Aging in females is associated with changes in respiratory modulation of sympathetic nerve activity and blood pressure.

Sympathetic nerve activity (SNA) is tightly coupled with the respiratory cycle. In healthy human males, respiratory modulation of SNA does not change with age. However, it is unclear how this modulation is affected by age in females. We investigated whether respiratory sympathetic modulation is altered in healthy postmenopausal (PMF) versus premenopausal female (YF), and younger male (YM) adults, and determined its relationship to resting blood pressure. Muscle SNA (MSNA; microneurography), respiration (transducer belt), ECG, and continuous blood pressure were measured in 12 YF, 13 PMF, and 12 YM healthy volunteers. Respiratory modulation of MSNA was quantified during two phases of the respiratory cycle: mid-late expiration and inspiration/postinspiration. All groups showed respiratory modulation of MSNA (P < 0.0005). There was an interaction between the respiratory phase and group for MSNA [bursts/100 heartbeats (HB) (P = 0.004) and bursts/min (P = 0.029)], with smaller reductions in MSNA during inspiration observed in PMF versus the other groups. Respiratory modulation of blood pressure was also reduced in PMF versus YF (6 [2] vs. 12 [9] mmHg, P = 0.008) and YM (13 [13] mmHg, P = 0.001, median [interquartile range]). The magnitude of respiratory sympathetic modulation was related to resting blood pressure in PMF only, such that individuals with less modulation had greater resting blood pressure. The data indicate that aging in postmenopausal females is associated with less inspiratory inhibition of MSNA. This correlated with a higher resting blood pressure in PMF only. Thus, the reduced modulation of MSNA could contribute to the age-related rise in blood pressure that occurs in females.NEW & NOTEWORTHY The current study demonstrates that respiratory modulation of sympathetic nerve activity (SNA) is reduced in healthy postmenopausal (PMF) versus premenopausal females (YF). Furthermore, respiratory sympathetic modulation was negatively related to resting blood pressure in postmenopausal females, such that blood pressure was greater in individual with less modulation. Reduced respiratory sympathetic modulation may have implications for the autonomic control of blood pressure in aging postmenopausal females, by contributing to age-related sympathetic activation and reducing acute, respiratory-linked blood pressure variation.

Retrograde blood flow in the internal jugular veins of humans with hypertension may have implications for cerebral arterial blood flow.

OBJECTIVES: To use multi-parametric magnetic resonance imaging (MRI) to test the hypothesis that hypertensives would have higher retrograde venous blood flow (RVBF) in the internal jugular veins (IJV) vs. normotensives, and that this would inversely correlate with arterial inflow and gray matter, white matter, and cerebrospinal fluid volumes. METHODS: Following local institutional review board approval and written consent, a prospective observational 3-T MRI study of 42 hypertensive patients (53 ± 2 years, BMI 28.2 ± 0.6 kg/m2, ambulatory daytime systolic BP 148 ± 2 mmHg, ambulatory daytime diastolic BP 101 ± 2 mmHg) and 35 normotensive patients (48 ± 2 years, BMI 25.2 ± 0.8 kg/m2, ambulatory daytime systolic BP 119 ± 3 mmHg, ambulatory daytime diastolic BP 90 ± 2 mmHg) was performed. Phase contrast imaging calculated percentage retrograde venous blood flow (%RVBF), brain segmentation estimated regional brain volumes from 3D T1-weighted images, and pseudo-continuous arterial spin labeling measured regional cerebral blood perfusion. Statistical analysis included two-sample equal variance Student's T tests, two-way analysis of variance with Tukey's post hoc correction, and permutation-based two-group general linear modeling (p < 0.05). RESULTS: In the left IJV, %RVBF was higher in hypertensives (6.1 ± 1.5%) vs. normotensives (1.1 ± 0.3%, p = 0.003). In hypertensives, there was an inverse relationship of %RVBF (permutation-based general linear modeling) to cerebral blood flow in several brain regions, including the left occipital pole and the cerebellar vermis (p < 0.01). Percentage retrograde flow in the left IJV correlated inversely with the total matter volume (gray plus white matter volume) in hypertensives (r = - 0.49, p = 0.004). CONCLUSION: RVBF in the left IJV is greater in hypertensives vs. normotensives and is linked to regional hypoperfusion and brain total matter volume. KEY POINTS: • Hypertensive humans have higher retrograde cerebral venous blood flow, associated with regional brain hypoperfusion and lower tissue volume, compared with controls. • Cerebral retrograde venous blood flow may add further stress to already hypoperfused tissue in hypertensive patients. • The amount of retrograde venous blood flow in hypertensive patients may predict which patients might be at higher risk of developing cerebral pathologies.

Left ventricular extracellular volume fraction and atrioventricular interaction in hypertension.

OBJECTIVES: Left atrial enlargement (LAE) predicts cardiovascular morbidity and mortality. Impaired LA function also confers poor prognosis. This study aimed to determine whether left ventricular (LV) interstitial fibrosis is associated with LAE and LA impairment in systemic hypertension. METHODS: Following informed written consent, a prospective observational study of 86 hypertensive patients (49 ± 15 years, 53% male, office SBP 168 ± 30 mmHg, office DBP 97 ± 4 mmHg) and 20 normotensive controls (48 ± 13 years, 55% male, office SBP 130 ± 13 mmHg, office DBP 80 ± 11 mmHg) at 1.5-T cardiovascular magnetic resonance was conducted. Extracellular volume fraction (ECV) was calculated by T1-mapping. LA volume (LAV) was measured with biplane area-length method. LA reservoir, conduit and pump function were calculated with the phasic volumetric method. RESULTS: Indexed LAV correlated with indexed LV mass (R = 0.376, p < 0.0001) and ECV (R = 0.359, p = 0.001). However, ECV was the strongest significant predictor of LAE in multivariate regression analysis (odds ratio [95th confidence interval] 1.24 [1.04-1.48], p = 0.017). Indexed myocardial interstitial volume was associated with significant reductions in LA reservoir (R = -0.437, p < 0.0001) and conduit (R = -0.316, p = 0.003) but not pump (R = -0.167, p = 0.125) function. Multiple linear regression, correcting for age, gender, BMI, BP and diabetes, showed an independent decrease of 3.5% LA total emptying fraction for each 10 ml/m2 increase in myocardial interstitial volume (standard ß coefficient -3.54, p = 0.002). CONCLUSIONS: LV extracellular expansion is associated with LAE and impaired LA reservoir and conduit function. Future studies should identify if targeting diffuse LV fibrosis is beneficial in reverse remodelling of LA structural and functional pathological abnormalities in hypertension. KEY POINTS: • Left atrial enlargement (LAE) and impairment are markers of adverse prognosis in systemic hypertension but their pathophysiology is poorly understood. • Left ventricular extracellular volume fraction was the strongest independent multivariate predictor of LAE and was associated with impaired left atrial reservoir and conduit function. • LV interstitial expansion may play a central role in the pathophysiology of adverse atrioventricular interaction in systemic hypertension.

Repaired coarctation of the aorta, persistent arterial hypertension and the selfish brain.

BACKGROUND: It has been estimated that 20-30% of repaired aortic coarctation (CoA) patients develop hypertension, with significant cardiovascular morbidity and mortality. Vertebral artery hypoplasia (VAH) with an incomplete posterior circle of Willis (ipCoW; VAH + ipCoW) is associated with increased cerebrovascular resistance before the onset of increased sympathetic nerve activity in borderline hypertensive humans, suggesting brainstem hypoperfusion may evoke hypertension to maintain cerebral blood flow: the "selfish brain" hypothesis. We now assess the "selfish brain" in hypertension post-CoA repair. METHODS: Time-of-flight cardiovascular magnetic resonance angiography from 127 repaired CoA patients (34 ± 14 years, 61% male, systolic blood pressure (SBP) 138 ± 19 mmHg, diastolic blood pressure (DBP) 76 ± 11 mmHg) was compared with 33 normotensive controls (42 ± 14 years, 48% male, SBP 124 ± 10 mmHg, DBP 76 ± 8 mmHg). VAH was defined as < 2 mm and ipCoW as hypoplasia of one or both posterior communicating arteries. RESULTS: VAH + ipCoW was more prevalent in repaired CoA than controls (odds ratio: 5.8 [1.6-20.8], p = 0.007), after controlling for age, sex and body mass index (BMI). VAH + ipCoW was an independent predictor of hypertension (odds ratio: 2.5 [1.2-5.2], p = 0.017), after controlling for age, gender and BMI. Repaired CoA subjects with VAH + ipCoW were more likely to have difficult to treat hypertension (odds ratio: 3.3 [1.01-10.7], p = 0.049). Neither age at time of CoA repair nor any specific repair type were significant predictors of VAH + ipCoW in univariate regression analysis. CONCLUSIONS: VAH + ipCoW predicts arterial hypertension and difficult to treat hypertension in repaired CoA. It is unrelated to age at time of repair or repair type. CoA appears to be a marker of wider congenital cerebrovascular problems. Understanding the "selfish brain" in post-CoA repair may help guide management. JOURNAL SUBJECT CODES: High Blood Pressure; Hypertension; Magnetic Resonance Imaging (MRI); Cardiovascular Surgery; Cerebrovascular Malformations.

Is High Blood Pressure Self-Protection for the Brain?

RATIONALE: Data from animal models of hypertension indicate that high blood pressure may develop as a vital mechanism to maintain adequate blood flow to the brain. We propose that congenital vascular variants of the posterior cerebral circulation and cerebral hypoperfusion could partially explain the pathogenesis of essential hypertension, which remains enigmatic in 95% of patients. OBJECTIVE: To evaluate the role of the cerebral circulation in the pathophysiology of hypertension. METHODS AND RESULTS: We completed a series of retrospective and mechanistic case-control magnetic resonance imaging and physiological studies in normotensive and hypertensive humans (n=259). Interestingly, in humans with hypertension, we report a higher prevalence of congenital cerebrovascular variants; vertebral artery hypoplasia, and an incomplete posterior circle of Willis, which were coupled with increased cerebral vascular resistance, reduced cerebral blood flow, and a higher incidence of lacunar type infarcts. Causally, cerebral vascular resistance was elevated before the onset of hypertension and elevated sympathetic nerve activity (n=126). Interestingly, untreated hypertensive patients (n=20) had a cerebral blood flow similar to age-matched controls (n=28). However, participants receiving antihypertensive therapy (with blood pressure controlled below target levels) had reduced cerebral perfusion (n=19). Finally, elevated cerebral vascular resistance was a predictor of hypertension, suggesting that it may be a novel prognostic or diagnostic marker (n=126). CONCLUSIONS: Our data indicate that congenital cerebrovascular variants in the posterior circulation and the associated cerebral hypoperfusion may be a factor in triggering hypertension. Therefore, lowering blood pressure may worsen cerebral perfusion in susceptible individuals.

Hypertensive heart disease versus hypertrophic cardiomyopathy: multi-parametric cardiovascular magnetic resonance discriminators when end-diastolic wall thickness ≥ 15 mm.

OBJECTIVES: European guidelines state left ventricular (LV) end-diastolic wall thickness (EDWT) ≥15mm suggests hypertrophic cardiomyopathy (HCM), but distinguishing from hypertensive heart disease (HHD) is challenging. We identify cardiovascular magnetic resonance (CMR) predictors of HHD over HCM when EDWT ≥15mm. METHODS: 2481 consecutive clinical CMRs between 2014 and 2015 were reviewed. 464 segments from 29 HCM subjects with EDWT ≥15mm but without other cardiac abnormality, hypertension or renal impairment were analyzed. 432 segments from 27 HHD subjects with EDWT ≥15mm but without concomitant cardiac pathology were analyzed. Magnitude and location of maximal EDWT, presence of late gadolinium enhancement (LGE), LV asymmetry (>1.5-fold opposing segment) and systolic anterior motion of the mitral valve (SAM) were measured. Multivariate logistic regression was performed. Significance was defined as p<0.05. RESULTS: HHD and HCM cohorts were age-/gender-matched. HHD had significantly increased indexed LV mass (110±27g/m2 vs. 91±31g/m2, p=0.016) but no difference in site or magnitude of maximal EDWT. Mid-wall LGE was significantly more prevalent in HCM. Elevated indexed LVM, mid-wall LGE and absence of SAM were significant multivariate predictors of HHD, but LV asymmetry was not. CONCLUSIONS: Increased indexed LV mass, absence of mid-wall LGE and absence of SAM are better CMR discriminators of HHD from HCM than EDWT ≥15mm. KEY POINTS: • Hypertrophic cardiomyopathy (HCM) is often diagnosed with end-diastolic wall thickness ≥15mm. • Hypertensive heart disease (HHD) can be difficult to distinguish from HCM. • Retrospective case-control study showed that location and magnitude of EDWT are poor discriminators. • Increased left ventricular mass and midwall fibrosis are independent predictors of HHD. • Cardiovascular magnetic resonance parameters facilitate a better discrimination between HHD and HCM.

Deep brain stimulation for the treatment of resistant hypertension.

Hypertension is a leading risk factor for the development of several cardiovascular diseases. As the global prevalence of hypertension increases, so too has the recognition of resistant hypertension. Whilst figures vary, the proportion of hypertensive patients that are resistant to multiple drug therapies have been reported to be as high as 16.4 %. Resistant hypertension is typically associated with elevated sympathetic activity and abnormal homeostatic reflex control and is termed neurogenic hypertension because of its presumed central autonomic nervous system origin. This resistance to conventional pharmacological treatment has stimulated a plethora of medical devices to be investigated for use in hypertension, with varying degrees of success. In this review, we discuss a new therapy for drug-resistant hypertension, deep brain stimulation. The utility of deep brain stimulation in resistant hypertension was first discovered in patients with concurrent neuropathic pain, where it lowered blood pressure and improved baroreflex sensitivity. The most promising central target for stimulation is the ventrolateral periaqueductal gray, which has been well characterised in animal studies as a control centre for autonomic outflow. In this review, we will discuss the promise and potential mechanisms of deep brain stimulation in the treatment of severe, resistant hypertension.

Carotid body dysregulation contributes to Long COVID symptoms.

BACKGROUND: The symptoms of long COVID, which include fatigue, breathlessness, dysregulated breathing, and exercise intolerance, have unknown mechanisms. These symptoms are also observed in heart failure and are partially driven by increased sensitivity of the carotid chemoreflex. As the carotid body has an abundance of ACE2 (the cell entry mechanism for SARS-CoV-2), we investigated whether carotid chemoreflex sensitivity was elevated in participants with long COVID. METHODS: Non-hositalised participants with long-COVID (n = 14) and controls (n = 14) completed hypoxic ventilatory response (HVR; the measure of carotid chemoreflex sensitivity) and cardiopulmonary exercise tests. Parametric and normally distributed data were compared using Student's unpaired t-tests or ANOVA. Nonparametric equivalents were used where relevant. Peason's correlation coefficient was used to examine relationships between variables. RESULTS: During cardiopulmonary exercise testing the VE/VCO2 slope (a measure of breathing efficiency) was higher in the long COVID group (37.8 ± 4.4) compared to controls (27.7 ± 4.8, P = 0.0003), indicating excessive hyperventilation. The HVR was increased in long COVID participants (-0.44 ± 0.23 l/min/ SpO2%, R2 = 0.77 ± 0.20) compared to controls (-0.17 ± 0.13 l/min/SpO2%, R2 = 0.54 ± 0.38, P = 0.0007). The HVR correlated with the VE/VCO2 slope (r = -0.53, P = 0.0036), suggesting that excessive hyperventilation may be related to carotid body hypersensitivity. CONCLUSIONS: The carotid chemoreflex is sensitised in long COVID and may explain dysregulated breathing and exercise intolerance in these participants. Tempering carotid body excitability may be a viable treatment option for long COVID patients.

Patients with long COVID suffer from breathlessness during exercise, leading to exercise intolerance. We know that SARS-CoV-2, the virus that causes COVID-19, can infect carotid bodies which is a small sensory organ that sends signals to the brain for regulating breathing and blood pressure. This is called the carotid chemoreflex. However, it is not clear if SARS-CoV-2 infection affects carotid chemoreflex. Here, we examine whether the normal functioning of carotid chemoreflex is disrupted in non-hospitalised patients with long COVID and if this is linked to excessive breathing during exercise. Our study shows that carotid chemoreflex is more sensitive in long COVID patients, who are otherwise healthy. The carotid bodies could be a good therapeutic target for treating breathlessness in patients with long COVID.

Chemohypersensitivity and autonomic modulation of venous capacitance in the pathophysiology of acute decompensated heart failure.

Heart failure is increasing in prevalence around the world, with hospitalization and re-hospitalization as a result of acute decompensated heart failure (ADHF) presenting a huge social and economic burden. The mechanism for this decompensation is not clear. Whilst in some cases it is due to volume expansion, over half of patients with an acute admission for ADHF did not experience an increase in total body weight. This calls into question the current treatment strategy of targeting salt and water retention in ADHF. An alternative hypothesis proposed by Fallick et al. is that an endogenous fluid shift from the splanchnic bed is implicated in ADHF, rather than an exogenous fluid gain. The hypothesis states further that this shift is triggered by an increase in sympathetic tone causing vasoconstriction in the splanchnic bed, a mechanism that can translocate blood rapidly into the effective circulating volume, generating the raised venous pressure and congestion seen in ADHF. This hypothesis encourages a new clinical paradigm which focuses on the underlying mechanisms of congestion, and highlights the importance of fluid redistribution and neurohormonal activation in its pathophysiology. In this article, we consider the concept that ADHF is attributable to episodic sympathetic hyperactivity, resulting in fluid shifts from the splanchnic bed. Chemosensitivity is a pathologic autonomic mechanism associated with mortality in patients with systolic heart failure. Tonic and episodic activity of the peripheral chemoreceptors may underlie the syndrome of acute decompensation without total body salt and water expansion. We suggest in this manuscript that chemosensitivity in response to intermittent hypoxia, such as experienced in sleep disordered breathing, may explain the intermittent sympathetic hyperactivity underlying renal sodium retention and acute volume redistribution from venous storage sites. This hypothesis provides an alternative structure to guide novel diagnostic and treatment strategies for ADHF.

Ventilatory Efficiency Is Reduced in People With Hypertension During Exercise.

Background An elevated ventilatory efficiency slope during exercise (minute ventilation/volume of expired CO2; VE/VCO2 slope) is a strong prognostic indicator in heart failure. It is elevated in people with heart failure with preserved ejection, many of whom have hypertension. However, whether the VE/VCO2 slope is also elevated in people with primary hypertension versus normotensive individuals is unknown. We hypothesize that there is a spectrum of ventilatory inefficiency in cardiovascular disease, reflecting an increasingly abnormal physiological response to exercise. The aim of this study was to evaluate the VE/VCO2 slope in patients with hypertension compared with age-, peak oxygen consumption-, and sex-matched healthy subjects. Methods and Results Ramped cardiovascular pulmonary exercise tests to peak oxygen consumption were completed on a bike ergometer in 55 patients with primary hypertension and 24 normotensive controls. The VE/VCO2 slope was assessed from the onset of exercise to peak oxygen consumption. Data were compared using unpaired Student t test. Age (mean±SD, 66±6 versus 64±6 years; P=0.18), body mass index (25.4±3.5 versus 24±2.4 kg/m2; P=0.13), and peak oxygen consumption (23.2±6.6 versus 24±7.3 mL/min per kg; P=0.64) were similar between groups. The VE/VCO2 slope was elevated in the hypertensive group versus controls (31.8±4.5 versus 28.4±3.4; P=0.002). Only 27% of the hypertensive group were classified as having a normal VE/VCO2 slope (20-30) versus 71% in the control group. Conclusions Ventilatory efficiency is impaired people with hypertension without a diagnosis of heart failure versus normotensive individuals. Future research needs to establish whether those patients with hypertension with elevated VE/VCO2 slopes are at risk of developing future heart failure.

Cerebrovascular Variants and the Role of the Selfish Brain in Young-Onset Hypertension.

BACKGROUND: Variants in the posterior anatomy of the cerebral circulation are associated with hypertension and lower cerebral blood flow in midlife (age ≈55 years); however, whether these variants are a result of aging or long-term exposure to high blood pressure is unclear. Additionally, the role these variants play in early onset of hypertension (<40 years) and poor cerebral perfusion in this population is unknown. METHODS: We retrospectively examined whether specific cerebrovascular variants (vertebral artery hypoplasia and absent/hypoplastic posterior communicating arteries (an incomplete posterior circle of Willis) measured via magnetic resonance angiography) were associated with a diagnosis of hypertension in 220 young adults (<40 years; n=164 primary hypertensive [mean age±SD, 32±6 years] and n=56 [30±6 years] normotensive adults). Whether cerebrovascular variants were associated with lower cerebral blood flow (phase-contrast angiography) was measured in the hypertensive group only (n=146). RESULTS: Binary logistic regression (adjusted for age, sex, and body mass index) showed that vertebral artery hypoplasia with an incomplete posterior circle of Willis was associated with hypertension diagnosis (P<0.001, odds ratio; 11.79 [95% CI, 3.34-41.58]). Vertebral artery hypoplasia plus an incomplete circle of Willis was associated with lower cerebral blood flow in young adults with hypertension (P=0.0172). CONCLUSIONS: Vertebral artery hypoplasia plus an incomplete posterior circle of Willis independently predicts hypertension in young adults suggesting that this variant is not acquired with aging into midlife. Importantly this variant combination was associated with lower cerebral perfusion, which may have long-term consequences on cerebrovascular health in young adults with hypertension.

Sympathetic-transduction in untreated hypertension.

Transduction of muscle sympathetic nerve activity (MSNA) into vascular tone varies with age and sex. Older normotensive men have reduced sympathetic transduction so that a given level of MSNA causes less arteriole vasoconstriction. Whether sympathetic transduction is altered in hypertension (HTN) is not known. We investigated whether sympathetic transduction is impaired in untreated hypertensive men compared to normotensive controls. Eight untreated hypertensive men and 10 normotensive men (age 50 ± 15 years vs. 45 ± 12 years (mean ± SD); p = 0.19, body mass index (BMI) 24.7 ± 2.7 kg/m2 vs. 26.0 ± 4.2 kg/m2; p = 0.21) were recruited. MSNA was recorded from the peroneal nerve using microneurography; beat-to-beat blood pressure (BP; Finapres) and heart rate (ECG) were recorded simultaneously at rest for 10 min. Sympathetic-transduction was quantified using a previously described method. The relationship between MSNA burst area and subsequent diastolic BP was measured for each participant with the slope of the regression indicating sympathetic transduction. MSNA was higher in the hypertensive group compared to normotensives (73 ± 17 bursts/100 heartbeats vs. 49 ± 19 bursts/100 heart bursts; p = 0.007). Sympathetic-transduction was lower in the hypertensive versus normotensive group (0.04%/mmHg/s vs. 0.11%/mmHg/s, respectively; R = 0.622; p = 0.006). In summary, hypertensive men had lower sympathetic transduction compared to normotensive individuals suggesting that higher levels of MSNA are needed to cause the same level of vasoconstrictor tone.

Prospective multiparametric CMR characterization and MicroRNA profiling of anthracycline cardiotoxicity: A pilot translational study.

Background: Anthracycline cardiotoxicity is a significant clinical challenge. Biomarkers to improve risk stratification and identify early cardiac injury are required. Objectives: The purpose of this pilot study was to prospectively characterize anthracycline cardiotoxicity using cardiovascular magnetic resonance (CMR), echocardiography and MicroRNAs (MiRNAs), and identify baseline predictors of LVEF recovery. Methods: Twenty-four patients (age 56 range 18-75 years; 42 % female) with haematological malignancy scheduled to receive anthracycline chemotherapy (median dose 272 mg/m2 doxorubicin equivalent) were recruited and evaluated at three timepoints (baseline, completion of chemotherapy, and 6 months after completion of chemotherapy) with multiparametric 1.5 T CMR, echocardiography and circulating miRNAs sequencing. Results: Seventeen complete datasets were obtained. CMR left ventricular ejection fraction (LVEF) fell significantly between baseline and completion of chemotherapy (61 ± 3 vs 53 ± 3 %, p < 0.001), before recovering significantly at 6-month follow-up (55 ± 3 %, p = 0.018). Similar results were observed for 3D echocardiography-derived LVEF and CMR-derived longitudinal, circumferential and radial feature-tracking strain. Patients were divided into tertiles according to LVEF recovery (poor recovery, partial recovery, good recovery). CMR-derived mitral annular plane systolic excursion (MAPSE) was significantly different at baseline in patients exhibiting poor LVEF recovery (11.7 ± 1.5 mm) in comparison to partial recovery (13.7 ± 2.7 mm), and good recovery (15.7 ± 3.1 mm; p = 0.028). Furthermore, baseline miRNA-181-5p and miRNA-221-3p expression were significantly higher in this group. T2 mapping increased significantly on completion of chemotherapy compared to baseline (54.0 ± 4.6 to 57.8 ± 4.9 ms, p = 0.001), but was not predictive of LVEF recovery. No changes to LV mass, extracellular volume fraction, T1 mapping or late gadolinium enhancement were observed. Conclusions: Baseline CMR-derived MAPSE, circulating miRNA-181-5p, and miRNA-221-3p were associated with poor recovery of LVEF 6 months after completion of anthracycline chemotherapy, suggesting their potential predictive role in this context. T2 mapping increased significantly on completion of chemotherapy but was not predictive of LVEF recovery.

The corrected left ventricular ejection fraction: a potential new measure of ventricular function.

Left ventricular ejection fraction (LVEF) has a limited role in predicting outlook in heart diseases including heart failure. We quantified the independent geometric factors that determine LVEF using cardiac MRI and sought to provide an improved measure of ventricular function by adjusting for such independent variables. A mathematical model was used to analyse the independent effects of structural variables and myocardial shortening on LVEF. These results informed analysis of cardiac MRI data from 183 patients (53 idiopathic dilated cardiomyopathy (DCM), 36 amyloidosis, 55 hypertensives and 39 healthy controls). Left ventricular volumes, LVEF, wall thickness, internal dimensions and longitudinal and midwall fractional shortening were measured. The modelling demonstrated LVEF increased in a curvilinear manner with increasing mFS and longitudinal shortening and wall thickness but decreased with increasing internal diameter. Controls in the clinical cohort had a mean LVEF 64  ±  7%, hypertensives 66  ±  8%, amyloid 49 ±  16% and DCM 30  ±  11%. The mean end-diastolic wall thickness in controls was 8  ±  1 mm, DCM 8  ±  1 mm, hypertensives 11  ±  3 mm and amyloid 14  ±  3 mm, P < 0.0001). LVEF correlated with absolute wall thickening relative to ventricular size (R2 = 0.766). A regression equation was derived from raw MRI data (R2 = 0.856) and used to 'correct' LVEF (EFc) by adjusting the wall thickness and ventricular size to the mean of the control group. Improved quantification of the effects of geometric changes and strain significantly enhances understanding the myocardial mechanics. The EFc resulted in reclassification of a 'ventricular function' in some individuals and may provide an improved measure of myocardial performance especially in thick-walled, low-volume ventricles.

Investigation and Treatment of High Blood Pressure in Young People: Too Much Medicine or Appropriate Risk Reduction?

Hypertension among young people is common, affecting 1 in 8 adults aged between 20 and 40 years. This number is likely to increase with lifestyle behaviors and lowering of hypertension diagnostic thresholds. Early-life factors influence blood pressure (BP) although the mechanisms are unclear; BP tracks strongly within individuals from adolescence through to later life. Higher BP at a young age is associated with abnormalities on heart and brain imaging and increases the likelihood of cardiovascular events by middle age. However, diagnosis rates are lower, and treatment is often delayed in young people. This reflects the lack of high-quality evidence that lowering BP in young adults improves cardiovascular outcomes later in life. In this review, we evaluate the current evidence regarding the association between BP in young adult life and adverse cardiovascular outcomes later in life. Following this, we discuss which young people with raised BP should be investigated for secondary causes of hypertension. Third, we assess the current models to assess cardiovascular risk and show a lack of validation in the younger age group. Fourth, we evaluate the evidence for lifestyle interventions in this age group and demonstrate a lack of persistence in BP lowering once the initial intervention has been delivered. Fifth, we address the pros and cons of drug treatment for raised BP in young people. Finally, there are unique life events in young people, such as pregnancy, that require specific advice on management and treatment of BP.

Cerebral Blood Flow Response to Simulated Hypovolemia in Essential Hypertension: A Magnetic Resonance Imaging Study.

Hypertension is associated with raised cerebral vascular resistance and cerebrovascular remodeling. It is currently unclear whether the cerebral circulation can maintain cerebral blood flow (CBF) during reductions in cardiac output (CO) in hypertensive patients thereby avoiding hypoperfusion of the brain. We hypothesized that hypertension would impair the ability to effectively regulate CBF during simulated hypovolemia. In the present study, 39 participants (13 normotensive, 13 controlled, and 13 uncontrolled hypertensives; mean age±SD, 55±10 years) underwent lower body negative pressure (LBNP) at -20, -40, and -50 mmHg to decrease central blood volume. Phase-contrast MR angiography was used to measure flow in the basilar and internal carotid arteries, as well as the ascending aorta. CBF and CO decreased during LBNP (P<0.0001). Heart rate increased during LBNP, reaching significance at -50 mmHg (P<0.0001). There was no change in mean arterial pressure during LBNP (P=0.3). All participants showed similar reductions in CBF (P=0.3, between groups) and CO (P=0.7, between groups) during LBNP. There was no difference in resting CBF between the groups (P=0.36). In summary, during reductions in CO induced by hypovolemic stress, mean arterial pressure is maintained but CBF declines indicating that CBF is dependent on CO in middle-aged normotensive and hypertensive volunteers. Hypertension is not associated with impairments in the CBF response to reduced CO.

Vitamin D(2) supplementation induces the development of aortic stenosis in rabbits: interactions with endothelial function and thioredoxin-interacting protein.

Understanding of the pathophysiology of aortic valve stenosis (AVS) and finding potentially effective treatments are impeded by the lack of suitable AVS animal models. A previous study demonstrated the development of AVS in rabbits with vitamin D(2) and cholesterol supplementation without any hemodynamic changes in the cholesterol supplemented group alone. The current study aimed to determine whether AVS develops in an animal model with vitamin D(2) supplementation alone, and to explore pathophysiological mechanisms underlying this process. The effects of 8 weeks' treatment with vitamin D(2) alone (n=8) at 25,000 IU/4 days weekly on aortic valve structure and function were examined in male New Zealand white rabbits. Echocardiographic aortic valve backscatter (AV(BS)), transvalvular velocity, and transvalvular pressure gradient were utilized to quantitate changes in valve structure and function. Valvular histology/immunochemistry and function were examined after 8 weeks. Changes in valves were compared with those in endothelial function and in valvular measurement of thioredoxin-interacting protein (TXNIP), a marker/mediator of reactive oxygen species-induced oxidative stress. Vitamin D(2) treated rabbits developed AVS with increased AV(BS) (17.6+/-1.4 dB vs 6.7+/-0.8 dB, P<0.0001), increased transvalvular velocity and transvalvular pressure gradient (both P<0.01 via 2-way ANOVA) compared to the control group. There was associated valve calcification, lipid deposition and macrophage infiltration. Endothelial function was markedly impaired, and intravalvular TXNIP concentration increased. In this model, vitamin D(2) induces the development of AVS with histological features similar to those of early AVS in humans and associated endothelial dysfunction/redox stress. AVS development may result from the loss of nitric oxide suppression of TXNIP expression.

Antihypertensive Treatment Fails to Control Blood Pressure During Exercise.

An exaggerated blood pressure (BP) response to maximal exercise is an independent risk factor for cardiovascular events and mortality. It is unclear whether treating BP to guideline recommended levels could normalize the rise in BP during exercise, which is mediated by the metaboreflex. We aimed to assess the BP response to incremental exercise testing and metaboreflex activation in treated-controlled hypertension (n=16), treated-uncontrolled hypertension (n=16), and untreated hypertension (n=11) and 16 control participants with normal BP (n=16). All groups were matched for age and body mass index. BP was measured during an incremental Vo2 peak test on a cycle ergometer and during metaboreflex isolation using postexercise ischemia. Data were analyzed using 2-way ANOVA with Tukey test for multiple comparisons. Aerobic fitness was similar among groups (P=0.97). The rise in absolute systolic BP from baseline at peak exercise was similar in controlled, uncontrolled, and untreated hypertension but greater compared with normotensive controls (Δ71±3, 81±7, 79±8.5 versus 47±5 mm Hg; P=0.0001). Metaboreflex sensitivity was also similar in controlled, uncontrolled, and untreated hypertension but augmented compared with normotensive controls (Δsystolic BP: 21±2, 28±2, 25±3 versus 12±2 mm Hg; P<0.0001). An amplified pressor response to exercise occurred in patients taking antihypertensive medication, despite having controlled BP at rest and was potentially caused (in part) by enhanced metaboreflex sensitivity. Poor BP control during exercise, partially mediated by the metaboreflex, may contribute to the heightened risk of an adverse cardiovascular event even in treated-controlled patients.

Noctural dipping status and left ventricular hypertrophy: A cardiac magnetic resonance imaging study.

We investigate the impact of dipper status on cardiac structure with cardiovascular magnetic resonance (CMR). Ambulatory blood pressure monitoring and 1.5T CMR were performed in 99 tertiary hypertension clinic patients. Subgroup analysis by extreme dipper (n = 9), dipper (n = 39), non-dipper (n = 35) and reverse dipper (n = 16) status was performed, matched in age, gender and BMI. Left ventricular (LV) mass was significantly higher for extreme dippers than dippers after correction for covariates (100 ± 6 g/m2 vs 79 ± 3 g/m2 , P = .004). Amongst extreme dippers and dippers (n = 48), indexed LV mass correlated positively with the extent of nocturnal blood pressure dipping (R = .403, P = .005). On post-hoc ANCOVA, the percentage of nocturnal dip had significant effect on indexed LV mass (P = .008), but overall SBP did not (P = .348). In the tertiary setting, we found a larger nocturnal BP drop was associated with more LV hypertrophy. If confirmed in larger studies, this may have implications on nocturnal dosing of anti-hypertensive medications.

B-type natriuretic peptide-guided therapy for heart failure (HF): a systematic review and meta-analysis of individual participant data (IPD) and aggregate data.

BACKGROUND: We estimated the effectiveness of serial B-type natriuretic peptide (BNP) blood testing to guide up-titration of medication compared with symptom-guided up-titration of medication in patients with heart failure (HF). METHODS: Systematic review and meta-analysis of randomised controlled trials (RCTs). We searched: MEDLINE (Ovid) 1950 to 9/06/2016; Embase (Ovid), 1980 to 2016 week 23; the Cochrane Library; ISI Web of Science (Citations Index and Conference Proceedings). The primary outcome was all-cause mortality; secondary outcomes were death related to HF, cardiovascular death, all-cause hospital admission, hospital admission for HF, adverse events, and quality of life. IPD were sought from all RCTs identified. Random-effects meta-analyses (two-stage) were used to estimate hazard ratios (HR) and confidence intervals (CIs) across RCTs, including HR estimates from published reports of studies that did not provide IPD. We estimated treatment-by-covariate interactions for age, gender, New York Heart Association (NYHA) class, HF type; diabetes status and baseline BNP subgroups. Dichotomous outcomes were analysed using random-effects odds ratio (OR) with 95% CI. RESULTS: We identified 14 eligible RCTs, five providing IPD. BNP-guided therapy reduced the hazard of hospital admission for HF by 19% (13 RCTs, HR 0.81, 95% CI 0.68 to 0.98) but not all-cause mortality (13 RCTs; HR 0.87, 95% CI 0.75 to 1.01) or cardiovascular mortality (5 RCTs; OR 0.88, 95% CI 0.67 to 1.16). For all-cause mortality, there was a significant interaction between treatment strategy and age (p = 0.034, 11 RCTs; HR 0.70, 95% CI 0.53-0.92, patients < 75 years old and HR 1.07, 95% CI 0.84-1.37, patients ≥ 75 years old); ejection fraction (p = 0.026, 11 RCTs; HR 0.84, 95% CI 0.71-0.99, patients with heart failure with reduced ejection fraction (HFrEF); and HR 1.33, 95% CI 0.83-2.11, patients with heart failure with preserved ejection fraction (HFpEF)). Adverse events were significantly more frequent with BNP-guided therapy vs. symptom-guided therapy (5 RCTs; OR 1.29, 95% CI 1.04 to 1.60). CONCLUSION: BNP-guided therapy did not reduce mortality but reduced HF hospitalisation. The overall quality of the evidence varied from low to very low. The relevance of these findings to unselected patients, particularly those managed by community generalists, are unclear. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42013005335.