strategies recommended in guidelines and testing key model variables for decision uncertainty, to advise clinical implementations.

Dietary nitrate prevents progression of carotid subclinical atherosclerosis through blood pressure-independent mechanisms in patients with or at risk of type 2 diabetes mellitus.

AIMS: To test if 6 months' intervention with dietary nitrate and spironolactone could affect carotid subclinical atherosclerosis and stiffness, respectively, vs. placebo/doxazosin, to control for blood pressure (BP). METHODS: A subgroup of participants in our double-blind, randomized-controlled, factorial VaSera trial had carotid imaging. Patients with hypertension and with/at risk of type 2 diabetes were randomized to active nitrate-containing beetroot juice or placebo nitrate-depleted juice, and spironolactone or doxazosin. Vascular ultrasound for carotid diameter (CD, mm) and intima-media thickness (CIMT, mm) was performed at baseline, 3- and 6-months. Carotid local stiffness (CS, m/s) was estimated from aortic pulse pressure (Arteriograph) and carotid lumen area. Data were analysed by modified intention to treat and using mixed-model effect, adjusted for confounders. RESULTS: In total, 93 subjects had a baseline evaluation and 86% had follow-up data. No statistical interactions occurred between the juice and drug arms and BP was similar between the juices and between the drugs. Nitrate-containing vs. placebo juice significantly lowered CIMT (-0.06 [95% confidence interval -0.12, -0.01], P = .034), an overall difference of ~8% relative to baseline; but had no effect on CD or CS. Doxazosin appeared to reduce CS from baseline (-0.34 [-0.62, -0.06]) however, no difference was detected vs. spironolactone (-0.15 [-0.46, 0.16]). No differences were detected between spironolactone or doxazosin on CIMT and CD. CONCLUSIONS: Our results show that 6 months' intervention with dietary nitrate influences vascular remodelling, but not carotid stiffness or diameter. Neither spironolactone nor doxazosin had a BP-independent effect on carotid structure and function.

Direct cardiac versus systemic effects of inorganic nitrite on human left ventricular function.

Inorganic nitrite is a source of nitric oxide (NO) and is considered as a potential therapy in settings where endogenous NO bioactivity is reduced and left ventricular (LV) function impaired. However, the effects of nitrite on human cardiac contractile function, and the extent to which these are direct or indirect, are unclear. We studied 40 patients undergoing diagnostic cardiac catheterization who had normal LV systolic function and were not found to have obstructive coronary disease. They received either an intracoronary sodium nitrite infusion (8.7-26 µmol/min, n = 20) or an intravenous sodium nitrite infusion (50 µg/kg/min, n = 20). LV pressure-volume relations were recorded. The primary end point was LV end-diastolic pressure (LVEDP). Secondary end points included indices of LV systolic and diastolic function. Intracoronary nitrite infusion induced a significant reduction in LVEDP, LV end-diastolic pressure-volume relationship (EDPVR), and the time to LV end-systole (LVEST) but had no significant effect on LV systolic function or systemic hemodynamics. Intravenous nitrite infusion induced greater effects, with significant decreases in LVEDP, EDPVR, LVEST, LV dP/dtmin, tau, and mean arterial pressure. Inorganic nitrite has modest direct effects on human LV diastolic function, independent of LV loading conditions and without affecting LV systolic properties. However, the systemic administration of nitrite has larger effects on LV diastolic function, which are related to reduction in both preload and afterload. These contractile effects of inorganic nitrite may indicate a favorable profile for conditions characterized by LV diastolic dysfunction.NEW & NOTEWORTHY This is the first study to assess the direct and indirect effects of inorganic nitrite on invasive measures of left ventricular function in humans in vivo. Inorganic nitrite has a modest direct myocardial effect, improving diastolic function. Systemic administration of nitrite has larger effects related to alterations in cardiac preload and afterload. The changes induced by nitrite appear favorable for potential use in conditions characterized by LV diastolic dysfunction.

Estimating Central Pulse Pressure From Blood Flow by Identifying the Main Physical Determinants of Pulse Pressure Amplification.

Several studies suggest that central (aortic) blood pressure (cBP) is a better marker of cardiovascular disease risk than peripheral blood pressure (pBP). The morphology of the pBP wave, usually assessed non-invasively in the arm, differs significantly from the cBP wave, whose direct measurement is highly invasive. In particular, pulse pressure, PP (the amplitude of the pressure wave), increases from central to peripheral arteries, leading to the so-called pulse pressure amplification (ΔPP). The main purpose of this study was to develop a methodology for estimating central PP (cPP) from non-invasive measurements of aortic flow and peripheral PP. Our novel approach is based on a comprehensive understanding of the main cardiovascular properties that determine ΔPP along the aortic-brachial arterial path, namely brachial flow wave morphology in late systole, and vessel radius and distance along this arterial path. This understanding was achieved by using a blood flow model which allows for workable analytical solutions in the frequency domain that can be decoupled and simplified for each arterial segment. Results show the ability of our methodology to (i) capture changes in cPP and ΔPP produced by variations in cardiovascular properties and (ii) estimate cPP with mean differences smaller than 3.3 ± 2.8 mmHg on in silico data for different age groups (25-75 years old) and 5.1 ± 6.9 mmHg on in vivo data for normotensive and hypertensive subjects. Our approach could improve cardiovascular function assessment in clinical cohorts for which aortic flow wave data is available.

Effect of diuretics on plasma renin activity in primary hypertension: A systematic review and meta-analysis.

AIMS: Plasma renin activity (PRA) is regarded as a marker of sodium and fluid homeostasis in patients with primary hypertension. Whether effects of diuretics on PRA differ according to class of diuretic, whether diuretics lead to a sustained increase in PRA, and whether changes in PRA relate to those in blood pressure (BP) is unknown. We performed a systematic review and meta-analysis of trials investigating the antihypertensive effects of diuretic therapy in which PRA and/or other biomarkers of fluid homeostasis were measured before and after treatment. METHODS: Three databases were searched: MEDLINE, EMBASE and The Cochrane Central Register of Controlled Trials. Titles were firstly screened by title and abstract for relevancy before full-text articles were assessed for eligibility according to a predefined inclusion/exclusion criteria. RESULTS: A total of 1684 articles were retrieved of which 61 met the prespecified inclusion/exclusion criteria. PRA was measured in 30/61 studies. Diuretics led to a sustained increase in PRA which was similar for different classes of diuretic (standardised mean difference [95% confidence interval] 0.481 [0.362, 0.601], 0.729 [0.181, 1.28], 0.541 [0.253, 0.830] and 0.548 [0.159, 0.937] for thiazide, loop, mineralocorticoid receptor antagonists/potassium-sparing and combination diuretics respectively, Q = 0.897, P = .826), and did not relate to the average decrease in blood pressure. CONCLUSION: In antihypertensive drug trials, diuretics lead to a sustained increase in average PRA, which is similar across different classes of diuretic and unrelated to the average reduction in blood pressure.

Impact of arterio-ventricular interaction on first-phase ejection fraction in aortic stenosis.

AIMS: First-phase ejection fraction (EF1), the EF at the time to peak aortic jet velocity, has been proposed as a novel marker of peak systolic function in aortic stenosis (AS). This study aimed to explore the association of myocardial contractility and arterial load with EF1 in AS patients. METHODS AND RESULTS: Data from a prospective, cross-sectional study of 114 patients with mild, moderate, and severe AS with preserved left ventricular EF (>50%) were analysed. EF1 was measured as the volume change from end-diastole to the time that corresponded to peak aortic jet velocity. Myocardial contractility was assessed by strain rate measured by speckle tracking echocardiography. Arterial stiffness was assessed by central pulse pressure/stroke volume index ratio (PP/SVi). The total study population included 48% women, median age was 73 years, and mean peak aortic jet velocity was 3.47 m/s. In univariable linear regression analyses, lower EF1 was associated with higher age, higher peak aortic jet velocity, lower global EF, lower global longitudinal strain, lower strain rate, and higher PP/SVi. There was no significant association between EF1 and heart rate or sex. In multivariable linear regression analysis, EF1 was associated with lower strain rate and higher PP/SVi, independent of AS severity. Replacing PP/SVi by valvular impedance did not change the results. CONCLUSION: In patients with AS, reduced myocardial contractility and increased arterial load were associated with lower EF1 independent of the severity of valve stenosis.

Effects of Inhibition of Nitric Oxide Synthase on Muscular Arteries During Exercise: Nitric Oxide Does Not Contribute to Vasodilation During Exercise or in Recovery.

Background Basal release of nitric oxide (NO) from the vascular endothelium regulates the tone of muscular arteries and resistance vasculature. Effects of NO on muscular arteries could be particularly important during exercise when shear stress may stimulate increased NO synthesis. Methods and Results We investigated acute effects of NO synthase inhibition on exercise hemodynamics using NG-monomethyl-l-arginine (l-NMMA), a nonselective NO synthase -inhibitor. Healthy volunteers (n=10, 5 female, 19-33 years) participated in a 2-phase randomized crossover study, receiving l-NMMA (6 mg/kg, iv over 5 minutes) or placebo before bicycle exercise (25-150 W for 12 minutes). Blood pressure, cardiac output (measured by dilution of soluble and inert tracers) and femoral artery diameter were measured before, during, and after exercise. At rest, l-NMMA reduced heart rate (by 16.2±4.3 bpm relative to placebo, P<0.01), increased peripheral vascular resistance (by 7.0±1.4 mmHg per L/min, P<0.001), mean arterial blood pressure (by 8.9±3.5 mmHg, P<0.05), and blunted an increase in femoral artery diameter that occurred immediately before exercise (change in diameter: 0.14±0.04 versus 0.32±0.06 mm after l-NMMA and placebo, P<0.01). During/after exercise l-NMMA had no significant effect on peripheral resistance, cardiac output, or on femoral artery diameter. Conclusions These results suggest that NO plays little role in modulating muscular artery function during exercise but that it may mediate changes in muscular artery tone immediately before exercise.