FW型轴流泵的体外溶血与动物实验研究

目的为给心力衰竭患者提供有效的心室机械辅助治疗,研制出可以部分或完全代替心室功能的FW（Fu Wai）型轴流式心室辅助血泵,评价其流体力学性能和血液相容性能。方法通过体外测试台和5只小尾寒羊的动物实验,对FW型轴流式心室辅助血泵的流体力学性能和血液相容性能进行了测试。结果轴流泵在转速为8400r／min、后负荷为100mm Hg的情况下,流量可达5L／min;体外溶血试验检测结果表明轴流泵的标准溶血指数（NIH）为0．17±0．06mg／L。动物实验结果表明,血浆游离血红蛋白含量在30mg／dl左右。结论FW型轴流式心室辅助血泵的血液相容性能良好,体外和体内试验结果达到了国际标准,有望在完善动物实验的基础上进入临床试验阶段。     

国内首例自制叶轮血泵作双心室辅助的临床试用

目的为抢救１名法洛三联症及术后低心排血量患者，将研制的离心型人工心脏叶轮血泵首次应用于临床。方法应用叶轮血泵行双心室辅助，左泵从左心房输送血液至主动脉，右泵从右心房输送血液至肺动脉。结果血泵工作４３小时，运行正常，患者心功能得到一定程度的恢复，主动脉平均压几次达到１０．６７ｋＰａ（８０ｍｍＨｇ），但因肾功能衰竭出现水肿，最终中止抢救拆除人工心脏泵。结论患者未能存活的原因有人工心脏使用不及时，生命体征好转后过早尝试降低辅助流量，以及使用升压药导致肾血流量灌注减小等。     

第三代血泵的研究进展

心室辅助装置已经逐渐成为治疗急、慢性心力衰竭的一种重要手段,而作为心室辅助装置主要部件的血泵也已经进展到了第三代。第三代血泵采用磁悬浮和/或液悬浮技术,在运转时血泵内用于驱动血液流动的叶轮悬浮在泵体内。第三代血泵主要由悬浮系统和驱动系统两部分组成,其发展经历了三个阶段,即悬浮和驱动系统分离的外马达间接驱动叶轮阶段,悬浮和驱动系统分离的马达直接驱动叶轮阶段以及悬浮与驱动系统融合阶段。由于第三代血泵的叶轮在运转时与其他结构没有接触,因此血泵具有溶血少、血栓发生率低、无机械磨损及能效比高的优势。目前第三代血泵大多处于研发阶段,只有少部分已进入了临床实验和应用阶段。我们就目前已报道的第三代血泵的发展史、分类、机械原理和研发现状等进行综述。     

计算流体力学在心脏血泵溶血设计中的应用

人工心脏辅助血泵已经成为治疗心力衰竭不可缺少的治疗手段,在临床上的应用越来越多.早期的血泵设计都是在实验和经验的基础上进行改进,研制周期长;近年来,随着计算机并行技术和流体力学的发展,计算流体力学(computational fluid dynamics ,CFD)的广泛应用大大缩短了血泵研制的周期,为开发高效率、体积小的血泵提供了有力的保证.本文就CFD在心脏辅助血泵研制中,主要在血液相容性方面的应用作一综述.     

搏动辅助血尕的设计构思与实践——从旋涡泵到罗叶泵

目的 由于国际市场供应的各种血泵价格过于昂贵，为降低其成本而不降低其质量，我们设计制作了旋涡泵和罗叶泵，以保持良好的血液流态，减少栓塞和溶血等并发症的发生率。方法 为命名血液在泵动周期中始终保持连续的流线和旋涡流态以充分冲洗泵体四周，同时避免湍流、再循环和潴流，旋涡泵设计为出入血口位地不同的平面上，并对泵血功能进行了测定。在血液流态、溶血试验等方面与通用血泵在模拟循环台中进行了比较。罗叶泵遵循相同的原理，泵体为拱顶形，其顶部有一锥形下凹伸入泵体内部，出入血管道相互交叉。由于泵体拱顶不对称，出血口高于入血口，在收缩期时血流盘旋上升，出血口处阻力小于入血口，排血更为迅速和彻底。结果 旋涡泵在血液流态和溶血试验中与通用血泵比较，前者均优于后者。旋涡泵在13次的绵羊实验中，最后4只未经抗凝处理的绵羊，于平稳转流14天后处死（其中1条21天），尸体解剖泵内、双肾内均无栓塞。罗叶泵已于1999年应用于临床，成功抢救了1例危重患者。结论 辅助循环血泵的设计，其连续的流态流态、避免滴流、血流潴留和再循环区是防止栓塞形成的关键。     

离心泵在胸主动脉瘤手术中的应用(文献综述)

左心转流是降主动脉瘤手术中有效辅助方法之一,尤其是将氧合器做为贮血器,便于控制出血和输血,并可调节温度,提高了手术疗效。但因全身肝素化和人工心肺机对血液有形成份带来了破坏损伤,同时术中剥离创面广泛渗血和肺出血,易发生术后肾衰和凝血功能紊乱等并发症。近年报道BioMedicus离心泵(以下简称Bio泵)具有对血液损伤程度小和肝素用量少的优点,由此Bio泵左心转流在降主动脉瘤切除术中的应用日渐增多。     

自制轴流血泵对左心功能不全辅助作用的实验研究

左心辅助装置是治疗心源性休克、心脏术后低心排、心脏移植前过渡支持的有效手段。自１９９０年起，我们根据轴流血泵原理，自行设计制造Ⅲ型微型血泵，并用于左心梗动物实验。自制Ⅲ型微型血泵的泵体外径０．８ｃｍ，泵血量在１７０００ｒｐｍ时为每分钟３Ｌ。经吻合于绵羊降主动脉的人工血管插入左心室、于左前降支阻断１小时开放后进行左心辅助，观察心排量（ＣＯ）、左房压（ＬＡＰ）、股动脉压、游离血红蛋白（Ｈｂ）、血乳酸（ＬＡ）、过氧化脂质（ＬＰＯ）、左室梗塞面积。结果见，辅助组左前降支开放后动脉压上升、ＣＯ很快恢复到阻断前水平，相应ＬＡＰ、游离Ｈｂ、ＬＡ、ＬＰＯ和左室梗塞面积均较对照组降低。作者认为，自制Ⅲ型微型血泵用于左心梗实验动物可明显增加ＣＯ、缩小梗塞面积，对血细胞破坏程度在临床允许范围内，达到了原设计要求。进一步改进后可过渡到临床试验     

搏动辅助血泵的设计构思与实践——从旋涡泵到罗叶泵

目的　由于国际市场供应的各种血泵价格过于昂贵 ,为降低其成本而不降低其质量 ,我们设计制作了旋涡泵和罗叶泵 ,以保持良好的血液流态 ,减少栓塞和溶血等并发症的发生率。　方法　为使血液在泵动周期中始终保持连续的流线和旋涡流态以充分冲洗泵体四周 ,同时避免湍流、再循环和潴流 ,旋涡泵设计为出入血口位于不同的平面上 ,并对泵血功能进行了测定。在血液流态、溶血试验等方面与通用血泵在模拟循环台中进行了比较。罗叶泵遵循相同的原理 ,泵体为拱顶形 ,其顶部有一锥形下凹伸入泵体内部 ,出入血管道相互交叉。由于泵体拱顶不对称 ,出血口高于入血口 ,在收缩期时血流盘旋上升 ,出血口处阻力小于入血口 ,排血更为迅速和彻底。　结果　旋涡泵在血液流态和溶血试验中与通用血泵比较 ,前者均优于后者。旋涡泵在 13次的绵羊实验中 ,最后 4只未经抗凝处理的绵羊 ,于平稳转流 14天后处死(其中 1条 2 1天 ) ,尸体解剖泵内、双肾内均无栓塞。罗叶泵已于 1999年应用于临床 ,成功抢救了 1例危重患者。结论　辅助循环血泵的设计 ,其连续的流线流态、避免湍流、血液潴留和再循环区是防止栓塞形成的关键     

轴流血泵的研究进展

心力衰竭是各种心脏病患者最主要的死亡原因.近年来,终末期心力衰竭的治疗日益成为临床心血管医师所面临的巨大挑战.由于药物治疗和常规外科手术的局限性,以及供体心脏的缺乏,促进了心脏机械辅助循环装置的快速发展.电机学、机械工程学、流体力学、材料学和医学等多学科的联合研发,探寻可长期植入式新型叶轮血泵已成为当今国内外的研究热点.轴流血泵具有结构简单、重量轻、流量大、效率高、易植入和取出等优点,同时无需安装人工瓣膜,减少了血栓形成的几率.与离心泵相比较,轴流血泵体积更小,血液破坏程度更轻.目前轴流血泵的研究已经成为心脏外科和生物医学工程领域关注的焦点.现对轴流血泵的工作原理、特点和当前轴流血泵研究中面临的一些关键技术问题进行综述.     

冠脉旁路移植左室辅助装置植入手术1例的护理配合

正左心辅助装置(left ventricular assist device,LVAD)利用泵血装置驱动左心室血液流入主动脉,可部分或完全替代心脏泵血功能,维持血液循环~([1]),通常用于心脏移植的过渡、心肌功能的恢复以及心力衰竭的永久治疗~([2、3])。我院2018年2月行冠脉旁路移植加左室辅助装置植入术1例,为我院心外科和"久安心"人工心脏项目专家共同完成的     

Development of the MEDOS/HIA DeltaStream extracorporeal rotary blood pump

The DeltaStream blood pump has been developed for extracorporeal circulation with one focus on potential integration into simplified bypass systems (SBS). Its small size and an embedded electric motor are the basic pump properties. A variation of the impeller design has been performed to optimize hydraulic and hematologic characteristics. A simple impeller design was developed which allows flow and pressure generation for cardiopulmonary bypass applications. The option of a pulsatile flow mode for ventricular assist device applications also was demonstrated in vitro. Impeller washout holes were implemented to improve nonthrombogenicity. The pump was investigated for potential thermal hazards for blood caused by the integrated electric motor. It could be demonstrated that there is no thermal risk associated with this design. Durability tests were performed to assess the lifetime of the pump especially with regard to the incorporated polymeric seal. Seal lifetimes of up to 28 days were achieved using different blood substitutes. In animal tests using either the pump as a single device or in an SBS setup, biocompatibility, low hemolysis, and nonthrombogenicity were demonstrated. In summary, the DeltaStream pump shows great potential for different extracorporeal perfusion applications. Besides heart-lung machine and SBS applications, ventricular assist and extracorporeal membrane oxygenation up to several days also appear promising as potential applications.     

Subchronic Centrifugal Mechanical Assist in an Unheparinized Calf Model

Abstract. The purpose of this study was to determine whether the major centrifugal pumps currently in use in the United States (Medtronic, BioMedicus BioPump and Carmeda-coated BioPump, Sams 3M centrifugal pump, and St. Jude Medical Lifestream) could function as left mechanical assist devices in the subchronic (72 h) unheparinized calf model. Calves were instrumented for left atrial to aorta ex vivo assist, and the pump flow was set at 3.5 ± 0.4 L/min. Two calves (Sarns 3M and St. Jude) survived 72 h of pumping without clinical complications. The other 2 calves died at 62 and 66 h (Medtronic Bio-Pump and Carmeda-coated BioPump, respectively); both had pelvic limb paralysis. The seal of the Sarns 3M pump head ruptured after approximately 36 h of pumping and required replacement. On postmortem examination, pump-associated thromboembolic lesions were detected in 3 of the 4 calves in one or more of the following organs: kidney, pancreas, abomasum, duodenum, ileum, spleen, and lumbar spinal cord. The calf with the Sarns 3M pump had no discernable lesions. Because of the clinical abnormalities and postmortem lesions in the unheparinized calf model, it was suggested that anticoagulation is necessary for conducting centrifugal mechanical assist studies in calves using presently available technology.     

Evaluation of left ventricular assist device performance and hydraulic force in a complete mock circulation loop

Centrifugal pump performance characteristics are vital in determining the ability of a prototype left ventricular assist device (LVAD) to meet the physiological circulation requirements of the cardiovascular system. These characteristics influence the static hydraulic forces encountered by the pump impeller, which determine the required load stiffness of suspension type bearings to minimize impeller touchdown. Performance investigations were conducted on an LVAD design while characterizing the impeller static hydraulic forces of various impeller/volute configurations. The pumps were inserted into a complete systemic and pulmonary mock circulation rig configured to provide suitable nonpulsatile or simulated pulsatile left heart failure environments. The single volute and closed shroud impeller configuration exhibited lowest radial (0.01 N) and axial (3 N) force at nonpulsatile design flow conditions, respectively. Normal hemodynamic conditions of 5.1 L/min at 94 mm Hg were re-established upon inserting the device into the left heart failure environment, where the pump operated along the nonpulsatile characteristic curve for 2200 rpm. The operational limits on this curve were dictated by the required pressure differential across the pump during systolic and diastolic periods. The reduction of left atrial pressure (25 to 8 mm Hg) indicated the alleviation of pulmonary congestion. The ability for the LVAD to support circulation in a left heart failure environment was successfully demonstrated in the mock circulation loop. The impeller hydraulic force characteristics attained will aid the bearing designer to select the best volute and impeller configuration to minimize impeller touchdown in magnetic, hydrodynamic or mechanical type bearing applications.     

Anesthetic management for implantation of the Jarvik 2000 left ventricular assist system

The Jarvik 2000 Heart(TM) is a left ventricular assist device that produces continuous nonpulsatile axial flow by means of a single, rotating, vaned impeller. Anesthetic and perioperative considerations of the Jarvik 2000 Heart(TM) differ from those of conventional assist devices. The Jarvik 2000 is implanted within the left ventricle through a left thoracotomy, which is aided by left lung isolation. A brief period of cardiopulmonary bypass and induced ventricular fibrillation facilitate implantation. Transesophageal echocardiography is essential to assure proper intraventricular positioning of the device and aortic outflow, confirmed by observation of aortic valve opening in the presence of adequate left ventricular volume. Because continuous flow devices function best in the presence of lower systemic and pulmonary vascular resistance, milrinone was preferentially used as an inotropic drug. In the first group of 10 patients to receive the Jarvik 2000, the pump provided a cardiac output of up to 8 L/min, depending on preload, afterload, and pump speed. There were no early perioperative deaths. The average support duration was 81.2 days; the range was 13-214 days. Seven of the 10 patients survived to transplantation. Survivors underwent complete physical rehabilitation during pump support. IMPLICATIONS: The Jarvik 2000 is a left ventricular assist device that produces continuous nonpulsatile axial flow by means of a rotating, vaned impeller. Because the anesthetic considerations differ from those of conventional left ventricular assist devices, we report the perioperative management of the first 10 patients who participated in a bridge-to-transplantation feasibility study of the Jarvik 2000.     

Development and Evaluation of Antithrombogenic Centrifugal Pump: The Baylor C–Gyro Pump Eccentric Inlet Port Model

Abstract: The Baylor C–Gyro Pump Eccentric Inlet Port Models (C1E) have been developed aiming for a longterm centrifugal ventricular assist device (VAD) as well as a cardiopulmonary bypass pump. The eccentric inlet port models are characterized by their unique inlet port and secondary impeller vanes. An inlet female pivot bearing, which was fixed to a supporting bar in the prototype model, is directly embedded into the ceiling of the pump casing. An inlet port is then placed off–center to avoid the bearing area, and it is angled between 0 to 90° from the upright position. In addition, small secondary vanes were incorporated into the impeller bottom to accelerate the washout flow behind the impeller. These features attained design objectives proposed for higher antithrombogenicity: a seal–less pump chamber, no stationary parts in the blood path, and acceleration of the secondary flow behind the impeller. The first in vivo experiment using C1E pumps showed excellent antithrombogenicity for up to 18 days when the experiment ceased due to severe infection in the calf.     

One-month biocompatibility evaluation of the pediatric TinyPump in goats

The TinyPump is an extracorporeal, magnetically driven centrifugal blood pump with its impeller suspended magnetically and hydrodynamically to provide short-term mechanical circulatory support for children and infants. We have previously demonstrated that the in vivo experiments of the experimental TinyPump showed acceptable stable performance at pump flows averaging around 1.0 L/min with low hemolytic and thrombogenic properties for up to 2 weeks. We present here the 1-month in vivo evaluation of the TinyPump, whose design was modified further for more durable operation. The pump was implanted as a left ventricular assist device in five goats (12.5-26.7 kg), with inflow inserted into the left ventricular apex and outflow anastomosed to the descending aorta. Five animals were supported for 110 pump days, with mean pump flow of 1.19 ± 0.03 L/min at a pump speed of 2679 ± 97 rpm. Two animals reached the scheduled end point of 30 days without device failure, and mean plasma-free hemoglobin was 1.7 ± 0.8 mg/dL. Hematologic and biochemical data of these two animals showed no evidence of cardiovascular, renal, or hepatic dysfunction. Although further experiments are needed, the modified TinyPump offers promise as a short-term mechanical circulatory support device in pediatric population.     

Reliable long-term non-pulsatile circulatory support without anticoagulation.

OBJECTIVE: The Terumo implantable left ventricular assist system (T-ILVAS) consists of a titanium centrifugal pump with a unique magnetically suspended impeller producing continuous (non-pulsatile) flow up to 10 l/min. The interior surface is heparin-coated and there is no purge system. We implanted the device into six sheep to ascertain in-vivo haemodynamic function, mechanical reliability and biocompatibility. METHODS: The T-ILVAS was implanted via left thoracotomy without cardiopulmonary bypass. The inflow cannula was placed in the left ventricular apex and a Dacron outflow graft anastomosed to the descending aorta. All animals recovered well. No anticoagulation (heparin or warfarin) was given after the surgery. Suspension position, motor current, impeller speed and pump flow were continuously monitored and stored by on-line computer. Serial blood samples were collected to determine haematological and biochemical indices of renal function, liver function and haemolysis. All animals were electively euthanized between 3 and 7 months postoperatively. The explanted pumps were examined for mechanical reliability and thrombus formation. Major organs were examined macroscopically and histologically for thromboembolism. RESULTS: All animals appeared completely normal for up to 210 days. At speeds between 1500 and 2000 rev./min the device pumped up to 8 l/min capturing all mitral flow. There were no major complications (pump failure, thromboembolism, haemorrhage, or driveline infection). Indices of haemolysis, liver and renal function remained within normal limits. All pumps were mechanically sound and free from thrombus. One embolus was found in a sectioned kidney. CONCLUSION: The T-ILVAS successfully supported the systemic circulation without anticoagulation for up to 210 days. Mechanical reliability and biocompatibility were demonstrated. Organ function remained within normal limits during continuous non-pulsatile flow.     

Realization of a Permanent Implantable Pulsatile Impeller Heart with Magnetically Suspended Motor

Abstract: A permanent impeller heart that could work for years was once an idea. However, now this idea is turning into reality through the use of the magnetically suspended motor. Recently, with our implantable pulsatile impeller pump, 3 left ventricular assisted calves survived for about 2 months (62, 54, and 46 days, respectively). The termination of the experiments was related to wear of the mechanical bearing, which resulted in vibration of the rotor and pump failure. All the experimental animals were in good condition prior to pump failure. It seemed as if the experiments could have lasted indefinitely if the bearing had not failed. All the hematological and biochemical data of the calves remained in normal or acceptable ranges; neither blood damage nor organ dysfunction of any animal was detected. During autopsy, no severe thrombus formation was found in the pump or vessels although a low dose of heparin (0.548 g/h) was given to increase the activated coagulation time (ACT) to 1.5–2.0 times its normal value. To solve the problem of bearing wear, a magnetically suspended motor was investigated and applied to the impeller pump. On the opposite sides of a disc connected to the rotor, 2 permanent magnet rings were embedded, one for driving and the other for axial suspension. Because both the driving and suspending coils with iron cores attract the disc, no radial bearing was needed. This newly devised impeller heart promises to have long-term and permanent applications.     

Particles released from the Gyro C1E3 during simulated extracorporeal circulation

Evaluation of released particles from the blood pump during extracorporeal circulation is an important aspect because the particles may cause microembolism. The Gyro C1E3 is a centrifugal blood pump that has an impeller suspended by double pivot bearings inside the housing; therefore, it is important to evaluate the released particles. The C1E3 was driven for 14 days to simulate clinical left ventricular assist device (LVAD) and percutaneous cardiopulmonary support (PCPS). Also, a roller pump was driven for 2 days as a comparison. Released particles were weighed and examined by SEM. After 14 days of pumping, the particles from the C1E3 were 238.6 microg in an LVAD condition. The particles with the roller pump were 270.2 microg after only 2 days. Average particle sizes with the roller pump and C1E3 were 3.7 and 0.6 microm, respectively. These results suggest that the Gyro C1E3 substantially reduces the risk of microembolism from released particles.     

New centrifugal blood pump with dual impeller and double pivot bearing system: wear evaluation in bearing system, performance tests, and preliminary hemolysis tests

Abstract:  A new dual impeller centrifugal blood pump has been developed as a research collaboration between Baylor College of Medicine and Institute Dante Pazzanese of Cardiology for long-term left ventricle assist device (LVAD). A design feature of this new pump is a dual impeller that aims to minimize a stagnant flow pattern around the inlet port. Several different materials were tested in order to adopt a double pivot bearing design originally developed by Prof. Dr. Yukihiko Nosé from Baylor College of Medicine. Hydraulic performance tests were conducted with two different inlet ports' angle configurations 30° and 45°. Pump with inlet port angle of 45° achieved best values of pressure ahead and flow after 1800 rpm. Preliminary hemolysis tests were conducted using human blood. The pump showed good performance results and no alarming trace of hemolysis, proving to be a feasible long-term LVAD.