The Cardiac Pacemaker Current if

Pacemaker Current if. Since the hyperpolarization-activated current, if, was originally associated with the diastolic depolarization phase of action potential in the sinoatrial (SA) node in 1979, its central role in the generation and control of pacemaker activity has become increasingly clear through a series of experimental findings, some of which have substantially modified the pre-existing theories of cardiac pacemaking and its modulation by the autonomic transmitters. Thus, the pacemaker current of Purkinje fibers, formerly described as a deactivating pure potassium (K) current, was found to be in fact, like the nodal if, inward and activating on hyperpolarization. Furthermore, in SA node cells, as well as mediating rhythm acceleration induced by catecholamines, if was found to underlie the slowing effect of low acetylcholine (ACh) concentrations, in contrast with the generally accepted hypothesis that activation of a K conductance is the main process responsible for cardiac slowing. A final, atypical property of if recently demonstrated concerns the activating action exerted on if by intracellular cAMP. Unlike that on other voltage-gated, cAMP-modulated cardiac channels, this action is independent of phosphorylation and involves a direct binding of cAMP to if channels. (J Cardiovasc Electrophysiol, Vol. 3, pp. 334–344, August 1992)     

三腔起搏器的临床应用

应用三腔起搏器治疗病窦以及同时有房室传导异常合并快速房性心律失常患者６例,其中５例为阵发房颤,１例为阵发房扑,心电图示房间阻滞。植入冠状窦电极及普通右房和右室电极,用Ｙ型转换器以右房耳电极为负极,冠状窦电极为正极构成新的双极电极。将４例患者ＤＤＤ起搏器调至ＡＡＴ模式,２例患者为ＤＤＤ模式,房性快速心律失常消失。随访２～６个月,疗效满意。三腔心脏起搏器适用于治疗病窦并有房室传导异常合并房内阻滞的阵发房扑和房颤的患者。     

The Use of the Implanted Pacemaker as an In Vivo Electrophysiology Laboratory

A growing number of patients require invasive electrophysiological testing initially to evaluate a predisposition of symptomatic tachyarrhythmias. Once confirmed, periodic repeat testing is required to assess the status of the arrhythmia and the effectiveness of any therapeutic intervention. Many of these patients also have a single- or dual-chamber pacemaker for bradycardia support. Beginning in 1980, these systems have been noninvasively coupled to a programmable stimulator enabling the already implanted system to serve as an in vivo electrophysiology laboratorry. This has precluded the need for repetitive invasive procedures and sometimes hospitalization. The experience with this technique is reviewed.     

核磁共振成像与心脏起搏器的研究进展

核磁共振成像（MRI）环境可严重影响起搏器功能,从而植入心脏起搏器患者接受MRI检查成为禁忌.为了解决MRI对心脏起搏器产生的危害,MRI兼容性起搏器应运而生 现对MRI与心脏起搏器相互作用、心脏起搏器的改进及MRI兼容性起搏器的类型等方面作一阐述.     

超声引导下实施永久心脏起搏器的临床应用分析

目的探讨超声引导下心室起搏电极导管植入的定位和效果。方法采用超声技术对33例需置入永久起搏器患者进行起搏电极导管的植入和定位，分别取剑下上腔静脉切面、剑下或心尖四腔切面、左侧位心尖四腔和胸骨旁四腔切面和剑下右室流出道长轴切面，反复确认电极导管尖端经上腔静脉、右房、三尖瓣定于右室心尖部并测定电极各参数。结果33例患者手术均一次成功，电极导管定位指标及参数均较满意。随访6月～76月，除1例电极导管脱位重新定位外，无其他并发症，起搏系统工作正常。结论超声引导下实施心脏起搏可作为X线透视下永久起搏术的替代和补充，采用多切面、动态观察电极导管尖端走向是定位成功的关键。     

植入起搏器同时行冠状动脉造影的可行性及临床意义

对２３例植入起搏器患者（病窦综合征１２例、房室阻滞１１例，其中临床诊断冠心病１９例）在起搏器安置术同时作冠状动脉造影，结果发现冠状动脉狭窄２例。围手术期１例高龄患者合并股动脉穿刺部位出血，其余患者无并发症发生。表明在起搏器植入同时行冠状动脉造影是可行的。提出对过缓性心律失常作出冠心病的病因诊断应慎重     

Remote Monitoring of Patients With Implanted Cardiac Devices

Three different types of implantable cardiac devices are now commonly used in clinical medicine: pacemakers (including cardiac resynchronization systems), cardiac defibrillators, and loop recorders. Although pacing specialists and electrophysiologists have traditionally been responsible for device follow‐up, the newest generation of implanted devices stores a wealth of information that can be useful to the clinical cardiologist. Important information, in addition to device function, such as incidence and type of arrhythmias, general clinical condition of the patient, and hemodynamic status can now be stored on large databases that are available via web access to all physicians caring for an individual patient. The advent of the remote monitoring capability of implanted devices has initiated a rapidly accelerating paradigm shift in device follow‐up that can potentially improve patient care at lower cost. Copyright © 2010 Wiley Periodicals, Inc.     

生物起搏器的研究进展和展望

心脏生物起搏器是近年来心脏起搏的研究热点,目前主要集中在三大治疗策略;(1)细胞治疗;(2)基因治疗;(3)激素治疗.心脏生物起搏器处于研究初步阶段,应用于临床面临许多问题,但是随着分子生物学和基因-工程技术的发展,心脏生物起搏器必将造福于人类.     

永久起搏器植入常见并发症分析和处理

目的探讨永久起搏器常见并发症发生原因及预防措施。方法回顾分析651例植入永久起搏器患者的临床资料。其中,病态窦房结综合征292例。窦性心律伴二度～三度房室传导阻滞87例,心房颤动合并二度及高度房室传导阻滞240例,扩张型心肌病7例,尖端扭转型室性心动过速2例。起搏器更换29例。结果并发症共35例,其中误穿刺入锁骨下动脉1例、气胸4例、冠状静脉窦口夹层1例、感知障碍5例、起搏器综合征1例、电极脱位5例、心脏穿孔3例、囊袋血肿10例、囊袋溃破4例、起搏器过敏1例。结论规范操作,术后随访及起搏器知识教育,有助于减少并发症的发生。     

气囊电极床边紧急心脏临时起搏的临床观察

总结 36例经右颈内静脉、左锁骨下静脉及右股静脉三种不同的途径穿刺插管 ,行气囊电极床边紧急心脏临时起搏的经验。按Seldiger方法行静脉穿刺置管 ,按Swan Ganz球囊导管操作方法推送气囊电极导管 ,在无X线透视条件下 ,根据心腔内心电图、室性早搏出现或体表起搏心电图判断电极进入右室 ,行右室心内膜临时起搏。结果 :36例全获成功 ,其中右颈内静脉 (中位法 ) 16例、左锁骨下静脉 (下位法 ) 12例、右股静脉 8例。前两者开始穿刺至起搏成功时间为 3～ 10min ,后者为 10～ 2 5min。起搏效果肯定 ,起搏时间 2～ 2 0天。经股静脉插管者 2例误入下腔静脉分支 ,1例导管扭曲受阻 ,此 3例重新插管起搏成功。经左锁骨下静脉插管 1例误入左颈内静脉 ,改右颈内静脉起搏成功。全组除 11例腔内心电图和 5例边起搏边送管方法确定导管头位置外 ,余 2 0例在边送管边观察室性早搏出现的方法判断电极进入右室。术后胸片证实导管头位置与体表起搏图形定位的部位完全一致。除 3例电极移位和 2例短阵室性心动过速外 ,全部病例未发生心脏穿孔、气胸、血胸及感染等并发症 ,除 2例死于原发病外 ,余均痊愈出院。结论 :本法创伤小、方便快速、安全有效、无需X线引导 ,值得急救推广应用     

Ethnic Differences in Atrial Fibrillation Identified Using Implanted Cardiac Devices

Ethnic Difference in Atrial Fibrillation Incidence. Introduction: Atrial fibrillation (AF) is suggested to be less common among black and Asian individuals, which could reflect bias in symptom reporting and access to care. In the Asymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial (ASSERT), patients with hypertension but no history of AF had AF recorded via an implanted pacemaker or defibrillator, thus allowing both symptomatic and asymptomatic AF incidence to be determined without ascertainment bias. Methods and Results: The ASSERT enrolled 2,580 patients in 23 countries in North America, Europe, and Asia. AF was defined as device‐recorded AF episodes >190/min, lasting either for >6 minutes or >6 hours in duration. All ethnic groups with >50 patients were enrolled. Ethnic groups studied include Europeans (n = 1900), black Africans (n = 73), Chinese (n = 89), and Japanese (n = 105) patients. Compared to Europeans, black Africans had more risk factors for AF such as heart failure (27.8 vs 14.6%) and diabetes (41.7 vs 26.3%). At 2.5 years follow‐up, all 3 non‐European races had a lower incidence of AF (8.3%, 10.1%, and 9.5% vs 18.0%, respectively, for AF>6 minutes, P < 0.006). When adjusted for baseline difference, Chinese had a lower incidence of AF > 6 minutes (P < 0.007), and Japanese and black Africans had a lower incidence of AF > 6 hours (P < 0.04 and P = 0.057, respectively). Conclusions: Black Africans, Chinese, and Japanese had lower incidence of AF compared to Europeans. In the case of black Africans, this is despite an increased prevalence of AF risk factors. (J Cardiovasc Electrophysiol, Vol. 24, pp. 381‐387, April 2013)