Arterial stiffness and wave reflection: Biomarkers of cardiovascular risk

Arterial stiffness and excessive pressure pulsatility have emerged as important risk factors for cardiovascular disease. Arterial stiffness increases with age and in the presence of traditional cardiovascular disease risk factors, such as hypertension, diabetes and lipid disorders. Pathologic stiffening of large arteries with advancing age and risk factor exposure predominantly involves the elastic aorta and carotid arteries, whereas stiffness changes are relatively limited in muscular arteries. Aortic stiffening is associated with increased pulse wave velocity and pulse pressure, which are related but distinct measures of the pulsatile energy content of the pressure waveform. A dramatic increase in pulsatile energy content of pressure and flow waves in the arterial system places considerable pulsatile stress on the heart, large arteries and distal circulation. Large artery stiffening is associated with abnormalities in microvascular structure and function that may contribute to tissue damage, particularly in susceptible high flow organs such as the brain and kidneys. This brief review summarizes results of recent research on risk factors for and adverse effects of large artery stiffening.     

300例高血压前期者脉搏波传导速度与颈动脉硬化改变及相关性

目的 探讨高血压前期人群大动脉顺应性和颈动脉硬化的情况及相关性.方法 分层随机抽取高血压前期、高血压、正常血压各300例作为研究对象.采用动脉硬化诊断装置VP-1000测定肱踝脉搏波传导速度和踝臂指数,多普勒彩色超声观察颈总动脉内膜-中膜厚度以及斑块形成情况,比较三组间差异.比较各血压组合并颈动脉斑块时脉搏波传导速度的变化情况,分析颈动脉内膜-中膜厚度与脉搏波传导速度的相关性.结果 (1)随着血压从正常向高血压转变,肱踝脉搏波传导速度呈上升趋势,高血压前期组(1 390±171 cm/s)较正常血压组(1 293±151 cm/s)升高但低于高血压组(1 652±291 cm/s,P<0.01);踝臂指数高血压前期组(1.115±0.060)与正常血压组(1.114±0.061)相比差异无统计学意义(P>0.05),但在高血压组明显升高(1.132±0.067,P<0.01).(2)颈动脉内膜-中膜厚度增厚率及斑块发生率在高血压前期组与正常血压组相比差异均无统计学意义,但在高血压组显著升高(P<0.01);颈总动脉内膜-中膜厚度在高血压前期组(0.73±0.10mm)与正常血压组(0.72±0.12 mm)相比差异无统计学意义(P>0.05),但在高血压组显著增厚(0.78±0.16 mm,P<0.01).(3)有或无合并颈动脉斑块时,高血压前期组脉搏波传导速度均较正常血压组升高(P<0.01),但低于高血压组(P<0.01);各血压组合并颈动脉斑块时脉搏波传导速度较无颈动脉斑块时均升高(P<0.01).肱踝脉搏波传导速度与颈总动脉内膜-中膜厚度呈正相关(r=0.271,P<0.01),校正血压因素后相关性仍存在(r=0.156,P<0.01).结论 高血压前期肱踝脉搏波传导速度显著升高.提示存在早期动脉硬度改变.肱踝脉搏波传导速度与颈动脉内膜-中膜厚度呈正相关,肱踝脉搏波传导速度可作为评估高血压前期动脉硬度有效且简便易行的指标.     

血压正常高值者动脉僵硬度与动态血压参数的关系

目的探讨血压正常高值者动脉僵硬度与动态血压参数的关系。方法选择理想血压者63例,血压正常高值者74例,高血压者67例。监测所有入选者24 h动态血压,应用脉搏波传导速度测定仪测定颈动脉-桡动脉脉搏波传导速度。结果血压正常高值组24 h收缩压、24 h舒张压、白昼收缩压、白昼舒张压、夜间收缩压、24 h脉压、白昼脉压及夜间脉压均高于理想血压组,低于高血压组(P<0.05或P<0.01);血压正常高值组夜间舒张压低于高血压组(P<0.05)。血压正常高值组颈动脉-桡动脉脉搏波传导速度(9.67±1.12 m/s)显著高于血压理想组(8.27±0.99 m/s),低于高血压组(10.55±1.71 m/s;P<0.05或P<0.01)。多元线性回归分析显示,24 h收缩压、24 h脉压、夜间收缩压是颈动脉-桡动脉脉搏波传导速度的影响因素(β值分别为0.385、0.351及0.247,P<0.05)。结论血压正常高值者动脉僵硬度增高,24 h收缩压、24 h脉压、夜间收缩压是影响动脉弹性的主要因素。     

P Wave Indices to Predict Atrial Fibrillation Recurrences Post Pulmonary Vein Isolation

Background

P-wave indices are appealing markers for predicting atrial fibrillation (AF) recurrences post ablation.

Objective

This study evaluates the value of P wave indices to predict recurrences post pulmonary vein isolation (PVI) in patients with paroxysmal AF.

Methods

We selected 198 patients (57 ± 8 years, 150 males) with symptomatic drug-refractory paroxysmal AF undergoing PVI in our hospital. A 12-lead electrocardiogram was used to measure P wave duration in lead II, P wave terminal force (PWTF) in lead V1, P wave axis and dispersion.

Results

During a follow-up of 9 ± 3 months, recurrences occurred in 60 (30.3%) patients. The patients that had AF recurrence had longer mean P wave duration (122.9 ± 10.3 vs 104.3 ± 14.2 ms, p < 0.001), larger P wave dispersion (40.7 ± 1.7 ms vs 36.6 ± 3.2 ms, p < 0.001). P wave duration ≥ 125 ms has 60% sensitivity, 90% specificity, positive predictive value (PPV) of 72% and negative predictive value (NPV) of 83.7%, whereas P wave dispersion ≥ 40 ms has 78% sensitivity, 67% specificity, PPV of 51% and NPV of 87.6% 48/66 (72.7%) patients with PWTF ≤ - 0.04 mm/second vs 12/132(9%) with PWTF > -0.04 mm/second showed recurrence of AF (p < 0.001). P wave axis was not different between two groups. On multivariate analysis, P wave indices were not independent from left atrial size and age.

Conclusions

P wave duration ≥ 125 ms, P wave dispersion ≥ 40 ms and PWTF in V1 ≤ - 0.04 mm/sec are good clinical predictors of AF recurrences post PVI in patients with paroxysmal atrial fibrillation; however they were not independent from left atrial size and age.     

Environmental epidemiology of intestinal schistosomiasis and genetic diversity of Schistosoma mansoni infections in snails at Bugoigo village,Lake Albert

Intestinal schistosomiasis continues to be hyper-endemic in the fishing community of Bugoigo located on the eastern shore of Lake Albert, Uganda. Our study aimed to identify the factors that determine the local distribution and abundance of Biomphalaria, as well as infection(s) with Schistosoma mansoni inclusive of their genetic diversity. In addition, a DNA barcoding approach was taken to genotype schistosome cercariae, exploring the micro-epidemiology of infections. Over a 3-week period in June–July 2010, several hundred Biomphalaria spp. were collected, together with environmental information, from 10 selected sites, representive of both putative wave-exposed (n = 5) and wave-sheltered shorelines (n = 5). A Mann–Whitney U-test and a generalized linear model were used to assess associations with snail abundance and parasite infections across the shoreline. Levels of local wave action were recorded over the 19-day period using digital accelerometers. The general absence of wave action on the sheltered shoreline likely helped to raise and focalize other environmental parameters, such as water conductivity by lack of mixing, that foster transmission of intestinal schistosomiasis. Over the study period, a total of 10 infected snails were encountered and a selection of schistosome cercariae from each infected snail was harvested for analysis by DNA barcoding. In total, 91 DNA barcodes were generated with 15 unique barcode types identified. Of these, 4 barcodes had been found previously in Lake Albert and (or) Victoria, the remaining 11 were newly encountered here and described. The distribution of DNA barcodes across infected snails and sampled locations revealed a complicated spatial sub-structuring. By shedding new light on the fine-scale patterning of infections, DNA barcoding has revealed a rather heterogeneous landscape of cercariae, likely inclusive of multi-miracidial infections within the snail, which will in turn interplay with human water contact activities to shape the genetic diversity of worm populations within infected people.     

The reservoir-wave model

This paper is based on a talk given at the Arterial Hemodynamics: Past, Present and Future symposium in June 2016. Like the talk it is divided into three different but related parts. Part 1 describes the calculation of reservoir and excess pressure from clinical pressure waveforms measured at 5 different aortic sites in 40 patients. The main results are that the reservoir pressure waveform propagates down the aorta and is effectively constant from the aortic root to the aortic bifurcation. Part 2 describes a low-frequency asymptotic analysis of the input impedance of an arterial tree. Neglecting terms of second order, the results show that the low-frequency component of the pressure waveform is uniform throughout the arterial tree and is delayed by an effective wave travel time that depends on the properties of the network. The low-frequency pressure waveform shares all of the properties of the reservoir pressure waveform, but it is premature to say that they are identical. Part 3 describes the analysis of arterial hemodynamicsusing wave fronts. It shows that every wave front introduced at the root of the aorta generates an exponentially increasing number of reflected and transmitted waves with exponentially decreasing amplitudes. The long-time response of the arterial tree can be described by a number of exponentially decaying eigen-modes, each with a different time constant. The analysis is applied to a 55-artery model of the human circulation and the modes and their time constants are shown. This theory provides an alternative method for studying arterial hemodynamics and helps in the interpretation of reservoir and excess pressure.     

基线高敏C反应蛋白水平对臂踝脉搏波传导速度的影响

目的 探讨不同基线高敏C反应蛋白（hs-CRP）水平对臂踝脉搏波传导速度（baPWV）的影响。方法 采用前瞻性队列研究,在2006～2007年参加健康体检的101 510例开滦集团职工中随机分层抽取5 852例作为研究对象,进行统一问卷调查及血液生物化学检查,符合入选标准的为5 440例。于2010～2011年度进行第3次健康体检并测量baPWV,最终纳入统计分析的有效数据为4 651例。依据2006～2007年健康体检时hs-CRP浓度将研究人群分为3组,对影响baPWV的相关危险因素进行多因素线性回归分析及多因素Logistic回归分析。结果 （1）hs-CRP<1 mg/L（n＝2 682）、1 mg/L≤hs-CRP≤3 mg/L（n＝1 307）、hs-CRP>3 mg/L（n＝662）各组平均baPWV分别为1 505.82 cm/s、1 612.48 cm/s、1 671.04 cm/s（P<0.001）;baPWV≥1 400 cm/s 各组检出率分别为55.1%、64.8%、72.1%（P<0.001）;（2）在校正其他危险因素后的多元线性回归分析中,基线lg_CRP每增加一个单位,baPWV增加6.448 cm/s（P＝0.034）;（3）影响baPWV的多因素Logistic回归分析显示：与hs-CRP<1 mg/L组相比,hs-CRP>3 mg/L组为baPWV增加的危险因素,其RR值为1.34（95%CI 1.04～1.72）。结论 随着基线hs-CRP浓度的升高,baPWV逐渐增加;血清hs-CRP>3 mg/L是总人群baPWV增加的独立危险因素,在男性人群中更加显著。     

臂踝脉搏波传导速度及踝臂指数对高血压患者早期动脉硬化的诊断价值

目的　探讨臂踝脉搏波传导速度（baPWV）及踝臂指数（ABI）对高血压患者早期动脉粥样硬化（As）的诊断价值。方法　选取2010年1月至2014年12月期间我院2400例高血压患者,其中1200例不伴有As（非As高血压组）,1200例伴有As（As高血压组）,以1248例同期健康体检者为对照组。检测和比较各组baPWV、ABI、颈动脉内膜中膜厚度（IMT）。结果　与对照组相比,非As高血压组及As高血压组baPWV、收缩压、舒张压、甘油三酯、低密度脂蛋白胆固醇水平均明显升高（P<0.05）;与非As高血压组相比,As高血压组baPWV、甘油三酯、低密度脂蛋白胆固醇水平均明显升高（P<0.05）。与对照组相比,As高血压组ABI、高密度脂蛋白胆固醇水平显著降低,IMT增厚率明显升高（P<0.05）,而非As高血压组ABI、IMT增厚率均没有明显变化（P>0.05）。在对照组和非As高血压组中,baPWV与ABI没有明显相关性,而在As高血压组中,baPWV与ABI呈显著负相关（r＝-0.718,P<0.05）。结论　baPWV及ABI能够较为准确地反映高血压患者血管结构和功能的变化,并与动脉硬化程度明显相关,有助于早期诊断高血压患者动脉硬化病变。