“勾股定理”测量的左右心室电极间距离与心脏再同步化治疗临床疗效的相关性和预测性分析

【摘要】背景：再同步化治疗能改善心力衰竭患者的预后,但大约有1/3患者不能从中获益,也就是无反应者。目的：探讨在勾股定理方法测量下的实际左右心室电极间距离与心脏再同步化治疗临床疗效的相关性和预测性。方法：回顾性的研究在我院所有因符合CRT指征而行CRT植入术的患者,采集患者术前、术后6个月基本资料（年龄、左心室射血分数（LVEF）、左心室舒张末内径（LVEDD）、左心房前后径（LAAPD）、QRS 时限（QRSd）、N-端脑利钠肽前体(NT-proBNP)、美国纽约心脏病协会（NYHA）心功能分级等）;在术后的透视影像下,用游标卡尺测量正侧位左右心室间电极直接距离（L）（水平距离 V ,垂直距离 H）,正前位心脏横径（C）、胸腔横径（T）,根据勾股定理左、右心室电极植入位置间直接距离（DD2=V12+L22）或（DD2=V22+L12）;计算左、右心室电极植入位置间 DD/C。并根据术后心脏彩超变化或临床症状评估分为显著有效（A组）,有效（B组）和无效（C组）。结果：共有108个患者（平均年龄 64.34±9.35岁,51.9%男性,57.4%扩心病）纳入研究,A组（31）、有效组（56）和无效组（31）;三组患者术后6月的LVEF、6-MWT、LVEDD、QRSd、NT-ProBNP较术前均有明显改善（P＜0.05）,DD及DD/C在组内及组间均有统计学意义（P＜0.05）;且A组＞B组＞C组;多因素Logistic回归分析示DD和DD/C是CRT临床疗效的独立影响因素;在ROC曲线分析中,DD（DD/C）曲线下面积分别为0.709（0.713）和0.741（0.835）,A组和B组、B组和C组之间的DD（DD/C）截断值分别为54.84mm（0.551）和43.5mm（0.395）（P＜0.05）。结论：在勾股定理方法测量下的实际心室间电极距离与CRT临床疗效呈正相关,DD（DD/C）越大,CRT临床效果越好,并且也是预测CRT临床效果的预测因素。     

Laboratory Study on the Stability of Large-Size Graded Crushed Stone under Cyclic Rotating Axial Compression

In this paper, the stability of large-size graded crushed stone used for road base or cushioning under repeated load is investigated. Using an in-house developed device, large-size crushed stone mix was compacted and molded by the vibration and rotary compaction method. Cyclic rotating axial compression was applied, and the shakedown theory was used to study the cumulative deformation of the large-size crushed stone specimens. The effects of gradation parameters on the cumulative strain and stability behavior were analyzed, and the critical stability and failure loads were determined according to the shakedown theory. The test results indicate that there are three obvious instability behavior stages of large-size graded crushed stone under cyclic rotating axial compression: elastic stability, plastic creep, and incremental plastic failure. Large-size graded crushed stone has a higher critical stability load stiffness than conventional-size graded crushed stone. The critical shakedown load of the specimen is mainly affected by the skeleton structure performance, and the critical failure load by the properties of the crushed stone material. Increasing the content and compactness of large-size crushed stone in the specimen can improve the stiffness and stability performance, and to achieve improvements, the content of large-size crushed stone should be controlled between 22% and 26%. The critical shakedown load increases with the increase in the California bearing ratio (CBR) value, while, on the other hand, the CBR value has little relationship with the critical failure load.     

Allostatic load,metabolic syndrome and self-rated health in overweight/obese Non-Hispanic White,non-Hispanic Black and Mexican American adults

AimThis study examined the associations of high allostatic load (h_ALS) and metabolic syndrome (MetS) with and self-rated poor health (SRPH) in overweight/obese non-Hispanic White (NHW), non-Hispanic Black (NHB), and Mexican American (MA) adults.MethodsThe 2015–16 and 2017-18 US National Health and Nutrition Examination Survey data (n = 4403) were used for this study.ResultsRates of h_ALS in overweight/obese NHW, NHW, and MA participants were 56.9%, 58.8%, and 51.9%, respectively (P < .05). The corresponding rates for MetS were 26.9%, 31.9%, and 46.5%, respectively. High ALS was associated with 2.19 (95% CI: 1.87–4.59), 1.82 (1.42–2.58), and 1.47 (95% CI: 1.08–1.64) increased odds of SRPH in overweight/obese NHW, NHB, and MA, respectively, after adjusting for age, education, gender, income, lifestyle behaviors, and marital status. The corresponding values for MetS were 1.86 (95% CI: 1.54–2.40), 2.77 (95% CI: 1.36–5.63), and 1.22 (95% CI: 1.06–2.32), respectively.ConclusionsThe effect of h_ALS on SRPH was much stronger in NHW, while the effect of MetS was strongest among NHB overweight/obese adults. The result of this study provides further evidence in favor of race/ethnic-tailored interventions, including education and weight control to reduced risks of bodywear and tear and SRPH.     

Cardiac monitoring for patients with palpitations

Palpitations are one of the most common reasons for medical consultation. They tend to worry patients and can affect their quality of life. They are often a symptom associated with cardiac rhythm disorders, although there are other etiologies. For diagnosis, it is essential to be able to reliably correlate the symptoms with an electrocardiographic record allowing the identification or ruling out of a possible rhythm disorder. However, reaching a diagnosis is not always simple, given that they tend to be transitory symptoms and the patient is frequently asymptomatic at the time of assessment. In recent years, electrocardiographic monitoring systems have incorporated many technical improvements that solve several of the 24-h Holter monitor limitations. The objective of this review is to provide an update on the different monitoring methods currently available, remarking their indications and limitations, to help healthcare professionals to appropriately select and use them in the work-up of patients with palpitations.     

Biological Safety Evaluation and Surface Modification of Biocompatible Ti–15Zr–4Nb Alloy

We performed biological safety evaluation tests of three Ti–Zr alloys under accelerated extraction condition. We also conducted histopathological analysis of long-term implantation of pure V, Al, Ni, Zr, Nb, and Ta metals as well as Ni–Ti and high-V-containing Ti–15V–3Al–3Sn alloys in rats. The effect of the dental implant (screw) shape on morphometrical parameters was investigated using rabbits. Moreover, we examined the maximum pullout properties of grit-blasted Ti–Zr alloys after their implantation in rabbits. The biological safety evaluation tests of three Ti–Zr alloys (Ti–15Zr–4Nb, Ti–15Zr–4Nb–1Ta, and Ti–15Zr–4Nb–4Ta) showed no adverse (negative) effects of either normal or accelerated extraction. No bone was formed around the pure V and Ni implants. The Al, Zr, Nb, and Ni–Ti implants were surrounded by new bone. The new bone formed around Ti–Ni and high-V-containing Ti alloys tended to be thinner than that formed around Ti–Zr and Ti–6Al–4V alloys. The rate of bone formation on the threaded portion in the Ti–15Zr–4Nb–4Ta dental implant was the same as that on a smooth surface. The maximum pullout loads of the grit- and shot-blasted Ti–Zr alloys increased linearly with implantation period in rabbits. The pullout load of grit-blasted Ti–Zr alloy rods was higher than that of shot-blasted ones. The surface roughness (Ra) and area ratio of residual Al₂O₃ particles of the Ti–15Zr–4Nb alloy surface grit-blasted with Al₂O₃ particles were the same as those of the grit-blasted Alloclassic stem surface. It was clarified that the grit-blasted Ti–15Zr–4Nb alloy could be used for artificial hip joint stems.     

True Strength of Ceramic Fiber Bundles: Experiments and Simulations

A study on the strength of ceramic fiber bundles based on experimental and computational procedures is presented. Tests were performed on single filaments and bundles composed of two fibers with different nominal fiber counts. A method based on fiber rupture signals was developed to estimate the amount of filament rupture during the test. Through this method, the fiber bundle true strength was determined and its variation with the initial fiber count observed. By using different load-sharing models and the single filament data as input parameter, simulations were also developed to verify this behavior. Through different approaches between experiments and simulations, it was noted that the fiber bundle true strength increased with the fiber count. Moreover, a variation of the fibers’ final proportion in the bundles relative to the initial amount was verified in both approaches. Finally, discussions on the influence of different load-sharing models on the results are presented.     

The blood pressure and heart rate during sauna bath correspond to cardiac responses during submaximal dynamic exercise

ObjectivesIn the present study, the reaction of blood pressure and heart rate are examined during and after a single acute sauna application.DesignIn 19 healthy adult volunteers (7 women, aged 46.4±10.2 years, BMI 24.4±2 kg /m²), blood pressure (BP) and heart rate (HR) were measured during a 25-minute sauna session (93°C, 13 % humidity) and during a subsequent 30-minute rest period. The parameters obtained were compared with the BP and HR responses during submaximal dynamic exercise testing.ResultsThe heat exposure resulted in a significant (p<0.01) and progressive increase in systolic and diastolic BP. After the sauna bath, BP decreased and showed significantly (p<0.001) lower values compared to baseline. HR also increased continuously during heat application (p<0.001), resulting in a significant increase (p<0.001) in systolic BP x HR as a measure of myocardial oxygen consumption. After the end of the sauna session, both the BP and the HR decreased steadily (p<0.001).When comparing BP and HR during the sauna session with the reaction during a dynamic exercise test, sauna bathing was equivalent to an exercise load of about 60-100 watts.ConclusionsContrary to popular belief, acute sauna use does not lead to a reduction, but to an increase in BP and HR with a consequent increase in myocardial oxygen consumption. The cardiac load during the sauna use corresponds to a moderate physical load of 60-100 watts.     

Family presence during resuscitation: Updated review and clinical pearls

There is mounting evidence that Family Presence During Resuscitation (FPDR) can benefit family members who wish to observe the resuscitation efforts of a loved one. Given that older patients have poor resuscitation outcomes, presence of a family advocate could add value to the process of end of life decision making. A review of the current literature from the perspectives of patients, families, and health-care providers will help in reassessing family involvement during resuscitation and developing best practices for health care facilities.