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Roland E. Schmieder - One of the best experts on this subject based on the ideXlab platform.
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Retinal Capillary and arteriolar changes in patients with chronic kidney disease.
Microvascular research, 2018Co-Authors: Agnes Bosch, Joanna Harazny, Roland E. Schmieder, Johannes B. Scheppach, Ulrike Raff, Kai-uwe Eckardt, Markus P. SchneiderAbstract:Abstract Rationale Premature cardiovascular disease is a leading cause of death in patients with chronic kidney disease (CKD). In animal models CKD has been shown to cause renal and extrarenal vascular remodeling and Capillary Rarefaction, but data in humans with CKD are sparse. Retinal arteriolar wall-to-lumen ratio (WLR) is an established marker of early end-organ damage and there is evidence that arteriolar and Capillary changes in the retinal circulation mirror those in the general and in particular the cerebrovascular microcirculation. Objective The aim of this study was to compare retinal Capillary density and arteriolar structure between patients with CKD and healthy individuals. Methods We compared 76 patients with CKD stage 3+ or proteinuria >500 mg/g creatinine in the presence of a normal GFR from the German Chronic Kidney Disease cohort to 53 healthy control subjects, who participated in clinical trials during 2007 and 2015 in our Clinical Research Center. Retinal vascular parameters were measured non-invasively in vivo by scanning laser Doppler Flowmetry (SLDF, Heidelberg Engineering, Germany). Capillary Rarefaction was assessed by interCapillary distance. Results Patients with CKD showed greater WLR (0.403 ± 0.11 vs 0.351 ± 0.11, p = 0.010) and greater wall thickness (WT) (15.1 ± 4.1 vs 13.5 ± 3.8, p = 0.026) compared to healthy individuals. InterCapillary distance (ICD) (22.4 ± 5.7 vs 20.2 ± 4.1, p = 0.008) was greater in the CKD group compared to the healthy control group. After adjustment for differences in clinical characteristics of the groups (age, gender, BMI, serum cholesterol) WLR (p = 0.046), WT (p = 0.025) and ICD (p = 0.003) remained significantly different between the two groups. There was a correlation between serum phosphate level and WLR in the CKD group (r = 0.288, p = 0.013). Conclusion Patients with moderately severe CKD show retinal signs of end-organ damage indicated by an increased wall-to-lumen ratio and Capillary Rarefaction.
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Retinal Capillary Rarefaction in patients with untreated mild-moderate hypertension.
BMC cardiovascular disorders, 2017Co-Authors: Agnes Bosch, Joanna Harazny, Iris Kistner, Stefanie Friedrich, Joanna Wojtkiewicz, Roland E. SchmiederAbstract:Microvascular Rarefaction influences peripheral vascular resistance, perfusion and metabolism by affecting blood pressure and flow pattern. In hypertension microvascular Rarefaction has been described in experimental animal studies as well as in capillaroscopy of skin and biopsies of muscle tissue in patients. Retinal circulation mirrors cerebral microcirculation and allows non-invasive investigations. We compared Capillary Rarefaction of retinal vessels in hypertensive versus normotensive subjects. In this study retinal Capillary Rarefaction in 70 patients with long time (more than 67 month of disease duration) and 64 patients with short time hypertension stage 1 or 2 has been compared to 55 healthy control subjects, who participated in clinical trials in our Clinical Research Center ( www.clinicaltrials.gov : NCT01318395, NCT00627952, NCT00152698, NCT01319344). Retinal vascular parameters have been measured non-invasively and in vivo in perfusion image by scanning laser Doppler flowmetry (Heidelberg Engineering, Germany). Capillary Rarefaction was assessed by Capillary area (CapA) (in pixel-number) and interCapillary distance (ICD) (in μm). Additionally retinal Capillary flow (RCF) was measured. ICD was greater in the long time hypertensive group compared to healthy individuals (24.2 ± 6.3 μm vs 20.1 ± 4.2 μm, p = 0.001) and compared to short time hypertensive patients (22.2 ± 5.2 μm, p = 0.020). Long time hypertensive patients showed less CapA compared to healthy people (1462 ± 690 vs 1821 ± 652, p = 0.005). Accordingly, RCF was significantly lower in the long time hypertensive group compared to the healthy control group (282 ± 70 AU vs 314 ± 60 AU, p = 0.032). Our data indicate a lower level of retinal Capillary density in hypertensive patients, especially in those with long time hypertension. Patients with hypertension stage 1 or 2 showed retinal Capillary Rarefaction in comparison to healthy normotensive subjects. Retinal Capillary Rarefaction was intensified with duration of disease.
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Retinal Capillary Rarefaction in Patients with Type 2 Diabetes Mellitus.
PloS one, 2016Co-Authors: Agnes Jumar, Joanna Harazny, Iris Kistner, Stefanie Friedrich, Christian Ott, Kristina Striepe, Roland E. SchmiederAbstract:Purpose In diabetes mellitus type 2, Capillary Rarefaction plays a pivotal role in the pathogenesis of end-organ damage. We investigated retinal Capillary density in patients with early disease. Methods This cross-sectional study compares retinal Capillary Rarefaction determined by interCapillary distance (ICD) and Capillary area (CapA), measured non-invasively and in vivo by scanning laser Doppler flowmetry, in 73 patients with type 2 diabetes, 55 healthy controls and 134 individuals with hypertension stage 1 or 2. Results In diabetic patients, ICD was greater (23.2±5.5 vs 20.2±4.2, p = 0.013) and CapA smaller (1592±595 vs 1821±652, p = 0.019) than in healthy controls after adjustment for differences in cardiovascular risk factors between the groups. Compared to hypertensive patients, diabetic individuals showed no difference in ICD (23.1±5.8, p = 0.781) and CapA (1556±649, p = 0.768). Conclusion In the early stage of diabetes type 2, patients showed Capillary Rarefaction compared to healthy individuals.
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improvement in retinal Capillary Rarefaction after valsartan treatment in hypertensive patients
Journal of Clinical Hypertension, 2016Co-Authors: Agnes Jumar, Joanna Harazny, Iris Kistner, Stefanie Friedrich, Christian Ott, Roland E. SchmiederAbstract:Decreased Capillary density influences vascular resistance and perfusion. The authors aimed to investigate the influence of the renin-angiotensin receptor blocker valsartan on retinal Capillary Rarefaction in hypertensive patients. Retinal vascular parameters were measured noninvasively and in vivo by scanning laser Doppler flowmetry before and after 4 weeks of treatment with valsartan in 95 patients with hypertension stage 1 or 2 and compared with 55 healthy individuals. Retinal Capillary Rarefaction was determined with the parameters interCapillary distance (ICD) and Capillary area (CapA). In hypertensive patients, ICD decreased (23.4±5.5 μm vs 21.5±5.6 μm, P<.001) and CapA increased (1564±621 vs 1776±795, P=.001) after valsartan treatment compared with baseline. Compared with healthy normotensive controls (ICD 20.2±4.2 μm, CapA 1821±652), untreated hypertensive patients showed greater ICD (P<.001) and smaller CapA (P=.019), whereas treated hypertensive patients showed no difference in ICD (P=.126) and CapA (P=.728). Therapy with valsartan for 4 weeks diminished Capillary Rarefaction in hypertensive patients.
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Improvement in Retinal Capillary Rarefaction After Valsartan Treatment in Hypertensive Patients.
Journal of clinical hypertension (Greenwich Conn.), 2016Co-Authors: Agnes Jumar, Joanna Harazny, Iris Kistner, Stefanie Friedrich, Christian Ott, Roland E. SchmiederAbstract:Decreased Capillary density influences vascular resistance and perfusion. The authors aimed to investigate the influence of the renin-angiotensin receptor blocker valsartan on retinal Capillary Rarefaction in hypertensive patients. Retinal vascular parameters were measured noninvasively and in vivo by scanning laser Doppler flowmetry before and after 4 weeks of treatment with valsartan in 95 patients with hypertension stage 1 or 2 and compared with 55 healthy individuals. Retinal Capillary Rarefaction was determined with the parameters interCapillary distance (ICD) and Capillary area (CapA). In hypertensive patients, ICD decreased (23.4±5.5 μm vs 21.5±5.6 μm, P
Isaac Manyonda - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Low Birth Weight on the Microcirculation in the 1st Year of Life
Hypertension, 2018Co-Authors: Muti Goloba, Isaac Manyonda, Duolao Wang, Rajendra Raghuraman, Uzma Khan, Amelia Brown, Monique Klein, Nansi Botros, Donovan Duffy, T AntoniosAbstract:Abstract Introduction: Capillary Rarefaction, defined as a reduction in Capillary density, is an established hallmark of essential hypertension. Low birth weight (LBW) infants, known to have an increased risk of developing hypertension as adults, were unexpectedly found to have a significantly higher Capillary density at birth when compared to normal birth weight (NBW) infants. We therefore hypothesised that there is a microcirculatory window in the 1st year of life of LBW infants, during which a process of extensive Capillary loss, known as “hyperpruning”, occurs. Methods: The George’s Capillary Rarefaction Offspring Study (G-CROS) is a longitudinal, multi-centre study of which 284 infants were NBW, born at term, and 77 were LBW. Intravital microscopy was used to measure the functional (also known as basal) Capillary density (BCD), and the structural (also known as maximal) Capillary density (MCD) at birth, 3 months, 6 months and 12 months. Results: LBW infants had a significantly higher Capillary density at birth when compared to NBW infants (p < 0.0001). NBW infants showed a gradual reduction in Capillary density between birth and 12 months, with their greatest reduction occurring between birth and 3 months (BCD mean difference = -27.62 cap/field, p
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Microvascular Remodelling in Preeclampsia: Quantifying Capillary Rarefaction Accurately and Independently Predicts Preeclampsia
American journal of hypertension, 2013Co-Authors: Tarek F.t. Antonios, Vivek Nama, Duolao Wang, Isaac ManyondaAbstract:BACKGROUND: Preeclampsia is a major cause of maternal and neonatal mortality and morbidity. The incidence of preeclampsia seems to be rising because of increased prevalence of predisposing disorders, such as essential hypertension, diabetes, and obesity, and there is increasing evidence to suggest widespread microcirculatory abnormalities before the onset of preeclampsia. We hypothesized that quantifying Capillary Rarefaction could be helpful in the clinical prediction of preeclampsia. METHODS: We measured skin Capillary density according to a well-validated protocol at 5 consecutive predetermined visits in 322 consecutive white women, of whom 16 subjects developed preeclampsia. RESULTS: We found that structural Capillary Rarefaction at 20-24 weeks of gestation yielded a sensitivity of 0.87 with a specificity of 0.50 at the cutoff of 2 capillaries/field with the area under the curve of the receiver operating characteristic value of 0.70, whereas Capillary Rarefaction at 27-32 weeks of gestation yielded a sensitivity of 0.75 and a higher specificity of 0.77 at the cutoff of 8 capillaries/field with area under the curve of the receiver operating characteristic value of 0.82. Combining Capillary Rarefaction with uterine artery Doppler pulsatility index increased the sensitivity and specificity of the prediction. Multivariable analysis shows that the odds of preeclampsia are increased in women with previous history of preeclampsia or chronic hypertension and in those with increased uterine artery Doppler pulsatility index, but the most powerful and independent predictor of preeclampsia was Capillary Rarefaction at 27-32 weeks. CONCLUSIONS: Quantifying structural Rarefaction of skin capillaries in pregnancy is a potentially useful clinical marker for the prediction of preeclampsia.
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138 MICROVASCULAR REMODELLING IN PREECLAMPSIA; QUANTIFYING Capillary Rarefaction ACCURATELY AND INDEPENDENTLY PREDICTS PREECLAMPSIA
Heart, 2013Co-Authors: Tarek F.t. Antonios, Vivek Nama, Duolao Wang, Isaac ManyondaAbstract:Background Preeclampsia is a major cause of maternal and neonatal mortality and morbidity. There is increasing evidence to suggest widespread microcirculatory abnormalities before the onset of preeclampsia. We have recently reported that women who later on in pregnancy developed preeclampsia had significant reduction in their skin Capillary density (ie, Rarefaction) before the onset of preeclampsia. We hypothesised that quantifying Capillary Rarefaction could be helpful in the clinical prediction of preeclampsia. Methods We measured skin Capillary density according to a well-validated protocol at 5 consecutive predetermined visits in 322 consecutive Caucasian women, of which 305 subjects completed the study. Results We found that structural Capillary Rarefaction at 20–24 weeks gestation yielded a sensitivity of 0.87 with a specificity of 0.50 at the cut-off of 2 capillaries/mm 2 with the Area Under the Curve of the Receiver Operating Characteristic value of 0.70 whilst Capillary Rarefaction at 27–32 weeks gestation yielded a sensitivity of 0.75 and a higher specificity of 0.77 at the cut-off of 8 capillaries/mm 2 with ROC AUC value of 0.82. Combining Capillary Rarefaction with uterine artery Doppler pulsatility index increased the sensitivity and specificity of the prediction. Multivariate analysis shows that the odds of preeclampsia are increased in women with previous history of preeclampsia or chronic hypertension, in those with increased uterine artery Doppler pulsatility index, but the most powerful and independent predictor of preeclampsia was Capillary Rarefaction at 27–32 weeks. Conclusions Quantifying structural Rarefaction of skin capillaries in pregnancy is a potentially useful and accurate clinical marker for the prediction of preeclampsia.
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142 Onset of preeclampsia is preceded by structural Capillary Rarefaction
Heart, 2012Co-Authors: Vivek Nama, Isaac Manyonda, Joseph Onwude, Tarek F AntoniosAbstract:Introduction Microvascular Rarefaction, defined as reduced vascular density, is a consistent finding in hypertension. Functional and structural Capillary Rarefaction occurs in individuals with sustained and borderline essential hypertension, and in their normotensive offspring. Women who develop preeclampsia are at increased risk of hypertension in later life. We hypothesised that Capillary Rarefaction precedes the onset of preeclampsia and could play a role in its pathogenesis. Methods In this longitudinal cohort study we recruited 322 Caucasian women, of which 305 subjects completed the study. We used intravital video-microscopy to measure basal (ie, functional) and maximal (ie, structural) skin Capillary densities according to a well-validated protocol and measured plasma angiogenic and anti-angiogenic factors. Subjects were studied at five consecutive visits. Results Preeclampsia occurred in 16 women (mean onset at 35.6±4.8 weeks) and 272 women had normal pregnancy. In women with normal pregnancy significant structural reduction in Capillary density occurred at 27–32 weeks, which had resolved by the puerperium (mean change: −2.2 capillaries/field, 95% CI −3.6 to −0.7). In contrast, in women who developed preeclampsia, more significant structural Rarefaction was observed earlier at 20–24 weeks (mean change: −6.1 capillaries/field, 95% CI −9.2 to −2.9), which persisted into the puerperium. We also found that the change in soluble Endoglin from 11–16 weeks to 27–32 weeks was significantly correlated with the change in structural Capillary density. Conclusions This is the first study to show that significant structural Capillary Rarefaction precedes the onset of preeclampsia. Capillary Rarefaction could play a role in the pathogenesis of this disease.
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Capillary remodeling in infants born to hypertensive pregnancy: pilot study.
American journal of hypertension, 2012Co-Authors: Tarek F.t. Antonios, Duolao Wang, Rohan D'souza, Rajendra Raghuraman, Preetha Nathan, Isaac ManyondaAbstract:BACKGROUND Capillary Rarefaction is pathognonnonic of essential hypertension. We have previously shown significant Capillary Rarefaction in normotensive adult offspring of hypertensive parents, suggesting a familial predisposition in which Capillary Rarefaction represents a primary vascular abnormality that antedates the onset of sustained elevation of blood pressure (BP). We have recently reported that low-birth weight (LBW) infants, born at term or preterm, to normotensive mothers do not have Capillary Rarefaction at birth. We hypothesized that infants born to mothers with hypertensive disorders of pregnancy (HDP) would have significant Capillary Rarefaction at birth when compared to infants of normotensive mothers. METHODS We studied 22 infants born to hypertensive mothers and compared them to 40 normal birth weight infants born at term to normotensive mothers. We used orthogonal polarized spectroscopy to measure basal (i.e., functional) and maximal (i.e., structural) skin Capillary densities according to a well-validated protocol. RESULTS We found that term infants born to hypertensive mothers had significantly lower maximal Capillary density (MCD) (mean difference of -5.0 capillaries/mm(2); P < 0.05). However, preterm infants with LBW born to hypertensive mothers tended to have higher basal and maximal skin Capillary densities compared with term infants. CONCLUSIONS While the results in term infants are consistent with our belief that Capillary Rarefaction in essential hypertension is likely to be a primary vascular abnormality, the results in preterm infants may suggest that the intrauterine environment may exert some influences on the remodeling of the microcirculation which may delay the onset of Capillary Rarefaction in these infants.
David H. Wasserman - One of the best experts on this subject based on the ideXlab platform.
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muscle specific vascular endothelial growth factor deletion induces muscle Capillary Rarefaction creating muscle insulin resistance
Diabetes, 2013Co-Authors: Jeffrey S. Bonner, Louise Lantier, Clinton M. Hasenour, Freyja D. James, Deanna P. Bracy, David H. WassermanAbstract:Muscle insulin resistance is associated with a reduction in vascular endothelial growth factor (VEGF) action and muscle Capillary density. We tested the hypothesis that muscle Capillary Rarefaction critically contributes to the etiology of muscle insulin resistance in chow-fed mice with skeletal and cardiac muscle VEGF deletion (mVEGF−/−) and wild-type littermates (mVEGF+/+) on a C57BL/6 background. The mVEGF−/− mice had an ∼60% and ∼50% decrease in capillaries in skeletal and cardiac muscle, respectively. The mVEGF−/− mice had augmented fasting glucose turnover. Insulin-stimulated whole-body glucose disappearance was blunted in mVEGF−/− mice. The reduced peripheral glucose utilization during insulin stimulation was due to diminished in vivo cardiac and skeletal muscle insulin action and signaling. The decreased insulin-stimulated muscle glucose uptake was independent of defects in insulin action at the myocyte, suggesting that the impairment in insulin-stimulated muscle glucose uptake was due to poor muscle perfusion. The deletion of VEGF in cardiac muscle did not affect cardiac output. These studies emphasize the importance for novel therapeutic approaches that target the vasculature in the treatment of insulin-resistant muscle.
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Muscle-Specific Vascular Endothelial Growth Factor Deletion Induces Muscle Capillary Rarefaction Creating Muscle Insulin Resistance
Diabetes, 2012Co-Authors: Jeffrey S. Bonner, Louise Lantier, Clinton M. Hasenour, Freyja D. James, Deanna P. Bracy, David H. WassermanAbstract:Muscle insulin resistance is associated with a reduction in vascular endothelial growth factor (VEGF) action and muscle Capillary density. We tested the hypothesis that muscle Capillary Rarefaction critically contributes to the etiology of muscle insulin resistance in chow-fed mice with skeletal and cardiac muscle VEGF deletion (mVEGF(-/-)) and wild-type littermates (mVEGF(+/+)) on a C57BL/6 background. The mVEGF(-/-) mice had an ~60% and ~50% decrease in capillaries in skeletal and cardiac muscle, respectively. The mVEGF(-/-) mice had augmented fasting glucose turnover. Insulin-stimulated whole-body glucose disappearance was blunted in mVEGF(-/-) mice. The reduced peripheral glucose utilization during insulin stimulation was due to diminished in vivo cardiac and skeletal muscle insulin action and signaling. The decreased insulin-stimulated muscle glucose uptake was independent of defects in insulin action at the myocyte, suggesting that the impairment in insulin-stimulated muscle glucose uptake was due to poor muscle perfusion. The deletion of VEGF in cardiac muscle did not affect cardiac output. These studies emphasize the importance for novel therapeutic approaches that target the vasculature in the treatment of insulin-resistant muscle.
Bonita Falkner - One of the best experts on this subject based on the ideXlab platform.
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Original Research: Capillary Rarefaction in treated and untreated hypertensive subjects
Therapeutic advances in cardiovascular disease, 2008Co-Authors: Cynthia Cheng, Constantine Daskalakis, Bonita FalknerAbstract:This study aimed to determine if Capillary Rarefaction is detectable and associated with endothelial dysfunction in persons with mild systolic blood pressure (SBP) elevation. Capillary density and endothelial function were quantified for 150 nondiabetic participants, grouped by blood pressure (BP) as normotensive, untreated high BP, and treated high BP. Structural Capillary Rarefaction measures were not different between the three groups. Functional Capillary Rarefaction measures were significantly lower in both high BP groups compared to normotensives, and correlated inversely with endothelial function. The study findings indicate that the hypertensive vascular pathologic process is already underway at modest levels of blood pressure elevation.
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Functional Capillary Rarefaction in mild blood pressure elevation.
Clinical and translational science, 2008Co-Authors: Cynthia Cheng, James J. Diamond, Bonita FalknerAbstract:Capillary Rarefaction is described in patients with moderate-to-severe hypertension. The study objective was to determine if structural and/or functional Capillary Rarefaction is detectable and associated with endothelial dysfunction in patients with mild blood pressure elevation (HBP: Systolic blood pressure 130–160 mm Hg). Capillary density was quantified by direct capillaroscopy in 110 nondiabetic black and non-black subjects. Endothelial function was quantified by plethysmographic measures of flow-mediated vasodilation. Compared to normotensives (NBP: N = 90), functional Capillary Rarefaction was detected in HBP (N = 20; p < 0.001). Functional Capillary density measures correlated with endothelial function (p < 0.001). Functional, but not structural, Capillary Rarefaction is detectable and associated with endothelial dysfunction in both black and non-black individuals with mild blood pressure elevation.
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Capillary Rarefaction in treated and untreated hypertensive subjects.
Therapeutic advances in cardiovascular disease, 2008Co-Authors: Cynthia Cheng, Constantine Daskalakis, Bonita FalknerAbstract:This study aimed to determine if Capillary Rarefaction is detectable and associated with endothelial dysfunction in persons with mild systolic blood pressure (SBP) elevation. Capillary density and endothelial function were quantified for 150 nondiabetic participants, grouped by blood pressure (BP) as normotensive, untreated high BP, and treated high BP. Structural Capillary Rarefaction measures were not different between the three groups. Functional Capillary Rarefaction measures were significantly lower in both high BP groups compared to normotensives, and correlated inversely with endothelial function. The study findings indicate that the hypertensive vascular pathologic process is already underway at modest levels of blood pressure elevation.
Tarek F Antonios - One of the best experts on this subject based on the ideXlab platform.
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142 Onset of preeclampsia is preceded by structural Capillary Rarefaction
Heart, 2012Co-Authors: Vivek Nama, Isaac Manyonda, Joseph Onwude, Tarek F AntoniosAbstract:Introduction Microvascular Rarefaction, defined as reduced vascular density, is a consistent finding in hypertension. Functional and structural Capillary Rarefaction occurs in individuals with sustained and borderline essential hypertension, and in their normotensive offspring. Women who develop preeclampsia are at increased risk of hypertension in later life. We hypothesised that Capillary Rarefaction precedes the onset of preeclampsia and could play a role in its pathogenesis. Methods In this longitudinal cohort study we recruited 322 Caucasian women, of which 305 subjects completed the study. We used intravital video-microscopy to measure basal (ie, functional) and maximal (ie, structural) skin Capillary densities according to a well-validated protocol and measured plasma angiogenic and anti-angiogenic factors. Subjects were studied at five consecutive visits. Results Preeclampsia occurred in 16 women (mean onset at 35.6±4.8 weeks) and 272 women had normal pregnancy. In women with normal pregnancy significant structural reduction in Capillary density occurred at 27–32 weeks, which had resolved by the puerperium (mean change: −2.2 capillaries/field, 95% CI −3.6 to −0.7). In contrast, in women who developed preeclampsia, more significant structural Rarefaction was observed earlier at 20–24 weeks (mean change: −6.1 capillaries/field, 95% CI −9.2 to −2.9), which persisted into the puerperium. We also found that the change in soluble Endoglin from 11–16 weeks to 27–32 weeks was significantly correlated with the change in structural Capillary density. Conclusions This is the first study to show that significant structural Capillary Rarefaction precedes the onset of preeclampsia. Capillary Rarefaction could play a role in the pathogenesis of this disease.
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Structural Capillary Rarefaction and the onset of preeclampsia.
Obstetrics and gynecology, 2012Co-Authors: Vivek Nama, Isaac Manyonda, Joseph Onwude, Tarek F AntoniosAbstract:OBJECTIVE:To estimate if reduced Capillary density (ie, Capillary Rarefaction) precedes the onset of preeclampsia and if it could play a role in its pathogenesis. Capillary Rarefaction is a consistent finding in essential hypertension.METHODS:In this longitudinal cohort study, we recruited 322 conse
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effect of modest salt reduction on skin Capillary Rarefaction in white black and asian individuals with mild hypertension
Hypertension, 2010Co-Authors: Maciej Marciniak, Nirmala D Markandu, Tarek F Antonios, Graham A MacgregorAbstract:Microvascular Rarefaction occurs in hypertension. We carried out a 12-week randomized double-blind crossover trial to determine the effect of a modest reduction in salt intake on Capillary Rarefaction in 71 whites, 69 blacks, and 29 Asians with untreated mildly raised blood pressure. Both basal and maximal (during venous congestion) skin Capillary density were measured by capillaroscopy at the dorsum and the side of the fingers. In addition, we used orthogonal polarization spectral imaging to measure skin Capillary density at the dorsum of the fingers and the hand web. With a reduction in salt intake from 9.7 to 6.5 g/day, there was an increase in Capillary density (capillaries per millimeter squared) from 10121 to 10623 (basal) and 10822 to 11522 (maximal) at the dorsum, and 10125 to 10726 (basal) and 11026 to 11626 (maximal) at the side of the fingers (P0.001 for all). Orthogonal polarization spectral imaging also showed a significant increase in Capillary density both at the dorsum of the fingers and the web. Subgroup analysis showed that most of the changes were significant in all of the ethnic groups. Furthermore, there was a significant relationship between the change in 24-hour urinary sodium and the change in Capillary density at the side of the fingers. These results demonstrate that a modest reduction in salt intake, as currently recommended, improves both functional and structural Capillary Rarefactions that occur in hypertension, and a larger reduction in salt intake would have a greater effect. The increase in Capillary density may possibly carry additional beneficial effects on target organs. (Hypertension. 2010;56:253-259.)
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Structural skin Capillary Rarefaction in essential hypertension.
Hypertension (Dallas Tex. : 1979), 1999Co-Authors: Tarek F Antonios, Nirmala D Markandu, Donald R. J. Singer, Peter S. Mortimer, Graham A MacgregorAbstract:A reduction in the density of capillaries (Rarefaction) is known to occur in many tissues in patients with essential hypertension. This Rarefaction may play a role in increasing peripheral resistance. However, the mechanism underlying this Capillary Rarefaction is not understood. The aim of this study was to assess the extent of structural versus functional Capillary Rarefaction in the skin of dorsum of fingers in essential hypertension. The Capillary microcirculation was examined with video microscopy before and after maximizing the number of perfused capillaries by venous congestion. The study group comprised 17 patients with essential hypertension (mean supine blood pressure, 155/96 mm Hg) and 17 closely matched normotensive controls (mean blood pressure, 127/77 mm Hg). We used intravital video microscopy with an epi-illuminated microscope to examine the skin of the dorsum of left middle phalanx before and after venous congestion at 60 mm Hg for 2 minutes. A significantly lower mean Capillary density occurred at baseline in hypertensive subjects versus normotensive subjects. With venous occlusion, Capillary density increased significantly in both groups; however, maximal Capillary density remained significantly lower in the hypertensive subjects than in the normotensive subjects. The study strongly suggests that much of the reduction in Capillary density in the hypertensive subjects is caused by structural (anatomic) absence of capillaries rather than functional nonperfusion.
