Flow-Mediated Dilatation: A Review of Techniques and Applications

Fitness Level- and Sex-related Differences in Macro- and Microvascular Responses during Reactive Hyperemia

PURPOSE

Reactive hyperemia (RH) is widely used for the investigation of macrovascular (Flow-Mediated Dilation, FMD) and microvascular (Near Infrared Spectroscopy-Vascular Occlusion Test, NIRS-VOT) function. Mixed results have been reported on fitness level- and sex-related differences in FMD outcomes, and little is known about microvascular differences in untrained and chronically trained males and females.

METHODS

Fifteen chronically trained (CT: 8 MALES, 7 FEMALES) and sixteen untrained (UT: 8 MALES, 8 FEMALES) individuals participated in this study. Aerobic fitness (V[Combining Dot Above]O2max) was assessed during a cycling incremental exercise test to volitional exhaustion. FMD and NIRS-VOT were performed simultaneously on the lower limb investigating superficial femoral artery and vastus lateralis muscle, respectively.

RESULTS

%FMD was not different between groups (CT MALES, 4.62 ± 1.42; CT FEMALES, 4.15 ± 2.23; UT MALES, 5.10 ± 2.53; CT FEMALES, 3.20 ± 1.67). Peak blood flow showed greater values in CT vs UT (p ≤ 0.0001) and MALES vs FEMALES (p = 0.032). RH blood flow AUC was greater in CT vs UT (p = 0.001). At the microvascular level, desaturation and reperfusion rates were faster in CT vs UT (p = 0.018 and p = 0.013) and MALES vs FEMALES (p = 0.011 and p = 0.005). V[Combining Dot Above]O2max was significantly correlated with reperfusion rate (p = 0.0005) but not with %FMD.

CONCLUSION

Whereas NIRS-VOT outcomes identified fitness- and sex-related differences in vascular responses, %FMD did not. However, when reactive hyperemia-related outcomes from the FMD analysis were considered, fitness- and/or sex-related differences were detected. These data highlight the importance of integrating FMD and NIRS-VOT outcomes for a more comprehensive evaluation of vascular function.

Endothelial dysfunction in COPD: a systematic review and meta-analysis of studies using different functional assessment methods

Background

Cardiovascular disease is a major cause of morbidity and mortality in COPD. Endothelial dysfunction is suggested to be one of the pathogenetic mechanisms involved. This is a systematic review and meta-analysis of studies using any available functional method to examine differences in endothelial function between patients with COPD and individuals without COPD (controls).

Methods

Literature search involved PubMed and Scopus databases. Eligible studies included adult patients and evaluated endothelial damage via functional methods. The Newcastle–Ottawa scale was applied to evaluate the quality of retrieved studies. Subgroup analyses were performed to explore heterogeneity across the studies. Funnel plots were constructed to evaluate publication bias.

Results

Of the 21 reports initially identified, 19 studies with a total of 968 participants were included in the final meta-analysis. A significantly impaired response in endothelium-dependent (weighted mean between-group difference (WMD) −2.59, 95% CI −3.75 to −1.42) and -independent vasodilation (WMD −3.13, 95% CI −5.18 to −1.09) was observed in patients with COPD compared to controls. When pooling all studies together, regardless of the technique used for assessment of vascular reactivity, pronounced endothelial dysfunction was observed in COPD compared to controls (standardised mean difference (SMD) −1.19, 95% CI −1.69 to −0.68). Subgroup analysis showed that the difference was larger when patients with COPD were compared with nonsmoking controls (SMD −1.75, 95% CI −2.58 to −0.92). Sensitivity analyses confirmed the results.

Conclusions

Patients with COPD have significantly impaired endothelial function compared to controls without COPD. Future studies should delineate the importance of endothelial dysfunction towards development of cardiovascular disease in COPD.

COPD is significantly associated with endothelial dysfunction of both conduit vessels and microvasculature. This association is further strengthened when patients with COPD are compared to nonsmoking controls.https://bit.ly/2NlWLFN

Vascular endothelial damage in COPD: current functional assessment methods and future perspectives

Introduction: Cardiovascular disease is a major cause of death in chronic obstructive pulmonary disease (COPD), but the relationship between these two entities is not fully understood; smoking, inflammation, arterial stiffness and endothelial dysfunction are significant determinants. Endothelial dysfunction is not only associated with cardiovascular disease, but also with COPD severity.Areas covered: Several functional methods have been developed to evaluate endothelial function in healthy and diseased individuals; from the invasive angiography of epicardial coronary arteries and Venous-Occlusion-Plethysmography, to more modern, noninvasive approaches such as Flow-Mediated-Dilatation, Peripheral-Arterial-Tonometry and Near-Infrared-Spectroscopy, all these methods have boosted clinical research in this field. In this context, this narrative review, which included articles published in PubMed and Scopus up to 25-November-2020, summarizes available functional methods for endothelial damage assessment in COPD and discusses existing evidence on their associations with comorbidities and outcomes in this population.Expert opinion: Accumulated evidence suggests that endothelial dysfunction occurs in early stages of CΟPD and worsens with pulmonary obstruction severity and during acute exacerbations. Novel methods evaluating endothelial function offer a detailed, real-time assessment of different parameters related to vascular function and should be increasingly used to shed more light on the role of endothelial damage on cardiovascular and COPD progression.

Impaired endothelial function irrespective of systemic inflammation or atherosclerosis in mastocytosis

BACKGROUND

Knowledge on endothelial dysfunction and its relation to atherosclerosis in mastocytosis is limited.

OBJECTIVE

To investigate the endothelial function in mastocytosis by flow-mediated dilatation (FMD) and biomarkers related to vascular endothelia and to evaluate its relationship with the presence of subclinical atherosclerosis by carotid intima media thickness (CIMT).

METHODS

A total of 49 patients with mastocytosis and 25 healthy controls (HCs) were included. The FMD and CIMT during transthoracic echocardiography biomarkers including endocan, endothelin-1, and vascular endothelial growth factor (VEGF) were measured in the sera of participants. Tumor necrosis factor-alpha, interleukin 6, and high-sensitive C-reactive protein were determined as inflammatory biomarkers.

RESULTS

The mean FMD % was lower in the patients than HCs (11.26% ± 5.85% vs 17.84% ± 5.27% P < .001) and was the lowest in the advanced systemic mastocytosis and smoldering systemic mastocytosis group among the patients (P = .03). The median value of VEGF was considerably higher in patients than HCs (73.30 pg/mL; minimum-maximum 32.46-295.29 pg/mL vs 46.64 pg/mL; minimum-maximum, 11.09-99.86 pg/mL; P = .001) and it was the highest in the advanced systemic mastocytosis and smoldering systemic mastocytosis group (P = .01). The FMD was inversely correlated with endocan (r = -0.390; P = .006), endothelin-1 (r = -0.363; P = .01) and VEGF (r = -0.402; P = .004) but there were no correlations between FMD and tumor necrosis factor-alpha, interleukin 6, and high-sensitive C-reactive protein. No differences in CIMT values between patients and HCs and no correlation between CIMT and the biomarkers were observed.

CONCLUSION

Endothelial dysfunction in mastocytosis becomes evident with decreased FMD and elevated serum VEGF in the absence of atherosclerosis or systemic inflammation and is related to disease severity.

Assessment of Endothelial and Microvascular Function in CKD: Older and Newer Techniques, Associated Risk Factors, and Relations with Outcomes

BACKGROUND

Endothelium is the inner cellular lining of the vessels that modulates multiple biological processes including vasomotor tone, permeability, inflammatory responses, hemostasis, and angiogenesis. Endothelial dysfunction, the basis of atherosclerosis, is characterized by an imbalance between endothelium-derived relaxing factors and endothelium-derived contracting factors.

SUMMARY

Starting from the semi-invasive venous occlusion plethysmography, several functional techniques have been developed to evaluate microvascular function and subsequently used in patients with CKD. Flow-mediated dilatation of the forearm is considered to be the "gold standard," while in the last years, novel, noninvasive methods such as laser speckle contrast imaging and near-infrared spectroscopy are scarcely used. Moreover, several circulating biomarkers of endothelial function have been used in studies in CKD patients. This review summarizes available functional methods and biochemical markers for the assessment of endothelial and microvascular function in CKD and discusses existing evidence on their associations with comorbid conditions and outcomes in this population. Key Messages: Accumulated evidence suggests that endothelial dysfunction occurs early in CKD and is associated with target organ damage, progression of renal injury, cardiovascular events, and mortality. Novel methods evaluating microvascular function can offer a detailed, real-time assessment of underlying phenomena and should be increasingly used to shed more light on the role of endothelial dysfunction on cardiovascular and renal disease progression in CKD.

Inter-operator Reliability for Measuring Pulse Wave Velocity and Augmentation Index

Background: Arterial stiffness is a reversible precursor to hypertension. However, research is needed to determine the minimum amount of training required before acceptable arterial stiffness measurements are collected by novice operators. Objective: To compare novice vs. experienced operator measurements over a 2-week training period to assess when expert-like measures are achieved by the novice operator. Method: Forty-one participants (18 males, 23 females, age: 46.6 ± 14.9 years; BMI: 25.2 ± 3.8; systolic blood pressure: 122.8 ± 14.7 mmHg) received alternating novice and experienced operator arterial stiffness assessments. Measurements included: pulse wave velocity (PWV; using the automatic-capture time-periods of 5-, 10-, and 20-s) and augmentation index (AIx75) measurements using the SphygmoCor XCEL System v1 (AtCor Medical Pty Ltd., Sydney, Australia). Data were chronologically arranged into quintiles. Results: The intraclass correlation coefficient for PWV substantially improved from quintile 1 (r < 0.8) to quintile 2 and beyond (typically r > 0.8) while AIx75 improved consistently (r = 0.7 in quintile 1 and r = 0.97 in quintile 5). The coefficient of variation was lowest in quintile 4 (PWV: 4.7-6% across the three measurement time-periods; and 15% for AIx75) but increased in quintile 5 (PWV: 6.2-10.5%; and 25% for AIx75). All measurements demonstrated acceptable to excellent reliability after quintile 2. Conclusion: To achieve expert-like PWV measurements in this study, the novice operator underwent a familiarization session including guided practice measurements on 5 different people, for 10-15 min per person on two occasions (~2.5 h). The novice operator then required ≥14 practice measurements, with accuracy continuing to improve up to 30 participants. At least 30 training measurements are recommended for novices to take acceptable AIx75 measurements after a familiarization training.

Preeclampsia: Maternal Systemic Vascular Disorder Caused by Generalized Endothelial Dysfunction Due to Placental Antiangiogenic Factors

Preeclampsia, a systemic vascular disorder characterized by new-onset hypertension and proteinuria after 20 weeks of gestation, is the leading cause of maternal and perinatal morbidity and mortality. Maternal endothelial dysfunction caused by placental factors has long been accepted with respect to the pathophysiology of preeclampsia. Over the past decade, increased production of placental antiangiogenic factors has been identified as a placental factor leading to maternal endothelial dysfunction and systemic vascular dysfunction. This review summarizes the recent advances in understanding the molecular mechanisms of endothelial dysfunction caused by placental antiangiogenic factors, and the novel clinical strategies based on these discoveries.

Impaired endothelial function may predict treatment response in restless legs syndrome

While dopaminergic dysfunction is believed to be a crucial role in restless legs syndrome (RLS), changes in peripheral microvasculature system such as peripheral hypoxia and altered skin temperature, have been found. This study aimed to investigate whether patients with RLS would have a cerebral and peripheral endothelial dysfunction, and this may have association with treatment responsiveness. We evaluated cerebral endothelial function using breath-holding index (BHI) on transcranial Doppler in bilateral middle cerebral artery (MCA), posterior cerebral artery (PCA) and basilar artery (BA) and peripheral endothelial function using brachial flow-mediated dilation (FMD) in 34 patients with RLS compared with age and sex-matched controls. The values of BHI in both MCA and BA were significantly lower in RLS group than control group. The values of FMD also were significantly lower in RLS patients. There was a weak correlation between BHI and FMD (p = 0.038 in Rt MCA, p = 0.032 in Lt MCA, p = 0.362 in BA) in RLS, but not in controls. BHI differed according to treatment responsiveness. (p < 0.005). Our study suggests that RLS patients have poorer cerebral and peripheral endothelial function than controls, showing an underlying mechanism of RLS and further evidence of a possible association between RLS and cardiovascular disease.

Association between Preoperative Vascular Function and Postoperative Arteriovenous Fistula Development

Arteriovenous fistula (AVF) maturation failure is the primary cause of dialysis vascular access dysfunction. To evaluate whether preoperative vascular functional properties predict postoperative AVF measurements, patients enrolled in the Hemodialysis Fistula Maturation Study underwent up to five preoperative vascular function tests (VFTs): flow-mediated dilation (FMD), nitroglycerin-mediated dilation (NMD), carotid-femoral pulse wave velocity, carotid-radial pulse wave velocity, and venous occlusion plethysmography. We used mixed effects multiple regression analyses to relate each preoperative VFT to ultrasound measurements of AVF blood flow rate and venous diameter at 1 day, 2 weeks, and 6 weeks after AVF placement. After controlling for AVF location, preoperative ultrasound measurements, and demographic factors (age, sex, race, and dialysis status), greater NMD associated with greater 6-week AVF blood flow rate and AVF diameter (per absolute 10% difference in NMD: change in blood flow rate =14.0%; 95% confidence interval [95% CI], 3.7% to 25.3%; P<0.01; change in diameter =0.45 mm; 95% CI, 0.25 to 0.65 mm; P<0.001). Greater FMD also associated with greater increases in 6-week AVF blood flow rate and AVF diameter (per absolute 10% difference in FMD: change in blood flow rate =11.6%; 95% CI, 0.6% to 23.9%; P=0.04; change in diameter =0.31 mm; 95% CI, 0.05 to 0.57 mm; P=0.02). None of the remaining VFT parameters exhibited consistent statistically significant relationships with both postoperative AVF blood flow rate and diameter. In conclusion, preoperative NMD and FMD positively associated with changes in 6-week AVF blood flow rate and diameter, suggesting that native functional arterial properties affect AVF development.

Association Between Psoriasis and Subclinical Atherosclerosis: A Meta-Analysis

The association between psoriasis and carotid intima-media thickness (CIMT) or impaired flow-mediated dilation (FMD) remains controversial. We aimed to evaluate the extent of subclinical atherosclerosis as measured by CIMT and FMD in patients with psoriasis by conducting a meta-analysis.A systematic literature search was performed using PubMed, Embase, Cochrane databases, China National Knowledge Infrastructure, and VIP databases up to February 2015. Observational studies investigating CIMT or FMD in patients with psoriasis and controls were eligible. Psoriatic patients and controls were at least age- and sex-matched. Random-effects analysis was used to estimate the weighted mean difference (WMD) and 95% confidence interval (CI) between psoriatic patients and controls.A total of 20 studies were identified and analyzed. Meta-analysis showed that psoriatic patients had a significantly thicker CIMT (WMD 0.11 mm; 95% CI 0.08-0.15) and lower FMD (WMD -2.79%; -4.14% to -1.43%) than those in controls. Subgroup analysis indicated that psoriatic arthritis appeared to have less impaired FMD (WMD -2.45%) and thinner CIMT (WMD 0.10 mm). Psoriatic patients with mean age >45 years had much thicker CIMT (WMD 0.13 mm). The impaired FMD (WMD -3.99%) seemed more pronounced in psoriatic patients with mean age <45 years.This meta-analysis suggests that patients with psoriasis are associated with excessive risk of subclinical atherosclerosis. Screening and monitoring CIMT and brachial artery FMD may be recommended to identify a subgroup of psoriatic patients at higher risk for cardiovascular events.

Investigation of Ultrasound-Measured Flow Rate and Wall Shear Rate in Wrist Arteries Using Flow Phantoms

The aim of this study was to evaluate the errors in measurement of volumetric flow rate and wall shear rate measured in radial and ulnar arteries using a commercial ultrasound scanning system. The Womersley equations were used to estimate the flow rate and wall shear rate waveforms, based on the measured vessel diameter and centerline velocity waveform. In the experiments, each variable (vessel depth, diameter, flow rate, beam-vessel angle and different waveform) in the phantom was investigated in turn, and its value was varied within a normal range while others were fixed at their typical values. The outcomes revealed that flow rate and wall shear rate were overestimated in all cases, from around 13% to nearly 50%. It is concluded that measurements of flow rate and wall shear rate in radial and ulnar arteries with a clinical ultrasound scanner are vulnerable to overestimation.

Association of non-alcoholic fatty liver disease with impaired endothelial function by flow-mediated dilation: A meta-analysis

AIM

Endothelial dysfunction was observed in patients with non-alcoholic fatty liver disease. The aim of the present study was to evaluate the extent of endothelial function impairment in patients with non-alcoholic fatty liver disease.

METHODS

We systematically searched through the PubMed, Embase, China National Knowledge Infrastructure and Wanfang databases for studies dated up to January 2015. All observational studies that compared endothelial function between non-alcoholic fatty liver disease patients and healthy controls were included. Endothelial function was measured by brachial artery flow-mediated dilation and nitrate-induced dilatation techniques.

RESULTS

Eleven observational studies were identified. Meta-analysis indicated that non-alcoholic fatty liver disease patients were associated with a reduction in brachial artery flow-mediated dilation (weighted mean difference, -4.82%; 95% confidence interval [CI], -5.63 to -4.00) compared with the healthy controls. Subgroup analysis indicated that the patients with non-alcoholic steatohepatitis or a body mass index of more than 30 kg/m(2) appeared to have a greater reduction in their flow-mediated dilation. However, no significant differences were observed in the nitrate-induced dilation (weighted mean difference, -0.4%; 95% confidence interval, -2.19 to 1.39).

CONCLUSION

Non-alcoholic fatty liver disease is associated with a greater risk of endothelial dysfunction as indicated by the decreased brachial artery flow-mediated dilation. Assessment of endothelial function may be recommended to identify subclinical atherosclerosis and to create subgroups of non-alcoholic fatty liver disease patients who are at higher risk of future cardiovascular events.

The presence of cerebral and/or systemic endothelial dysfunction in patients with leukoaraiosis--a case control pilot study

BACKGROUND

In spite of high prevalence and clinical relevance of leukoaraiosis (LA), its pathophysiology is still incompletely understood. Theories of ischaemic genesis and a leaky blood-brain barrier are contradictory yet could share a common denominator-endothelial dysfunction (cerebral, systemic or both), which has not been studied thoroughly in LA.

METHODS

Thirty patients with LA (58 years (SD 7)) and 30 gender- and age-matched controls without LA (55 years (SD 6)) were recruited. The vascular risk factors (VRF) were identical in both groups. Cerebral endothelial function was determined by cerebrovascular reactivity to L-arginine (CVR). Systemic endothelial function was determined by flow-mediated dilatation (FMD) of the brachial artery after hyperaemia. All participants underwent a brain MRI to search for radiological signs of LA that was classified according to the Fazekas score. Linear regression was used to explore the correlation between CVR and FMD in patients with LA. A 95 % confidence interval was used. For any statistical test used in the study, p ≤ 0.050 was regarded as statistically significant.

RESULTS

We found a marked and significant decrease in both CVR (9.6 % (SD 3.2) vs. 15.8 % (SD 6.1), p < 0.001) and FMD (4.8 % (SD 3.1) vs. 7.4 % (SD 3.8), p = 0.004) in LA patients compared to controls. Both CVR (7.4 % (SD 3.1) vs. 12.2 % (SD 2.6), p = 0.001) and FMD (3.0 % (SD 2.2) vs. 6.4 % (SD 3.1), p = 0.011) were significantly decreased in LA subgroup Fazekas 3 compared to subgroup Fazekas 1. CVR and FMD significantly positively correlated (b = 0.192, 95 % CI = 0.031-0.354, p = 0.02).

CONCLUSIONS

The results of our pilot study suggest that patients with LA have a significant impairment of both cerebral and systemic endothelial function that is larger than could be expected based on present VRF. Endothelial dysfunction increases in parallel with LA severity and correlates between cerebral and systemic arterial territory. Overall, our results suggest a so far unknown "intrinsic" generalised endothelial dysfunction in patients with LA that could be involved in LA pathophysiology. This interesting issue needs to be confirmed in larger samples since it could help better understand the mechanisms underlying LA.

Maternal arterial stiffness in normotensive pregnant women who subsequently deliver babies that are small for gestational age

OBJECTIVE

To assess the association between maternal arterial stiffness and delivery of a baby that is small for gestational age (SGA) in normotensive pregnant women.

STUDY DESIGN

Pulse wave analyses were performed to assess maternal arterial stiffness at 26-33 weeks of gestation in 40 normotensive women who subsequently delivered SGA babies (SGA group) and 111 normotensive women who delivered babies with normal growth (control group).

RESULTS

Central systolic pressure (CSP), augmentation index (AIx) and AIx at a heart rate of 75 beats/min (AIx-75) were significantly higher in the SGA group compared with the control group, but this was not the case for brachial systolic pressure, brachial diastolic pressure or brachial pulse pressure. Birth weight was significantly correlated with CSP (r=-0.26, p<0.01), AIx (r=-0.33, p<0.01) and AIx-75 (r=-0.27, p<0.01), but not with brachial systolic pressure, brachial diastolic pressure or brachial pulse pressure.

CONCLUSION

Increased arterial stiffness may be involved, in part, in the pathogenesis of SGA in normotensive women, suggesting an association between fetal growth and maternal endothelial function. Pulse wave analysis may be a clinically applicable method for assessment of maternal arterial stiffness, and may be more relevant to intrauterine fetal growth than conventional brachial blood pressure.

Variação do diâmetro da artéria braquial em crianças obesas: presente e futuro

OBJETIVO: Revisão da literatura acerca do uso da medida da variação do diâmetro da artéria braquial por ultrassonografia de alta resolução (dilatação mediada por fluxo) como preditor de risco para doença cardiovascular em crianças e adolescentes obesos. FONTES DE DADOS: Levantamento de publicações indexadas no Medline/PubMed de trabalhos publicados entre 2002 e 2011, rastreadas com a combinação dos descritores: "endothelium", "child", "ultrasonography" e "obesity", além de estudos e textos clássicos sobre o tema. Foram encontradas 54 publicações e 32 delas foram incluídas na presente revisão do tema. SINTESE DOS DADOS: O estudo da disfunção endotelial tem sido empregado como preditor de risco para doenças cardiovasculares, tais como aterosclerose e doença cardíaca coronariana, visto que a lesão endotelial é um importante evento na fisiopatologia de tais doenças. CONCLUSÕES: A dilatação mediada por fluxo da artéria braquial mostra-se importante como ferramenta diagnóstica e prognóstica na avaliação da função endotelial de crianças e adolescentes com excesso de peso por ser um método não invasivo, com boa aplicabilidade quanto ao custo, à inocuidade e ao benefício.

Aortic stiffness and flow-mediated dilatation in normotensive offspring of parents with hypertension

OBJECTIVES

Although hypertension has been shown to be one of the most important risk factors for atherosclerosis, data about the presence of subclinical atherosclerosis in normotensive offspring with parental history of hypertension are scarce. Accordingly, the current study was designated to evaluate flow-mediated dilatation and aortic stiffness, which are early signs of atherosclerosis in young subjects with parental history of hypertension.

METHODS

A total of 140 [corrected] healthy, non-obese subjects in the age group of 18-22 years were included in this study and divided into two groups. The first group included 70 offspring of hypertensive parents and the second group included 70 offspring of normotensive parents as controls. In all subjects, endothelium-dependent and endothelium-independent vasodilatation of the brachial artery and aortic elastic parameters were investigated using high-resolution Doppler echocardiography.

RESULTS

Offspring of hypertensive parents demonstrated higher values of aortic stiffness (7.1 plus or minus 1.88 and 6.42 plus or minus 1.56, respectively) but lower distensibility (9.47 plus or minus 1.33 and 11.8 plus or minus 3.36 square centimetres per dyne per 106) and flow-mediated dilatation (4.57 plus or minus 1.3 versus 6.34 plus or minus 0.83 percent, p equals 0.0001, respectively) than offspring of hypertensive parents.

CONCLUSION

We observed blunted endothelium-dependent dilatation and aortic stiffness in offspring of hypertensive parents compared with offspring of normotensive [corrected] parents. This is evident in the absence of overt hypertension and other diseases, suggesting that parental history of hypertension is a risk for subclinical atherosclerosis and it may contribute to the progression to hypertension and overt atherosclerosis in later life.

The optimal measure of microvascular function with velocity time integral for cardiovascular risk prediction

Recent evidence suggests that microvascular function may be important in cardiovascular risk prediction. One measure of microvascular function is hyperaemic velocity time integral (VTI). We assessed whether the VTI of more than one beat of reactive hyperaemia would provide a stronger correlate to traditional cardiovascular risk factors using a subset of subjects from the Firefighters and Their Endothelium (FATE) study. Vascular function was assessed by measurement of hyperaemic blood velocity with high-resolution ultrasound of the brachial artery. We evaluated three measures in the current analysis: the VTI of the first beat, average VTI of 10 beats, and maximum VTI of 10 beats post-cuff release. A total of 399 male subjects (45.5 ± 10 years) were included in this analysis. Univariate correlations between the three end points and cardiovascular risk factors were calculated, and multivariable regression models constructed. Intra-observer variability was approximately equal for all VTI end points (coefficient of variation: first = 1.6%, average = 1.4%, maximum = 1.4%). Univariate correlations between VTI and cardiovascular risk factors were similar across all three end points. In multivariable analyses, there were no differences in the relationships between cardiovascular risk factors and the various VTI end points ( R2 from 0.090 to 0.102). Age, systolic blood pressure, and BMI were predictors of the three VTI end points ( p < 0.05). In conclusion, the first beat of reactive hyperaemia remains the suitable measure of microvascular function.

Effects of therapeutic lifestyle changes on peripheral artery tonometry in patients with abdominal obesity

BACKGROUND AND AIMS

Abdominal obesity (AO) is associated with endothelial function (EF) alteration and increased global cardiovascular (CV) risk. Therapeutic lifestyle changes (TLSC) reduce CV risk, but the impact on EF assessed by peripheral artery tonometry (PAT) is unknown. In this study, we aimed to prospectively assess the effects of TLSC on EF measured by PAT in increased CV risk patients with AO.

METHODS AND RESULTS

150 patients with AO and moderate CV risk were randomized to groups receiving a one-year intervention of either conventional medical care (control group, CG) or an intensive TLSC program (intervention group, IG). Vascular studies (EF by PAT, intima-media thickness (IMT)) and lifestyle (LS) assessment were performed before and after intervention. The PAT ratio improved in the IG and worsened in the CG. The global CV risk was reduced (P = 0.017) in the IG due to a significant decrease in systolic blood pressure (P < 0.001), increase in HDL cholesterol and ApolipoproteinA1 (P = 0.013). More individuals in the IG than in the CG quit smoking (P = 0.001) and increased their physical activity (P = 0.014). The improvement in at least two LS components was associated with a PAT ratio increase (2.44 IC: 95% 0.99-6.00, P = 0.051). The PAT ratio increase determined less IMT progression (-1.1 IC: 95% 0.91-1.00, P = 0.053).

CONCLUSIONS

Good adherence to a TLSC program reduces global CV risk and determines PAT ratio improvement. The PAT ratio increase is the main determinant of lower IMT progression.

Endothelial function and left ventricular remodeling in diabetic and non-diabetic patients after acute coronary syndrome

BACKGROUND

Endothelial dysfunction is an independent predictor of future cardiac events.

MATERIAL/METHODS

We evaluated the relationship between flow-mediated dilation (FMD) in brachial artery and coronary risk factors in 93 patients (70 males, mean age: 62 ± 8 years) with ACS treated with primary angioplasty (PCI). The patients were divided into 2 subgroups: 43 patients with diabetes mellitus type 2 (DM) and 50 non-diabetics (non-DM). Patients were examined on the 3rd day after ACS and after 6 months. FMD on the 3rd day were significantly lower in DM than in non-DM (5.8 ± 2.2% vs. 8.8 ± 4.9%, p=0.0007) and after 6 months (6.2 ± 2.6% vs. 9.4 ± 4.4%, p<0.0001). It was also observed that the improvement of FMD in both groups after a 6-month follow-up inversely correlated with the increase of left ventricular end-diastolic volume (LVEDV) (r=-0.41, p<0.001).

RESULTS

There was an inverse relationship between FMD and age (r=-0.26, p<0.01), BMI (r=-0.26, p<0,005), total cholesterol (r=-0.56, p<0.001) and LDL cholesterol (r=-0.53, p<0.001). There was no relationship between triglycerides, hypertension and history of smoking. In the DM group, FMD negatively correlated with HbA1c (r=-0.68, p<0.001). Restenosis rate was significantly higher in the DM group (19% vs. 6%, p<0.001) but there was no relationship between FMD and restenosis.

CONCLUSIONS

Impaired FMD is more significant in diabetics than in non-diabetic patients with ACS. Lack of improvement of FMD after acute coronary syndrome can be a predictor of detrimental left ventricular remodeling in patients with ACS.

Cardiovascular dysfunction in obesity and new diagnostic imaging techniques: the role of noninvasive image methods

Obesity is a major public health problem affecting adults and children in both developed and developing countries. This condition often leads to metabolic syndrome, which increases the risk of cardiovascular disease. A large number of studies have been carried out to understand the pathogenesis of cardiovascular dysfunction in obese patients. Endothelial dysfunction plays a key role in the progression of atherosclerosis and the development of coronary artery disease, hypertension and congestive heart failure. Noninvasive methods in the field of cardiovascular imaging, such as measuring intima-media thickness, flow-mediated dilatation, tissue Doppler, and strain, and strain rate, constitute new tools for the early detection of cardiac and vascular dysfunction. These techniques will certainly enable a better evaluation of initial cardiovascular injury and allow the correct, timely management of obese patients. The present review summarizes the main aspects of cardiovascular dysfunction in obesity and discusses the application of recent noninvasive imaging methods for the early detection of cardiovascular alterations.

Effects of lower extremity revascularization on the endothelial functions measured with noninvasive brachial artery flow-mediated dilatation

BACKGROUND

Endothelial function is best measured with the noninvasive brachial artery flow-mediated dilatation (FMD) method. Peripheral arterial diseases and systemic cardiovascular diseases have FMD-lowering effect. The effects of lower extremity ischemia are associated with muscle inflammation and claudication, which may further lead to arterial stress. Our aim in this study was to investigate the effects of peripheral arterial revascularization on the endothelial functions through noninvasive brachial artery FMD.

METHODS

Between January 2007 and February 2008, 54 patients diagnosed with lower extremity arterial disease undergoing revascularization were included in the study. Endothelial function is measured preoperatively and at the fourth week postoperatively using the brachial artery FMD method. Blood samples were collected at the same intervals for the measurement of interleukin-6, leukocyte count, tumor necrosis factor-alpha, and nitric oxide values.

RESULTS

Femoropopliteal bypass grafting was performed in all patients with a synthetic graft. The mean ankle-brachial index in the preoperative period was 0.29 ± 0.083, and after the operation, dorsalis pedis and/or posterior tibial artery became palpable in all patients. The nitric oxide, interleukin-6, high-sensitivity C-reactive protein, and tumor necrosis factor-alpha levels decreased significantly after 4 weeks postoperatively as compared with the preoperative levels (p < 0.05). Postoperative Doppler ultrasonography FMD of brachial artery increased from preoperative value of 9.2 ± 2.1 to 16.2 ± 4.5 (p < 0.01) at postoperative week 4.

CONCLUSIONS

Systemic inflammation and muscle ischemia lead to reduced endothelial functions. After successful lower extremity revascularization, endothelial functions improve dramatically, which may be easily detected with the noninvasive brachial artery FMD method.

Improved endothelial function in patients with atrial fibrillation through maintenance of sinus rhythm by successful catheter ablation

BACKGROUND

Although atrial fibrillation (AF) is a risk factor for endothelial dysfunction (ED), the effect of catheter ablation (CA) on AF-associated ED has not been evaluated. The aims of this study are to determine if the degree of ED predicts the outcome of AF ablation and to evaluate whether ED can be improved through restoring sinus rhythm (SR) by successful CA.

METHODS

This study prospectively enrolled 80 subjects who underwent CA for AF (paroxysmal AF = 61, persistent AF = 19). Eighty subjects with no history of AF were enrolled as controls, all of whom were matched by age, gender, body mass index, and atherosclerotic risk factor distribution. Brachial artery flow-mediated dilatation (FMD) was measured at baseline, and at 1 month and 6 months post CA in AF subjects who remained in SR. Among controls, FMD was measured at baseline and at 6 months. We used high sensitivity C-reactive protein (hs-CRP), interleukin-6, soluble E- or P-selectin, and endothelin-1 as biomarker indices for inflammation and/or ED.

RESULTS

Compared with controls, AF subjects had lower FMD at baseline (FMD(baseline), P < 0.001). After successful CA, FMD was significantly improved at 1 month and 6 months, nearly approaching control levels. A multivariate analysis revealed that FMD(baseline), hs-CRP, and left atrial volume (LAV) were independent predictors for arrhythmia recurrence after CA. Other biomarkers were not related to rhythm outcome.

CONCLUSION

AF subjects have significantly impaired FMD, which can be reversed through maintenance of SR by successful CA. FMD(baseline), hs-CRP, and LAV are important predictors for AF recurrence after CA.