Clinical Evaluation of Automatic Tachycardia Diagnosis by an Implanted Device

Reliable discrimination between sinus tachycardia (ST) and pathologic tachycardia has been a major problem for automatic implantable antitachycardia devices. In patients whose sinus response to activity is as rapid or faster than their pathologic tachycardia (rate crossover), these unsophisticated devices deliver the programmed tachycardia response to either the pathologic or sinus tachycardia. Over a one-year period, 50 Intermedics Intertach Model 262–12 antitachycardia pulse generators were implanted to evaluate the specificity of a new group of tachycardia recognition algorithms. Patients were subjected to exercise testing and noninvasive programmed stimulation to demonstrate the efficacy of this new approach. The five recognition algorithms tested were various combinations of the following criteria: high rate HR), sudden onset (SO), rate stability (RS), and sustained high rate (SHR). False positive rates (tachycardia response inappropriately triggered by ST) were as follows: HR (93%); HR + SO (3%); HR + RS (63%); HR + (RS or SHR) (87%); HR + HS + SO (8%). Pair-wise significance testing between HR only and HR + SO (p < 0.001), HR + RS (p = 0.01) and HR + SO + RS (p < 0.001), demonstrated a significant reduction in the rate of false positives through the use of the sudden onset and rate stability criteria in concert with the standard high rate criterion.     

Cutaneous afferent activity in the median nerve during grasping in the primate

Neural activity was recorded from the median nerve of a monkey during grasping and lifting, using a chronically implanted cuff electrode. At the onset of lifting, there was an initial dynamic response during which the intensity of the neural signal increased rapidly. This neural response attained its peak value well before the displacement, the load force or the grip force. The time course and peak of the rectified, integrated neurogram were best correlated with the rate of change of grip force. The neural activity declined exponentially to a steady value following the initial peak. During steady holding the mean amplitude of the neurogram was best correlated with the mean grip force. At the end of the holding phase there was a short burst of neural activity as the monkey relaxed the grip force and released the object. During some blocks of trials pulse perturbations were applied to the object. When the monkey did not increase the grip force in advance of the perturbation, the perturbation produced a relatively large displacement of the object and a burst of neural activity whose onset coincided with the onset of displacement. When the monkey anticipated the perturbation by increasing the grip force during the holding period preceding the perturbation, the perturbation produced a relatively small displacement and relatively little increase in neural activity.     

使用新型倒刺电极的骶神经调节治疗神经源性膀胱的初步临床结果

目的探讨应用新型倒刺电极（Tined-lead）对神经源性膀胱患者行S骶神经调节（SNM）的初步疗效。方法对5例神经源性膀胱患者采用新型倒刺电极，在X线监测下将电极植入S3骶神经孔，进行SNM。术前、术后详细记录排尿日记，用影像尿动力学方法评估患者的膀胱尿道功能。结果患者1（隐性骶裂）术后排尿次数和排尿量分别改善22％和49％；患者2（隐性骶裂）术后排尿次数、排尿量和残余尿量分别改善0．7％、11％和46％；患者3（隐性骶裂）术后排尿次数、排尿量和残余尿量分别改善0．4％、18％和44％。患者4（脑外伤）术后漏尿次数和漏尿量分别改善36％和54％。患者5（高位截瘫）术后间歇导尿次数和导尿量分别改善42％和54％，尿动力学参数改善37％～45％。结论用新型倒刺电极进行SNM为神经源性膀胱的治疗提供了一条新的可供选择的微创方法。     

氨气敏电极法快速测定血氨

本文介绍使用氨气敏电极,采用标准曲线法简便、快速、准确测定血氨的方法。取空腹血1ml,用1M HClO_4沉淀蛋白,以0.1M NH_4Cl—0.6MNa_2SO_4作内充液,碱化后的上清液可在2～3min内测试完毕。40例正常成人血氨的测定结果:■=31.4μmol/L N;S=6.4μmol/L N;■±2S(正常值范围)为18.6～44.2μmol/L N。10份血样的平均回收率为100.4％。该法用血少、简便、快速;结果较稳定、准确,适用于临床检验。     

起搏器高度依赖性患者起搏器置换方法与疗效探讨

目的 :探讨起搏器高度依赖性患者起搏器置换方法与疗效。　方法 :对 8例起搏器高度依赖性患者 ,在起搏器与电极的接口松解前 ,应用在体起搏器间断接触法 ,使自身逸搏心律得已恢复 ,然后再行松解接口以及必要的起搏参数测试。　结果 :起搏器离体次数为 3～ 7(5± 2 )次 ,最长逸搏间期为 3.38～ 6 .2 0 (4.5 1± 1.11)s,自身逸搏心率为 30～ 4 3(38± 5 )次 /min ,均顺利完成起搏器置换。　结论 :在体起搏器间断接触法切实可行 ,能够明显提高起搏器高度依赖性患者起搏器置换的安全性     

The growth of the second underpotentially deposited silver layer on Pt(100)

The electrodeposition of Ag on Pt(100)-(1 × 1) in perchlorate electrolyte was studied by means of time-resolved in situ scanning tunnelling microscopy (STM) and cyclic voltammetry. One monolayer of Ag is deposited underpotentially (upd) ca. 500 mV positive of the Ag⁺/Ag equilibrium potential. Several millivolts positive of the equilibrium potential, a second well defined upd layer forms. Its growth was observed to proceed via island formation and coalescence. This process occurs in two separate stages that manifest themselves in voltammetric peaks as well as in the STM images.     

Left Ventricular Transvenous Electrode Dislodgement After Mustard Repair for Transposition of the Great Arteries

An 11-year-old girl who underwent Mustard's operation for complete transposition of the great arteries in infancy, developed Mobitz type II second-degree AV block 81/2 years later. A transvenous, active fixation left ventricular lead was inserted and connected to a rate responsive pacemaker. Two years later the lead dislodged due to the child's growth. A new active fixation electrode was positioned in the left ventricle below the pulmonary valve, leaving an electrode loop in the ventricle. Such an approach may prevent lead dislodgement due to growth after intraatrial repair for transposition of the great arteries, but regular radiological or echocardiographic follow-up of lead position is recommended in these patients.     

用混合粘合剂碳糊电极测定丁螺环酮

用混合粘合剂碳糊电极测定丁螺环酮张正奇，曾鸽鸣，刘传桂，黎艳飞（湖南大学化学化工系，长沙４１００８２）碳糊电极无毒，制作方便，表面更新容易，应用电位范围广，在药物分析中已有应用［１～５］。我们在液体石腊中加入添加剂，组成混合粘合剂，可显著改善电极的检...