Prediction of the external work of the native heart from the dynamic H-Q curves of the rotary blood pumps during left heart bypass

The ventricular performance is dependent on the drainage effect of rotary blood pumps (RBPs) and the performance of RBPs is affected by the ventricular pulsation. In this study, the interaction between the ventricle and RBPs was examined using the pressure-volume (P-V) diagram of the ventricle and dynamic head pressure-bypass flow (H-Q) curves (H, head pressure: arterial pressure minus ventricular pressure vs. Q, bypass flow) of the RBPs. We first investigated the relationships in a mock loop with a passive fill ventricle, followed by validation in ex vivo animal experiments. An apical drainage cannula with a micro-pressure sensor was especially fabricated to obtain ventricular pressure, while three pairs of ultrasonic crystals placed on the heart wall were used to derive ventricular volume. The mock loop-configured ventricular apical-descending aorta bypass revealed that the external work of the ventricle expressed by the area inside the P-V diagrams (EW(Heart) ) correlated strongly with the area inside dynamic H-Q curves (EW(VAD)), with the coefficients of correlation being R2 = 0.869 ～ 0.961. The results in the mock loop were verified in the ex vivo studies using three Shiba goats (10-25 kg in body weight), showing the correlation coefficients of R2 = 0.802 ～ 0.817. The linear regression analysis indicated that the increase in the bypass flow reduced pulsatility in the ventricle expressed in EW(Heart) as well as in EW(VAD) . Experimental results, both mock loop and animal studies, showed that the interaction between cardiac external work and H-Q performance of RBPs can be expressed by the relationships "EW(Heart) versus EW(VAD) ." The pulsatile nature of the native heart can be expressed in the area underneath the H-Q curves of RBPs EW(VAD) during left heart bypass indicating the status of the level of assistance by RBPs and the native heart function.     

A Passive Magnetically and Hydrodynamically Suspended Rotary Blood Pump

A combined hydrodynamic–magnetic bearing allows the design of rotary blood pumps that are not encumbered with mechanical bearings and magnets requiring sensors or electrical power. However, such pumps have so far needed very small and accurately manufactured gaps between rotor and housing to assure effective hydromagnetic bearing behavior. In order to use this concept in disposable pump heads, a design that allows larger rotor‐housing gaps, and thus larger manufacturing tolerances, is needed. A pump with passive magnetic bearings and a gap between rotor and housing in the range of 0.5 mm was designed. Numerical simulations were performed to optimize the rotor geometry at low levels of shear stress. An experimental test stand was used to find a range of speeds and gap settings that resulted in low levels of vibration and useful pressure–flow relationships. Three different rotor geometries were tested using a viscosity‐adjusted test fluid. Blood damage tests were conducted within the desirable range of speeds and gap settings. In this study stable pump performance was demonstrated at total gap widths between 0.3 and 0.7 mm at flows of 0–10 L/min, with afterloads up to 230 mm Hg. Best performance was achieved with rotors sliding on a fluid pillow between the rotor and the outer housing at a gap distance of 50 to 250 µm. The inner gap distance, between the rotor and the inner housing, could be as great as 500 µm. Hemolysis tests on the prototype within the chosen operating range showed lower values (NIH = 0.0029 ± 0.0012 g/100 L) than the Biomedicus BP‐80 pump (NIH = 0.0033 ± 0.0011 g/100 L). In conclusion, it is possible to build rotary blood pumps with passive hydromagnetic bearings that have large gaps between their rotors and housings. Rotor behavior is sensitive to the position of the permanent magnetic drive unit. To minimize vibration and blood damage, the fluid gaps and the rotational speed have to be adjusted according to the desired operating point of the pump. Further study is needed to optimize the magnetic drive unit and to ascertain its ability to withstand inertial loads imposed by sudden movements and external shock.     

Sealing Performance of a Magnetic Fluid Seal for Rotary Blood Pumps

A magnetic fluid (MF) for a rotary blood pump seal enables mechanical contact-free rotation of the shaft and, hence, has excellent durability. The performance of a MF seal, however, has been reported to decrease in liquids. We have developed a MF seal that has a "shield" mechanism and a new MF with a higher magnetization of 47.9 kA/m. The sealing performance of the MF seal installed in a rotary blood pump was studied. Under the condition of continuous flow, the MF seal remained in perfect condition against a pressure of 298 mm Hg (pump flow rate: 3.96 L/min). The seal was also perfect against a pressure of 170 mm Hg in a continuous flow of 3.9 L/min for 275 days. We have developed a MF seal that works in liquid against clinically used pressures. The MF seal is promising as a shaft seal for rotary blood pumps.     

Impact of Hyperthermal Rotary Blood Pump Surfaces on Blood Clotting Behavior: An Approach

The influence of heat dissipating systems, such as rotary blood pumps, was investigated. Titanium cylinders as rotary blood pump housing dummies were immersed in porcine blood and constantly tempered at specific temperatures (37–60°C) over a defined period of time. The porcine blood was anticoagulated either by low heparin dosage or citrate. At frequent intervals, samples were taken for blood analysis and the determination of the plasmatic coagulation cascade. Blood parameters do not alter at surface temperatures below 50°C. Hyperthermia-induced hemolysis could be confirmed. The plasmatic coagulation cascade is terminated at surface temperatures exceeding 55°C. The adhesion of blood constituents on surfaces is temperature and time dependent, and structural changes of adhesions and blood itself were detected.     

高压氧微重力培养提高冻存胰岛质量和移植效果的实验研究

目的 探讨胰岛冻存前后经高压氧细胞旋转培养系统(HORCCS)培养后移植入糖尿病大鼠能否提高胰岛移植的效果.方法 将分离纯化的大鼠胰岛分为:A.体外实验组:将各组大鼠胰岛经HORCCS培养或普通培养30 d,检测细胞内DNA和胰岛素含量,胰岛存活率,胰岛素分泌水平.B.胰岛移植实验组:将各组大鼠胰岛经HORCCS培养或普通培养7d,然后移植,观察移植受体血糖和胰岛素水平.电镜观察各胰岛移植实验组中培养7 d时的胰岛的超微结构改变.结果 经高压氧 RCCS培养14 d的胰岛存活率及胰岛素分泌水平高于普通培养组(P<0.05).移植了经HORCCS培养的胰岛后,受体血糖在移植后2周即恢复为正常值,并维持到移植后10周.全部受体维持正常血糖耐受曲线.电镜下可见经HORCCS培养后,冻存复苏胰岛表面形成微小的孔道.结论 胰岛冻存前后经高压氧RCCS培养后可以建立营养输送管道,不但有利于氧和营养物质的运输,更有利于胰岛内细胞的均匀一致的冻存,从而减少冻存对胰岛的损害,提高胰岛的分泌活性和成活率.     

超声引导在麦默通微创旋切系统治疗乳腺良性肿块中的应用

目的探讨超声引导技术在麦默通（Mammotome）微创治疗乳腺良性肿块中的应用价值。方法197例患者,575枚乳房肿块,经超声检查诊断均为良性肿块,在超声引导下行麦默通微创旋切治疗。结果超声在麦默通微创旋切治疗过程中均能清晰显示病变,引导成功率100%。术后2枚结节病理报告为乳腺浸润性导管癌,超声诊断准确率99.65%（573/575）;6例出现切除部位血肿、5例出现皮下青紫,局部血肿发生率共计5.58%（11/197）。术后3个月超声随访显示5枚病灶少许残留。结论超声引导技术在麦默通旋切治疗乳腺肿块中有重要作用。     

新型旋转镍钛器械Mtwo在老年人根管治疗中的应用

评价旋转镍钛器械Mtwo在老年患者根管治疗中应用的临床效果.随机选取老年患者中因牙髓炎或根尖周炎需行根管治疗的患牙80例,均分为2 组: M组使用旋转镍钛器械Mtwo、改良步退法预备根管;K组使用手用不锈钢K锉、步退法预备根管, 2 组均采用冷侧压法充填根管.M组能维持根管原有的走向,无根管偏移、台阶、侧穿等并发症;K组并发症的发生率显著多于M组(P<0.05).M组操作时间短,术后疼痛少.在老年患者的根管治疗中, 使用旋转镍钛器械Mtwo进行根管预备,快速、有效,成形效果好,值得临床推荐.     

影响腰椎间盘切吸术疗效的直接因素

目的通过回顾分析5例PLD术中出血病例的不良后果,以警示临床对切吸术中出血的认识,达到提高疗效之目的。方法通过手术病程记录保存资料,查阅5例切吸术中出血病例档案,收集其重要的相关临床资料,对切吸术前后出血的病例分别进行对照,分析与归纳。结果根据切吸术后不同时间的追踪复查经过,术后住院1周期间患者自觉症状相对减轻,临床相关体征亦有所改善。术后1个月患者自觉症状有不同程度加重,临床相关体征表现阳性或弱阴性,经过对患者腰部的热辐射治疗一般3个月可康复。结论PLD术中出血是影响疗效的直接因素,操作技术熟练可完全避免出血,经过热辐射治疗一般3个月可康复。帕斯卡定律可作为解释PLD的病理基础与切吸术治疗原理的应用依据。     

Magnetic drive system for a new centrifugal rotary blood pump

The purpose of this investigation was to design a novel magnetic drive and bearing system for a new centrifugal rotary blood pump (CRBP). The drive system consists of two components: (i) permanent magnets within the impeller of the CRBP; and (ii) the driving electromagnets. Orientation of the magnets varies from axial through to 60° included out‐lean (conical configuration). Permanent magnets replace the electromagnet drive to allow easier characterization. The performance characteristics tested were the axial force of attraction between the stator and rotor at angles of rotational alignment, ?, and the corresponding torque at those angles. The drive components were tested for various magnetic cone angles, θ. The test was repeated for three backing conditions: (i) non‐backed; (ii) steel‐cupped; and (iii) steel plate back‐iron, performed on an Instron tensile testing machine. Experimental results were expanded upon through finite element and boundary element analysis (BEM). The force/torque characteristics were maximal for a 12‐magnet configuration at 0° cone angle with steel‐back iron (axial force = 60 N, torque = 0.375 Nm). BEM showed how introducing a cone angle increases the radial restoring force threefold while not compromising axial bearing force. Magnets in the drive system may be orientated not only to provide adequate coupling to drive the CRBP, but to provide significant axial and radial bearing forces capable of withstanding over 100 m/s² shock excitation on the impeller. Although the 12 magnet 0° (θ) configuration yielded the greatest force/torque characteristic, this was seen as potentially unattractive as this magnetic cone angle yielded poor radial restoring force characteristics.     

不同激光角膜屈光术后角膜光密度的对比分析

目的　探讨高度近视患者行飞秒激光小切口角膜基质透镜取出术(SMILE) 、飞秒激光制瓣的准分子激光原位角膜磨镶术(FS-LASIK)以及准分子激光上皮瓣下角膜磨镶术(LASEK)术后不同时间不同直径范围内角膜光密度的对比及变化情况,及其与术中切削深度、切削厚度的相关性分析。方法　前瞻性队列研究。收集在青岛大学附属医院眼科就诊并进行屈光手术矫正的高度近视患者82例（164眼）,按手术方式分为SMILE组30例（60眼）;FS-LASIK组27例（54眼）;LASEK组25例（50眼）,于术前、术后1个月、术后3个月、术后6个月以及术后12个月行Pentacam三维眼前节分析系统检查,采用SPSS 22.0统计软件对术后同一时间不同术式角膜0～6 mm、>6～12 mm、整体直径范围内的角膜光密度采用随机区组方差分析,对术中切削深度、切削厚度与角膜光密度的关系采用Pearson相关分析。结果　术后1个月和术后6个月,不同组别患眼在同一直径范围内的角膜光密度相比差异均无统计学意义（均为P>0.05）;术后3个月,LASEK组患眼的角膜光密度在0～6 mm、>6～12 mm、整体直径范围内均显著低于SMILE组,在>6～12 mm、整体直径范围内均显著低于FS-LASIK组（均为P<0.05）;术后12个月,SMILE组患眼在0～6 mm、>6～12 mm、total直径范围内的角膜光密度均显著低于其他两组（均为P<0.05）。术后3个月,0～6 mm、>6～12 mm、total直径范围内的角膜光密度与术中角膜切削深度、切削厚度均呈正相关（均为P<0.05）;术后12个月,各直径范围内的角膜光密度与术中角膜切削深度、切削厚度均呈负相关（均为P<0.05）。结论　高度近视患者在行激光角膜屈光术后的早期修复中,SMILE术式的角膜透明性稍差,而LASEK术式则相对更佳,但SMILE术后患眼长期的角膜透明性更佳。角膜光密度与术中角膜的切削深度以及切削厚度密切相关。