单根电极心室起搏双腔感知双重反应型起搏器心房感知功能的测试观察

目的：观察单根电极心室起搏双腔感知双重反应型起搏器（ＶＤＤ）心房电极感知功能的稳定性。方法：测试了１４例安装单根电极ＶＤＤ的患者在不同体位、扩胸运动及日常活动时的心房漂浮电极的最低感知阈值。并将术中测得的Ｐ波与术后测得的心房最低感知阈值做相关及线性回归分析。结果：１４例中有１２例患者不同体位的心房感知阈值不一致。其中９例在坐、立位时感知阈值最低，将心房感知阈值调至较最低感知阈值低两档的位置后做Ｈｏｌｔｅｒ检查，全部患者心房感知、房室顺序起搏功能良好。扩胸运动中无一例患者出现过度感知。术中所测Ｐ波振幅与术后测得的最低心房感知阈值相关性良好（ｒ＝０．６９，Ｐ＜０．０５）。结论：单根电极ＶＤＤ可替代双电极导管的双腔起搏双腔感知双重反应型起搏器（ＤＤＤ），用于窦房结功能正常的高度房室传导阻滞患者的起搏治疗。     

Standardization of terminology of virological response in the treatment of chronic hepatitis C: panel recommendations

The treatment paradigm for hepatitis C virus (HCV) infection is at a critical point in its evolution. The addition of a protease inhibitor to peginterferon plus ribavirin has become the new standard-of-care treatment for most patients. Data from clinical trials of new antivirals have been difficult to interpret and compare, partly because of heterogeneity in trial design, and partly because of inconsistencies in terminology used to define viral responses and the populations evaluated. Present definitions of viral responses for treatment with peginterferon and ribavirin are insufficient for novel treatment paradigms. Further, categorization of prior patient treatment experience in clinical trials, particularly of nonresponders to prior therapy, is inconsistent. Existing terms and definitions must be updated, standardized and/or redefined for easier interpretation of data and effective communication among clinicians. A panel of experts in HCV infection treatment met on 3 December 2009. Goals of the panel were to evaluate terms and definitions used traditionally in treatment with peginterferon and ribavirin, to refine and clarify definitions of existing terms that have varying meanings and to propose new terms and definitions appropriate for novel treatment paradigms emerging with development of new agents. A number of recommendations were accepted unanimously by the panel. Adoption of these terms would improve communication among investigators, enhance comparability among clinical trials, facilitate development of therapeutic guidelines and provide a standardized terminology for use in clinical practice.     

The Effects of Ventricular Fibrillation Duration and a Preceding Unsuccessful Shock on the Probability of Defibrillation Success Using Biphasic Waveforms in Pigs

Influence of VF Duration on Defibrillation Efficacy. introduction: While the defibrillation threshold has been reported to increase with ventricular fibrillation (VF) duration for monophasic waveforms, the effect of VF duration for biphasic waveforms is unknown. Methods and Results: The ED 50 requirements (the 50% probability of defibrillation success) for an endocardial lead system, which included a subcutaneous array, were determined by logistic regression using a recursive up-down algorithm for a biphasic waveform ((6/6 msec). The study was performed in two parts, each with eight pigs. In part 1, ED 50 was compared for shocks delivered after 10 seconds of VF and for shocks delivered after 20 seconds of VF following a failed first shock at 10 seconds. Energy at ED 50 decreased from 6.5 ± 0.9, J for shocks delivered after 10 seconds of VF to 4.9 ± 0.8, J (P < 0.01) for shocks delivered after 20 seconds. To determine if improved second shock efficacy was a result of preconditioning by the failed first shock or a function of VF duration, part 2 of the study compared defibrillation efficacy between shocks delivered after 10 seconds of VF with shocks delivered after 20 seconds of VF with and without a failed first shock at 10 seconds. Mean energy at ED 50 decreased from 10.1 ± 2.4, J for shocks delivered after 10 seconds of VF to 7.9 ± 2.4 J (P < 0.01) and 7.5 ± 3.2 J (P < 0.01) for shocks delivered after 20 seconds of VF with and without a failed first shock, respectively. The mean energy at KD 50 for shocks delivered after 20 seconds of VK with and without a failed first shock was not significantly different (P = 0.53). A strong linear correlation for energy at ED 50 was found between shocks delivered after 10 seconds of VF and shocks delivered after 20 seconds of VF following a failed first shock (r = 0.95, P < 0.01). Conclusion: (1) As opposed to monophasic shocks, ED 50 is significantly lower for biphasic shocks delivered after 20 seconds of VF compared with shocks delivered after 10 seconds of VF in pigs. (2) An unsuccessful biphasic shock in pigs does not affect the defibrillation efficacy for a subsequent shock. (3) ED 50 for a biphasic shock delivered after 20 seconds of VK is linearly related to ED 50 for a shock delivered after 10 seconds of VK.     

Temporal Stability of Defibrillation Thresholds with an Active Pectoral Lead System

Stability of Defibrillation Thresholds. Introduction : Monophasic defibrillation thresholds rise over time with a variety of lead systems. These chronic changes are attenuated or eliminated by biphasic waveforms, although the effect appears dependent upon the lead system. With the downsizing of pulse generator size to allow for routine pectoral implantation, active can lead systems have now become standard. However, the temporal stability of such lead systems has not been evaluated previously.
Methods and Results : This study was a prospective assessment of the changes of active pectoral defibrillation thresholds over time. Thresholds were measured at implant, predischarge, and at a mean follow-up of 50 days in 46 patients with a uniform testing protocol and shock polarity. The lead system was a dual-coil Endotak DSP lead with an active pectoral pulse generator. Defibrillation thresholds were 9.9 ± 5.5 J at implantation, 8.5 ± 6.0 J predischarge, and 7.6 ± 5.5 J at follow-up (ANOVA, P = 0.007). Moreover, only two patients developed an increased threshold > 5 J, and no patient had an inadequate safety margin at follow-up.
Conclusion : These results indicate that active pectoral defibirillation thresholds are stable over the first 2 months postimplantation and question the need for routine serial defibrillation threshold testing.     

左室不同起搏部位对心脏再同步化治疗短期疗效的影响

目的探讨左室不同起搏部位对心脏再同步化治疗(CRT/D)患者术后短期(1周及6个月)疗效的影响。方法入选成功行CRT/D手术,且相关观察数据完整患者共36例。分析术中左室电极植入情况,左室起搏部位根据左室电极末端左前斜45度时的投影结合其相应心脏静脉的部位确定,分为靠近间隔部组(A组)和游离壁组(B组)。比较两组患者术后1周常规心脏超声变化,随访6个月CRT/D临床应答及并发症情况。结果术后1周,两组的左室射血分数均较术前明显提高;与A组相比,B组对心脏功能的改善更为明显,左房内径、左室收缩末期容积、二尖瓣返流情况仅在B组有所改善。术后随访6个月,35例有应答,B组中1例无应答,两组术后6个月无应答和并发症的发生率均无明显差别。结论 CRT/D治疗慢性心力衰竭在短期内即可使患者获益。左室电极位于游离壁可以更好的改善心脏功能,逆转心室重构。     

Microdislodgment of ventricular pacing lead undetectable during rapid pacing one year after implantation

A 71-year-old woman had undergone valvular heart surgery in 1981, and implantation of a permanent ventricular pacemaker for ventricular pauses during atrial fibrillation in 2001. One year after pacemaker implantation, she complained of faintness. When pacing at 100 beats/min the pacemaker functioned properly. However, pacing and sensing failure was detected at a pacing rate of 60 beats/min. At rapid pacing rates, the lead tip was in closer contact with the endocardium, and its microdislodgment was undetectable. The symptoms have resolved since the lead was repositioned.     

低水平脐血铅浓度与新生儿白细胞DNA端粒长度的相关性研究

目的 研究低水平脐血铅浓度与新生儿白细胞DNA端粒长度的相关性, 为低水平铅暴露对新生儿端粒长度及日后生长发育的影响提供新的客观依据。方法 选择脐血铅浓度低于100 μg/L足月顺产儿97例。以脐血铅浓度50 μg/L为界将其分为两组。A组:脐血铅浓度<50 μg/L, B组:脐血铅浓度≥50 μg/L。采用原子吸收光谱法测定血铅浓度, 实时荧光定量PCR法测白细胞DNA的相对端粒长度。结果 A组68例, B组29例。A组端粒长度为0.803±0.568, B组端粒长度为0.536±0.476, 两组比较差异有统计学意义(t=2.222, P=0.029);端粒长度与血铅浓度呈负相关(r=-0.303, P=0.003)。结论 新生儿白细胞DNA端粒长度与脐血铅浓度相关, 低水平脐血铅亦可致新生儿端粒长度的缩短。     

排铅咀嚼片促排铅功效的临床观察

目的 观察排铅咀嚼片对铅排出量及对儿童健康的影响。方法 采用自身对照及组间对照法,选择血铅含量在100μg／L以上儿童94例,随机分为排铅咀嚼片观察组和对照组,观察30天。结果服用排铅咀嚼片组儿童服药后第20天、第30天尿铅排出量自身服药前后比较及与对照组组间比较,差异均有显著性(P<0．05,P<0．01),且尿铅总排出量增加大于对照组(P<0．05)。结论排铅咀嚼片有明显促进排铅作用。服用后对尿钙、尿锌排除无明显影响;观察前后血、尿常规检测指标在正常范围内,亦说明排铅咀嚼片对观察者健康无损害。     

The isopotential plot--a new method for the assessment of ST amplitude changes provoked by an exercise test

A method is described for presenting ST changes provoked bythe exercise test. ST amplitudes are measured by a computerwhich continuously samples six chest leads and two limb leads(I and II, from which six limb leads are obtained). The chestleads in standard positions 1–6 are regarded as a spacedimension. Values for ST amplitudes, obtained 60 ms after theend of each QRS at the different electrode sites, are interpolatedand presented against lime as isopotential lines. A similarplot is made for the limb lead ECGs. In patients with coronary artery disease the isopotential linesgive a picture of the ST amplitude changes that greatly facilitatesthe reading of the ST response from the test. The continuoussampling and filtering principles lead to increased precisionof measurements and increased resolution in time. The method is illustrated by exercise tests in five patientswho have undergone coronary angiography.     

Closure of the subclavian artery puncture site with a percutaneous suture device after removal of an arterial pacemaker lead.

We describe the closure of a subclavian artery puncture site with a percutaneous suture device after removal of a pacemaker lead 1 week after its inadvertent positioning in the left ventricle via the subclavian artery. The lead was retracted from the left ventricle into the aorta and linked to a guiding catheter introduced via femoral artery access. The lead and the guiding catheter were removed from the artery to the subclavian area. This manoeuvre allowed the placement of a percutaneous arterial suture device (Perclose) to close the puncture site.