Sensitization Following LVAD Implantation Using Leucodepleted Blood Is Not Due to HLA Antibodies

Implantation of left ventricular assist devices (LVAD) is associated with HLA antibody sensitization. The objective of this study was to determine the specificity of antibodies produced by LVAD recipients using a combination of ELISA, Luminex and microcytotoxicity assays. Fifty-one LVAD patients were studied, from 44 to 838 days post-implantation. No patient developed HLA antibodies, although 24 produced IgG antibodies detectable in both ELISA and Luminex assays. These antibodies manifest as positive reactions with class I and class II wells of the ELISA and also blank wells. In Luminex assays, they produce high MFI readings with the negative control beads. Antibodies were detected 18 to 228 days after implantation. This reactivity was found to be directed against bovine serum albumin (BSA), commonly used to block non-specific binding in ELISA and Luminex assays; absorption of sera with BSA-coated beads completely abrogated reactivity in all solid phase assays, but did not eliminate anti-HLA antibodies in control sera. Ten of the 24 patients have proceeded to transplantation, with a 1-year graft survival of 69%. In conclusion, it appears that implantation of LVADS disrupts immunoregulatory pathways leading to production of anti-albumin antibodies. These can be misinterpreted as anti-HLA antibodies in solid phase assays.     

An Implantable Aortic Valvo-pump for Destination Therapy

To investigate the possibility of a long-term applicable left ventricular assist device, a 23 mm outer diameter and 31 g weight implantable aortic valvo-pump was developed. It consists of a rotor and a stator; the rotor has a driven magnets assemble and an impeller, the stator has a motor coil with iron core and a outflow guide vane. The device locates the position of aortic valve, delivers the blood directly from left ventricle to aorta. Neither connecting conduits nor “bypass” circuits are necessary. Therefore, the device has promisingly better antithrombogenicity than other heart pumps. In hemodynamic testing, the pump can produce a blood flow of 7 l/min volume with 50 mmHg pressure increase at 15,000 rpm rotating speed, and at zero flow rate the pump can maintain a diastolic pressure over 80 mmHg at same rotating speed. For further studies the blood compatibility and the durability of the device are of most importance.     

采用永磁悬浮的永久性左心室辅助装置

研制出一台采用永磁轴承的左心室辅助装置（LVAD）。该装置包括一个定子和一个转子，采用径向驱动方式；转子包括驱动磁钢和叶轮，电机定子线圈和泵壳组成定子。装置设计采用了一种特殊结构的永磁轴承。转子的位置测量表明，转子稳定悬浮的前提条件是必须有较高的转速（大于3250r／min）且流量大于1L/min。用猪血为介质所做的液动力测试表明，当转速达到3500r／min～4000r／min时，血泵输出流量达到4L/min～6L/min，输出压力达到100mmHg。该装置重200g，最大处直径为40mm。     

螺旋血泵的CFD分析

溶血和血栓是目前国内心室辅助装置不能应用于临床的主要原因。血泵的不良血液动力学特性是导致溶血和血栓的主要因数。计算流体力学（CFD）方法目前被广泛应用于血泵设计,它可以准确有效地反映血泵内部流场状态、血泵压力流量曲线以及血泵内部流场剪切力分布状态等。本研究采用CFD方法对自制螺旋血泵的泵腔、出入流口进行流场分析,内部流场采用三维彩图显示。结果显示CFD分析结果很好的与体外实验结果吻合。血泵血液动力学特性,以及内部血流状态采用CFD方法分析,可以有效地分析血泵血液相溶性方面的问题。     

左心辅助对心脏功能影响的实验研究

①目的：探讨左心辅助对心脏功能的影响。②方法：实验用成年健康要种犬10只,随机分为实验和对照组,采用结扎左冠状动脉前降支方法建立急性左心衰模型,利用气动泵经左心房至升主动脉对心衰犬进行左心辅助,以放射免疫学方法测定心衰前、后及应用左心辅助后各时相心脏局部肾素（RA）活性、血管紧张素Ⅱ（AngⅡ）的变化。③结果：两组比较,急性左心衰后心脏局部RA、AngⅡ水平明显增高（P＜0．05）;左心辅助可显降低左心局部RA、AngⅡ水平（P＜0．05）。辅助循环初期右心局部RA、AngⅡ水平明显降低（P＜0．05）,降低辅助时间的延长,右心局部AngⅡ、RA水平反又增高,与心衰前相比,差异显性（P＜0．05）。④结论：左心辅助可改善工心功能并对心功能有损害。     

The changing landscape of percutaneous technology leading to surgical complications

With new technology comes new complications. We discuss the interesting case presented by Bjelic and colleagues regarding a misplaced TAVR (transcatheter aortic valve replacement) valve into the inflow cannula of a left ventricular assist device, leading to hemodynamic collapse. The author describes the pitfalls of the new technology and interesting surgical maneuvers to address these complications.     

A case of electromagnetic interference between HeartMate 3 LVAD and implantable cardioverter defibrillator

Implantable cardioverter defibrillators (ICDs) have been shown to have a significant benefit in reducing sudden cardiac death (SCD) in patients with systolic heart failure. Additionally, cardiac devices as a bridge to transplant or destination therapy are often used in patients with end‐stage systolic heart failure. As a result, most patients with left ventricular assist devices (LVADs) also have an ICD. Here, we present an electromagnetic interference (EMI) between HeartMate 3 LVAD and ICD. This issue might be critical for both electrophysiologists and advanced heart failure cardiologists to understand prior to implantation of ICD/LVADs in these patients.