Rate-Related and Autonomic Effects on Atrioventricular Conduction Assessed Through Beat-to-Beat PR Interval and Cycle Length Variability

Atrioventricular Conduction Variability. Introduction: Atrioventricular AV) conduction time varies on a beat-by-beat basis in response to the influences of cardiac efferent autonomic activity and rate-dependent electrical recovery processes. The goals of this study were to distinguish these effects on AV conduction time and to compare the variability in sinoatrial and AV nodal function. Methods and Results: The PR interval on the surface ECG served as an index of AV conduction time in this study of 14 adult human subjects undergoing a random interval breathing protocol. P and R waves were located by a template-matching algorithm. Spectral analysis allowed frequency-domain comparisons between PR and RR interval variability. Spectra of PR and RR intervals had similar power distributions, although the power of the RR interval spectra was much greater. Autonomic blockade with atropine plus propranolol reduced the power of both spectra. Standing significantly decreased the spectral power from 0.15 to 0.5 Hz for PR and RR spectra, and introduced a peak near 0.1 Hz in the mean PR and RR spectra, although the latter finding was significant only for the RR interval spectra. Propranolol had no significant effects on the PR and RR interval spectra. Linear regression analysis allowed quantification of the autonomic and recovery effects on AV conduction and showed which effect predominated. Simple linear regression confirmed in adults a previous finding in children that conduction time may be either positively or negatively correlated with cycle length. By multiple regression and transfer function analysis, the inverse relation seen in some subjects was attributed to the effect of recovery from the preceding cycle. With the preceding recovery period accounted for, the conduction time and cycle length of the current beat were positively correlated, presumably due to the parallel autonomic effects on the sinoatrial and AV nodes. The magnitude of the recovery effect predicted by the regression analysis was similar to published values. Conclusion: A noninvasive evaluation of the surface ECG can be used to compare variability in AV conduction time and cycle length and characterize the effects of autonomic efferent activity and rate-related recovery on AV nodal function.     

起搏器更换时原起搏电极导线参数及更换指标分析

目的:分析74例更换起搏器时电极导线的各项参数的变化并探讨导线更换指标。方法:本组年龄12~87(62.8±18.4)岁,其中病窦综合征45例,房室传导阻滞29例,均为单腔VVI起搏。结果:至测量时原心室起搏电极导线的埋置时间60~148(97.4±22.8)月,首次埋置时起搏阈值为(0.48±0.24)V,更换时为(1.29±0.64)V(P(0.01),增加0.81V,增幅为168%,首次植入时R波幅为(7.8±3.6)mV,更换时为(5.9±3.4)mV(P(0.05)。植入时电极导线阻抗为(664±122)Ω,更换时阻抗为(726±148)Ω,增幅9.3%(P(0.05)。7例因起搏阈值大于2.0 V或阻抗大于1 250Ω而重新植入电极导线。原电极导线使用率为90.5%。结论:埋置起搏电极导线8~9年后,90.5%原电极导线仍在可使用的范围内,能否支持到再次更换需进一步随访。     

老年冠心病患者的动态心电图观察

对97例老年冠心病患者进行动态心电图观察,共检出97例患者缺血性ST段发作347阵,心率减慢时发生缺血48例(49.5％),全程无症状者75例(77.4%),缺血时有无胸痛与ST段下降程度无必然联系。     

Comparison between laser and electrical ablation of ventricle in dogs: Hemodynamic,pathologic and electrocardiographic observations

Summary To characterize and compare the pathologic, hemodynamic and electrocardiographic changes of both transeatheter laser and electrical energy on ventricle, 33 subendocardial myocardium lesions were induced at energy 60, 120 and 240 Joules by either transcatheter laser irradiation or electrical shock in 7 anesthetized dogs. The following results were observed: 1) Both laser and electrical ablation on myocardium created nonhomogeneous myocardium injury, but laser ablation caused mainly focal tissue vaporization and necrosis, while electrical shock induced widespread tissue degenerations; 2) Both laser and electrical induced-lesion dimensions increased parallel to the total dosage of energy; 3) Laser ablation caused mainly (90%) single ventricular premature beats and 86 % of them occurred within the first minute after energy discharged, while ventricular tachycardias were found in any electrical energy groups; ventricular fibrillations occurring during laser and electrical ablation were 5 % and 13 % respectively (P< 0.01): 4) A decrease in aortic blood pressure and an increase in central verous pressure induced by laser ablation were significantly less than that produced by the same amount of electrical energy (P<0.0l). Our preliminary results have shown that transeatheter laser ablation has great potential for becoming a practical method in the management of refractory tachycardias.     

妊娠晚期胎心监护异常曲线与胎儿宫内窘迫的临床研究

目的 :探讨胎心监护异常曲线与胎儿宫内窘迫的关系。方法 :使用胎儿电子监护仪对 1336例孕妇 ,经腹壁对胎心率和宫缩进行监测。结果 :1336例孕妇中 ,胎心监护异常曲线者 12 8例 ,占 9.5 8%。 12 8例中产后发现异常因素 10 1例 ,占 78.91%。新生儿窒息 4 6例及死亡 2例 ,占 37.5 0 %。结论 :胎心异常曲线对胎儿宫内窘迫的诊断具有重要价值。     

银丹心脑通软胶囊对垂体后叶素致心肌缺血大鼠心电图的影响

目的观察银丹心脑通软胶囊对垂体后叶素（pituitrin,Pit）致心肌缺血大鼠心电图的影响。方法采用大鼠舌下静脉注射Pit造成急性心肌缺血模型,观察各给药组在注射Pit后不同时间点Ⅱ导联心电图T波变化百分率和心率的变化。结果银丹心脑通软胶囊低、高剂量组与模型组比较,均能明显降低心肌缺血大鼠心电图T波峰值变化百分率（P〈0.05）,与注射Pit前比较,能对抗Pit致心率减慢的损伤（P〈0.05）。结论银丹心脑通软胶囊具有抗Pit引起的大鼠急性心肌缺血的作用。     

Integrated home monitoring predicts lead failure in a pacemaker dependent 4-year-old girl.

A 4-year-old girl with post-surgical complete atrioventricular block received an epicardial dual chamber pacemaker system. During further growth intermittent exit block occurred, first misinterpreted as neurological seizures. The epicardial lead was replaced using a transvenous approach, and a pacemaker with an integrated home monitoring facility was implanted. After her discharge, a rise in the pacing threshold automatically initiated an event message. On the basis of this information, the patient was called in and imminent dislodgement of the ventricular lead was diagnosed by x-ray. The lead was repositioned and was found stable over 1-year follow-up.     

医疗器械产品召回制度探讨与典型案例分析

着重介绍了国内外医疗器械产品召回制度现状,并以强生血糖仪、佳腾除颤器两起召回事件为案例,阐明整个召回事件处理的过程,旨在为我国建立和完善医疗器械产品召回制度提供借鉴。     

颅内疾病的心电图改变

目的 :探讨颅内疾病的心电图改变及对预后的影响。 方法 :将我院 1999年以来的 10 2例颅内疾病患者的心电图资料按病因分为 4组 ,所有患者均于发病 1～ 2d内入院 ,常规描记 12导联心电图 ,住院期间定期复查。结果 :心电图改变主要为复极障碍 (ST段下移 ,T波倒置、低平或双向以及Q T间期延长 ) ,其次为心律失常。 4 0例重型颅脑外伤及蛛网膜下腔出血者中心电图异常 36例 ,正常 4例 ,死亡组心电图异常率及程度均重于存活组。结论 :“脑型心电图改变”主要表现为ST T改变和冲动起源异常的心律失常是暂时的应激反应。发生急性颅内病变时要及时识别 ,积极予以处理 ,以减轻脑损伤所致的心脏损害。     

Primary Prevention of Sudden Cardiac Death in Heart Failure: Will the Solution Be Shocking?

Sudden cardiac death (SCD) may occur in as many as 40% of all patients who suffer from heart failure. This review describes the scope of the problem, risk factors for SCD, the effect of medications used in heart failure on SCD and the potential effect of the implantable cardioverter-defibrillator in primary prevention.