High Prevalence of Left Ventricle Diastolic Dysfunction in Severe COPD Associated with A Low Exercise Capacity: A Cross-Sectional Study

Background

A subclinical left ventricle diastolic dysfunction (LVDD) has been described in patients with chronic obstructive pulmonary disease (COPD).

Objectives

To evaluate the prevalence of LVDD in stable severe COPD patients, to analyze its relationship with exercise capacity and to look for its possible causes (lung hyperinflation, ventricular interdependence or inflammatory mechanisms).

Methods

We evaluated 106 consecutive outpatients with severe COPD (FEV₁ between 30–50%). Thirty-three (31%) were excluded because of previous heart disease. A pulmonary function test, a 6-minute walking test (6MWT), a Doppler echocardiography test, including diastolic dysfunction parameters, and an analysis of arterial blood gases, NT-proBNP and serum inflammatory markers (CRP, leucocytes), were performed in all patients.

Results

The prevalence of LVDD in severe stable COPD patients was 90% (80% type I, n=57, and 10% type II, n=7). A significant association between a lower E/A ratio (higher LVDD type I) and a lower exercise tolerance (6-minute walked distance (6MWD)) was found (r=0.29, p<0.05). The fully adjusted multivariable linear regression model demonstrated that a lower E/A ratio, a DLCO in the quartile 4^th and a higher tobacco consumption were associated with a lower 6MWD (76, 57 and 0.7 metres, respectively, p<0.05). A significant correlation between E/A ratio and PaO₂ was observed (r=0.26, p<0.05), but not with static lung hyperinflation, inflammation or right ventricle overload parameters.

Conclusion

In stable severe COPD patients, the prevalence of LVDD is high and this condition might contribute in their lower exercise tolerance. Hypoxemia could have a concomitant role in their pathogenesis.     

Nonlinear Elastic and Viscoelastic Deformation of the Human Red Blood Cell with Optical Tweezers

Studies of the deformation characteristics of single biological cells can offer insights into the connections among mechanical state, biochemical response and the onset and progression of diseases. Deformation imposed by optical tweezers provides a useful means for the study of single cell mechanics under a variety of well-controlled stress-states. In this paper, we first critically review recent advances in the study of single cell mechanics employing the optical tweezers method, and assess its significance and limitations in comparison to other experimental tools. We then present new experimental and computational results on shape evolution, force--extension curves, elastic properties and viscoelastic response of human red blood cells subjected to large elastic deformation using optical tweezers. Potential applications of the methods examined here to study diseased cells are also briefly addressed.     

超声心动图评价左室舒张性心力衰竭患者左心形态及舒张功能的应用价值

目的:研究超声心动图对左室舒张性心力衰竭(LVDHF)患者左心形态及舒张功能的评估价值。方法:选择2014年3月至2016年3月我院收治的LVDHF患者78例记为观察组,另选择同期健康志愿者80例记为对照组,两组受试者均进行血压、心率检查,并利用超声心动图技术检测两组受试者的心脏相关指标。结果:观察组的舒张压(DBP)、收缩压(SBP)、心率(HR)、左房内径(LAD)、室间隔厚度(IVST)、左室后壁厚度(LVPWT)、综合指标(E/Ea)及反向血流速度(Ar)水平均明显高于对照组,而早、晚期的运动速度比(Ea/Aa)、血流传播速度(Vp)及峰速比(S/D)水平明显低于对照组,差异均有统计学意义(P0.05)。结论:超声心动图能准确地反应LVDHF患者的左心形态以及舒张功能,可在临床进行推广。     

Transient analysis of cardiopulmonary interactions. I. Diastolic events

The etiology of the fall in left ventricular stroke volume (LVSV) with negative intrathoracic pressure (NITP) during inspiration has been ascribed to a reduction in LV preload. This study evaluated the effects of NITP with and without airway obstruction confined to early (ED), mid- (MD), or late diastole (LD) on the subsequent LVSV, anteroposterior (AP), and right-to-left (RL) aortic diameters (DAO) (series I, n = 6) as well as on phasic arterial blood flow out of the thorax (series II, n = 6) in anesthetized dogs. Transient NITP was obtained by electrocardiogram-triggered phrenic nerve stimulation. In series I, NITP applied for 60% of diastole with the airway obstructed caused decreases of LVSV during ED [-7.7 +/- 3.2% (SE) NS], MD (-11.7 +/- 3.9%, P less than 0.05), and LD (-14.6 +/- 1.5%, P less than 0.01) associated with significant increases of left ventricular end-diastolic pressures relative to both atmospheric and esophageal pressures during MD and LD. NITP increased DAO(AP) and DAO(RL), resulting in increases in diastolic aortic cross-sectional area by an average of 6.1-8.3% (P less than 0.01). Similar changes were seen with the airway unobstructed during NITP. In series II, NITP caused diminished diastolic antegrade carotid artery and/or descending aortic flow run off in all dogs. Transient retrograde arterial flows with NITP were observed in more than half of the animals consistent with increases in aortic diameters. We conclude that a decrease of intrathoracic pressure confined to diastole can 1) diminish the ensuing LVSV, presumptively reducing preload by ventricular interdependence; 2) distend the intrathoracic aorta; 3) diminish antegrade flow out of the thorax independent of effects on cardiac performance; and 4) cause transient retrograde carotid and aortic blood flow. The intrathoracic aorta and, presumably, the arterial intrathoracic vascular compartment can be viewed as an elastic container driven by changes in intrathoracic pressure.     

高血压前期患者颈动脉血管弹性超声参数与左室舒张功能的关系研究

摘要 目的：研究高血压前期患者颈动脉血管弹性超声参数与左室舒张功能的关系。方法：选取2019年12月-2020年12月因血压异常于河北北方学院附属第一医院接受诊断与治疗的161例患者,根据血压水平分为高血压前期组（82例）与高血压组（79例）;另选取同期于我院体检的80例健康志愿者作为对照组。收集三组临床资料,检测生化指标与血压;通过超声诊断仪中超声射频信号血管内中膜定量分析（QIMT）与动脉僵硬度定量分析（QAS）软件测量颈动脉血管弹性超声参数[颈动脉内中膜厚度（IMT）、顺应性系数（CC）、扩张性系数（DC）、血管弹性指数（α、β）、脉搏波传导速度（PWV）];超声心动图检查左室功能指标[左室射血分数（LVEF）、左室质量指数（LVMI）、舒张早期血流速度峰值（E）/舒张晚期血流速度峰值（A）、等容舒张时间（IVRT）、舒张期减速时间（DT）];采用Pearson相关性法分析颈动脉血管弹性超声参数与心室指标的相关性。结果：三组收缩压与舒张压水平存在统计学意义（P＜0.05）。高血压前期组与高血压组IMT、α、β、PWV高于对照组,DC、CC低于对照组（P＜0.05）,且高血压前期组IMT、α、β、PWV低于高血压组,DC、CC高于高血压组（P＜0.05）。高血压前期与高血压组E/A低于对照组,IVRT、DT高于对照组（P＜0.05）,且高血压前期组E/A高于高血压组,IVRT、DT低于高血压组（P＜0.05）。经Peason相关性分析显示,IMT、α、β、PWV与E/A呈负相关,与IVRT、DT呈正相关（P＜0.05）;DC、CC与E/A呈正相关,与IVRT、DT呈负相关（P＜0.05）。结论：高血压前期患者颈动脉血管弹性功能下降,且伴有左室舒张功能受损,颈动脉血管弹性超声参数与左室舒张功能密切相关。     

二尖瓣置换术后左心室破裂2 例并文献复习

目的:总结二尖瓣置换术后左心室破裂2例临床经验教训,方法:回顾性分析我院2006,1-2009,12二尖瓣置换术后左心室破裂2例的临床资料,两例均在监护室里发生突然大出血,紧急输血,输液,机械呼吸,抗休克治疗,并行开胸手术。结果:一例心外修补抢救成功,术后2周顺利出院,一例CPB下心内外修补,因低心排综合症死亡。结论:左心室破裂是二尖瓣置换术最严重的并发症,一旦发生死亡率极高,因此预防,避免其相关因素更关键。     

A Geometrical Approach for Automatic Shape Restoration of the Left Ventricle

This paper describes an automatic algorithm that uses a geometry-driven optimization approach to restore the shape of three-dimensional (3D) left ventricular (LV) models created from magnetic resonance imaging (MRI) data. The basic premise is to restore the LV shape such that the LV epicardial surface is smooth after the restoration and that the general shape characteristic of the LV is not altered. The Maximum Principle Curvature () and the Minimum Principle Curvature () of the LV epicardial surface are used to construct a shape-based optimization objective function to restore the shape of a motion-affected LV via a dual-resolution semi-rigid deformation process and a free-form geometric deformation process. A limited memory quasi-Newton algorithm, L-BFGS-B, is then used to solve the optimization problem. The goal of the optimization is to achieve a smooth epicardial shape by iterative in-plane and through-plane translation of vertices in the LV model. We tested our algorithm on 30 sets of LV models with simulated motion artifact generated from a very smooth patient sample, and 20 in vivo patient-specific models which contain significant motion artifacts. In the 30 simulated samples, the Hausdorff distances with respect to the Ground Truth are significantly reduced after restoration, signifying that the algorithm can restore geometrical accuracy of motion-affected LV models. In the 20 in vivo patient-specific models, the results show that our method is able to restore the shape of LV models without altering the general shape of the model. The magnitudes of in-plane translations are also consistent with existing registration techniques and experimental findings.     

A Tissue-Level Electromechanical Model of the Left Ventricle: Application to the Analysis of Intraventricular Pressure

The ventricular pressure profile is characteristic of the cardiac contraction progress and is useful to evaluate the cardiac performance. In this contribution, a tissue-level electromechanical model of the left ventricle is proposed, to assist the interpretation of left ventricular pressure waveforms. The left ventricle has been modeled as an ellipsoid composed of twelve mechano-hydraulic sub-systems. The asynchronous contraction of these twelve myocardial segments has been represented in order to reproduce a realistic pressure profiles. To take into account the different energy domains involved, the tissue-level scale and to facilitate the building of a modular model, multiple formalisms have been used: Bond Graph formalism for the mechano-hydraulic aspects and cellular automata for the electrical activation. An experimental protocol has been defined to acquire ventricular pressure signals from three pigs, with different afterload conditions. Evolutionary Algorithms have been used to identify the model parameters in order to minimize the error between experimental and simulated ventricular pressure signals. Simulation results show that the model is able to reproduce experimental ventricular pressure. In addition, electro-mechanical activation times have been determined in the identification process. For example, the maximum electrical activation time is reached, respectively, 96.5, 139.3 and 131.5 ms for the first, second, and third pigs. These preliminary results are encouraging for the application of the model on non-invasive data like ECG, arterial pressure or myocardial strain.     

Association of Arterial Stiffness and Electrocardiography-Determined Left Ventricular Hypertrophy with Left Ventricular Diastolic Dysfunction

Objectives

Increased arterial stiffness is associated with left ventricular diastolic dysfunction (LVDD), but this association may be influenced by left ventricular (LV) performance. Left ventricular hypertrophy (LVH) is not only a significant determinant of LV performance, but is also correlated with LVDD. This study is designed to compare LV diastolic function among patients divided by brachial-ankle pulse wave velocity (baPWV) and electrocardiography (ECG)-determined LVH and to assess whether increased baPWV and ECG-determined LVH are independently associated with LVDD.

Methods

This cross-sectional study enrolled 270 patients and classified them into four groups according to the median value of baPWV and with/without ECG-determined LVH. The baPWV was measured using an ABI-form device. ECG-determined LVH was defined by Sokolow-Lyon criterion. LVDD was defined as impaired relaxation, pseudonormal, and restrictive mitral inflow patterns. Groups 1, 2, 3, and 4 were patients with lower baPWV and without ECG-determined LVH, lower baPWV but with ECG-determined LVH, higher baPWV but without ECG-determined LVH, and higher baPWV and with ECG-determined LVH respectively.

Results

Early diastolic mitral velocity (Ea) was gradually decreased from group 1 to group 4 (p≦0.027). Patients in group 4 had the highest prevalence of LVDD (all p<0.001). After multivariate analysis, both baPWV and ECG-determined LVH were independent determinants of Ea (β = −0.02, P<0.001; β = −1.77, P<0.001 respectively) and LVDD (odds ratio = 1.02, P = 0.011 and odds ratio = 3.53, P = 0.013 respectively).

Conclusion

Our study showed the group with higher baPWV and ECG-determined LVH had the lowest Ea and highest prevalence of LVDD. In addition, both baPWV and ECG-determined LVH were independently associated with Ea and LVDD. Hence, assessment of arterial stiffness by baPWV and LVH by ECG may be useful in identifying the high risk group of LVDD.     

Stress Distribution in the Canine Left Ventricle during Diastole and Systole

A model is proposed for stress analysis of the left ventricular wall (LV wall) based on the realistic assumption that the myocardium is essentially composed of fiber elements which carry only axial tension and vary in orientation through the wall. Stress analysis based on such a model requires an extensive study of muscle fiber orientation and curvature through the myocardium. Accordingly, the principal curvatures were studied at a local site near the equator in ten dog hearts rapidly fixed in situ at end diastole and end systole; the fiber orientation for these hearts had already been established in a previous study. The principal radii of curvature were (a) measured by fitting templates to the endocardial and epicardial wall surfaces in the circumferential and longitudinal directions and (b) computed from measured lengths of semiaxes of ellipsoids of revolution representing the LV wall (“ellipsoid” data). The wall was regarded as a tethered set of nested shells, each having a unique fiber orientation. Results indicate the following. (a) Fiber curvature, k, is maximum at midwall at end systole; this peak shifts towards endocardium at end diastole. (b) The pressure or radial stress through the wall decreases more rapidly near the endocardium than near the epicardium at end diastole and at end systole when a constant tension is assumed for each fiber through the wall. (c) At end diastole the curve for the circumferential stress vs. wall thickness is convex with a maximum at midwall. In the longitudinal direction the stress distribution curve is concave with a minimum at midwall. Similar distributions are obtained at end systole when a constant tension is assumed for each fiber through the wall. (d) The curvature and stress distributions obtained by direct measurements at a selected local site agree well with those computed from “ellipsoid” data.     

Nonlinear Anisotropic Elastic Properties of the Canine Aorta

A nonlinear theory of large elastic deformations of the aortic tissue has been developed. The wall tissue has been considered to be incompressible and curvilinearly orthotropic. The strain energy density function for the tissue is expressed as a polynomial in the circumferential and longitudinal Green-St. Venant strains. Limiting application to states of strains wherein the geometric axes are the principal axes and truncating the energy expression to include terms with highest degrees 2, 3, and 4, three expressions with 3, 7, and 12 constitutive constants are obtained. Results of application of these expressions to data from three series of in vitro and in vivo experiments involving 31 dogs have been presented. Whereas all the three expressions are found to be applicable to various degrees, the third-degree expression for the strain energy density function with seven constitutive constants is particularly recommended for general use.     

强迫跑步等复合因素对Wistar大鼠左心室血流动力学的影响

目的　检测控食、强迫跑步及大剂量心得安等复合因素对Wistar大鼠左心室血流动力学的影响。方法　实验组实验全过程采用控食及强迫跑步的方法造模 ,第 17天起每日灌服心得安溶液 ,连续 4d。第 2 1天测定血流动力学。然后将余下的大鼠再平均分为药物反证组和鉴别反证组。药物反证组灌服补心气口服液 ,连续 12d。鉴别反证组灌服滋心阴口服液 ,连续 12d ,最后测定血流动力学。结果　实验组最大心室内压、平均 +dp dtmax、平均Vpm等指标均小于正常组 ,且差异有显著性。最小心室内压、平均 dp dtmax等指标均大于正常组 ,差异亦有显著性。结论　控食、强迫跑步及大剂量心得安等复合因素可抑制Wistar大鼠的心功能     

Inadvertent Lead Placement In The Left Ventricle: A Case Report And Brief Review

Inadvertent lead placement in the left ventricle (LV) is an uncommon and often under-diagnosed complication of cardiac device implantation. Thromboembolic (TE) events are common and usually secondary to fibrosis or thrombus formation on or around the lead. Anticoagulation can prevent TE events. Percutaneous and surgical LV lead extractions have been performed successfully, but the risks of percutaneous lead removal are not well-defined. In this report, we describe a case of inadvertent LV lead placement and briefly review the contemporary literature.     

Elastic properties of bacterial flagellar filaments: I. Free rotation case

Elongation of a helical bacterial flagellar filament in a fluid flow with one end attached to a slide glass is calculated. The flagellar filament is regarded as a coil spring. In this case, the spring constant is a function of the elastic constants of the flagellar filament. Relations between the elongation and the elastic constants are discussed.     

The Nature of the Disorder of Function in Chronic Postinfarction Aneurysm of the Left Ventricle

Assessment of left ventricular function in five patients with chronic postinfarction left ventricular aneurysm was carried out at the time of left heart catheterization and compared with that in six normal subjects. One patient was investigated before and after surgical resection of the aneurysm. The presence of the aneurysm placed the left ventricle at a mechanical disadvantage in systole and increased the resistance to diastolic filling (impedance). This was true even in patients with normal cardiac indices who were not badly disabled. Resection of the aneurysm corrected both these abnormalities, and, as well, lowered the time-tension index at a time when calculated left ventricular work was much increased. These differences between normals and patients with aneurysms, and the changes occurring as a result of resection of an aneurysm, show that the presence of the aneurysm places the left ventricle at a mechanical disadvantage in systole as well as altering its diastolic filling characteristics.