Arterial stiffness and wave reflections in patients with sickle cell disease

Impact of relative systemic hypertension on the heart in sickle cell anaemia

Sickle cell anaemia (SCA) is associated with macrovascular complications at relatively normal blood pressures. This has led to the development of the term 'relative systemic hypertension' (RSH). The electrocardiography (ECG) and echocardiography (ECHO) findings in these people has not been well highlighted. Patients with SCA in steady state were consecutively recruited. History, physical examination, ECG and ECHO information were obtained from all participants after informed consent was obtained. Eighty-three people were recruited in all- 15 of which had RSH, giving a prevalence of 18.1%. Those with RSH had higher packed cell volumes (PCV), smaller right atria area, lower tricuspid regurgitant velocities, lower incidence of early satiety, longer QTc and higher frequency of a history of vaso-occlusive crises. The indices of right and left ventricular function were normal in both groups. Right atrial area was the only significant determinant of RSH in this study. RSH is associated with higher PCV, longer QTc and smaller right atrial area in SCA patients. More studies to evaluate sympathetic output in SCA with RSH is required.

Unmasking hypertension in children and adolescents with sickle/beta-thalassemia

Sickle cell disease (SCD) is associated with increased risk of cardiovascular disease, although blood pressure (BP) levels have been reported to be lower in SCD patients compared to general population. Aims of the present study were to investigate the prevalence of BP phenotypes and levels of arterial stiffness in pediatric patients with SCD and to assess the differences with children at risk for hypertension. We included in the study 16 pediatric SCD (HbS/β-thalassemia, S/β-thal) patients and 16 consecutive children at risk for hypertension referred to our hypertension clinic that served as high-risk controls. All patients underwent ambulatory BP monitoring and measurement of carotid-femoral pulse wave velocity (PWV). S/β-thal patients had lower office systolic BP than the high-risk control group (115.43 ± 10.03 vs 123.37 ± 11.92, P = .05) but presented similar levels of day and night ambulatory BP. Office hypertension was found in 12.5% of the S/β-thal patients and in 43.8% of the high-risk controls (P = .06), while 18.8% of the S/β-thal patients and 25% of the high-risk controls presented hypertension by ambulatory BP levels (P = .21). All of the S/β-thal patients with ambulatory hypertension had night hypertension (one combined night and day hypertension) with office normotension (masked hypertension). S/β-thal patients and high-risk controls presented equal prevalence of masked hypertension (18.8%). Children and adolescents with S/β-thal present similar prevalence of BP phenotypes and levels of PWV with children at risk for hypertension. A significant number of children and adolescents with S/β-thal may have masked nighttime hypertension despite normal office BP levels.

Prevalence and determinants of blood pressure variability in pygmies of Southern region Cameroon

INTRODUCTION

The impact of urbanization and living conditions on the prevalence of hypertension in the Cameroonian population is poorly known.

AIM

To evaluate the prevalence and determinants of blood pressure (BP) in adult Pygmies and Bantus living in urban and rural areas of Southern Cameroon.

PARTICIPANTS AND METHODS

This was a cross-sectional comparative study of 406 adults (96 urban Bantus, 100 urban Pygmies, 111 rural Bantus and 99 tropical rainforest Pygmies with a traditional Pygmies way of life), recruited in Southern Cameroon (mean age 42 ± 17 years; 56.7% women). Sociodemographic, anthropometric and BP parameters were collected. Hypertension was defined as BP at least 140/90 mmHg and/or use of BP-lowering drug(s).

RESULTS

The age-standardized prevalence of hypertension in urban Bantus, rural Bantus, urban Pygmies and traditional Pygmies was 18.0, 13.5, 9.3 and 4.1%, respectively. Mean SBP and DBP differed significantly according to Bantu vs. Pygmy ethnicity, and urban vs. rural residency. After multiple adjustments, mean arterial pressure was significantly associated with age, BMI, Bantu ancestry and urban residency.

CONCLUSION

Bantu ethnicity and urban residency are significantly associated with high-BP among people from Southern Cameroon.

Sickle Cell Anemia Mediates Carotid Artery Expansive Remodeling That Can Be Prevented by Inhibition of JNK (c-Jun N-Terminal Kinase)

OBJECTIVE

Sickle cell anemia (SCA) causes chronic inflammation and multiorgan damage. Less understood are the arterial complications, most evident by increased strokes among children. Proteolytic mechanisms, biomechanical consequences, and pharmaceutical inhibitory strategies were studied in a mouse model to provide a platform for mechanistic and intervention studies of large artery damage due to sickle cell disease. Approach and Results: Townes humanized transgenic mouse model of SCA was used to test the hypothesis that elastic lamina and structural damage in carotid arteries increased with age and was accelerated in mice homozygous for SCA (sickle cell anemia homozygous genotype [SS]) due to inflammatory signaling pathways activating proteolytic enzymes. Elastic lamina fragmentation observed by 1 month in SS mice compared with heterozygous littermate controls (sickle cell trait heterozygous genotype [AS]). Positive immunostaining for cathepsin K, a powerful collagenase and elastase, confirmed accelerated proteolytic activity in SS carotids. Larger cross-sectional areas were quantified by magnetic resonance angiography and increased arterial compliance in SS carotids were also measured. Inhibiting JNK (c-jun N-terminal kinase) signaling with SP600125 significantly reduced cathepsin K expression, elastin fragmentation, and carotid artery perimeters in SS mice. By 5 months of age, continued medial thinning and collagen degradation was mitigated by treatment of SS mice with JNK inhibitor.

CONCLUSIONS

Arterial remodeling due to SCA is mediated by JNK signaling, cathepsin proteolytic upregulation, and degradation of elastin and collagen. Demonstration in Townes mice establishes their utility for mechanistic studies of arterial vasculopathy, related complications, and therapeutic interventions for large artery damage due to SCA.

Ultrasound Detection of Abnormal Cerebrovascular Morphology in a Mouse Model of Sickle Cell Disease Based on Wave Reflection

Sickle cell disease (SCD) is associated with a high risk of stroke, and affected individuals often have focal brain lesions termed silent cerebral infarcts. The mechanisms leading to these types of injuries are at present poorly understood. Our group has recently demonstrated a non-invasive measurement of cerebrovascular impedance and wave reflection in mice using high-frequency ultrasound in the common carotid artery. To better understand the pathophysiology in SCD, we used this approach in combination with micro-computed tomography to investigate changes in cerebrovascular morphology in the Townes mouse model of SCD. Relative to controls, the SCD mice demonstrated the following: (i) increased carotid artery diameter, blood flow and vessel wall thickness; (ii) elevated pulse wave velocity; (iii) increased reflection coefficient; and (iv) an increase in the total number of vessel segments in the brain. This study highlights the potential for wave reflection to aid the non-invasive clinical assessment of vascular pathology in SCD.

Arterial stiffness in black African ancestry patients with chronic kidney disease living in Cameroon

Background

Increased aortic pulse wave velocity (PWV), a direct measure of arterial stiffness (AS) is an independent predictor of cardiovascular events (CVEs) in chronic kidney disease (CKD) patients. This study assessed the patterns of PWV among Cameroonian patients with CKD in whom that marker of early vascular aging has not been explored so far.

Methods

We enrolled 150 Black African patients (mean age: 52±15 years, 56.7% males) with CKD in a cross-sectional study conducted at Douala General Hospital, Douala, Cameroon. Sociodemographic, anthropometric and biologic variables, blood pressure (BP) and PWV were recorded in all participants. Estimated aortic PWV was measured using a Mobil-O-Graph automatic brachial oscillometric device.

Results

PWV increased with aging (P<0.0001), and PWV adjusted for age, sex, body mass index and mean arterial BP (MAP) was higher in non-dialysed (n=90) than in hemodialysed (n=60) patients, even in pre-dialysis: 8.5±2.0 vs. 7.9±1.4 m/s (P=0.026); and in post-dialysis: 8.5±2.0 vs. 7.8±1.5 m/s (P=0.008). The mean PWV of all study participants was 8.2±1.8 m/s, with 61.3% of patients having a PWV ≥8.2 m/s, indicative of subclinical damage to the aorta, which was more pronounced in non-dialysis (67.8%) than in hemodialysis (53.3%) patients (P=0.033). Multivariable analysis performed in all participants revealed that advanced age, MAP and tobacco use were independently associated with PWV (all P<0.05).

Conclusions

Our findings suggest increased AS in Cameroonian CKD non-dialyzed as compared to dialyzed patients. Slower PWV in patients on maintenance hemodialysis suggests improvement of aortic distensibility following dialysis. However, further large-scale studies are needed to confirm our findings and to improve understanding of the underlying mechanisms of arterial stiffening in black African ancestry patients with CKD.

Pulse wave velocity is lower in trained than in untrained sickle cell trait carriers

BACKGROUND

Sickle cell trait (SCT) is a benign condition of sickle cell disease. Nevertheless, previous reports showed that SCT carriers have increased blood viscosity and decreased vascular reactivity compared to non-SCT carrier. The benefit of regular exercise on vascular function has been well documented in the general population but no study focused on the SCT population.

PURPOSE

The aim of our study was to compare arterial stiffness and blood viscosity between trained and untrained SCT carriers, as well as a group of untrained non-SCT.

METHODS

Arterial stiffness (finger-toe pulse wave velocity) and blood viscosity were evaluated in untrained non-SCT carriers (n = 10), untrained SCT carriers (n = 23) and trained SCT carriers (n = 17) who reported at least 10 hours of physical exercise per week.

RESULTS

Untrained SCT carriers had higher pulse wave velocity (p = 0.032) and blood viscosity (p < 0.001) than their trained counterparts. In addition, untrained SCT carriers had higher blood viscosity (p < 0.001) than the untrained non-SCT group. A positive association was noted between blood viscosity and pulse wave velocity in the whole study population.

CONCLUSION

Our study suggests that regular exercise may be beneficial for the vascular function of SCT carriers.

[Impact of sickle cell trait on arterial stiffness in African subjects]

Sickle cell trait (SCT) is the benign condition of sickle cell disease. Often asymptomatic, the carriers of the sickle cell trait have hemorheological disturbances with increased oxidative stress compared to healthy subjects. These disturbances can lead to structural and functional changes in large vessels. The aim of the study was to measure arterial stiffness, an independent marker of subclinical atherosclerosis, SCT carriers compared to sickle cell anemia (SCA) subjects. Nine SCT carriers aged 32±9 years (7 men) were compared to 14 SCA subjects aged 29±9 years (2 men) and 22 control subjects aged 34±9 years (11 men) recruited by the National blood transfusion center (CNTS) in Dakar (Senegal). Arterial stiffness was assessed by measurement of the finger-toe pulse wave velocity (PWVft) using pOpmètre^® (Axelife SAS-France). The cardiovascular risk (CVR) was assessed according to the Framingham Laurier score. The SCT carriers had a higher PWVft (m/s) than SCA subjects (8.2±2.2 vs 6.1±0.9m/s, P=0.004) but not different from that of healthy controls (8.2±2.2 vs 7.4±1.8m/s, P=0.33). Linear regression showed a positive relationship between PWVft and the pulse pressure (PP) (P˂0.001; r²=0.39; F=13.20). The results show that the SCT carriers have stiffer arteries than SCA subjects. Linear regressions adjusted for age, mean arterial pressure (MAP) and PP, showed that only age and PP were independently correlated with arterial stiffness in the entire population.

Central Hemodynamics for Management of Arteriosclerotic Diseases

Arteriosclerosis, particularly aortosclerosis, is the most critical risk factor associated with cardiovascular, cerebrovascular, and renal diseases. The pulsatile hemodynamics in the central aorta consists of blood pressure, flow, and stiffness and substantially differs from the peripheral hemodynamics in muscular arteries. Arteriosclerotic changes with age appear earlier in the elastic aorta, and age-dependent increases in central pulse pressure are more marked than those apparent from brachial pressure measurement. Central pressure can be affected by lifestyle habits, metabolic disorders, and endocrine and inflammatory diseases in a manner different from brachial pressure. Central pulse pressure widening due to aortic stiffening increases left ventricular afterload in systole and reduces coronary artery flow in diastole, predisposing aortosclerotic patients to myocardial hypertrophy and ischemia. The widened pulse pressure is also transmitted deep into low-impedance organs such as the brain and kidney, causing microvascular damage responsible for lacunar stroke and albuminuria. In addition, aortic stiffening increases aortic blood flow reversal, which can lead to retrograde embolic stroke and renal function deterioration. Central pressure has been shown to predict cardiovascular events in most previous studies and potentially serves as a surrogate marker for intervention. Quantitative and comprehensive evaluation of central hemodynamics is now available through various noninvasive pressure/flow measurement modalities. This review will focus on the clinical usefulness and mechanistic rationale of central hemodynamic measurements for cardiovascular risk management.

Arterial Stiffness Impairment in Sickle Cell Disease Associated With Chronic Vascular Complications

Background:

Although a blood genetic disease, sickle cell disease (SCD) leads to a chronic vasculopathy with multiple organ involvement. We assessed arterial stiffness in SCD patients and looked for associations between arterial stiffness and SCD-related vascular complications.

Methods:

The CADRE (Coeur Artères et Drepanocytose, ie, Heart Arteries and Sickle Cell Disease) study prospectively recruited pediatric and adult SCD patients and healthy controls in Cameroon, Ivory Coast, Gabon, Mali, and Senegal. Patients underwent clinical examination, routine laboratory tests (complete blood count, serum creatinine level), urine albumin/creatinine ratio measure, and a measure of carotid-femoral pulse wave velocity (cf-PWV) and augmentation index (AI) at a steady state. The clinical and biological correlates of cf-PWV and AI were investigated by using a multivariable multilevel linear regression analysis with individuals nested in families further nested in countries.

Results:

Included were 3627 patients with SCD and 943 controls. Mean cf-PWV was lower in SCD patients (7.5±2.0 m/s) than in controls (9.1±2.4 m/s, P <0.0001), and lower in SS-Sβ 0 than in SC-Sβ + phenotypes. AI, corrected for heart rate, increased more rapidly with age in SCD patients and was higher in SCD than in control adults. cf-PWV and AI were independently associated with age, sex, height, heart rate, mean blood pressure, hemoglobin level, country, and hemoglobin phenotype. After adjustment for these correlates, cf-PWV and AI were associated with the glomerular filtration rate and osteonecrosis. AI was also associated with stroke, pulmonary hypertension, and priapism, and cf-PWV was associated with microalbuminuria.

Conclusions:

PWV and AI are deeply modified in SCD patients in comparison with healthy controls. These changes are independently associated with a lower blood pressure and a higher heart rate but also with the hemoglobin phenotype. Moreover, PWV and AI are associated with several SCD clinical complications. Their prognostic value will be assessed at follow-up of the patients.

Abnormalities in aortic properties: a potential link between left ventricular diastolic function and ventricular-aortic coupling in sickle cell disease

Left ventricular (LV) diastolic dysfunction in patients with sickle cell disease (SCD) is associated with increased mortality. However, its mechanisms are not well known, preventing the development of effective therapies. We hypothesized that patients with SCD have altered aortic properties despite normal blood pressure, which may contribute towards the development of diastolic dysfunction. We studied 31 stable adult patients with SCD (32 ± 7 years) and 12 healthy controls of similar age (29 ± 10 years) who underwent echocardiography and cardiovascular magnetic resonance (CMR) imaging on the same day. Echocardiographic measurements of mitral inflow and mitral annulus velocities were used to evaluate LV diastolic function. CMR imaging included standard LV function evaluation and myocardial tissue characterization as well as velocity-encoded images of the ascending aorta to measure aortic diastolic cross-sectional area, distensibility, as well as peaks and volumes of the global, forward and backward blood flow rate. Compared to controls, SCD patients had increased aortic diastolic area, global stroke volume, and both forward and backward flow, while aortic distensibility and peripheral blood pressure were similar. Furthermore, peak backward flow rate and volume were able to discriminate between patients with and without diastolic dysfunction. Our findings show that some aortic properties are altered in SCD patients and may be associated with diastolic dysfunction despite normal systolic blood pressure. If confirmed in larger studies, these aortic changes could be a novel therapeutic target to prevent or delay the development of LV diastolic dysfunction in SCD and thus potentially improve outcomes in these patients.

Arterial Stiffness and Peripheral and Central Blood Pressure in Patients With Sickle Cell Disease

Blood pressure (BP) in patients with sickle cell disease (SCD) has been reported to be lower than in persons in the general population. Data on arterial stiffness, which is an important risk factor for the progression of BP, are inconclusive for this patient population. Forty-five adult patients with SCD and 40 controls matched for sex, age, and body mass index were studied. Brachial systolic BP (SBP) and diastolic BP (DBP) were significantly lower in the patient group (SBP 115.1±13.8 mm Hg vs 121.9±11.3 mm Hg and DBP 68.5±8.0 mm Hg vs 80.6±9.1 mm Hg, P<.05, respectively). Augmentation index (AIx), however, was significantly higher in SCD patients compared with healthy controls (24.9±9.6 for patients vs 12.4±10.8 for controls, P<.001), while carotid femoral pulse wave velocity was comparable between the two groups. The study shows that mechanisms other than arterial elasticity are involved in the low BP phenotype of patients with SCD.

Circulating cell membrane microparticles transfer heme to endothelial cells and trigger vasoocclusions in sickle cell disease

Intravascular hemolysis describes the relocalization of heme and hemoglobin (Hb) from erythrocytes to plasma. We investigated the concept that erythrocyte membrane microparticles (MPs) concentrate cell-free heme in human hemolytic diseases, and that heme-laden MPs have a physiopathological impact. Up to one-third of cell-free heme in plasma from 47 patients with sickle cell disease (SCD) was sequestered in circulating MPs. Erythrocyte vesiculation in vitro produced MPs loaded with heme. In silico analysis predicted that externalized phosphatidylserine (PS) in MPs may associate with and help retain heme at the cell surface. Immunohistology identified Hb-laden MPs adherent to capillary endothelium in kidney biopsies from hyperalbuminuric SCD patients. In addition, heme-laden erythrocyte MPs adhered and transferred heme to cultured endothelial cells, inducing oxidative stress and apoptosis. In transgenic SAD mice, infusion of heme-laden MPs triggered rapid vasoocclusions in kidneys and compromised microvascular dilation ex vivo. These vascular effects were largely blocked by heme-scavenging hemopexin and by the PS antagonist annexin-a5, in vitro and in vivo. Adversely remodeled MPs carrying heme may thus be a source of oxidant stress for the endothelium, linking hemolysis to vascular injury. This pathway might provide new targets for the therapeutic preservation of vascular function in SCD.

Endothelial Function and Vascular Properties in Children with Sickle Cell Disease

BACKGROUND

Sickle cell disease (SCD) is an inherited disorder characterized by recurrent painful crises with ischemia resulting from vascular occlusion. Adults with SCD have increased arterial stiffness and reduced flow-mediated dilation (FMD), due to impaired release of substances such as nitric oxide.

AIM

We aimed to assess the vascular properties of carotid and brachial arteries in children with SCD compared with a control group without cardiovascular risk factors.

METHODS

Thirty patients with SCD, mean age 12.3 ± 4.5 years, were prospectively enrolled. A control group was made up of 30 age- and gender-matched healthy subjects. Carotid intima-media thickness (IMT), cross-sectional compliance (CSC), cross-sectional distensibility (CSD), diastolic wall stress (DWS), incremental elastic modulus (Einc), and FMD were determined in both groups.

RESULTS

There was no significant difference in FMD between the two groups (8.2 ± 5.0% in the SCD group vs. 9.3 ± 4.2% in the control group, P = 0.15). There was no significant correlation between FMD and age, hemoglobin, LDH level, or transcranial Doppler findings. CSD was significantly elevated in the SCD group (0.96 ± 0.44 vs. 0.59 ± 0.21, P = 0.0002), whereas DWS and Einc were significantly lower in the SCD group. CSC did not differ significantly between the two groups.

CONCLUSIONS

Children with SCD have no marked endothelial dysfunction or change in arterial stiffness. These manifestations may be related to disease severity and duration. Changes may become evident later in life as the disease progresses.

Paradoxical Distribution of Augmentation Index Level in Chronic Kidney Diseases

Pulse wave velocity (PWV) and augmentation index (AI) are used as indexes of arterial stiffness and cardiovascular survival. Although PWV is known to increase as the stage of chronic kidney disease (CKD) advances, how this is related to AI and CKD stage has not yet been well defined.

A sub-analysis was performed using the data from the Antihypertensive and Blood Pressure of Central Artery in Japan study. This was a cross-sectional study on hypertensive patients. All the patients with available serum creatinine levels were selected, and estimated glomerular filtration rate (eGFR) was calculated according to the modification of diet in renal disease equation for a Japanese population. Augmentation indexes at different stages of CKD were compared.

Data from 1392 patients were pooled and analyzed. In addition to eGFR, there were differences in age (P<0.0001), pulse rate (P<0.0001), vasodilator antihypertensive drugs (P<0.005), systolic (P<0.005) and diastolic (P<0.01) blood pressure at 5 CKD stages. Multivariate regression showed that AI correlated to age (0.19%/year), pulse rate (-0.54%/bpm), systolic blood pressure (0.18%/mmHg) and vasodilator antihypertensive drugs (-2.42%/class). Therefore, AI was adjusted for these confounding factors. Adjusted AI in stage 5 (77±20%) was lower than that in stage 1 (84±19%, P<0.05).

These data indicate that AI varies according to CKD stage, and suggest that a cut-off value of AI should be set for each stage of CKD to detect cardiovascular disease.

Arterial stiffness and pulse wave reflection in young adult heterozygous sickle cell carriers

Objective: Pulse wave velocity (PWV) and aortic augmentation index (AI) are indicators of arterial stiffness. Pulse wave reflection and arterial stiffness are related to cardiovascular events and sickle cell disease. However, the effect of these parameters on the heterozygous sickle cell trait (HbAS) is unknown. The aim of this study is to evaluate the arterial stiffness and wave reflection in young adult heterozygous sickle cell carriers.

Materials and Methods: We enrolled 40 volunteers (20 HbAS cases, 20 hemoglobin AA [HbAA] cases) aged between 18 and 40 years. AI and PWV values were measured by arteriography.

Results: Aortic blood pressure, aortic AI, and brachial AI values were significantly higher in HbAS cases compared to the control group (HbAA) (p=0.033, 0.011, and 0.011, respectively). A statistically significant positive correlation was found between aortic pulse wave velocity and mean arterial pressure, age, aortic AI, brachial AI, weight, and low-density lipoprotein levels (p=0.000, 0.017, 0.000, 0.000, 0.034, and 0.05, respectively) in the whole study population. Aortic AI and age were also significantly correlated (p=0.026). In addition, a positive correlation between aortic PWV and systolic blood pressure and a positive correlation between aortic AI and mean arterial pressure (p=0.027 and 0.009, respectively) were found in HbAS individuals. Our study reveals that mean arterial pressure and heart rate are independent determinants for the aortic AI. Mean arterial pressure and age are independent determinants for aortic PWV.

Conclusion: Arterial stiffness measurement is an easy, cheap, and reliable method in the early diagnosis of cardiovascular disease in heterozygous sickle cell carriers. These results may depend on the amount of hemoglobin S in red blood cells. Further studies are required to investigate the blood pressure changes and its effects on arterial stiffness in order to explain the vascular aging mechanism in the HbAS trait population.

Conflict of interest:None declared.

Increased burden and severity of metabolic syndrome and arterial stiffness in treatment-naïve HIV+ patients from Cameroon

BACKGROUND

Human immunodeficiency virus (HIV) and its therapy are associated with increased aortic stiffness and metabolic syndrome (MetS) phenotype in Caucasian patients. We hypothesized that, independently of antiretroviral therapy, HIV infection in native black African patients is associated with increased burden of cardiometabolic risk factors that may accelerate arterial structural damage and translate into increased aortic stiffness.

PATIENTS AND METHODS

Ninety-six apparently healthy Cameroonian subjects (controls) were compared to 108 untreated Cameroonian HIV+ patients (HIV-UT) of similar age. In each participant, pulse wave velocity (Complior), aortic augmentation index (SphygmoCor), brachial blood pressure (Omron 705 IT), fasting plasma glucose (FPG), and lipids were recorded, as well as the prevalence and severity of MetS, based on the American Heart Association/National Heart, Lung, and Blood Institute score ≥3/5.

RESULTS

Prevalence of impaired fasting glucose (FPG 100-125 mg · dL⁻¹) and of diabetes (FPG > 125 mg · dL⁻¹) was higher in HIV-UT than in controls (47% versus 27%, and 26% versus 1%, respectively; both P < 0.01). Fasting triglycerides and the atherogenic dyslipidemia ratio were significantly higher in HIV-UT than in controls. Hypertension prevalence was high and comparable in both groups (41% versus 44%, respectively; not significant). HIV-UT patients exhibited a twice-higher prevalence of MetS than controls (47% versus 21%; P = 0.02). Age- and sex-adjusted pulse wave velocity was higher in HIV-UT than in controls (7.5 ± 2.2 m/s versus 6.9 ± 1.7 m/s, respectively; P = 0.02), whereas aortic augmentation index was significantly lower (6% ± 4% versus 8% ± 7%, respectively; P = 0.01).

CONCLUSION

Similar to Caucasian populations, native Cameroonian HIV-UT patients showed a higher prevalence of MetS and its phenotype, associated with increased aortic stiffness, an early marker of atherosclerosis.

Male gender, increased blood viscosity, body mass index and triglyceride levels are independently associated with systemic relative hypertension in sickle cell anemia

Patients with sickle cell anemia (SCA) have usually lower diastolic, systolic and mean blood pressure (BP) than the general population. However, BP values ≥120/70 mmHg considerably increase the risk for acute and chronic complications in SCA. The aim of this study was to identify biological factors associated with relative hypertension in adults with SCA. We compared the hematological, lipid and hemolytic profiles, as well as blood viscosity, between SCA patients with normal BP (<120/70 mmHg, n = 54) and those with relative hypertension (BP≥120/70 mmHg, n = 43). Our results demonstrated that male gender (OR: 3.49; 95%CI 1.20 to 10.16, p<0.05), triglycerides (OR: 9.19; 95% CI 2.29 to 36.95, p<0.01), blood viscosity (OR: 1.35; 95% CI 1.01 to 1.81, p<0.05) and body mass index (OR: 1.37; 95% CI 1.14 to 1.64, p<0.01) were independent risks factors for relative hypertension in SCA. No association was found between the BP status and the positive history of painful vaso-occlusive crisis or acute chest syndrome. An association between triglycerides level and the occurrence of these two major acute complications was detected. Our study suggests that male gender, increased triglycerides level, BMI and blood viscosity could increase the risk for developing relative hypertension in SCA. In addition, our results support a role of moderately elevated triglycerides in the pathophysiology of vaso-occlusive events.

Effects of hunter-gatherer subsistence mode on arterial distensibility in Cameroonian pygmies

We aimed to assess whether arterial distensibility estimated by pulse wave velocity (PWV) and augmentation index (AI) differs between Cameroon traditional pygmies (TPs) on hunter-gather subsistence mode, contemporary pygmies who migrated to semiurban area, and the Bantou farmers (BFs) sharing the same environment. For that purpose, we recorded carotid-femoral PWV (ComplioR) in age and sex carefully matched 20 TPs, 20 contemporary pygmies, and 22 BFs. Aortic AI corrected for heart rate and blood pressures were generated from pressure wave analysis (SphygmoCor). Lipid profile was determined in TP and BF participants. TPs were shorter (P=0.02) with lower body weight (P<0.01) in comparison with contemporary pygmies and BFs. TPs had lower low-density lipoprotein cholesterol but higher high-density lipoprotein cholesterol than BFs (P<0.01). Their PWV (5.81±0.21 m/s) was slower (P=0.006) than that of contemporary pygmies (6.82±0.36 m/s) or BFs (6.93±0.29 m/s); however, after its adjustment for age, mean arterial pressure, and heart rate, the difference was slightly attenuated (P=0.051). PWV adjusted for weight did not differ between groups (P=0.10). In the whole study population but not in TPs taken separately, multivariate regression analysis revealed that PWV was independently associated with mean arterial pressure, age, and TP status (P<0.001), whereas age, mean arterial pressure, and height emerged as independent determinants of aortic AI corrected for heart rate (P<0.001). Aortic AI corrected for heart rate did not differ in the 3 groups. In conclusion, hunter-gather lifestyle is associated with low atherosclerosis risk translated by lower aortic stiffness attributed at least partly to low weight and blunted effects of aging and blood pressures on TP arterial structure and function.

Relative systemic hypertension in patients with sickle cell disease is associated with risk of pulmonary hypertension and renal insufficiency

We analyzed entry data from 163 adult hemoglobin SS and Sbeta(0) thalassemia patients enrolled in the prospective Sickle Cell Pulmonary Hypertension Screening Study and stratified their ECHO-determined tricuspid regurgitant jet velocity (TRV) and serum creatinine concentration according to three systemic blood pressure categories. TRV was >or= 2.5 m/sec in 27% of the patients with systolic blood pressure (SBP) <120 mmHg and diastolic blood pressure (DBP) <70 mmHg, in 37% with SBP 120-139 mmHg or DBP 70-89 mmHg, and in 93% with SBP 140 mmHg or DBP 90 mmHg or higher (P<0.0005 for trend). Serum creatinine concentration was 1.0 mg/dL or higher in 7% of patients with SBP <120 mmHg and DBP <70 mmHg, in 17% with SBP 120-139 mmHg or DBP 70-89 mmHg and 50% with SBP 140 mmHg or DBP 90 mmHg or higher (P<0.0005 for trend). Over 2 years of follow-up, there were trends for more frequent progression to elevated TRV (P=0.073) or creatinine (P=0.037) values according to the higher systemic blood pressure categories. Our findings suggest that systemic SBP 120-139 mmHg or DBP 70-89 mmHg defines a category of relative systemic hypertension in patients with sickle cell disease that is associated with increased risk for pulmonary hypertension and renal dysfunction. Whether antihypertensive and/or nitric oxide donor therapy in sickle cell disease patients with relative hypertension prevents these and other complications should be determined by clinical trials.

Antihypertensive agents and arterial stiffness: relevance to reducing cardiovascular risk in the chronic kidney disease patient

PURPOSE OF REVIEW

Arterial stiffness is a sign of diffuse adventitial macrovascular disease. The purpose of the present review is to discuss, in patients with chronic kidney disease, the pathophysiology of increased arterial stiffness, the role of antihypertensive therapy on reduction of arterial stiffness, and the clinical ways by which the prognostication of cardiovascular disease in patients with chronic kidney disease can be refined using arterial stiffness monitoring.

RECENT FINDINGS

Arterial stiffness is increased with increasing prevalence of traditional cardiovascular risk factors. In patients with chronic kidney disease some unique factors further increase the risk of arterial stiffness, and include volume overload, activation of the renin-angiotensin system, anemia, and dysregulated mineral metabolism. Arterial stiffness is increased even in patients with early-stage chronic kidney disease. Blood pressure reduction when accompanied by a reduction in arterial stiffness is associated with improved prognosis. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers can preferentially improve arterial stiffness, which may be an additional mechanism of cardiovascular protection with these agents.

SUMMARY

The impact of improvement in arterial stiffness with antihypertensive agents on cardiovascular outcomes needs well designed clinical trials.

Endothelial function and arterial stiffness in sickle-thalassemia patients

BACKGROUND

Homozygous sickle-cell anemia and beta-thalassemia are characterized by impaired endothelial function, while data on arterial stiffness have hitherto been conflicting. We sought to investigate aortic elastic properties and endothelial function in sickle-thalassemia, which combines molecular and clinical features of the above conditions.

METHODS AND RESULTS

Forty-seven sickle-thalassemia patients, younger than 45 years, with preserved left ventricular (LV) function and no history of smoking, systemic or pulmonary hypertension, diabetes mellitus, dyslipidemia or thyroid disease, along with 40 healthy controls were studied. Aortic strain, distensibility and stiffness index were calculated by echocardiographically-obtained aortic root diameters. Brachial artery endothelial function was assessed by ultrasonographic evaluation of flow-mediated dilatation (FMD) and nitrate-mediated dilatation (NMD). Left ventricle was assessed by echocardiography. Patients had an impaired FMD (4.2+/-2.9% versus 9.2+/-3.8% in controls, p<0.001) with a preserved NMD (16.9+/-5.6% versus 15.2+/-4.8% in controls, p>0.05). Aortic strain and distensibility were lower and aortic stiffness index was higher in patients compared to controls (8.1+/-4.6 versus 5.8+/-2.9, p<0.01). Indexed LV diameters and mass were higher in patients. Systolic LV function was preserved, while 14.9% of patients had an impaired relaxation transmitral inflow pattern. Patients' LV mass index and diastolic mitral E wave deceleration time were positively correlated with aortic stiffness index (p<0.001).

CONCLUSION

Sickle-thalassemia is characterized by a complex vasculopathy, consisting of endothelial dysfunction and increased arterial stiffness, with a global effect on cardiovascular function.

Role of L-type Ca2+ channels in iron transport and iron-overload cardiomyopathy

Excessive body iron or iron overload occurs under conditions such as primary (hereditary) hemochromatosis and secondary iron overload (hemosiderosis), which are reaching epidemic levels worldwide. Primary hemochromatosis is the most common genetic disorder with an allele frequency greater than 10% in individuals of European ancestry, while hemosiderosis is less common but associated with a much higher morbidity and mortality. Iron overload leads to iron deposition in many tissues especially the liver, brain, heart and endocrine tissues. Elevated cardiac iron leads to diastolic dysfunction, arrhythmias and dilated cardiomyopathy, and is the primary determinant of survival in patients with secondary iron overload as well as a leading cause of morbidity and mortality in primary hemochromatosis patients. In addition, iron-induced cardiac injury plays a role in acute iron toxicosis (iron poisoning), myocardial ischemia–reperfusion injury, Friedreich ataxia and neurodegenerative diseases. Patients with iron overload also routinely suffer from a range of endocrinopathies, including diabetes mellitus and anterior pituitary dysfunction. Despite clear connections between elevated iron and clinical disease, iron transport remains poorly understood. While low-capacity divalent metal and transferrin-bound transporters are critical under normal physiological conditions, L-type Ca²⁺ channels (LTCC) are high-capacity pathways of ferrous iron (Fe²⁺) uptake into cardiomyocytes especially under iron overload conditions. Fe²⁺ uptake through L-type Ca²⁺ channels may also be crucial in other excitable cells such as pancreatic beta cells, anterior pituitary cells and neurons. Consequently, LTCC blockers represent a potential new therapy to reduce the toxic effects of excess iron.

An updated clinical primer on large artery mechanics: implications of pulse waveform analysis and arterial tonometry

PURPOSE OF REVIEW

The use of pulse wave analysis with arterial tonometry has accelerated over the last year. Despite approval from the US Food and Drug Administration in 2001 on the use of generalized transfer function to generate the central (aortic) pressure wave from the radial waveform, this technique is still questioned. This review summarizes major findings on (a) value of arterial tonometry in determining indices of cardiovascular function, (b) use of these indices in outcome and drug studies, (c) relevance to major trials on blood pressure reduction.

RECENT FINDINGS

Pulse pressure has emerged as a better predictor of cardiac ischemic events than systolic, diastolic, and mean brachial pressure. Central systolic and pulse pressure and augmentation index have shown an even better relation with cardiovascular events and with outcomes. The claim by specific angiotensin-converting enzyme inhibitor and angiotensin receptor blocker drugs of their benefits "beyond blood pressure lowering" has been challenged on the basis of greater reduction in central and aortic pressure compared with brachial pressure measured by cuff sphygmomanometer, as shown by the pREterax in regression of Arterial Stiffness in a contrOlled double-bliNd study. Augmentation index is higher in hypertension, is inversely related to body height, and can be reduced by exercise. Augmentation index shows a linear relation with age up to 60 years. Regrettably, recent major trials such as the Comparison of Amlodipine versus Enalapril to Limit Occurrences of Thrombosis, Prevention of Events with Angiotensin Converting Enzyme Inhibition, and Valsartan Antihypertensive Long-term Use Evaluation studies have not included pulse wave analysis to distinguish the relative benefit of different drugs.

SUMMARY

Pulse wave analysis will assist in a better understanding of hypertension as well as in establishing the extent of cardiovascular disease and for monitoring therapy.