Design and test of a vascular access device

Transarterial left ventricular assist devices (LVADs), such as the Hemopump, IABP, and PUCA-pump, are meant to be introduced into the body via the femoral or axillary artery without major surgery. For certain applications, introduction is performed directly into the aorta via an open thorax procedure. A prototype of a vascular access device has been realized that allows direct access into the aorta as an alternative for the common surgical graft anastomosis suturing technique. The device consists of a metal tube acting as a circular knife to cut a hole in the aortic wall, a screw to store the removed part of the aortic wall, and a plastic tube that is introduced through the hole and tightly connected to the aortic wall. The device could be placed without aortic clamping. The device has been tested on a slaughterhouse porcine aorta. A low-pressurized aorta appeared to be the worst case; thus, two animal experiments in the low-pressurized pulmonary artery were performed. No leakage occurred for pressures between 40 and 300 mm Hg.     

Is Avoidance of Air Contact Necessary for the In Vitro Evaluation of Thrombogenicity in Mechanical Circulatory Assist Devices?

An effective in vitro protocol for the investigation of thrombogenicity can provide many advantages in the development of mechanical circulatory assist devices. Strict avoidance of air contact with blood recently was proposed for reliable in vitro evaluation. This study was performed to confirm the necessity of avoidance of air contact for the in vitro test of thrombogenicity in a rotary pump. Two sets of mock circuits with the same rotary blood pumps, reservoirs, and connecting tubes were made. In one system, blood came in contact with air while the other did not. The test blood was heparinized at the dose of 1 IU per 1 ml of blood. The tests were terminated at an activated coagulation time of 1.5 times the control value. The levels of hematocrit, platelet, factors VIII and XII, fibrinogen, thromboxane B2, and plasma-free hemoglobin were measured during the procedures. After the experiments, the thrombi formed were observed, measured, and compared with those formed in in vivo circumstances. The tests were repeated 12 times. There were no statistically significant differences between the 2 groups in hematologic parameters and the amounts of thrombi formed. The thrombi observed in both groups showed the same pathologic findings as those formed in vivo with the exception of intermittent multiple air bubbles found in thrombi of the air-contact group. In conclusion, the effect of air contact in the in vitro investigation of thrombogenicity was negligible while the proposed in vitro test models of thrombogenesis in the mechanical circulatory assist device proved to be reliable.     

胸段食管癌三维适形放疗摆位误差研究

Objective To study the setup errors in three-dimensional conformal radiotherapy (3DCRT) for thoracic esophageal carcinoma using electronic portal imaging device(EPID) and calculate the margins from CTV to PTV. Methods Forty-one patients with thoracic esophageal carcinoma who received 3DCRT were continuously enrolled into this study. The anterior and lateral electronic portal images (EPI) were aquired by EPID once a week. The setup errors were obtained through comparing the difference between EPI and digitally reconstructed radiographs(DRR). Then the setup margins from CTV to PTV were calculat-ed. By using self paired design,22 patients received definitive radiotherapy with different margins. Group A: the margins were 10 mm in all the three axes;Group B: the margins were aquired in this study. The differ-ence were compared by Paired t-test or Wilcoxon signed-rank test. Results The margins from CTV to PTV in x,y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. Between the group A and group B, the difference of the maximum dose of the spinal cord was significant(4638.7 cGy±1449.6 cGy vs. 4310.2 cGy±1528.7 cGy; t=5.48, P=0.000), and the difference of NTCP for the spinal cord was also significant (4.82%±5.99% vs. 3.64%±4.70%;Z=-2.70,P=0.007). Conclusions For patients with tho-racic esophageal carcinoma who receive 3DCRT in author's department,the margins from CTV to PTV in x, y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. The spinal cord could be better protected by using these setup margins than using 10 mm in each axis.     

Transcatheter Closure of Atrial Septal Defects by the “Buttoned” Device: Complications and Need for Surgical Revision

Immediate and medium-term experience with transcatheter closure of a secundum atrial septal defect by the ``buttoned' device in seven patients is reported. Complications occurred in two patients during the procedure. In one patient with complications, the occluder was partly released in the right atrium. All efforts to correct its position were unsuccessful and caused considerable deformation of the device, which had to be removed surgically. In the other patient with complications, disconnection of the occluder and counteroccluder occurred immediately after removal of the loading wire. Both parts were retrieved by catheter. Five patients had uneventful closure of the atrial septal defect. On follow-up, however, displacement of the device towards the mitral valve was observed in two patients, which caused mitral regurgitation. Surgical removal of the device and repair of the mitral valve was necessary in both patients. Two years after the procedure, the atrial septal defect was closed completely in two of the remaining three patients and a small residual defect persisted in one patient.     

两种产后立即放置TCu380A宫内节育器方法的比较——910例12个月随访分析

目的：比较徒手和卵圆钳两种方法对产后立即放置（ＩＰＰＩ）宫内节育器（ＩＵＤ）效果的影响。方法：将９１０例阴道分娩产妇（其中９７．７％是首次分娩）随机分成两组，于胎盘娩出后１０分钟内放置ＴＣｕ３８０ＡＩＵＤ，其中４７０例徒手放置（手放组），４４０例用卵圆钳放置（钳放组）。随访１２个月，以生命表法统计、χ２检验比较两种放置方法的脱落率、妊娠率、因症取出率等。结果：６和１２个月的随访率分别为９５．１６％和９２．６４％。９１０例中未发生子宫穿孔和感染，仅手放组有１例带器妊娠。放置后主要停用原因是脱落，手放组与钳放组１２个月的粗累积脱落率分别为１５．８６／１００妇女和１５．８８／１００妇女，因症（出血、疼痛）取出率分别为２．１１／１００妇女和１．５７／１００妇女，差异无显著性（Ｐ均＞０．０５）。结论：徒手放置或卵圆钳放置对ＩＰＰＩ的效果无明显影响；ＴＣｕ３８０ＡＩＵＤ适合中国妇女产后立即放置。     

直肠癌低位前切除术双吻合器致吻合口瘘原因分析及预防

为研究直肠癌低位前切除术中双吻合器致吻合口瘘的原因,并探讨其预防方法,3年中共应用双吻合器实施直肠癌低位前切除术70例,对发生吻合口瘘者进行分析和总结。结果示,发生吻合口瘘4例,发生率为571%(4/70)。初步研究结果提示,直肠癌低位前切除术双吻合器吻合安全可靠。吻合口瘘的发生原因主要是术中止血不彻底及吻合操作不规范所致。     

4种活性宫内节育器放置7年的临床评价

目的 :进一步了解活性宫内节育器 (IUD)使用效果和不良反应 ,为临床选择IUD提供有效依据。方法 :对1993年1月～1995年6月在本中心放置的4种活性IUD进行随机抽样调查。抽查γ -IUD326例 ,Tcu220c331例、Vcu200310例、M1cu375sl302例 ,以生命表法统计4种IUD的续用情况。结果 :4种IUD放置36个月末每100名妇女累积续用率依次为93.2 %、84. 4 %、88. 9 %、80. 1 % (P<0 05) ,带器妊娠率依次为1. 6 %、2. 2 %、2 .6 %、3.6 % (P<0 01) ,脱落率依次为1 4 %、1 .6 %、2. 8 %、3. 2 % (P<0 01) ,因症取出率依次为2 8 %、10 5 %、4 7 %、11 7 % (P<0 .01)。36个月末4种IUD间差异有显著性。结论 :4种IUD的避孕效果均可接受 ,但γ -IUD更佳。γ -IUD和Tcu220c有留置时间更长的优势     

三七、茜草复方对置铜宫内节育器家兔子宫局部t-PA活性的影响

目的 探讨三七、茜草(SQ)复方治疗置铜宫内节育器(Cu-IUD)所致子宫异常出血的作用机理。方法 制 作家兔置Cu-IUD动物模型,以吲哚美辛作对照,观察SQ复方对置Cu-IUD家兔模型子宫匀浆中组织型纤溶酶原激 活物(t-PA)活性的影响。结果 置Cu-IUD家兔模型子宫匀浆中t-PA的含量增高(P<0．01),经SQ复方治疗后与模 型组比较有显著性差异(P<0．01),说明SQ复方能减少家兔子宫匀浆中t-PA的含量,降低t-PA的活性。结论 SQ 复方通过降低置Cu-IUD家兔子宫内膜局部的纤溶活性而达到止血的目的。     

Intermittent atrial level right-to-left shunt with temporary hypoxemia in a patient during support with a left ventricular assist device

We report a 56-year-old male patient developing hypoxemia after surgical replacement of infected valves of a left ventricular assist device (LVAD, Novacor) which had supported him during the previous 15 months. Contrast transesophageal echocardiography (TEE) revealed an atrial septal defect with intermittent right-to-left shunt across a patent foramen ovale. We postulate that the shunt detected in this patient occurred as a consequence of reduced pulmonary vascular compliance due to positive end-expiratory pressure (PEEP) and an increase of mean intrathoracic pressure. Furthermore, we hypothesize that synchronized LVAD operation exacerbates any potential right-to-left shunt due to the profound left ventricular unloading which occurs during LVAD support. In this first report of a right-to-left shunt from a previously unrecognized patent foramen ovale in a Novacor patient, the subsequent transient hypoxemia could be managed by avoiding PEEP of more than 3 mmHg, and mean airway pressure of more than 11 mmHg and by careful volume replacement in order to prevent the pump from completely emptying the left ventricle (LV) and the left atrium (LA). Thus, prior to every LVAD implantation a transesophageal contrast echocardiography with Valsalva maneuver should be performed to identify intracardiac right-to-left shunt.     

体内微型装置磁定位系统的计算机接口设计

在微型诊疗装置的应用中,微型装置的体内空间定位非常重要,而定位数据的采集是其中的关键环节.根据体内微型装置磁定位实验研究系统数据采集的特点,设计出一种基于单片机和串口通信的计算机接口用于定位数据的收集、传输等.实验表明,该接口电路能满足实时采集数据的需要,数据传输可靠,在计算机中可以进行现场采集数据的实时保存及其他后处理,能满足实验系统的要求.