Pacemaker Lead Induced Inferior Vena Caval Thrombosis Leading to Portal Hypertension

Inferior vena caval thrombosis is an unusual complication of permanent pacemaker implantation. The clinical presentation due to thrombosis depends on the site of thrombus. We have described here a rare case of pacemaker lead associated thrombosis of inferior vena cava, its diagnostic work up and briefly reviewed the existing literature of this uncommon complication.     

永久起搏器程控在心房颤动诊断中的临床应用及意义

摘要 目的：探究永久起搏器程控在心房颤动诊断中的临床应用及意义。方法：选择78例我院收治的心房颤动患者随机分为程控组和非程控组2组,其中观察组患者给与永久起搏器程控诊断,非程控组则仅给植入永久起搏器,但非程控。对比分析两组患者基本资料、房颤负荷、心房与心室起搏比、心房结构重构及左心功能、P波结果;比较永久起搏器程控诊断与临床诊断结果的差异,分析永久起搏器程控在心房颤动诊断敏感度。结果：程控组和非程控组患者的男女比例、年龄、心率失常的类型、存在的基础性疾病以及使用过的治疗药物比较,差异均无统计学意义（P>0.05）;程控组和非程控组患者的房颤负荷、VP值和P波最小时限均显著小于非程控组,AP值、P波最大时限和P波离散度则显著大于非程控组（P<0.05）;程控组和非程控组患者的LAD、RAD、LVEDD和LVEF值在植入前和植入后均不存在显著性差异（P>0.05）。与临床诊断结果比较可以发现,永久起搏器程控对心房颤动检出率为97.44 %,且永久起搏器程控应用于诊断心房颤动敏感度高达98.72 %。结论：对心房颤动患者采用永久起搏器程控进行诊断,可以在心电图检查的各项指标结果上对患者的心房颤动给与准确的判断,具有较高的临床应用价值,值得临床推广使用。     

Intermittent Right Ventricular Outflow Tract Capture due to Chronic Right Atrial Lead Dislodgement

A 58 year old male, known case of type 2 diabetes and hypertension, had undergone implantation of a dual chamber pacemaker(DDDR) in 2007 for complaints of recurrent syncope and trifascicular block with a normal ejection fraction andnormal coronaries. His post implantation parameters were normal at that time.He now presented to our pacemaker clinic where his ECG done showed two types o fpaced complexes. The first few complexes were consistent with atrial sensed right ventricular apical pacing with left superior axis. Later complexes showed loss of atrial sensing with pacing from right ventricular outflow tract(inferior axis) with subtle oscillation in it''s axis. On application of magnet, two pacemaker spikes were visible withinterspike interval of 120 ms and paced complexes with inferior axis starting from the first spike suggesting that the atrial lead was responsible for RVOT depolarization. On interrogation of the pacemaker, atrial EGM showed sensed activity from atrium followed by large sensed ventricular complex. Fluoroscopy confirmed that the atrial lead was dislodged and was intermittently prolapsing into the RVOT. Since the patient was asymptomatic, he refused any intervention and subsequentlyhis atrial lead was switched off by telemetry. The above case signifies that asymptomatic lead dislodgement is no talways manifested as loss of capture and even subtle variation of the axis o fthe paced complexes can provide us with a clue that can be confirmed by telemetry of the pacemaker and fluoroscopy.     

Transcatheter leadless permanent pacemaker in complex congenital heart disease with interrupted inferior vena cava: A challenging implantation

31 years lady with complete atrioventricular canal defect, large primum atrial septal defect (ASD), inlet ventricular septal defect (VSD) and Eisenmenger syndrome, presented with atrial flutter and complete heart block. She was not suitable for corrective cardiac surgery and not yet indicated for heart-lung transplantation. She was advised single chamber permanent pacemaker and eventually Micra VR transcatheter leadless pacemaker was finalised for her. Transcatheter leadless pacemaker was deployed in her RV septum despite some unforeseen technical problems. This patient had intrahepatic interruption of IVC with Azygous continuation draining into SVC but this altered venovascular course was detected only fluoroscopically midway during the pacemaker implantation procedure and this was not detected in the preprocedural transthoracic echocardiography. This abnormal venous course was clearly demonstrated in the cardiac CT which was performed only after completion of the pacemaker implantation procedure in this patient. The technical challenges encountered mainly were mostly during the manipulation of the 27F delivery catheter of Micra through this altered cardiovascular anatomy via transfemoral approach and also due to the presence of septal defects. Thus, transcatheter leadless permanent pacemaker was implanted successfully through transfemoral access in this complex congenital heart disease with interrupted IVC and azygous continuation. Besides transthoracic echocardiography, it may be better to perform transesophageal echocardiography or even preferably radiological imaging like cardiac CT or MRI prior to transcatheter leadless pacemaker implantation in patients with complex congenital heart disease to understand the cardiovascular anatomy and plan the procedure.     

非侵入性起搏器负荷超声心动图对永久起搏器植入术后合并冠脉病变的临床诊断意义

目的：探讨非侵入起搏器负荷超声心动图对永久起搏器植入术后合并冠脉病变的临床诊断意义。方法：采用前瞻性研究,实验对象为24名因房室传导阻滞或慢性心房纤颤而植入永久起搏器的患者（男12人,女12人,平均年龄70.2±6.1岁）,所有患者均因不典型心绞痛入院和完全起搏依赖,心电图改变无法判断是否存在心肌缺血。通过体外程控进行非侵入性起搏器负荷超声心动图检测室壁运动幅度如左室射血分数评估心功能,检测后行冠脉造影术评估冠脉狭窄情况,及实验前后测定B型脑钠肽的变化。结果：24例患者中,有13例通过起搏器负荷超声心动图应激实验测得LVEF随起搏心率增加而降低,这其中又有11例患者通过冠状动脉造影证实其冠脉存在不同程度的狭窄,诊断的准确性84.62%;11例冠脉造影结果阳性的患者实验后30分钟测得的BNP水平较实验前明显升高。结论：非侵入性起搏器负荷超声心动图应激实验作为一种简单、快速、安全及具有诊断意义的方法,可用来评价植入起搏器术后完全起搏依赖,心电图继发性ST-T改变难以判断的心肌缺血,为进一步检查及治疗提供可靠临床数据。     

Conduction barriers and pathways of the sinoatrial pacemaker complex: their role in normal rhythm and atrial arrhythmias

Since Keith and Flack's anatomical discovery of the sinoatrial node (SAN), the primary pacemaker of the heart, the question of how such a small SAN structure can pace the entire heart has remained for a large part unanswered. Recent advances in optical mapping technology have made it possible to unambiguously resolve the origin of excitation and conduction within the animal and human SAN. The combination of high-resolution optical mapping and histological structural analysis reveals that the canine and human SANs are functionally insulated from the surrounding atrial myocardium, except for several critical conduction pathways. Indeed, the SAN as a leading pacemaker requires anatomical (fibrosis, fat, and blood vessels) and/or functional barriers (paucity of connexins) to protect it from the hyperpolarizing influence of the surrounding atrium. The presence of conduction barriers and pathways may help explain how a small cluster of pacemaker cells in the SAN pacemaker complex manages to depolarize different, widely distributed areas of the right atria as evidenced functionally by exit points and breakthroughs. The autonomic nervous system and humoral factors can further regulate conduction through these pathways, affecting pacemaker automaticity and ultimately heart rate. Moreover, the conduction barriers and multiple pathways can form substrates for reentrant activity and thus lead to atrial flutter and fibrillation. This review aims to provide new insight into the function of the SAN pacemaker complex and the interaction between the atrial pacemakers and the surrounding atrial myocardium not only in animal models but also human hearts.     

Percutaneous Transvenous Angioplasty of Left Innominate Vein Stenosis Following Right Side Permanent Pacemaker Implantation- A Left Femoral Vein to Left Axillary Vein Approach

Central venous stenosis after the insertion of a permanent pacemaker is a well recognized complication. This late complication is encountered when there is a need to change the pacemaker lead or extract it. We describe a young male who had such a complication after many years after right side pacemaker implantation. The lesion was managed percutaneously leading to placement of a new lead from the left side.     

Atrial electrogram quality in single-pass defibrillator leads with floating atrial bipole in patients with permanent atrial fibrillation and cardiac resynchronization therapy

Many patients receiving cardiac resynchronization therapy (CRT) suffer from permanent atrial fibrillation (AF). Knowledge of the atrial rhythm is important to direct pharmacological or interventional treatment as well as maintaining AV-synchronous biventricular pacing if sinus rhythm can be restored. A single pass single-coil defibrillator lead with a floating atrial bipole has been shown to obtain reliable information about the atrial rhythm but has never been employed in a CRT-system. The purpose of this study was to assess the feasibility of implanting a single coil right ventricular ICD lead with a floating atrial bipole and the signal quality of atrial electrograms (AEGM) in CRT-defibrillator recipients with permanent AF.

Possible complications of subclavian crush syndrome

A 70-year-old woman with symptomatic Mobitz type II atrioventricular block underwent implantation of a dual-chamber pacemaker 11 years ago. The leads were inserted through a percutaneous puncture of the right subclavian vein, using standard techniques. Both leads were passive fixation leads. Due to battery failure and end of life criteria, the pulse generator (PG) had been routinely replaced six years previously. Predischarge pacemaker control revealed normal pacing, sensing thresholds and impedance for both leads. Because of a syncopal attack subsequent to lead fractures, most likely secondary to right subclavian crush syndrome (SCS) of both leads, she underwent a double lead re-implantation one year after PG replacement by access via left subclavian vein puncture.After a symptom-free period of few years she was re-analysed because of palpitations, dizziness, angina pectoris and tiredness. Pulmonary embolisation and myocardial perfusion defects were detected utilising scintigraphic techniques. Chest X-ray revealed the crushed atrial lead dislocated from the right subclavian region and lodged into the right ventricle towards the inferior septum. Because she was symptomatic, a retrieval technique was applied and the crushed atrial lead was pulled back from the right ventricle and securely fixed to its former position. On maintenance medical treatment, she remains well.     

Percutaneous transcatheter repositioning of displaced permanent pacemaker atrial lead with a simple system

A 48-year-old man who was implanted with a DDD-R pacemaker because of sick sinus syndrome eight days ago presented to our institute with a syncopal attack. Fluoroscopy showed a dislodged active fixation atrial pacemaker lead. With a snare system simply improvised from a 0.014 inch guidewire and a NIH catheter, the lead was repositioned via percutaneous transfemoral approach. The procedure was easy and completed without any complication. Follow-up controls after two weeks and three months showed stability of the lead position with normal pacing and sensing functions.     

Dual chamber pacing mode in an atrial antitachycardia pacing device without a ventricular lead – A necessary evil

We present a case of a single chamber atrial pacemaker implanted for sinus node dysfunction and treatment of macroreentrant atrial tachycardias with atrial antitachycardia pacing. The patient presented with sustained atrial tachycardia above the detection rate, however, the device was unable to detect the tachycardia and did not deliver the programmed therapy. We discuss the nuances of the atrial tachyarrhythmia detection algorithms, and the programming strategies to maximize detection of atrial arrhythmias in a single chamber atrial pacemaker.     

起搏器术后新发房性心律失常的影响因素分析

目的:探讨起搏器术后新发房性心律失常的发生情况及其相关影响因素。方法:选择2006年1月至2007年12月于沈阳军区总医院首次植入永久起搏器的107例患者,男性50例,平均年龄65.0±11.9岁,术前通过追问病史及相关检查均排除房性心律失常(房颤、房扑、房速),术后平均随访3.9年,观察新发房性心律失常情况。按术后是否出现房性心律失常,将患者分为新发房性心律失常组和无房性心律失常组,比较两组患者术前和术后心脏超声结果的变化、心室起搏比例、起搏部位及起搏模式,并通过logistic回归分析起搏器术后发生房性心律失常的影响因素。结果:新发房性心律失常组26例(24.3%),其中房颤17例(15.9%),房扑2例(1.9%),房速7例(6.5%);无房性心律失常组81例。与无房性心律失常组比较,新发房性心律失常组左房内径明显增加(P=0.040)、二尖瓣返流程度较重(P=0.032)及左室射血分数明显下降(P=0.001),心室起搏百分比(VP%)显著升高(P=0.017)。心尖部起搏患者房性心律失常的发生率明显高于间隔部起搏(33.3%vs 16.9%,P<0.05),双腔起搏组患者房性心律失常发生率明显低于单腔起搏器组(18.7%vs 37.5%,P<0.05)。Logistic回归分析显示术后新发房性心律失常的发生与高比例的心室起搏(P=0.006)、VVI(R)起搏模式(P=0.014)及右心室起搏电极导线植于心尖部(P=0.024)显著相关。结论:起搏模式、心室起搏百分比、起搏部位是起搏器术后发生房性心律失常的影响因素。     

Clinical application of pacemakers in atrial tachyarrhythmias

The diagnostic programmes of modern pacemakers have increased our knowledge of atrial tachyarrhythmias (ATAs) in chronically paced patients. These programmes also support the evaluation of the effects of pharmacological treatment of ATAs. The success of interruption and/or prevention of ATAs with pacemakers depends strongly on the diagnostic accuracy and the properties of the pacing algorithms, their individual programming and the site and configuration of the pacing leads. Atrial septum pacing can be beneficial in patients with paroxysmal atrial fibrillation and prolonged P wave duration. Recent large-scale studies on preventive and interruptive atrial pacing of ATAs show modestly positive or no results. Therefore, atrial pacing therapy for ATAs should be considered cautiously, serving as an adjuvant to pharmacological treatment rather than as a primary intervention. This also applies for pacing interventions for ATAs in cardiac resynchronisation therapy. The pacemaker algorithms for the detection of ATAs and atrial lead configuration are crucial for the success of pacemaker-mediated prevention or interruption of ATAs. The success of these interventions is dependant on future improvements of pacemaker technology. (Neth Heart J 2008;16 (suppl 1): S20-S24.)     

Hybrid Access to Atria via the Guiraudon Universal Cardiac Introducer for Arrhythmia Ablation After Total Cavopulmonary Derivation

ABSTRACT: We report the first use of a new platform, the Guiraudon Universal Cardiac Introducer (GUCI), in humans for accessing the left atrium for catheter-based ablations in patients with resistant atrial arrhythmias after total cavopulmonary derivation. The GUCI was originally designed for intracardiac access for closed, beating instrumental intracardiac surgery.The patient was a 29-year-old man with problematic atrial arrhythmias resistant to antiarrhythmic drugs because of severe uncontrolled bradycardia and because his pacemaker was explanted for infection.The GUCI was attached to the left atrial appendage via an anterior left thoracotomy. The GUCI was modified to accommodate introduction and manipulation of multiple catheters. This allowed electrophysiologists to perform catheter-based exploration and ablation. A DDD pacemaker was implanted, with an atrial endocardial lead introduced via the GUCI cuff and a ventricular epicardial lead.Postoperative atrial arrhythmias were controlled using amiodarone and atrial pacing. At the 12-month follow-up, the patient was arrhythmia- and drug-free and returned to full employment.This new access offers an additional new alternative atrial access to treat resistant arrhythmia after total cavopulmonary derivation. The current state-of-the-art makes patient selection difficult and uncomfortable for the surgeons because of incomplete preoperative electrophysiological data, such as a return to the beginning of surgery for arrhythmia; however, more cumulative experience with intraoperative electrophysiological data and new mapping technologies should address these limitations.     

Atrial Pacing to Control Heart Rate and Rhythm in Acute Cardiac Conditions

Increasing the heart rate by a bedside atrial pacing technique was successfully utilized to treat serious cardiac arrhythmia or failure in 13 patients. Nine of these had ventricular arrhythmia refractory to drugs. Seven had evidence of sinus node depression or disease since their sinus pacemaker was below 70 beats per minute under decompensated conditions. In five, coronary artery disease was associated with the bradycardia and in two, digitalis toxicity was related to depression of the intrinsic pacemaker rate. Two patients in the coronary group required implantation of a permanent demand ventricular pacemaker. Hemodynamic studies were performed in seven patients. Only one patient had no increase in cardiac output with pacing rates above his resting rate. The other six patients showed an increase in cardiac output from 22 to 81% at paced rates between 70 and 125/minute. The duration of pacing ranged from one hour to 14 days and averaged five days.     

射频消融术治疗房颤后并发血栓栓塞形成的机制

心房颤动是临床上常见的心律失常之一,可因心房丧失收缩功能及长期心率增快而导致心房内血栓形成,并脱落至身体各处形成栓塞,严重时甚至可导致心力衰竭,增加患者的死亡率。射频消融术是目前可治愈心房颤动的有效的治疗手段,且在老年患者中具有较高的成功率和安全性。但血栓形成和栓塞仍是其主要并发症之一,发生率甚至可高达7%,一旦栓塞事件发生,将严重影响患者术后生存质量。目前研究结果表明,射频消融术治疗心房颤动后发生血栓及栓塞是一种多因素参与的系统性改变。     

Current developments on the physiology of the cardiac atrial pacemaker an excitation conduction of the left atrium]

According to recent developments the atrial pacemaker area and the right atrium show a peculiar morpho-functional organization, i.e.: 1) The pacemaker area is formed of clusters of cells containing relatively few myofibrils and showing embryologic characteristics. Such cells are known as nodal cells and between these and the atrial muscles are in general situated transitional cells. Each cluster is separated from the other by collagenous boundaries. The resistance of the membranes to the current flow seems to be relatively low between the cells of the same cluster but the collagenous boundaries are, according to TRAUTWEIN e UCHIZONO (1963), very poor conductors. The pacemaker activity seems to originate inside the various clusters. 2) The functional relationships between the sinoatrial node and the atrioventricular node as well as the interatrial relationship would take place through preferential pathways. These pathways corresponding approximately to the tracts described by JAMES (1966) (anterior, posterior and middle internodal tracts) and to the interatrial or Bachmann bundle, seems to show a higher velocity conduction. In general the fibres of which the tracts are composed are neither morphologically nor functionally isolated from the atrial muscle. The functional consequences of the above mentioned nodal and atrial organization seems to be: a) The possible conditioning of the pacemaker functions by the various clusters activity i.e. the dominance of one cluster over another. b) The shifting of the pacemaker activity from one cluster to anothr due to the arrival of nervous stimuli or chemical substances, etc. According to some Authors as a consequence of the shift the pacemaker area can sometimes move out side the nodal tissue and settle inside an area belonging to the internodal pathways. c) Another consequence of the shift can be the different involvement of the conducting pathways which can lead to a change in the dynamics of the atrial invasion by the excitement.     

Pacemaker lead-related macroreentrant atrial tachycardia

Macroreentrant atrial circuits are frequently associated with scarring. Previous reports have shown the possible development of scar tissue that is adjacent to pacemaker (PM) leads. However, reports of PM lead-related reentrant tachycardia are scarce. We report the case of a 63-year-old woman who presented with macroreentrant atrial tachycardia (MAT), related to the atrial trajectory of an old single-lead ventricular PM, that was successfully treated with radiofrequency ablation after a conventional electrophysiological study ruled out isthmus-dependent atrial flutter and provided sufficient data to confirm this diagnosis. This report presents a case of MAT originating around the trajectory of a PM lead, probably because of scar tissue that developed adjacent to the lead. Experimental studies have already shown that interstitial atrial fibrosis may develop adjacent to a ventricular single-lead. This finding suggests that MAT develops in patients with this specific condition. Recognizing this condition is important for managing these arrhythmias and performing safe ablation with the preservation of PM lead integrity.     

Effect of atrial dilatation on the tendency of atrial arrhythmias

The arrhythmogenic effect of atrial dilatation was studied by electrophysiological investigations carried out on 24 dogs. Atrial distension was evoked by increasing the pressure in the right atrium (12 to 14 mm Hg) or by the balloon dilatation of the left atrium. Programmed electrical stimulation of the heart was used for the electrophysiological investigations. In addition to the superficial ECG leads also atrial and ventricular epicardial electrograms were obtained for the ECG recording. Acute atrial dilatation led to shortening of the atrial refractory period, whereas neither impulse conduction of the heart, nor pacemaker activity of the sinus node exhibited any alteration. Atrial dilatation resulted in pathological atrial irritability, and early or frequent atrial stimulation caused atrial tachycardia of shorter (non sustained) or longer (sustained) duration. Repetitive atrial extrasystoles in response to early stimuli could also frequently be observed during atrial dilatation. The obtained results indicate that atrial dilatation is arrhythmogenic and may lead to the development of atrial tachycardia.