Computational investigation of hemodynamics in hardshell venous reservoirs: A comparative study

Extracorporeal circulation using heart-lung-machines is associated with a profound activation of corpuscular and plasmatic components of circulating blood, which can also lead to deleterious events such as systemic inflammatory response and hemolysis. Individual components used to install the extracorporeal circulation have an impact on the level of activation, most predominantly membrane oxygenators and hardshell venous reservoirs as used in extracorporeal systems. The blood flows in two different hardshell reservoirs are computationally investigated. A special emphasis is placed on the prediction of an onset of transition and turbulence generation. Reynolds-averaged numerical simulations (RANS) based on a transitional turbulence model, as well as large eddy simulations (LES) are applied to achieve an accurate prediction. In the LES analysis, the non-Newtonian behavior of the blood is considered via the Carreau model. Blood damage potential is quantified applying the Modified Index of Hemolysis (MIH) based on the predicted flow fields. The results indicate that the flows in both reservoirs remain predominantly laminar. For one of the reservoirs, considerable turbulence generation is observed near the exit site, caused by the specific design for the connection with the drainage tube. This difference causes the MIH of this reservoir to be nearly twice as large as compared to the alternative design. However, a substantial improvement of these performance criteria can be expected by a local geometry modification.     

Numerical study of a new ventricular assist device

The present work presents a numerical study of two axial ventricular assist devices (VADs) with two different designs. The geometry of the first design was inspired by DeBakey's rotary blood pump and the geometry of the second design is based on BioCirc’s pediatric VAD. The goal is to see which of the two designs has promising capabilities in terms of pressure differential, flow rate, and thrombosis before proceeding to deeper investigations. In this study a computational fluid dynamics tool was used to simulate and calculate the hemodynamics in the two investigated models. Both models were investigated for a flow rate of 5 L/min at rotational speeds between 10 000 and 15 000 rpm.     

Quantum Implementation of Numerical Methods for Convection-Diffusion Equations: Toward Computational Fluid Dynamics

We present quantum numerical methods for the typical initial boundaryvalue problems (IBVPs) of convection-diffusion equations in fluid dynamics. The IBVPis discretized into a series of linear systems via finite difference methods and explicittime marching schemes. To solve these discrete systems in quantum computers, wedesign a series of quantum circuits, including four stages of encoding, amplification,adding source terms, and incorporating boundary conditions. In the encoding stage,the initial condition is encoded in the amplitudes of quantum registers as a state vectorto take advantage of quantum algorithms in space complexity. In the following threestages, the discrete differential operators in classical computing are converted into unitary evolutions to satisfy the postulate in quantum systems. The related arithmeticcalculations in quantum amplitudes are also realized to sum up the increments fromthese stages. The proposed quantum algorithm is implemented within the open-sourcequantum computing framework Qiskit [2]. By simulating one-dimensional transientproblems, including the Helmholtz equation, the Burgers’ equation, and Navier-Stokesequations, we demonstrate the capability of quantum computers in fluid dynamics.     

A new reconstructive procedure after segmental pancreatectomy: an experimental study of pancreatic end-to-end (duct-to-duct) anastomosis

We produced experimental models of pancreatic end-to-end anastomosis, including ductal end-to-end anastomosis (with or without stent) and pancreaticojejunostomy, using mongrel dogs, with a view to evaluating reconstructive procedures after segmental pancreatectomy. We examined macroscopic findings, pancreatograms, and microangiographic and histopathological findings to determine whether pancreatic end-to-end anastomosis was as practicable as pancreaticojejunostomy. Macroscopic findings showed no suture failure in any animal in the end-to-end anastomosis group. Pancreatography revealed obstruction of the stent tube in the stent subgroup, but good patency in the no-stent subgroup. On the imaging of the microvasculature in the end-to-end anastomosis group, proliferation of neovascular vessels and formation of communicating vessels were detected. Histopathologically, no suture failure was detected, and the viability of the pancreatic end-to-end anastomosis was confirmed. From this experiment, we concluded it that it was possible to employ pancreatic end-to-end anastomosis after segmental pancreatectomy in the clinical situation. Received: October 12, 2000 / Accepted: February 15, 2001     

Computational fluid dynamics analysis of the pediatric tiny centrifugal blood pump (TinyPump)

We have developed a tiny rotary centrifugal blood pump for the purpose of supporting circulation of children and infants. The pump is designed to provide a flow of 0.1-4.0 L/min against a head pressure of 50-120 mm Hg. The diameter of the impeller is 30 mm with six straight vanes. The impeller is supported by a hydrodynamic bearing at its center and rotated with a radial coupled magnetic driver. The bearing that supports rotation of the impeller of the tiny centrifugal blood pump is very critical to achieve durability, and clot-free and antihemolytic performance. In this study, computational fluid dynamics (CFD) analysis was performed to quantify the secondary flow through the hydrodynamic bearing at the center of the impeller and investigated the effects of bearing clearance on shear stress to optimize hemolytic performance of the pump. Two types of bearing clearance (0.1 and 0.2 mm) were studied. The wall shear stress of the 0.1-mm bearing clearance was lower than that of 0.2-mm bearing clearance at 2 L/min and 3000 rpm. This was because the axial component of the shear rate significantly decreased due to the narrower clearance even though the circumferential component of the shear rate increased. Hemolysis tests showed that the normalized index of hemolysis was reduced to 0.0076 g/100 L when the bearing clearance was reduced to 0.1 mm. It was found that the CFD prediction supported the experimental trend. The CFD is a useful tool for optimization of the hydrodynamic bearing design of the centrifugal rotary blood pump to optimize the performance of the pump in terms of mechanical effect on blood cell elements, durability of the bearing, and antithrombogenic performance.     

BPH微创术后前列腺段尿道形态对排尿力学的影响

目前众多的经尿道微创术式治疗良性前列腺增生(BPH)均通过扩大或再造前列腺段尿道(PU)的腔内空间发挥作用,因此,探讨BPH微创术后PU形态对排尿的力学影响,具有重要的指导意义。本研究采用计算流体力学(CFD)技术探讨PU/膀胱颈横径比(RPU-1)对尿流的影响。结果表明,在RPU-1>0.79时,PU两侧出现涡流;且...     

外科治疗小儿先天性胆总管囊肿20例体会

目的 总结外科治疗小儿先天性胆总管囊肿的疗效。方法 20例先天性胆总管囊肿患儿，6例先行外引流术，待3～5周病情平稳后，2例行Ⅱ期囊肿切除、胆总管空肠Roux-en-Y吻合术；9例行胆总管囊肿后壁囊内粘膜剥离及囊肿空肠Roux-en-Y吻合术；5例小囊肿行囊肿全切除及肝总管空肠Roux-en-Y吻合术。结果 1例行外引流的患者术后2d死于感染性休克、DIC，余19例中术后发牛腹水3例，胆肠吻合口瘘2例，切口裂开2例，肺部感染1例，经对症治疗后治愈。16例获8个月～8年获访，无明显胆道感染的临床表现。13例胃肠道钡餐检查，仅2例有反流但不超过空肠胆支的1／3；无一例发生癌变。结论 小儿先天性胆总管囊肿一经确诊应早期手术，手术时应尽量切除病变，并行适宜的胆道重建术。     

应用改良Fontan术治疗小儿复杂先心病

１０例小儿复杂先心病用房内板障和全腔肺连接改良Ｆｏｎｔａｎ术作纠治。病种包括三尖瓣闭锁和右室双出口各４例，单心室２例。手术死亡２例。存活８例中７例随访情况良好。作者认为：改良Ｆｏｎｔａｎ术可减少术后心律紊乱及肺静脉梗阻弊病；房内板障应作成一光滑、挺直、圆柱形通道，各吻合口足够宽畅，无压差。死亡２例系严重心内复杂畸形病人，属改良Ｆｏｎｔａｎ高危病例之列，应作双向腔肺分流术。     

阴茎皮肤撕脱伤患者术后勃起功能评估（附9例报告）

目的：评估阴茎皮肤撕脱伤患者手术治疗后勃起功能的恢复情况.方法：回顾性分析我院20042009年经手术治疗的9例阴茎皮肤撕脱伤患者.吻合手术后,5例连通背深静脉、2条背动脉及至少2条背神经;2例仅连通2条背动脉及至少2条背神经;1例连接了单侧背动脉及同侧背神经;1例连接背深静脉及2条背神经.全部患者入院时均行国际勃起功能指数（IIEF-5）评分;随访时均接受化学假体及RigiScan阴茎硬度检测.并再次评定IIEF-5.结果：术后随访9～64 个月.5例完全吻合患者中,1例RigiScan、化学假体检测及IIEF-5评分均提示勃起功能障碍,手术前后IIEF-5评分无差异,其余4例阴茎勃起功能正常.2例仅吻合2条背动脉及背神经的患者术前IIEF-5评分1例正常,1例提示轻度勃起功能障碍,术后随访时IIEF-5评分均正常.本组另2例患者术后随访时均提示有不同程度的勃起功能障碍,且随访时IIEF-5评分均低于术前.结论：阴茎皮肤撕脱伤手术治疗时,血运的恢复状况可能是预测术后勃起功能的重要因素.     

A prospective study on size and function of paediatric kidneys (<10 years) transplanted to adults

BACKGROUND: There is increasing evidence that paediatric kidneys transplanted to adults have good graft function and satisfactory graft survival. The relationship between size increment and functional potential of paediatric kidneys following transplantation is not defined in detail. We therefore initiated a prospective single centre study, comprising detailed and repeated measurements of size and function of paediatric kidneys transplanted to adults. METHODS: Nineteen adults receiving a first kidney transplant from a paediatric donor (<10 years of age) were included in the study. All patients were followed for 12 months post-transplant. Increment in size and function of the transplanted kidneys were assessed by ultrasound, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). All tests were performed during the first week, post-transplant and subsequently repeated at 1, 3, 6 and 12 months. RESULTS: Kidney volume increased 2.6-fold at 12 months (P < 0.001). GFR and ERPF showed a slightly more moderate increase, 1.8-fold and 1.6-fold, respectively. Patient and graft survival at 1 year were 100% and serum creatinine was 91 micromol/l (66-169). CONCLUSION: The study indicates that paediatric kidneys for transplantation may be considered as excellent rather than being referred to as suboptimal for adult recipients, at least the first year after transplantation.     

Microsurgical management of cerebral aneurysms based in CT angiography with three-dimensional reconstruction (3D-CTA) and without preoperative cerebral angiography

Summary  Objective. To study the posibilities of the microsurgical management of ruptured intracranial aneurysms with the sole preoperative information provided by computed tomography angiography with three-dimensional reconstruction (3D-CTA).  Methods. Patients were studied with 3D-CTA after diagnosis of subarachnoid hemorrhage. If the study had an adequate quality and revealed an aneurysm congruent with the clinical findings or neurological examination and/or with the location of the bleeding on computed tomography (CT) scan an early microsurgical clipping of the lesion was done. When the quality of the 3D-CTA study was not adequate or the quality being adequate displayed no lesions or the findings were not accurate enough to warrant direct microsurgical treatment, the patient was studied with cerebral digital substraction (DS) angiography. A total of 44 consecutive patients harbouring a total of 47 intracranial aneurysms diagnosed by 3D-CTA and without preoperative DS angiography were submitted to microsurgical clipping and included in the study.  Results. The overall mortality was 15.9% and the favourable results evaluated 6 months after discharge by means of the Glasgow Outcome Scale reached 70.4%. All lesions were successfully clipped. Surgery was done a mean of 4.1 days after the admission bleeding. A total of four microlesions undiagnosed by 3D-CTA were found at surgery and clipped. Postoperative DS angiography and necropsy findings were also used as control of the 3D-CTA findings but no additional information was provided excepting the finding in DS angiography of an asymptomatic intracavernous aneurysm. Therefore the sensitivity of the 3D-CTA for diagnosis of symtomatic aneurysms was 100% and the overall sensitivity 90.4%.  Conclusions. We have reached similar results in patients operated on with or without preoperative angiography. 3D-CTA provides very valuable anatomical information, which has an additional value in the microsurgical treatment of aneurysms of the anterior communicating artery complex. Finally, selected cases of ruptured intracranial aneurysms can be successfully managed with the preoperative information provided by 3D-CTA and without DS angiography.     

Treatment of Unresectable Cholangiocarcinoma with Gemcitabine-Based Transcatheter Arterial Chemoembolization (TACE): A Single-Institution Experience

Background Survival for patients with unresectable cholangiocarcinoma is reported to range from only 5–8 months without treatment. Systemic chemotherapy has not been shown to significantly improve survival, but newer regimens involving gemcitabine have shown increased response rates. Transcatheter arterial chemoembolization (TACE) has been shown to prolong survival in hepatocellular carcinoma patients, but experience using TACE in the treatment of cholangiocarcinoma is limited. We report our experience treating cholangiocarcinoma with TACE using chemotherapeutic regimens based on the well-tolerated drug gemcitabine. Methods Forty-two patients with unresectable cholangiocarcinoma were treated with one or more cycles of gemcitabine-based TACE at our institution. Chemotherapy regimens used for TACE included: gemcitabine only (n = 18), gemcitabine followed by cisplatin (n = 2), gemcitabine followed by oxaliplatin (n = 4), gemcitabine and cisplatin in combination (n = 14), and gemcitabine and cisplatin followed by oxaliplatin (n = 4). Results Patients were 59 years of age (range 36–86) and received a median of 3.5 TACE treatments (range 1–16). Thirty-seven patients (88%) had central cholangiocarcinoma, and five (12%) had peripheral tumors. Nineteen patients (45%) had extrahepatic disease. Grade 3 adverse events (AEs) after TACE treatments were seen in five patients, whereas grade 4 AEs occurred in two patients. No patients died within 30 days of TACE. Median survival from time of first treatment was 9.1 months overall. Results did not vary by patient age, sex, size of largest initial tumor, or by the presence of extra-hepatic disease. Treatment with gemcitabine–cisplatin combination TACE resulted in significantly longer survival (13.8 months) compared to TACE with gemcitabine alone (6.3 months). Conclusions Our report represents the largest series to date regarding hepatic-artery-directed therapy for unresectable cholangiocarcinoma and provides evidence in favor of TACE as a promising treatment modality in unresectable cholangiocarcinoma. Our results suggest that gemcitabine-based TACE is well tolerated and confers better survival when given in combination therapy (with cisplatin or oxaliplatin) for patients with unresectable cholangiocarcinoma. Presented at the 2007 American Hepato-Pancreato-Biliary Association, Las Vegas, Nevada, April 19–22, 2007 (President’s Plenary Oral Presentation).     

股前外侧（肌）皮瓣交腿修复胫前大面积软组织缺损

目的寻求一种对胫前区大片软组织缺损修复的手术新方法,降低截肢率.方法对10例胫前严重的开放性损伤伴大面积软组织缺损病例,采用股前外侧(肌)皮瓣交腿血管吻合移植方法,移植皮瓣12×8～28×15cm2,随访6个月-5年.结果除2例,皮瓣边缘部分坏死外,其余8例皆一期愈合,外形、功能满意.结论交腿皮瓣移植术可降低某些小腿严重开放性创伤的伤残率.