Non-invasive estimation of the diastolic elastic and viscoelastic properties of the left ventricle

The present study applies a non-invasive method to the quantitative evaluation of left ventricular stiffness in normal subjects and in patients with ischaemic heart disease (IHD). We have studied 20 patients with IHD and 25 healthy subjects. The third heart sound (S3) was detectable in all patients. We have correlated the energy spectrum of S3, divided into 15 Hz bands, with a series of echocardiographic parameters. The existence of a significant correlation between the spectrum energy and the diameter and thickness of the left ventricle at the moment of S3 allowed us to explore the possibility of interpreting the origin of S3 based on a mathematical model. Our hypothesis has been that, once the left ventricle starts vibrating, it behaves as a simple physical model composed of a mass and an elastic element. To this purely elastic model one can add a factor accounting for viscosity, with a damping effect, to obtain a more complex viscoelastic model. The stiffness coefficient 'k' was computed in both models from the peak frequency of S3 and the left ventricular mass at the moment of S3. Furthermore, in the viscoelastic model, the damping element 'c' was also computed. Both parameters--k and c--were significantly increased in the group with IHD compared with the control group. Although a simplification of the vibrating system, these models make it possible to obtain non-invasively information on the characteristics of the left ventricle through the combined use of echocardiography and spectral analysis of S3.     

动脉分支处的红细胞流变学研究与小动脉端侧吻合

为了探讨动脉分支处及小动脉端侧吻合处的血液流动方式，采用微循环电视显微镜成像技术，活体观察大鼠肠系膜微动脉分支区域血液流动方式和红细胞流变行为，研究动脉血流方向的改变对血流方式的影响。实验中观察到，在形态各异的大鼠肠系膜微动脉分支区域血液流态为稳定层流；红细胞通过不规则变形能很好地适应血管腔不同的几何形态，以保持血液流态的稳定。结果表明，微小动脉血流方向的改变未能在分支区域导致湍流发生，小动脉端侧吻合只是人为增加了侧支循环，同样不会导致血流紊乱和增加血栓形成的危险     

The effect of ionic strength on the kinetics of rigor development in skinned fast-twitch skeletal muscle fibres

 Recent atomic 3-D reconstructions of the acto-myosin interface suggest that electrostatic interactions are important in the initial phase of cross-bridge formation. Earlier biochemical studies had also given strong evidence for the ionic strength dependence of this step in the cross-bridge cycle. We have probed these interactions by altering the ionic strength (Γ/2) of the medium mainly with K⁺, imidazole⁺ and EGTA^2– to vary charge shielding. We examined the effect of ionic strength on the kinetics of rigor development at low Ca²⁺ (experimental temperature 18–22°C) in chemically skinned single fast-twitch fibres of mouse extensor digitorum longus (EDL) muscle. On average the delay before rigor onset was 10 times longer, the maximum rate of rigor tension development was 10 times slower, the steady-state rigor tension was 3 times lower and the in-phase stiffness was 2 times lower at high (230 mM) compared to low (60 mM) ionic strength. These results were modelled by calculating ATP depletion in the fibre due to diffusional loss of ATP and acto-myosin Mg.ATPase activity. The difference in delay before rigor onset at low and high ionic strength could be explained in our model by assuming a 15 times higher Mg.ATPase activity and a threefold increase in K _m in relaxing conditions at low ionic strength. Activation by Ca²⁺ induced at different time points before and during onset of rigor confirmed the calculated time course of ATP depletion. We have also investigated ionic strength effects on rigor development with the activated troponin/tropomyosin complex. ATP withdrawl at maximum activation by Ca²⁺ induced force transients which led into a ”high rigor” state. The peak forces of these force transients were very similar at low and high ionic strength. The subsequent decrease in tension was only 10% slower and steady-state ”high rigor” tension was reduced by only 27% at high compared to low ionic strength. Addition of 10 mM phosphate to lower cross-bridge attachment strongly suppressed the transient increases in force at high ionic strength and reduced the steady-state rigor tension by 17%. A qualitatively similar but smaller effect of phosphate was observed at low ionic strength where steady-state rigor force was reduced by 10%. The data presented in this study show a very strong effect of ionic strength on rigor development in relaxed fibres whereas the ionic strength dependence of rigor development after thin filament activation was much less. The data confirm the importance of electrostatic interactions in cross-bridge attachment and cross-bridge-attachment-induced activation of thin filaments. Received: 3 September 1997 / Received after revision and accepted: 12 December 1997     

矽肺患者肺功能与血气分析

以６７名Ⅱ、Ⅲ期矽肺患做了肺功能（ＶＣ，ＦＶＣ，ＦＥＶ，ＦＥＶ１／ＦＶＣ，ＭＶＶ，ＤＬＣＯ和血气分析（ＰａＯ２，ＰａＣｏｇｍ２，ｐＨ）。结果表明Ⅲ期矽肺肺功能较Ⅱ期矽肺降低，其中ＶＣ，ＦＶＣ、ＭＶＶ降低有显著差异，ＰａＯ２和ｐＨ随矽肺期别增加呈降低有显著差异。ＰａＯ２降低尤为明显，ＰａＣＯ２呈增高趋势。肺功能与ＰａＯ２改变显著相关，与ＰａＣＯ２和ＰＨ无相关关系。ＰａＯ２〈１０ｋＰａ发生率与尘肺劳动     

静脉血气分析及其临床应用进展

动脉血气分析是严重心肺疾病和许多代谢性疾病的重要检测手段，在血流动力学稳定状态下，动、静脉血气的CO2气体含量和酸碱参数非常接近，但在循环功能衰竭等情况下，动、静脉血气出现分离现象，此时可能需同时作静脉血气。静脉血气分析对危重患者特别是循环衰竭的患者可以提供组织氧合和酸碱状态更切实的评价，并可能对有效复苏提供更好的指导。     

DSA—Control of implanted devices for arterial hepatic perfusion

In contrast to conventional film angiography, the perfusion pattern of hepatic arterial chemotherapy was consistently visualized by DSA in 40 patients with implanted Infusaid pump or Port-A devices. Incomplete perfusion of a liver region by the cytotoxic agent was recognized by DSA as accurately as by nuclide scintigraphy. Furthermore, DSA appeared to be more sensitive in determining aberrantly perfused extrahepatic regions; this was especially true when there was a nonligated right hepatic artery. Specific details of vascular lesions and associated complicating events also could be satisfactorily analyzed by DSA only.     

Arterial and pseudoaneurysm ruptures complicating liver transplantation

Ruptures of the hepatic artery and hepatic pseudoaneurysms (PA) are rare but serious complications of hepatic transplantation. We conducted a retrospective study of 640 liver transplantations performed in our institution for a variety of pathologies. After surgery, seven major arterial bleeds occurred (0.9%). Of these seven cases, there were due to hepatic artery rupture (HAr) and four to PA rupture; all confirmed at either surgery (six cases) or autopsy (one case). Five of the seven patients died. In all cases the transplantation was difficult. All vascular injuries but one were caused by sepsis and occurred either after an undetermined cause septicemic syndrome (five cases) or graft dysfunction (one case). The last vascular injury was biliary drainage related. Six of the seven patients had imaging studies. Sonography (five cases) found a sub-hepatic hypoechoic collection in three cases but failed to do so in two. Duplex doppler (three cases) failed in all three cases to demonstrate a PA. Computed tomography (three cases) showed one PA, one perihilar sub-hepatic collection and failed in one. Conventional angiography (three cases) depicted a PA in all three cases. At the present time, our practice is to perform systematic angiography in patients with undetermined cause septicemic syndrome to research a PA. And if angiography is normal, to then puncture systematically any sub-hepatic collection to determine the bacteriological nature of this collection. Correspondence to: H. Caillet     

距骨的血液供应及其临床意义

本文观察了２４侧尸体足标本，均无已知临床血管疾病。在死后３６～４８小时之间行动脉灌注ＡＢＳ填充剂，以化学腐蚀和手工剔除的方法清除软组织。距骨的血供来自小腿下部三根主要动脉的分支，即跗骨管动脉和三角支、近端和远端跗骨窦动脉、颈上支及后结节血管丛。跗骨管动脉常发自足底内侧动脉，而三角支多单独自胫后动脉发出；跗骨管动脉通常比三角支和跗骨窦动脉都来得细小。以上的这些动脉相互吻合，形成了一个骨膜血管网，覆盖于全部的距骨非关节面上。而且，环绕着跗骨管、跗骨窦、距骨颈的上面和距骨体部的内侧面，由三角支、跗骨管动脉、跗骨窦动脉、颈上支及其相互之间的吻合血管网形成了一个不定形的距骨动脉环。本文还讨论了距骨缺血性坏死与动脉环的可能关系，距骨骨折脱位或手术后的缺血性坏死是由于距骨动脉环的毁损或功能受影响所致。三角支在距骨骨折脱位时具有重要意义，手术或手法复位时应注意保护。     

动脉硬化性脑白质病的CT表现与临床分析

目的 :探讨动脉硬化性脑白质病的临床与CT表现特点。方法 :收集 10 0例动脉硬化性脑白质病的临床与CT资料进行综合分析。结果 :10 0例的CT表现为 :弥漫性脑白质低密度改变 ,主要分布在双侧脑室旁及半卵圆中心白质区 ,病灶多呈条带状及月晕状。合并脑萎缩 90例 ;脑梗塞 76例 ,其中 2 5例有大的梗塞灶 ,其余为腔隙性梗塞 ;脑出血 9例 ,其中位于壳核 5例 ,丘脑 3例 ,小脑 1例 ;有 15例伴发基底节区软化灶。增强扫描 8例 ,显示病灶无明显增强。结论 :动脉硬化性脑白质病是发生于老年人的缺血性脑血管病 ,高血压动脉硬化是其主要发病因素。