Nitroglycerin reduces augmentation index and central blood pressure independent of effects on cardiac preload

Objective To determine whether reduction in central pressure augmentation and central systolic blood pressure by nitroglycerine (NTG) results from effects on pre-load or is due to arterial dilation. Methods We compared effects of NTG with those of lower body negative pressure (LBNP). Hemodynamic measurements were made at rest,during LBNP (10,20 and 30 mmHg,each for 15 min) and after NTG (10,30 and 100 μg/min,each dose for 15 min) in ten healthy volunteers. Cardiac pre-load,stroke volume and cardiac output were assessed by echocardiography. Central pressure augmentation and central systolic pressure were obtained by radial tonometry using a transfer function. Results LBNP (20 mmHg) and NTG (30 μg/min) reduced pre-load (as measured by the peak velocity of the S wave in the superior vena cava) to a similar degree [by (26.8±3.8)% and (23.9±3.4)%,respectively]. Compared to LBNP,NTG reduced systemic vascular resistance [by (32.9±7.5)%,P<0.01],decreased peripheral and central pressure augmentation [by (20.8±3.4)% units and (12.9±2.9)% units,respectively,each P<0.01]. Conclusion These results suggest that a reduction in pre-load does not explain reduction in pressure augmentation and central systolic blood pressure by NTG and that these effects are mediated through arterial dilation.

Sex modification of the association of the radial augmentation index and incident hypertension in a Chinese community-based population

BACKGROUND Arterial stiffness,as assessed by aortic ultrasound and pulse wave velocity,is associated with incident hypertension.However,there is still no consensus on whether the augmentation index(AI)affects new onset of hypertension.This study investigated the relationship of radial AI(r AI)and incident hypertension in a Chinese community-based population without hypertension at baseline.METHOD A total of 1,615 Chinese non-hypertensive participants from an atherosclerosis cohort in Beijing,China were included in our analysis.Baseline r AI normalized to heart rate of 75 beats/min(r AIp75)was obtained using HEM-9000 AI.New-onset hypertension was defined as blood pressure≥140/90 mm Hg or self-reported hypertension or taking anti-hypertensive medications at the follow up survey.Multivariate regression models were used to evaluate the impact of r AIp75 on the risk of new-onset hypertension.RESULTS After a mean 2.35-year follow-up,213(13.19%)participants developed incident hypertension.No significant relation between r AIp75 and incident hypertension was observed in the whole population after adjustment for possible confounders(adjusted odds ratio(OR)and 95%confidence interval(CI):1.09[0.95-1.27];P=0.2260).However,r AIp75 was significantly associated with incident hypertension in women,but not in men(adjusted OR and 95%CI:1.29[1.06-1.56],P=0.0113 for women;0.91[0.72-1.15],P=0.4244 for men;P for interaction=0.0133).CONCLUSIONS Sex modified the effect of the r AI on incident hypertension in a Chinese,community-based,non-hypertensive population.Screening of the r AI could be considered in women with a high risk of hypertension for the purpose of primary intervention.

Trees with Given Diameter Minimizing the Augmented Zagreb Index and Maximizing the ABC Index

Let G be a simple connected graph with vertex set V（G） and edge set E（G）.The augmented Zagreb index of a graph G is defined asAZI（G） =∑uv∈E（G）(d;d;/（d;+ d;-2）);,and the atom-bond connectivity index（ABC index for short） of a graph G is defined asABC（G） =∑uv∈E（G）(（d;+ d;-2）/d;d;),where d;and d;denote the degree of vertices u and v in G,respectively.In this paper,trees with given diameter minimizing the augmented Zagreb index and maximizing the ABC index are determined,respectively.

On Augmented Zagreb Index of Molecular Graphs

The augmented Zagreb index displays a good correlation with the formation heat of octanes and heptanes. The augmented Zagreb index of catacondensed hexagonal systems and molecular trees was discussed. By using the methods of analysis of graph structure and mathematical induction,the catacondensed hexagonal systems with extreme augmented Zagreb index were characterized.The lower bound for augmented Zagreb index of molecular trees with fixed numbers of pendent vertices was given,and the extremal trees were characterized. From these results,we can compare the formation heat of catacondensed hexagonal systems and molecular trees.

Increased Risk of Arterial Stiffness in Rhumatoid Arthritis Patients in a Sub-Saharan African Setting

Background: Analysis of arterial stiffness (AS) is a good marker of early arterial disease and an important determinant of cardiovascular risk, independent of other traditional cardiovascular risk factors. Carotid-femoral pulse wave velocity (CfPWV) is the gold standard to evaluate arterial stiffness. There is evidence that patients with rheumatoid arthritis (RA) have a higher arterial stiffness than their age-matched healthy counterparts and thus have higher cardiovascular (CV) risk. However, data on arterial stiffness in African rheumatoid arthritis patients is scarce. Objectives: To determine the patterns of arterial stiffness in rheumatoid arthritis patients in a sub-Saharan African setting, using CfPWV and Augmentation index (AIx). Method: We conducted a case-control study, at the Douala general hospital over four months (February to May 2018) on 63 subjects among which 31 RA patients matched for age and sex with 32 healthy subjects. AIx and CfPWV were determined non-invasively by radial pulse wave analysis and carotid femoral wave analysis respectively, using a sphygmocor Atcor device (SphygmoCor, PWV Medical, Sydney, Australia). Results: The mean age of RA patients was 47 ± 14 years with most of them being females (n = 26, 83.9%). CfPWV was significantly higher in RA patients compared to the control group (mean: 8.85 ± 2.1 vs 7.45 ± 1.38;p ≤ 0.01) as well as was AIx (Median: 33 [26 - 43] vs 26 [20 - 31];p = 0.01). RA (OR: 6.105;95% CI: 1.52 - 24.54;p 1.34;95% CI: 1.14 - 5.17;p = 0.05), elevated CRP levels (OR: 4.01;95% CI: 1.16 - 13.68;p = 0.03) and Hypertension (OR: 5.75;95% CI: 1.24 -11.60;p Conclusion: Arterial stiffness, a well-recognized marker of cardiovascular risk is increased among patients suffering from rheumatoid arthritis when compared to a healthy control group.

Association of glomerular filtration rate with arterial stiffness in Chinese women with normal to mildly impaired renal function

Objective Both decreased glomemlar filtration rate （GFR） and arterial stiffness were considered as risk factors for atherosclerosis. Previous studies have suggested the association between central arterial stiffness and the degree of GFR loss. Whether decreased GFR contributes to peripheral artery stiffness remains controversial. Moreover, data analyzed from a cohort of Chinese women are rare. Our aim was to explore the relationship between GFR and regional arterial stiffness in Chinese women. Methods In this cross-sectional study, we randomly recruited 1131 adult women residents with GFR 〉 60 mL/min per 1.73 m2 estimated by the Chinese Modification of Diet in Renal Disease equation from three large communities. Central and peripheral arterial stiffness were estimated simultaneously by measuring carotid-femoral pulse wave velocity （PWVcf） and carotid-radial PWV （PWVcr） using a validated automatic device. Augmentation Index at heart rate 75 beats/minutes （AIx-75） was measured by pulse wave analysis as a composite parameter reflecting both large and distal arterial properties. Results The mean estimated GFR （eGFR） of the study group was 100.05 ＋ 23.26 mL/minute per 1.73 m2. Subjects were grouped by tertiles of eGFR level. PWVef and AIx-75 increased ongoing from the top to the bottom eGFR tertile, while the values of PWVcr were comparable. Both univariate Pearson correlations and multiple stepwise regression analyses showed that eGFR significantly correlated to PWVcf, but not to PWVcr and AJx-75. Conclusions In Chinese women with normal to mildly impaired renal function, decreased eGFR affected carotid-to-femoral rather than carotid-to-radial stiffening. This provides rational to conduct future prospective studies to investigate predictors of atherosclerosis in this population.

The effect of acute aerobic exercise on central arterial stiffness,wave reflections,and hemodynamics in adults with diabetes:A randomized cross-over design

Background:Individuals with diabetes have greater central arterial stiffness,wave reflections,and hemodynamics,all of which promote the accelerated cardiovascular pathology seen in this population.Acute aerobic exercise has been shown to be an effective strategy for reducing central arterial stiffness,wave reflections,and hemodynamics in healthy individuals;however,the effects of acute aerobic exercise in reducing these outcomes is not well established in people with diabetes.Recently,implementation of high-intensity interval exercise(HIIE)has shown superior improvements in cardiovascular health outcomes when compared to traditional aerobic exercise.Yet,the effect of HIIE on the aforementioned outcomes in people with diabetes is not known.The purpose of this study was to(i)describe the central arterial stiffness,wave reflections,and hemodynamic responses to a bout of HIIE and moderate-intensity continuous exercise(MICE)in adults with diabetes;and(ii)compare the effects of HIIE and MICE on the aforementioned outcomes.Methods:A total of 24 adult men and women(aged 29-59 years old)with type 1(n=12)and type 2(n=12)diabetes participated in a randomized cross-over study.All participants completed the following protocols:(i)HIIE:cycling for 4×4 min at 85%-95%of heart rate peak(HR_(peak)),interspersed with 3 min of active recovery at 60%-70%HR_(peak);(ii)MICE:33 min of continuous cycling at 60%-70%HR_(peak);and(iii)control(CON):lying quietly in a supine position for 30 min.Results:A significant group￡time effect was found for changes in central systolic blood pressure(F=3.20,p=0.01)with a transient reduction for the HIIE group but not for the MICE or CON groups.There was a significant group￡time effect for changes in augmentation index at a heart rate of 75 beats/min(F=2.32,p=0.04)with a decrease following for HIIE and MICE but not for CON.For all other measures of central arterial stiffness and hemodynamics,no significant changes were observed(p>0.05).Conclusion:A bout of HIIE appears to lead to a greater transient reduction in central systolic blood pressure than the reduction observed following MICE;however,both HIIE and MICE improved augmentation index at a heart rate of 75 beats/min in people with diabetes.There was no significant difference in response to HIIE and MICE in all outcomes.This provides preliminary evidence on the role of HIIE on such outcomes in people with diabetes.

Albuminuria as a marker of arterial stiffness in chronic kidney disease patients

AIM： To access the association between albuminuria levels and arterial stiffness in non-diabetic patients with hypertension and chronic kidney disease （CKD） stages 1-2, treated with renin angiotensin blockade agents plus other hypertensive drugs when needed.METHODS： One hundred fifteen patients [median age 52 years （68% males）] were consequently enrolled in the study. For each patient, we recorded gender, age, body mass index （BMI）, peripheral systolic blood pressure （pSBP）, peripheral diastolic blood pressure, peripheral pulse pressure, central systolic blood pressure （cSBP）, central diastolic blood pressure （cDBP）, central pulse pressure （cPP）, hematocrit, hemoglobin, hsCRP, total cholesterol triglycerides, high-density lipoprotein-C, low-density lipoprotein-C, calcium, phosphorus, parathormone, and albumin, as well as 24 h urine albumin excretion. According to 24-h urine albumin collection, patients were then classified as those with moderately increased albuminuria （formerly called macroalbuminuria） （≤ 300 mg/d） and those with severely increased albuminuria （formerly called macroaluminuria （〉 300 mg/d）. We considered aortic stiffness （AS） indices [carotid femoral pulse wave velocity （PWVc-f） and augmentation index （AIx）] as primary outcomes of the study. We explored potential correlations between severely increased albuminuria and AS indices using a multiple linear regression model. RESULTS： Fifty-eight patients were included in the moderately increased albuminuria group and 57 in the severely increased albuminuria. Blood pressure measurements of the study population were 138 ± 14/82 ± 1.3 mmHg （systolic/diastolic）. There were no significant differences in age, sex, and BP measurements between the two groups. Patients with severely increased albuminuria had higher PWV and AIx than patients with moderately increased albuminuria （P 〈 0.02, P 〈 0.004, respectively）. In addition these patients exhibited higher BMI （P 〈 0.03）, hsCRP （P 〈 0.001）, and fibrinogen levels （P 〈 0.02） compared to patients with moderately increased albuminuria. In multivariate linear regression analysis, severely increased albuminuria （β = 1.038, P 〈 0.010） pSBP （β = 0.028, P 〈 0.034） and Ht （β = 0.171, P = 0.001） remained independent determinants of the increased PWVc-f. Similarly, severely increased albuminuria （β = 4.385, P 〈 0.012）, cSBP （β = 0.242, P 〈 0.001）, cPP （β = 0.147, P 〈 0.01） and Ht levels （β = 0.591, P 〈 0.013） remained independent determinants of increased AIx.CONCLUSION： These fndings demonstrate an independent association between AS indices and severely increased albuminuria in non-diabetic, hypertensive patients with CKD stages 1-2 treated with renin angiotensin aldosterone system blockers.

Modulation by anti-oketsu formulations in Kampo medicine of human arterial stiffness

Objective:In traditional herbal medicine(Kampo medicine in Japan),'sho'is diagnosed by the traditional assessments of clinical conditions.Among a variety of the shos,there is an'oketsu'syndrome,which is a stagnation and disturbance of microcirculation.The prompt effects of four anti-oketsu formulations in Kampo medicine on cardiovascular functions were compared in oketsu and non-oketsu persons.Methods:The arterial pulse wave from radial artery is formed by the combination with ejection and reflection pulses.An augmentation index(AI),a ration of the ejection and reflection pulses,indicates a degree of arteriosclerosis.For both seventy-six students with oketsu and thirty-seven students with non-oketsu,Kampo formulations overcoming oketsu of Tokishakuyakusan(TS,Dang-Gui-Shao-Yao-San),Kamishoyosan(KS,Jia-Wei-Xiao-Yao-San),Keisibukuryogan(KB,Gui-Zhi-Fu-Ling-Wan)and Tokakujokito(TJ,Tao-He-Cheng-Qi-Tang)were taken once,and then,the cardiovascular functions including blood pressure,heart rate,central arterial blood pressure(CBP)and AI were examined for 60 min.Results:At 40-60 min after an intake,these formulations decreased the AI almost by 6-18%(n=76),by 18.3±3.1%(P<0.01,n=15)with TJ.Simultaneously,the CBP was reduced by 9.0±1.8%(P<0.05,n=23)with KS and by 9.1±2.0%(P<0.05,n=15)with TJ.On the other hands,non-oketsu group had less or no effect by any kinds of the formulations.Conclusion:The anti-oketsu formulations can exert the ameliorative action for oketsu persons via decreasing AI and CBP.

Non-invasive cuffless blood pressure and heart rate monitoring using impedance cardiography

Background Continuous blood pressure(BP)monitoring provides additional information about how changes in BP may correlate with daily activities and sleep patterns.Recommendations from the American Heart Association and American College of Cardiology strongly suggest confirming a diagnosis of hypertension with continuous BP monitoring.Non-invasive and non-intrusive detection of haemodynamic parameters is emerging as a norm,based on self-monitoring wearable medical devices.Researchers have carried out several studies using non-invasive and continuous BP measurements as an alternative to conventional cuff-based measurements.In this work,we proposed a novel method for cuffless estimation of BP using impedance cardiography(ICG).Methods We conducted a single-centre,cross-sectional study of 104 subjects(of whom 30 were categorized as controls and the remaining 74 as the disease group)at the Medical College and Hospital,Kolkata.The disease group consisted of patients with confirmed coronary artery disease,while the individuals in the control group were deemed to be healthy.All subjects underwent electrocardiogram recording by on-duty doctors in order to determine their health status.A custom-made device based on the principle of impedance plethysmography was designed to record impedance changes due to subjects’peripheral blood flow.The device was used to record ICG signals.In this study,we developed a novel auto-adaptive algorithm based on ICG signals for non-invasive,cuffless,continuous monitoring of BP and heart rate.Separate mathematical models were developed for all the estimated parameters(BP and heart rate)for both the study groups(control and disease).The developed models were auto-adaptive and did not require subject-specific calibration.Performance indicators including,𝑟2,error percentage,standard deviation,and mean difference were used to quantify the performance of the models.Results The ICG signal recorded by the device was used to extract features and compute the augmentation index.The calculated augmentation index values showed strong correlations with systolic BP(𝑟=0.99,𝑃<0.05),diastolic BP(𝑟=0.95,𝑃<0.05),and heart rate(𝑟=0.78,𝑃<0.05).The models were also shown to have a high degree of accuracy for systolic and diastolic BP.Error margins were in the range±2.33 and±1.79 mmHg for systolic BP in disease and control subjects,respectively,and±3.60 and±1.82 mmHg for diastolic BP.However,the accuracy was lower in the prediction of heart rate in disease subjects,with a reported𝑟2 value of 0.72 and an error margin of±2.88 beats per min;for healthy subjects,the results were marginally better,with an error margin of±1.82 beats per min.All statistical analyses were performed using MATLAB(R2017a,MathWorks R○,USA).Conclusion In this study,we developed a non-invasive cuffless approach for estimation of systemic peripheral BP and heart rate using ICG.The proposed methodology eliminated any discomfort to patients caused by inflation of the cuff(in the case of cuff-based BP monitoring)or the need to constantly wear a fingertip photoplethysmography device(in the case of cuffless BP monitoring).The results obtained appeared promising and increased the potential scope of ICG for monitoring other haemodynamic parameters related to heart function.

Influence of cardiorespiratory fitness and body composition on resting and post-exercise indices of vascular health in young adults

Poor cardiorespiratory fitness may mediate vascular impairments at rest and following an acute bout of exercise in young healthy individuals.This study aimed to compare flow mediated dilation(FMD)and vascular augmentation index(AIx75)between young adults with low,moderate,and high levels of cardiorespiratory fitness before and after an acute bout of aerobic exercise.Forty-three participants(22 men;21 women)between 18 and 29 years of age completed the study.Participants were classified into low,moderate,and high health-related cardiorespiratory fitness groups according to age-and sex-based relative maximal oxygen consumption(V_O2 max)percentile rankings.FMD was performed using Doppler ultrasound and AIx75 was performed using pulse wave analysis at baseline and 60-min after a 30-min bout of treadmill running at 70%V_O2 max.A significant interaction(p=0.047;ηp 2=0.142)was observed,with the moderate fitness group exhibiting a higher FMD post-exercise compared with baseline([6.7%3.1%]vs.[8.5%2.8%],p=0.028;d=0.598).We found a significant main effect of group for AIx75(p=0.023;ηp 2=0.168),with the high fitness group exhibiting lower AIx75 compared to low fitness group([10%10%]vs.[2%10%],respectively,p=0.019;g=1.07).This was eliminated after covarying for body fat percentage(p=0.489).Our findings suggest that resting FMD and AIx75 responses are not significantly influenced by cardiorespiratory fitness,but FMD recovery responses to exercise may be enhanced in individuals with moderate cardiorespiratory fitness levels.