Effects of Internal Defibrillation on an Implanted Pacing System with Programmable Polarity

Management of multiple cardiac arrhythmias in some patients with both an implantable cardioverter defibrillator (ICD) and a pacemaker has demonstrated several advantages. In such circumstances, it is imperative that pacemaker function and its programmed parameters be preserved following a deftbrillation shock. This article describes the effects encountered by a specific programmable polarity pacemaker (Relay® 294–03) when subjected to electrical defibrillation in a canine model. Three pacemakers were repeatedly tested in three separate dog experiments. Each pacemaker, with its leads implanted in the right atrium and the right ventricle, was subjected to a minimum total number of 24 high energy biphasic and monophasic shocks (600–700 V) delivered by a coexisting ICD system using three different defibrillating lead configurations. None of the pacemaker systems showed any failure in function; all pacemakers continued to function within preshock specification and conversion to unipolar pacing and/ or backup mode was not observed in any of the tests. Intracardiac electrical potentials measured directly off the ICD and the pacemaker leads, during a defibrillation shock (mean 566.6 V; 23.7 J), showed that potentials measured in a bipolar configuration (tip-ring: mean 21.0 V in atrium, 12.0 V in ventricle) were significantly less than potentials measured in a unipolar configuration (tip-can: mean 387.9 V in atrium, 394.0 V in ventricle; ring-can: mean 405.6 V in atrium, 395.4 V in ventricle). Our compatibility tests demonstrate that use of this programmable-polarity pacemaker in concert with an ICD system appears to be safe. Testing similar to the present study should be conducted prior to complete clinical acceptance of combined ICD and pacemaker implantation.     

Transatrial Implantation of Transvenous Pacing Leads is an Alternative to Implantation of Epicardial Leads

BYRD, C.L.: Transatrial Implantation of Transvenous Pacing Leads as an Alternative to Implantation of Epicardial Leads. State-of-the-art pacing modalities are not readily utilized with conventional epicardial pacing lead implantation techniques. A transatrial implantation technique was developed combining a limited surgical approach with transvenous leads. Six patients who were poor candidates for transvenous implants have received DDD or DDDR pacemakers by this approach. The limited surgical approach includes resection of the third or fourth costal cartilage through a small skin incision, reflection of the pleura, and opening of the pericardium. The introducer and transvenous leads are inserted through a right atrial pursestring suture. The leads are positioned in the right ventricle and right atrium using standard fluoroscopic techniques. Through the incision, the subcutaneous tissue pocket is constructed on the right anterior chest wall. The leads are connected to the pacemaker without the need for adaptors or tunneling. There were no procedure-related complications. The magnitude of the surgery and postoperative morbidity are significantly less than for a standard thoracotomy, median sternotomy, and transdiaphragmatic epigastric or subcostal approach. The utility of the transatrial implantation technique is that it allows the use of state-of-the- art bipolar dual chamber pacemakers restoring access to all pacing modalities for those patients not candidates for transvenous implantation.     

Late Fatal Right Ventricular Perforation as Complication of Permanent Pacing Leads

Perforation of the right ventricle during placement of pacing electrodes is a well-documented complication. Most of these perforations occur intraoperatively and rarely cause symptoms. This case report describes a fatal cardiac perforation that occurred 10 days after implantation of a permanent cardiac pacemaker. This complication should be considered as one of the potential mechanisms responsible for the high rate of sudden death observed in paced patients during the first year after pacemaker implantation.     

Entrapment of pacemaker lead by a large netlike Eustachian valve within the right atrium

Summary During pacemaker implantation in a patient with permanent atrial fibrillation, it remained impossible to advance a passive fixation lead with fins through the right atrium. However, a lead with a retractable screw easily passed the right atrium and was positioned in the right ventricle. Transesophageal echocardiography revealed an extensive net–like perforated Eustachian valve within the right atrium that had caused entrapment of the anchor fins during lead implantation. Remnants of embryonal structures within the right atrium should be considered a rare possible barrier during pacemaker implantation.     

Oozing from the pericardium as an etiology of cardiac tamponade associated with screw-in atrial leads

Screw-in atrial pacing leads are widely used. Cardiac tamponade is a complication. An 81-year-old woman with advanced atrioventricular block underwent permanent pacemaker implantation and subsequently developed cardiac tamponade. At surgery, the lead-tip screw was found penetrated through the right atrium but not through the pericardium. The source of bleeding was confirmed to scratching the inner pericardial membrane by the screw tip. Although cardiac tamponade due to perforation and leakage is known, tamponade caused by the trauma of an atrial screw on the pericardium with resultant ooze is less well described.     

Delayed perforation of right ventricle with cardiac tamponade: a complication of pacemaker implantation.

We report a case of delayed cardiac tamponade that resulted from pacemaker implantation in the emergency room of a large urban hospital. A 19-year-old male patient with a pacemaker implanted 10 days earlier suffered from delayed perforation of the right ventricle with cardiac tamponade. A review of the literature revealed that cardiac tamponade is a rare complication of pacemaker implantation. Pacemakers should only be implanted by physicians with relevant experience, and emergency room physicians should be aware of the possibility of the associated complications and be prepared to treat them.     

Steroid Eluting High Impedance Pacing Leads Decrease Short and Long-Term Current Drain: Results from a Multicenter Clinical Trial.

Pacemaker lead technology has changed considerably over the past decades. The widespread use of low polarization highly porous electrodes and steroid elution electrodes has resulted in low chronic pacing thresholds, as well as a decrease in the incidence of exit block. Efforts to develop pacing leads with high impedance might theoretically lead to lower lead current drain, which is a component of battery capacity. Pulse generator longevity can be increased without sacrificing pacemaker capabilities if pacing current drain can be decreased. Decreasing the size of the stimulation electrode results in increased pacing impedance, and if pacing thresholds are unchanged, a decreased current drain is predicted by Ohm's law (I = V/R). There is limited data available on the pacing characteristics of large numbers of patients with high impedance leads, despite their recent general availability and increasing widespread use. This multicenter, controlled trial examined the differences in performance between standard steroid-eluting pacing leads in the atrium (Medtronic model 5524) and ventricle (Medtronic model 5024), and new high impedance steroid-eluting pacing leads in the atrium (Medtronic model 5534) and ventricle (Medtronic model 5034). Measurements of bipolar pacing thresholds at 2.5 V, pacing impedance, and sensing thresholds were determined within 24 hours of pacemaker implantation, and at 0.5, 1, 3, 6 and 12 months after pacemaker implantation in 609 patients. Pacing and sensing thresholds were similar for the control and high impedance leads at all times except for a slightly larger R wave with the high impedance leads at implantation and 12 months. The mean impedance of the high impedance pacing leads in the atrium and ventricle at 12 months was 992 ± 175 and 1,080 ± 220 Ω, compared to 522 ± 69 and 600 ± 89 Ω for the standard pacing leads in the atrium and ventricle (P ≤ 0.001 for the high impedance leads compared to standard leads in each chamber). The mean atrial lead current (measured at 2.5 V) at 12 months was 2.6 ± 0.5 mA with the high impedance lead, and 4.9 ± 0.7 mA with the standard lead in the atrium (P ≤ 0.001). In the ventricle, the mean lead current at 12 months was 2.4 ± 0.4 mA with the high impedance pacing lead and 4.3 ± 0.6 mA with the standard lead (P ≤ 0.001). High impedance leads are associated with lower lead current drain than standard pacing leads in the atrium and ventricle for up to 1 year. No clinically important differences in sensing characteristics was noted with the high impedance leads in the atrium or ventricle compared to standard pacing leads. High impedance leads may result in increased pulse generator longevity.     

Malposition of Transvenous Pacing Lead in the Left Ventricle

Malposition of pacemaker leads has been described in several locations but rarely in the left ventricle. The incidence and clinical course of this pacemaker complication are unknown. We describe clinical, electrocardiographic, chest X ray, and echocardiographic findings in four patients in whom the transvenous pacing lead was inadvertendy placed through the interatrial septum and mitral valve into the left ventricle, in these patients, lead misplacement was not recognized at the time of implantation and lead malposition was diagnosed a mean of 2 years later. All four patients had right bundle branch block configuration paced complexes. In retrospect, chest X rays suggested atypical lead position in all, but the initial posterioranterior and lateral chest X rays were misinterpreted and contributed to the delay in diagnosis. When lead misplacement in the left ventricle was considered it was confirmed by two-dimensional echocardiography. One patient subsequently presented with a stroke and the remainder were diagnosed when they presented with other unrelated problems. Pacing thresholds were normal at the time of implantation and behaved normally during follow-up. The patient presenting with stroke was anticoagulated and the other three have been managed expectantly without anticoagulafion. Diagnosis of left ventricular lead malposition is not difficult but requires a high index of suspicion. A 12-lead ECC and posterior-anterior and lateral chest X rays after implantation can be diagnostic. Patients with pacing lead in the left ventricle may remain asymptomatic with normal lead function during long-term follow-up. Anticoagulation should be considered when this problem comes to attention for the first time during follow-up.     

Uncomplicated heart and lung perforation by a displaced ventricular pacemaker lead: a case report

Lead perforation is a rare complication of pacemaker implantation and associated with the risk of disastrous results like cardiac tamponade or pneumo-hemothorax. We report a patient in whom a ventricular lead perforated the right ventricle and left lung parenchyma without the development of cardiac tamponade, pneumothorax, or hemothorax. No objective evidence for perforation was found on echocardiographic evaluation and thorax computed tomography has made the definite diagnosis. In the literature available to us, it is the first reported case of an uncomplicated right ventricular and lung parenchymal perforation associated with pacemaker implantation.     

Cerebral Embolism Due to Left Ventricular Pacemaker Lead: Removal with Cardiopulmonary Bypass

Malposition of a cardiac pacemaker lead within the left ventricle represents a source of early and late thromboembolic complications. We report a case of cerebral embolism, caused by an inadvertently misplaced left ventricular electrode, occurring 3 years after implantation. The lead was removed via a transaortic approach with extracorporeal circulation.     

Cardiac tamponade as complication of active-fixation atrial lead perforations: proposed mechanism and management algorithm

BACKGROUND: Cardiac tamponade is a rare complication after implantation of dual chamber pacemaker or defibrillator systems. Its pathophysiology and optimal management are not currently well established. METHODS: Three cases of cardiac tamponade following successful implantation of transvenous dual chamber pacemakers with active-fixation atrial leads were identified. RESULTS: All three patients with post-implant cardiac tamponade were suspected to have the same etiology of bleeding into the pericardial space. This was due to protrusion of the helix of the active-fixation atrial pacing lead through the atrial wall with subsequent abrasion of visceral pericardial layer and bleeding from the atrium through the perforation. In two patients, the perforation sites were visualized and repaired during open thoracotomy in the operating room. The third patient underwent lead repositioning under fluoroscopic guidance in the electrophysiology laboratory. CONCLUSION: Based on the reviewed cases, we describe the pathophysiology of, and recommend a safe conservative algorithm for, the management of cardiac tamponade after successful transvenous lead implantation. Percutaneous pericardiocentesis with placement of the pericardial drain followed by lead repositioning under fluoroscopic guidance with surgical backup appears to be safe and effective.     

永久心脏起搏器植入术后并发症的原因分析及护理对策

目的探讨永久心脏起搏器植入术后并发症及其原因,并总结护理对策。方法回顾分析2005年1月至2007年2月54例永久心脏起搏器植入术患者的临床和护理资料。结果术后发生并发症9例(11例次),发生率为20.4%(11/54),其中电极脱位5例次(45.4%),囊袋积血3例次(27.3%),起搏器感知功能障碍2例次(18.2%),起搏器综合征1例次(9.1%);所有并发症经相应处理后,患者均恢复正常。结论永久心脏起搏器植入术后并发症以电极脱位和囊袋积血为多见;熟悉永久起搏器植入术相关理论知识、术后密切观察和护理,对预防及减少术后并发症的发生有重要作用。     

Inadvertent Left Ventricle Endocardial or Uncomplicated Right Ventricular Pacing: How to Differentiate in the Emergency Department

Background

Temporary transvenous pacemaker implantation is an important and critical procedure for emergency physicians. Traditionally, temporary pacemakers are inserted by electrocardiography (ECG) guidance in the emergency department because fluoroscopy at the bedside in an unstable patient can be limited by time and equipment availability. However, in the presence of atrial septal defect, ventricular septal defect, and patent foramen ovale, the pacemaker lead can be implanted inadvertently into the left ventricle or directly into the coronary sinus instead of right ventricle. Regular pacemaker rhythm can be achieved despite inadvertent implantation of the pacemaker lead into the left ventricle, leading to ignorance of the possibility of lead malposition.

经头静脉双扩张行双腔起搏器安置

目的观察82例按常规经头静脉置入起搏电极失败者,改用经头静脉双扩张法送入起搏电极安置双腔起搏器,探讨该方法的可行性、安全性。方法沿胸大肌与三角肌之间的肌间沟做斜行切口3.5cm。在肌间沟内分离出头静脉,剪开头静脉,送入起搏电极,送入失败者,改用双扩张头静脉方法,分别送入心室和心房电极。结果从头静脉送入起搏电极未成功的82例,改用经头静脉双扩张法送入起搏电极成功75例。其中有7例改用泥鳅钢丝后头静脉扩张成功。成功率为91.4%。未成功的7例改为穿刺锁骨下静脉送入起搏电极。结论经双扩张头静脉送入心室、心房电极安置双腔起搏器,增加了从头静脉送入2根电极的成功率,方法简单、可行。有效地减少因穿刺锁骨下静脉发生的近远期并发症。     

Postpacemaker implant pericarditis: incidence and outcomes with active-fixation leads

Pericarditis has been noted as a potential complication of pacemaker implantation. This study evaluated the risk of developing pericarditis following pacemaker implantation with active-fixation atrial leads. Included were 1,021 consecutive patients (mean age 73.4+/-0.4 years, range 16-101 years; 45.2% women) undergoing new pacemaker system implantation between 1991 and 1999 who were reviewed for the complication of pericarditis. The incidence and outcomes of postimplantation pericarditis in patients receiving active-fixation atrial leads were compared to those not receiving these leads. Of 79 patients who received active-fixation atrial leads, 4 (5%) developed pericarditis postpacemaker implantation. Of 942 patients with passive-fixation atrial leads or no atrial lead (i.e., a ventricular lead only), none developed pericarditis postoperatively (P < 0.001). Of patients receiving active-fixation ventricular leads only (n = 97), none developed pericarditis. No complications were apparent at the time of implantation in patients who developed pericarditis. Pleuritic chest pain developed between 1 and 28 hours postoperatively. Three patients had pericardial rubs without clinical or echocardiographic evidence of tamponade. They were treated conservatively with acetylsalicylic acid or ibuprofen and their symptoms resolved without sequelae in 1-8 days. One patient (without pericardial rub) died due to cardiac tamponade on postoperative day 6. Postmortem examination revealed hemorrhagic pericarditis with no gross evidence of lead perforation. Pericarditis complicates pacemaker implantation in significantly more patients who receive active-fixation atrial leads. It may be precipitated byperforation of the atrial lead screw through the thin atrial wall. Patients developing postoperative pericarditis should befollowed closely due to the risk of cardiac tamponade.     

Particularities of Dual Chamber Pacemaker Therapy in Patients after Orthotopic Heart Transplantation

Since August 1981, 33 orthotopic heart transplantations were performed in our hospital. Three of these patients (9%) had sinus bradycardias with rates as low as 30 beats/min; they were treated by implantation of a dual chamber pacemaker. These patients had two atria as a result of orthotopic heart transplantation, but only the donor atrium was suitable for positioning the atrial lead. In the postoperative period, some nonsurgical complications were observed in one patient who developed atrial fibrillation which we treated with drugs. A cyclosporin-evoked tremor produced several asystoles due to false inhibition by myopotential interference in the VVI mode. During an episode of acute rejection combined with renal insufficiency, loss of atrial and ventricular sensing occurred. The other patients showed no pacemaker-related complications. Our findings in this unique population of pacemaker patients are discussed.     

经胸二维和实时三维超声对人工心脏起搏器电极导线位置的观察

目的比较经胸二维和实时三维超声心动图在人工心脏起搏器电极导线位置定位中的应用价值。方法采用Philips公司Sonos7500型彩色超声心动图仪,经胸二维和实时三维超声心动图观察18例单腔或双腔人工心脏起搏器安置术后起搏电极导线在心腔内的行走路径、导线顶端嵌入位置以及起搏电极与三尖瓣及瓣下结构的关系。结果经胸二维超声能显示大部分患者起搏电极导线及导线顶端位置。经胸实时三维超声能清晰显示绝大部分患者起搏电极导线在心腔内的行走路径、导线顶端位置,更能立体直观显示电极导线与三尖瓣及瓣下结构的关系,结合实时三维彩色血流显像技术可观察有无三尖瓣返流及返流是否与电极导线有关。结论经胸二维和实时三维超声心动图作为对起搏器安置术后患者的随访观察有肯定的临床应用价值,实时三维超声较二维超声能更直观、准确地显示起搏电极导线在心腔内的位置、周邻关系及所致三尖瓣活动的改变,可望广泛应用于临床。     

Recurrent Pulmonary Embolization Following Implantation of Transvenous Pacemaker

A 44-year-old man developed recurrent pulmonary embolization after implantation of a permanent transvenous DVI pacemaker connected to polyurethane leads. Thrombus was found in the left innominate and subclavian veins around the pacemaker leads, but not in the right atrium or in the venous system of the pelvis and the lower extremities. The recurrence of pulmonary embolization followed discontinuation of treatment with Coumadin. This case demonstrates that lifelong anticoagulation is indicated in patients who have had pulmonary embolization and/or venous thrombosis around the pacemaker leads.     

Serial Lead Impedance Measurements Confirm Fixation of Helical Screw Electrodes During Pacemaker Implantation

The purpose of this study was to determine whether serial measurements of helical screw pacemaker lead impedance could reliably confirm electrode fixation in the right atrium and right ventricle. Fixation is generally assessed fluoroscopically, which can be misleading because the myocardium is radio lucent. Alternatively, because the electrical conductivity of blood is greater than that of myocardium, serial measurements of the lead impedance might be expected to show an impedance increase with appropriate fixation of the pacemaker electrode when the electrode becomes embedded in myocardial tissue. Impedance measurements were made during the placement of 23 atrial and 28 ventricular active fixation electrodes in 31 consecutive patients. Impedance measurements were recorded in unipolar and bipolar electrode configurations with the electrode free floating in the chamber, unfixed (with exposed screws) but touching the endocardial surface, and after fixation. No significant impedance differences were found between free-floating and unfixed electrode positions. With fixation, the lead impedance increased significantly in the ventricle (P = 0.0001, unipolar and bipolar) and the atrium (P = 0.0069 unipolar and 0.0052 bipolar). Typical increases, reflected by median values, were 197 ohms unipolar and 203 ohms bipolar in the ventricle and 47 ohms unipolar and 53 ohms bipolar in the atrium for electrodes with permanently exposed or retractable screw designs. Comparing serial measurements of lead impedance before and after electrode fixation is a valid electrical method of confirming appropriate fixation of helical screw electrodes.     

Safety of Implantation of a Leadless Pacemaker via Femoral Approach in the Presence of an Inferior Vena Cava Filter

A 61‐year‐old woman with symptomatic complete heart block was referred for permanent pacemaker. The presence of a left‐sided arteriovenous fistula and right‐sided mastectomy with lymph node dissection precluded the implantation of a transvenous pacemaker, and therefore, a leadless pacemaker was recommended. The patient also had an inferior vena cava (IVC) filter. The passage of a 27‐French introducer sheath housing the leadless pacemaker through IVC filter was carefully visualized under fluoroscopy and advanced to the right ventricle without any compromise to the filter. This case report shows the safety of passage of large sheaths via the IVC filter.