左心室与血管耦合的动力学模型

目的采用一种新的左心室．体循环耦合方法来验证作者自己的假设：射血始停时刻是耦合的结果，而非耦合的参数。耦合通过影响射血开始时刻t1，和停止时刻t2对动脉的血压和流量产生影响。方法采用三弹性腔九元件模型模拟体循环，E(t)模型描述左心室，利用最小输出功率原理进行耦合，并在耦合中引入射血始停时刻。结果新方法下得到跟射血期实验结果更为吻合的数值结果。t1，t2很好的解释了血压和流量与其他变量的关系。结论t1，t2是耦合的结果，它们在心室血管耦合中具有重要的作用。     

彩色多普勒超声心动图对青年人收缩期柔和杂音的原因分析

目的 探讨青年人Ⅰ－Ⅱ／６级收缩期心杂音产生的原因。方法 选择体检时心前区有Ⅰ－Ⅱ／６级收缩期杂音的青年人６０名,运用彩色多普勒超声心动图检测其心内结构及血流动力学改变。结果 受检者中心脏结构异常７例,无明显异常５３例。结论 体检时发现心前区有Ⅰ－Ⅱ／６级收缩期杂音时,应及时做彩色多普勒超声心动图检查,以明确心脏杂音是否有病理意义,帮助临床医师判断体检是否合格。     

肾动脉血流速度和阻力指数对慢性肾病的意义

目的探讨肾动脉收缩期峰值流速(Vs)和阻力指数(RI)的检测在诊断慢性肾病中的意义。方法运用多普勒超声技术对慢性肾病先兆、慢性肾病、慢性肾衰患者,进行主肾动脉和段动脉Vs和RI检测,并与健康人进行对比分析。结果异常组的主肾动脉和段动脉Vs均低于对照组(P<0.01)。慢肾先兆组RI低于对照组(P<0.01),慢性肾病组RI与对照组无明显差异,慢性肾衰组RI高于对照组(P<0.01)。结论肾动脉Vs减慢、RI降低或升高都可能是慢性肾病迹象。     

运动前后心电时限指标比值的比较

目的 鉴于基于心电R波峰点(Rp)与T波终点(Tn)的心室收缩期与舒张期比率(RSDI)易受Tn定位精度的影响,揭示基于Rp与T波峰点(Tp)的心电时限指标比值(RSD2)能否反映RSDI的趋势.方法 计算Rp至Tp的时限(RpTp)与心室收缩期(RpTn)的相关系数,计算Tp至其后Rp的时限(TpRp)与心室舒张期(...     

Aortic wall elasticity and left ventricular function in hypertensive patients with nonsignificant coronary artery disease

PurposeHypertension is an important cause of nonischemic heart failure. It is important to identify subclinical left ventricular dysfunction in patients with hypertension in an early stage to lower the risk of progression to more severe illness. The aim of our study was to assess the correlation between indices of left ventricular function and aortic stiffness in patients with hypertension.MethodsOur study was a case control study of 42 hypertensive and 40 normotensive patients with nonsignificant coronary artery disease. All the patients underwent echocardiography and left ventricular ejection fraction, global longitudinal strain, post systolic index, pulsed Doppler early transmitral peak flow velocity, early diastolic mitral annular velocity (e′), and aortic elasticity measurements were calculated.ResultsThe hypertensive patients were older (58.47 ± 9.57 vs. 52.94 ± 10.38 years, p = 0.018) and had a higher body mass index (30.09 ± 5.08 vs. 27.48 ± 4.17 kg/m², p = 0.013) and E/e′ ratio (8.16 ± 1.81 vs. 6.56 ± 1.71, p < 0.001) and a lower e′ velocity (8.25 ± 2.28 vs. 9.52 ± 2.34 cm/s, p = 0.015) than normotensives. They also had a lower aortic distensibility (p = 0.008) and a higher aortic stiffness index (p = 0.039) compared with the normotensive group. The hypertensive patients did not show any association between aortic elasticity and stiffness with age or e′ velocity despite significant association in normotensives.ConclusionHypertension is associated with a high prevalence of diastolic dysfunction, elevated left ventricular filling pressure, and increased arterial stiffness, all of which have significant association with adverse outcomes. The measurements found in the hypertensive patients compared with the normotensive group may be due to several age-independent mechanisms.     

Is 'diastolic heart failure' a diagnosis of exclusion? Echocardiographic parameters of diastolic dysfunction in patients with heart failure and normal systolic function

Background: Diastolic heart failure (DHF) is reported to account for 30–50% of heart failure presentations, but its prevalence in the absence of overt coronary disease is unclear. Diastolic heart failure is usually defined by exclusion (heart failure with normal left ventricular (LV) systolic function), and few studies have sought a specific diagnosis of diastolic dysfunction. The objective of the present study was to determine the prevalence of isolated DHF and characterise LV diastolic function in patients without clinical evidence of coronary disease, who were referred for LV function assessment.

Methods: Among 938 consecutive patients referred for assessment of LV function, diastolic dysfunction was sought in patients with clinical heart failure, normal systolic function, and no valvular or coronary disease. The evaluation was based on measurement of early (E) and late (A) transmitral velocities and E wave deceleration time (DT). Pulmonary vein systolic, diastolic and atrial reversal velocities were used to differentiate pseudonormal filling in patients with normal E/A and DT.

Results: Normal LV systolic function was present in 331 patients (35%), of whom 53 (6%) met criteria for a clinical diagnosis of DHF. Diastolic dysfunction was confirmed by echocardiography in 38 patients (72% of clinical DHF patients), of whom 27 had impaired LV relaxation, 10 had pseudonormal filling, and one had restrictive filling. Diastolic function was normal in 13 and indeterminate in two patients. Pseudonormal or restrictive LV filling were more prevalent in patients with acute heart failure (7/20, P < 0.05).

Conclusions: Carefully defined, isolated DHF is uncommon, but most of these patients demonstrate echocardiographic evidence of diastolic dysfunction.     

Right ventricular diastolic dysfunction in arterial systemic hypertension: analysis by pulsed tissue Doppler.

AIMS: This study analyses right ventricular longitudinal function in arterial systemic hypertension by pulsed tissue Doppler. METHODS AND RESULTS: Thirty normotensives and 30 hypertensives, free of cardiac drugs, underwent standard Doppler echocardiography and pulsed tissue Doppler of right ventricular lateral tricuspid annulus and left ventricular lateral mitral annulus. By tissue Doppler, systolic and diastolic measurements were obtained. Hypertensives had higher left ventricular mass and impaired Doppler diastolic indexes, without changes of global systolic function. Tissue Doppler showed reduction of right ventricular E/A ratio and prolongation of relaxation time in comparison with controls (both P<0.00001). In the overall population, the length of tissue Doppler derived right ventricular relaxation time was positively related to right ventricular anterior wall thickness while right ventricular E/A ratio was positively related to E/A ratio of left ventricular mitral annulus (both P<0.00001). These relations remained significant even after adjusting for clinical and echocardiographic confounders by separate multivariate models. CONCLUSIONS: Arterial systemic hypertension is associated to right ventricular longitudinal diastolic dysfunction. This dysfunction involves the prolongation of active relaxation, which is independently associated with the degree of right ventricular hypertrophy and the impairment of passive wall properties, which is mainly due to ventricular interaction occurring under left ventricular pressure overload conditions.     

The heart of cognitive control: Cardiac phase modulates processing speed and inhibition

Bodily states are heavily intertwined with cognitive processes. A prominent communication channel between bodily signals and brain structures is provided by baroreceptors. Their phasic activity associated with the cardiac phase has been shown to modulate cognitive control in socio-emotional contexts. However, whether this effect is specific to the affective dimension or impacts general cognitive control processes remains controversial. The aim of the present study is to investigate the effect of cardiac phase on different facets of cognitive control. We built a nonemotional cognitive control task to delineate mechanisms such as processing speed, response selection, response inhibition, and conflict monitoring. We showed that the systole (after the blood is ejected from the heart), compared to the diastole, was related to faster responses. Moreover, the cardiac phase dynamics also impacted response inhibition, with an increased probability of failure toward the middle of the course of systole. Although the reported effects were small in terms of magnitude, they highlight the influence of bodily states on abstract cognitive processes.