Elasticity changes in the large arteries of human limbs in response to cycle ergometry performed with upper and lower limbs

Summary At rest and after cycle ergometry the elastic properties of the large arteries of limbs of healthy men were examined using an original non-invasive quantitative oscillometric method. It has been shown that in response to muscle work performed with the legs there is a decrease of the effective inner radius, and an increase of the characteristic impedance modulus and bulk modulus and of the elastic resistance of the intact and relaxed wall in the large arteries in the upper limbs. All these changes testify to an increase of vascular tension in the upper limbs. In response to work performed with the hands, there is an increase of the effective inner radius of large arteries of the upper limbs, a large increase of the pulsatile blood volume increment of the intact vessels and a decrease of the characteristic impedance modulus, of the bulk modulus and of the elastic resistance of the intact arterial wall. These changes indicate a decrease of the vascular tension of these arteries. In response to work performed either with the legs or with the hands a decrease of the effective inner radius of large arteries and an increase of the elastic resistance of the relaxed arterial wall were observed in the lower limbs, all these changes indicating relatively small changes in tone of these vessels. It is concluded that the wall tension of large arteries supplying blood to the muscles of non-working limbs is increased. Vascular tension changes in the arteries in working limbs are accounted for by the superimposition of centrally originating vasoconstriction with local vasodilatation, which also affects large arteries.     

Clinicopathologic findings in congenital aneurysms of the great vessels

We describe the clinical, histopathologic, and angiographic findings in four children with congenital abnormalities of the great vessels of unknown cause, comprising either single or multiple arterial aneurysms, aortic/arterial dilatation, vessel tortuosity, or combinations of these abnormalities. Two children had early and severe respiratory distress due to aneurysmal compression of the trachea. All children had diffuse dilatation of several arteries, and two children also had tortuosity of multiple arteries. Progression of these abnormalities was clearly evident in one child, in whom diffuse vessel irregularity and tortuosity affected intra-abdominal, and intra and extra-cranial arteries. One child died at 5 years, while the other three have undergone successful surgical repair in the first 3 months of life and are now well, between age 2.5 and 7 years. The phenotype of each child appears unique but all have in common the rare finding of aneurysms of the aorta and main pulmonary artery. Congenital aortic aneurysms did not occur as an isolated finding in any of these children. © 1996 Wiley-Liss, Inc.     

Effects of filtering and delays on the estimates of a nonlinear respiratory mechanics model

Estimation of mechanical properties of the respiratory system may be disturbed by instrumentation and physical set-up. The effects of lowpass filtering, filter mismatch and inter-channel delay in the digital converter are assessed on numerically simulated signals from a nonlinear model of the respiratory system. Large biases in model parameter estimates (up to about -300% for some parameters) were caused by these instrumental interferences and were reduced by including an inertance in the retrieved model. The results reinforce the importance of a careful evaluation of the instrumental set-up used in physiological measurements.     

3D morphometric analysis of the arterial switch operation using in vivo MRI data

The arterial switch operation (ASO) is widely used nowadays as the surgical strategy of choice to repair transposition of the great arteries (TGA). Residual morphological and geometrical abnormalities of the aorta, pulmonary arteries and coronary arteries, however, have not been fully studied in a three‐dimensional (3D) domain. These morphometric complications might have implications on long‐term outcomes of ASO patients, hence the need to explore them in detail and study them with reference to healthy controls of comparable age and body surface area. These anatomical characteristics were examined using 3D patient‐specific anatomical models reconstructed from cardiovascular magnetic resonance (CMR) images of 20 ASO patients (mean age 14.4 ± 2.4 years, 16 males and 4 females) compared with healthy controls (mean age 15.2 ± 2.0 years, 17 males and 3 females). It was found that the aorta, pulmonary arteries and re‐implanted coronary arteries of ASO patients were significantly different morphologically and geometrically to those of healthy controls. In particular, the aortic root was dilated, with abnormal 3D angulation and additional acute angulation of the curvature of the aortic arch in the ASO group compared with controls. This could theoretically impinge on aortic flow profiles and physiological stresses, which can act as a primer for the development of early atherosclerotic disease in the ASO population. Clin. Anat. 27:1212–1222, 2014. © 2014 Wiley Periodicals, Inc.     

Identification of the three-element windkessel model incorporating a pressure-dependent compliance

A new one-step computational procedure is presented for estimating the parameters of the nonlinear three-element windkessel model of the arterial system incorporating a pressure-dependent compliance. The data required are pulsatile aortic pressure and flow. The basic assumptions are a steadystate periodic regime and a purely elastic compliant element. By stating two conditions, zero mean flow and zero mean power in the compliant element, peripheral and characteristic resistances are determined through simple closed form formulas as functions of mean values of the square of aortic pressure, the square of aortic flow, and the product of aortic pressure with aortic flow. The pressure across as well as the flow through the compliant element can be then obtained so allowing the calculation of volume variation and compliance as functions of pressure. The feasibility of this method is studied by applying it to both simulated and experimental data relative to different circulatory conditions and comparing the results with those obtained by an iterative parameter optimization algorithm and with the actual values when available. The conclusion is that the proposed method appears to be effective in identifying the three-element windkessel even in the case of nonlinear compliance.     

全腰椎非线性有限元模型的建立与有效性验证

目的　为人体腰椎生物力学有限元分析建立有效的全腰椎非线性数字仿真模型。 方法　采集一名25岁的健康男性腰椎（L1~5）CT影像数据,依次通过Mimics 17.0、Geomagic Studio 2013、UG8.5、Hypermesh 13.0、Abaqus6.14-4五个软件建立模型,赋予各组织对应的属性。首先进行网格收敛性测试,选取合适的网格划分方案以提高分析效率。然后通过给模型施加不同的力矩载荷来模拟腰椎的6种运动（前屈、后伸、左侧弯、右侧弯、左轴向旋转、右轴向旋转）,计算腰椎各功能节段（functional spinal unit,FSU）的活动度（range of motion,ROM）。 结果　模型得出的结果与体外试验的数据类似,两者变化趋势规律一致。 结论　本研究使用的全腰椎非线性有限元模型的建立与验证方法可用于未来脊柱相关疾病的建模与分析。     

The bovine kidney as an experimental model: Simulated partial nephrectomy of the cranial pole and proportional analysis of the arterial segments

Previous studies have shown that the pig kidney is not a good model for some procedures. This study aimed to describe the relationship between the collecting system and the intrarenal arteries, the arterial segments, and to evaluate the bovine kidney as an experimental model for partial nephrectomy of the cranial pole. Polyester resin endocasts of the kidney collecting system together with the intrarenal arteries were prepared. Thirty-two kidneys were used to evaluate the relationship between the collecting system and the intrarenal arteries, while 25 kidneys were transversally sectioned at different points to simulate partial nephrectomy of the cranial pole. Polyester resin of different colors was injected into each segmental artery of the 24 kidneys to evaluate the arterial segments proportionally. The renal artery was divided into cranial and caudal primary branches in 75% of the cases. The cranioventral branch curved on the cranial pole and ran toward the ventral mid-zone in 56.3% of the cases, resembling the retropelvic artery of the human kidney. The kidney was divided into two (25%) or three (75%) arterial segments. The caudal arterial segment had the highest proportional volume (62%). The cranioventral branch was damaged in 28.6% of the kidneys sectioned 1 cm inside the hilum. The arterial branching pattern, the arterial segmentation, and the impairment of the arterial supply after the simulated partial nephrectomy of the cranial pole are quite different from those found in humans. Thus, all differences should be taken into account when using the bovine kidney as a model.     

Quantitative evaluation of the systemic arterial bed by parameter estimation of a simple model

The parameters of a simple model (r-L-C-R) of the systemic circulation are estimated from aortic root pressure and flow, which are either simulated by a complex model of the systemic circulation or measured in dogs. This model contains one additional parameter (inductance L) as compared with the r-C-R model proposed by Westerhof; it allows for a better representation of the input impedance of the complex model and of the systemic circulation in dog, resulting in meaningful values for the parameters r, C, R. Because there is a good relation between C and the sum of the compliances of the complex model, and because C varies in the direction of the expected changes in compliance following angiotensin and sodium nitroprusside administration in dogs, C appears to be a valid estimate of the total systemic arterial compliance. The good relation between r and the characteristic impedance in the complex model or in the upper thoracic aorta of the dog indicates that r is a good measure of the characteristic impedance. The r-L-C-R model therefore appears to provide a better characterisation of the left ventricular afterload than the r-C-R model. The identification of this r-L-C-R model also permits a more convenient quantification of the afterload than the classical computation of input impedance.     

吻合趾——指血管的显微外科解剖及急诊拇手指再造

目的：为改进急诊拇、手指部分缺损的再造方法，缩短手术时间。方法：根据第２足趾及拇、手指的血管、神经分布的解剖学规律。１９９３年３月至１９９５年７月，利用第２足趾，采用吻合趾—指血管的方法急诊再造拇、手指１２例１２指。结果：再造拇、手指全部成活，恢复了拇、手指对掌及捏握功能，病人自觉满意。结论：第２足趾及拇、手指血管、神经解剖恒定，远侧指（趾）间关节以近的指固有动脉、趾底动脉及指（趾）背静脉口径在０．５ｍｍ以上，完全可以吻合。急诊再造适合于：局部污染不重，无广泛严重挫伤的拇指Ⅲ度以内缺损及近侧指关节以远的手指缺损，手指近节远端的缺损也可以应用。     

Optimal structure of the arterial network of skeletal muscles

A criterion of optimal structure of the arterial network of a skeletal muscle is suggested, namely minimization of its hydraulic resistance during intensive work. By the use of this criterion the ratio between the mean diameter of the vessels of different orders of branching can be determined. Equations were obtained showing dependence of the hydraulic resistance, volume, and pressure in vessels of different caliber on the order of branching. Rough quantitative estimates of the possible increase in blood flow in an intensively working muscle compared with the same muscle at rest are given.Department of Physics of Living Systems, Moscows Physicotechnical Institute. Laboratory of Biophysics and Pathophysiology of the Circulation, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 9, pp. 259–262, September, 1978.     

完全性大动脉错位动脉转位术后新主肺动脉发育的随访

目的报道应用动脉转位术（ASO）治疗完全性大动脉错位（TGA）术后超声心动图的随访结果,评价TGA术后主、肺动脉的发育情况。方法以2001年3月至2007年3月于复旦大学附属儿科医院心血管中心实施ASO治疗TGA术后存活患儿作为研究对象,于2008年8～9月进行随访,行超声心动图检查,测定新主动脉根部内径、新主动脉瓣环内径、新肺动脉内径和新肺动脉瓣环内径,获取的数据与正常参考值做比较。结果研究期间ASO治疗TGA患儿共72例,术中死亡6／72例（8．3％）,存活率为91．7％。失访10／66例,有效数据56例,其中室间隔完整的完全性TGA（TGA／IVS）32例,完全性TGA合并室间隔缺损（TGA／VSD）24例。随访距手术18—168（86．46±23．51）个月。新主动脉根部内径为（16．97±2．71）mm（t=6．936,P〈0．001）,12／56例（21．4％）〉正常参考值90％CI的上限,44／56例（78．6％）在正常参考值90％CI内,平均Z值为1．10±0．70。新主动脉瓣环内径为（16．27±2．38）mm（t=4．52,P〈0．001）,56例均在正常参考值90％CI内,平均Z值为0．66±0．65。新肺动脉内径为（14．29±1．92）mm（t=-3．2,P=0．005）,40／56例（71．4％）在正常参考值90％CI内,16／56例（28．6％）〈正常参考值90％CI的下限,平均Z值为-0．95±1．33。新肺动脉瓣环内径为（14．00±1．92）mm（t=0．132,P=0．897）,42／56例（75．0％）在正常参考值90％CI内,14／56例（25．O％）〈正常参考值90％CI的下限,平均Z值为0．05±1．85。16／56例（28．6％）存有主动脉瓣轻度反流,均为TGA／VSD病例,平均随访（46．0±22．2）个月;40／56例（71．4％）未见主动脉瓣反流,平均随访（46．8±25．3）个月,两组随访时间差异无统计学意义（P=0．899）。随访中未见主动脉狭窄病例。肺动脉瓣上狭窄7／56例（12．5％）,2／56例（3．6％）为轻度狭窄,5／56例（8．9％）为极轻度狭窄。结论目前在复旦大学附属儿科医院心血管中心开展ASO治疗TGA术后新主动脉根部和瓣环内径均有所扩张,新肺动脉根部内径有所缩减,但其瓣环发育良好。主动脉瓣反流常见于TGA／VSD病例,但其反流程度较轻。肺动脉瓣上狭窄是TGA术后常见的并发症,但大多数病例狭窄程度极轻。     

Periosteal and Intraosseous arteries of the human femur: Sphincter-arteries in the medullary cavity

Microanatomic injection and corrosion casts were made of 30 human femora of all ages to study the distribution of periosteal and intraosseous arteries; additionally, the marrow of 85 femora (also from all ages) was harvested for histological examination of these vessels. Examination of the diaphyseal and metaphyseal periosteal arteries revealed slight rarefication in density during the lifespan, whereas endosteal arteries were significantly changed in appearance. Two broad dense arterial trees (one located in the proximal half and the other in the distal half) with regular branching crowns were found in the fetal femur. By the second decade of life, the two vascular trees were reduced to an irregular, sparse structure that often showed glomuslike convolutions. Histologically, the intraosseous arteries often developed single or grouped axially oriented smooth muscle cells located in any of the layers of the arterial wall or were sometimes found included within the internal elastic lamina. In about 10% of the glomuslike convolutions, circumscribed intra-arterial cushions and sphincters of modified epithelioid smooth muscle cells were found. These structures may be part of arteriovenous anastomoses that serve to regulate blood pressure and may release humoral agents. The transformation of the arterial distribution pattern and the occurrence of arterial cushions and sphincters parallel the change of red haematopoetic marrow into yellow marrow. © 1993 Wiley-Liss, Inc.     

Variations of the arterial pattern in the upper limb revisited: a morphological and statistical study, with a review of the literature

A total of 192 embalmed cadavers were examined in order to present a detailed study of arterial variations in the upper limb and a meta-analysis of them. The variable terminology previously used was unified into a homogenous and complete classification, with 12 categories covering all the previously reported variant patterns of the arm and forearm.     

A study of temperature regulation in the human body with the aid of an analogue computer

Summary To be able to predict man's thermal response to any given environment it is essential to have a thorough understanding of man's thermo-regulatory mechanism. The mechanism is dependant on a number of highly non-linear variables. An analogue computer can be of great value with such a problem as non-linear control characteristics are easily incorporated into its programme. The computer is used as a model to reproduce man's thermal behaviour. This paper describes the application of such a computer. A number of tests were made to study some thermal control characteristics and the results are compared with those of a series of experiments performed on two resting subjects who were exposed to various environmental conditions in a climatic chamber.     

Separate determination of the pulsatile elastic and viscous forces developed in the arterial wall in vivo

The viscoelastic behaviour of arteries in vivo is analyzed by separate representation of the purely elastic and the purely viscous properties, using natural pressure and diameter pulses of various dog arteries recorded under steady-state conditions. The circumferential wall stress () and the radius (r) of the mean wall layer are calculated as functions of time and the hysteresis of the -r diagram is represented. The stress is regarded as the sum of an elastic stress (_el) which is a function ofr, and a viscous stress (_vis) which is a function ofdr/dt. Thus _el=–_vis. Since the _el-r diagram must be free from hysteresis, the disappearance of the loop is the criterion that indicates that _el has been found._vis is formulated as a second degree polynomial ofdr/dt whose coefficients are determined using that criterion.The _el-r curve is always nonlinear and the elastic modulus increases with increasing radius. The _vis-dr/dt curve, too, is nonlinear. Its slope decreases with increasingdr/dt. The same applies to the wall viscosity (pseudoplastic behaviour). The nonlinear properties can be represented adequately by processing the experimental data in the time domain. Problems inherent in investigations based on the frequency domain, as reported in the literature, are pointed out.