Removal of Endocardial Defibrillation Leads

Two patients, each with an endocardial defibrillation lead system (Endotak O62), required lead removal; one because of chronic lead infection and the second because of spurious shocks caused by lead insulation damage. Neither lead could be removed by simple traction. The defective lead was removed by a combination of catheterization techniques including a steerable ablation catheter and traction, both under general anesthesia. The lead with the insulation defect was rapidly removed with a locking stylet, suggesting that endocardial lead defibrillating leads can be removed similarly to pacemaker leads, thus avoid thoracotomy.     

Effects of a Thin-Sized Lead Body of a Transvenous Single Coil Defibrillation Lead on ICD Implantation

SCHUCHERT, A., et al. : Effects of a Thin‐Sized Lead Body of a Transvenous Single Coil Defibrillation Lead on ICD Implantation. In the interest of patients receiving implantable cardioverter defibrillators (ICDs), the clinical benefits of newer and thinner transvenous defibrillation leads have to be determined. The aims of this study were to evaluate the ICD procedure duration and the frequency of lead dislocation at the 3‐month follow‐up of a new defibrillation lead with a thin‐sized lead body and its conventionalsized predecessor. The thin‐sized single coil defibrillation lead (Kainox RV, Biotronik; lead body 6.7 Fr) was implanted in 61 patients and the conventional‐sized defibrillation lead (SPS, Biotronik; lead body 7.8 Fr) in 60 patients. Both leads were connected to a left‐sided, prepectorally implanted Phylax ICD (Biotronik) with active housing. The lead implantation time and total procedure duration were determined. Lead implantation time was defined as the time from lead insertion to the end of the pacing measurements. The total procedure duration spanned skin incision to closure. The incidence of lead repositioning during the lead implantation time and during ventricular fibrillation conversion testing was also assessed. The frequency of lead dislocations was recorded at the 3‐month follow‐up. Mean lead implantation time and total procedure duration of the thin‐sized lead (23 ± 22 minutes 76 ± 37 minutes ) were not statistically different from the time needed for the conventional‐sized lead (22 ± 20 minutes 81 ± 34 minutes ). The number of lead repositionings during the lead implantation time was similar (thin‐sized lead: 1.4 ± 2.4 ; conventional‐sized lead: 1.1 ± 1.9 ). An additional lead repositioning was not necessary during ventricular fibrillation conversion testing in 93.4% of the patients with thin‐sized and in 94.4% with conventional‐sized leads (not significant). At the 3‐month follow‐up, there were four (6.6%) lead dislocations in the thin‐sized and four (6.7%) in the conventional‐sized lead group. In conclusion, the downsized lead body of the new defibrillation lead influenced neither ICD procedure duration nor the incidence of lead dislocation during follow‐up.     

Failure of Defibrillator Paddle as Mimic for Subcutaneous Patch Lead During Nonthoracotomy Implantable Cardioverter Defibrillator Lead Configuration Assessment

It is a common, although virtually unsubstantiated, practice to assess the efficacy of nonthoracotomy lead systems for implantable cardioverter defibrillators using a defibrillator paddle as mimic for the subcutaneous patch lead. We report a case in which an adequate defibrillation threshold was documented with the nonthoracotomy lead system using a defibrillator paddle but not following implantation of the true subcutaneous patch lead. This case suggests that the substitution of a defibrillator paddle for the subcutaneous patch lead during nonthoracotomy lead system evaluation may have significant limitations in assessing lead configuration efficacy.     

Effect of a Single Element Subcutaneous Array Electrode Added to a Transvenous Electrode Configuration on the Defibrillation Field and the Defibrillation Threshold

Even with the use of biphasic shocks, up to 5% of patients need an additional subcutaneous lead to obtain a defibrillation safety margin of at least 10 J. The number of patients requiring additional subcutaneous leads may even increase, because recent generation devices have a < 34 J maximum output in order to decrease their size. In 20 consecutive patients, a single element subcutaneous array lead was implanted in addition to a transvenous lead system consisting of a right ventricular (RV) and a vena cava superior lead using a single infraclavicular incision. The RV lead acted as the cathode; the subcutaneous lead and the lead in the subclavian vein acted as the anode. The biphasic defibrillation threshold was determined using a binary search protocol. Patients were randomized as to whether to start them with the transvenous lead configuration or the combination of the transvenous lead and the subcutaneous lead. In addition, a simplified assessment of the defibrillation field was performed by determining the interelectrode area for the transvenous lead only and the transvenous lead in combination with the subcutaneous lead from a biplane chest X ray. The intraoperative defibrillation threshold was reconfirmed after 1 week, after 3 months, and after 12 months. The mean defibrillation threshold with the additional subcutaneous lead was significantly (P = 0.0001) lower (5.7 ± 2.9 J) than for the transvenous lead system (9.5 ± 4.6 J). With the subcutaneous lead, the impedance of the high voltage circuit decreased from 48.9 ± 7.4 Ω to 39.2 ± 5.0 Ω. In the frontal plane, the interelectrode area increased by 11.3%± 5.5% (P < 0.0001) and in the lateral plane by 29.5%± 12.4% (P < 0.0001). The defibrillation threshold did not increase during follow-up. Complications with the subcutaneous electrode were not observed during a follow-up of 15.8 ± 2 months. The single finger array lead is useful in order to lower the defibrillation threshold and can be used in order to lower the defibrillation threshold.     

Chronic lead exposure: a problem for minority workers

1. Despite regulatory and case identification efforts, lead exposure continues to pose a major health problem for minority workers. 2. Minority workers are overrepresented in lead industries such as lead smelting, lead storage batteries, lead pigment production and pottery. 3. Preliminary data from recently instituted lead registries in California and Texas suggest that minority workers continue to be overexposed to lead. 4. A federal policy that strengthens enforcement of the OSHA lead standard is needed to reduce lead exposure among minority workers.     

Self-Entwinement of an Active Fixation Pacemaker Electrode

We report a case in which an active fixation atrial lead tip became entwined on the proximal lead body during implantation. It was not possible to disengage the tip or to remove the resultant lead loop atraumatically through the insertion site. Removal of the lead was accomplished using a Dotter intravascular snare inserted via a femoral vein, with subsequent successful implantation of a new lead. This unusual technique-related complication emphasizes the need for meticulous fluoroscopic visualization during lead manipulation.     

Late Complications in Patients with Pectoral Defibrillator Implants with Transvenous Defibrillator Lead Systems: High Incidence of Insulation Breakdown

As the majority of ICDs with transvenous leads are now implanted in tbe pectoral region, complications associated with the technique are being identified. To determine the incidence of lead complications in patients with transvenous defibrillator leads and ICDs implanted in the pectoral region, 132 unselected consecutive patients with transvenous defibrillator leads had ICDs implanted in the pectoral region. Three lead systems were used:(1) lead system 1(45 patients) consisted of a transvenous pacing sensing lead and a superior vena cava coil with a submuscular patch used for defibrillation;(2) lead system 2(36 patients) utilized a CPI Endotak lead system: and(3) lead system 3(51 patients) utilized a Medtronic Transvene lead system. Patients were followed for 3–54 months(cumulative 2,269, mean 18 months). The average duration of follow-up with the three systems was 32, 12, and 11 months, respectively. At 30 months follow-up, all three lead systems had a low incidence of complications. However, there was a 13% overall incidence(45% actuarial incidence) of erosion of the insulation of the pacing sensing lead of system 1 at 50 months of follow-up. All lead complications were seen in patients with ICDs whose weights were > 195 g and volumes > 115 cc. The erosion was probably a consequence of the pressure by the large ICD against the lead in the pectoral pocket. Follow-up with lead systems 2 and 3 is relatively short(average 12 months) but no lead erosions were seen. Pectoral implantation of ICDs with long transvenous leads and large generators is associated with a moderate risk of late complications in the form of insulation breaks caused by pressure of the generator against the leads. The use of less redundant leads coupled with smaller ICDs will probably eliminate this complication.     

环境铅污染与难治性佝偻病

近年来 ,环境铅污染对儿童健康的危害已引起了人们的广泛关注。现介绍环境铅污染的来源、儿童铅代谢的特点以及我国儿童目前的血铅水平 ,从铅对维生素D、钙磷代谢及成骨细胞的影响等方面阐明铅对儿童骨代谢的作用机制 ,指出了环境铅污染可能是我国儿童佝偻病高发病率及常规治疗效果不佳的原因之一 ,并提出了儿童铅危害的主要防治措施。     

Modeling the effect of succimer (DMSA; dimercaptosuccinic acid) chelation therapy in patients poisoned by lead

Context: Kinetic models could assist clinicians potentially in managing cases of lead poisoning. Several models exist that can simulate lead kinetics but none of them can predict the effect of chelation in lead poisoning. Our aim was to devise a model to predict the effect of succimer (dimercaptosuccinic acid; DMSA) chelation therapy on blood lead concentrations.

Materials and methods: We integrated a two-compartment kinetic succimer model into an existing PBPK lead model and produced a Chelation Lead Therapy (CLT) model. The accuracy of the model’s predictions was assessed by simulating clinical observations in patients poisoned by lead and treated with succimer. The CLT model calculates blood lead concentrations as the sum of the background exposure and the acute or chronic lead poisoning. The latter was due either to ingestion of traditional remedies or occupational exposure to lead-polluted ambient air. The exposure duration was known. The blood lead concentrations predicted by the CLT model were compared to the measured blood lead concentrations.

Results: Pre-chelation blood lead concentrations ranged between 99 and 150?μg/dL. The model was able to simulate accurately the blood lead concentrations during and after succimer treatment. The pattern of urine lead excretion was successfully predicted in some patients, while poorly predicted in others.

Conclusions: Our model is able to predict blood lead concentrations after succimer therapy, at least, in situations where the duration of lead exposure is known.     

Predictors of Fracture Risk of a Small Caliber Implantable Cardioverter Defibrillator Lead

Introduction: The Sprint Fidelis 6949 implantable cardioverter defibrillator (ICD; Medtronic Inc., Minneapolis, MN, USA) lead has a high rate of fracture. Identification of predictors of subsequent fracture is useful in decision making about lead replacement and for future lead design. We sought to determine if there are clinical, procedural, or radiological features associated with a greater risk of subsequent lead fracture. Methods: Patients with Sprint Fidelis 6949 lead fractures (Fracture group) were identified from our institutional database. Each patient in the Fracture group was matched to two controls, immediately preceeding and succeeding Sprint Fidelis 6949 implant. Clinical and procedural characteristics were compared. Chest radiographs performed 2 weeks after ICD implant were reviewed by an observer blinded to outcomes. The following features were assessed: ICD tip location, lead slack, kinking of the lead body (≥90°), and presence of lead “crimping” within the anchoring sleeve. Results: Twenty‐six patients with Sprint Fidelis 6949 lead fractures were identified and were matched to 52 control patients. On univariate analysis, a higher left ventricular ejection fraction (LVEF), prior ipsilateral device implant, history of prior ICD lead fracture, and noncephalic venous access were associated with risk of lead fracture. On multivariate analysis, a higher LVEF was the only independent predictor of lead fracture (P = 0.006). Radiological features were similar between the two groups. Conclusions: In this study, a higher LVEF was associated with a greater risk of lead fracture in patients with Sprint Fidelis 6949 ICD leads. Radiographic features did not predict subsequent risk of lead fracture in our population. (PACE 2010; 437–443)     

Permanent Interatrial Septal Pacing: Feasibility and Advantages

One hundred eighty-nine implanted atrial pacing leads have been analyzed. A double screw-in active fixation lead was attached to the interatrial septum in eight patients and a J lead in one patient. The right atrial appendage was the site used in the 97 other patients with a double screw-in lead; a J-shaped lead was used in three and an anchored (active fixation) lead in the remaining 80 patients. Though pacing from the interatrial septum has different characteristics of lead stability, it offers a number of advantages over right atrial appendage stimulation.     

Blood lead levels in the United States “Oldest-Old” population

Context. Previous studies have suggested significant endogenous lead release from bony stores in the elderly raising the concern for elevated blood lead levels in that population. Objective. We undertook to determine the range of blood lead levels in the “oldest-old” population, a demographic category that includes persons aged 80 years and older. Materials and methods. We analyzed blood lead level data from the National Health and Nutrition Examination Survey (NHANES) for the years 1999–2010 for persons aged 80 years and older. We also screened an inner-city population of patients aged 80 years of age and older presenting to an emergency department. Results. Among persons aged 80 years and older sampled in the NHANES surveys, the geometric mean blood lead level each year varied from 1.98 to 2.66 mcg/dL. Of the 2,168 measured blood lead levels, only 15 samples (0.69%) exceeded our a priori definition of an elevated blood lead level (greater than 10 mcg/dL). Of those 15 samples, the highest blood lead level was 15.3 mcg/dL. For our screening of an inner-city oldest-old population, we enrolled 76 subjects and found a geometric mean blood lead level of 1.72 mcg/dL. Discussion. Several considerations place elderly persons at a theoretically increased risk of elevated blood lead level, including previously documented birth cohort effect for blood lead levels with older cohorts having higher mean blood lead levels and concern for endogenous lead exposure due to release of lead from bony stores. However, our statistical analysis of NHANES data and screening of an inner-city oldest-old population suggests that elevated blood lead levels in this population are rare. Conclusion. Routine blood lead level screening in the elderly is not indicated.     

某蓄电池厂铅作业工人尿铅检测分析

[目的]了解某蓄电池厂职业性铅危害情况，探索职业卫生预防模式。[方法]收集481名铅作业工人晨尿，按照WS／T17—1996方法进行尿铅检测。参照GBZ37—2002（（职业性慢性铅中毒诊断标准》，尿铅〉10．07mg／L为超标（即观察对象限值），比较不同车间、性别的尿铅超标率差异。[结果]481名铅作业工人尿铅均数为（0．077±0．099）mg／L，超标人数92人，超标率为19．13％。外销组、成品车间的工人尿铅超标率分别为6．78％、23．14％，其超标率差异有统计学意义（t〈0．05）。男女工人尿铅超标率分别为21．00％和14．49％，但差异无统计学意义（t〉0．05）。[结论]某蓄电池厂铅作业工人尿铅超标明显，男性工人尿铅超标率高于女性。该厂铅作业工人受铅危害影响情况较重，工作场所中高浓度的铅烟、铅尘是造成铅作业工人血铅、尿铅含量增加的重要因素，该厂应进行工艺改革，采取有效措施控制铅污染，定期进行职业健康检杏，以及时发现问题，预防铅中毒的发生。     

Incidence and significance of pacemaker and implantable cardioverter-defibrillator lead masses discovered during transesophageal echocardiography

Background: Pacemaker and implantable cardioverter‐defibrillator device infections are feared complications. The finding of a lead‐associated mass on transesophageal echocardiogram (TEE) raises concern for endocarditis. However, the incidence and clinical importance of lead masses is not currently known. Methods: Consecutive patients with transvenous leads undergoing TEE from July 1, 2003, to June 30, 2005, were identified and assessed for a clinical diagnosis of endocarditis. An echocardiographer blinded to clinical information reviewed all TEEs. Results: Of 177 TEEs performed on 153 patients, a visible mass on a device lead was observed in 25 (14%), including 11 TEEs showing a lead vegetation, 13 TEEs showing lead strands, and one study showing both. Seventeen patients were adjudicated to have endocarditis, of which eight had a mass seen on a lead during TEE. Thus, 72% of patients (18 of 25) with a lead‐associated mass did not have evidence of an infection. In TEEs performed for indications other than to rule out endocarditis, lead masses were seen in 13 of 136 studies (10%), with only one patient adjudicated to clinically have an infected device. Conclusion: During this 2‐year study of consecutive patients with a tranvenous lead undergoing TEE, lead‐associated masses were found in 14% of patients. In 72% of patients, the mass did not prove to be secondary to infectious causes. Thus, masses attached to a device lead should be interpreted in the overall clinical context and, in the absence of concomitant evidence of endocarditis, should not mandate device and lead removal. (PACE 2011; 679–683)     

Pseudo-fracture of Pacemaker Lead Due to Securing Suture: A Case Report

With improved pacemaker lead design and materials, complications caused by lead problems have decreased.^4,5 There have been isolated reports of leads severed by suture material but they have been rare. Presented is a case of suture-induced "pseudo-fracture" in a urethane-insulated ventricular lined endocardial lead (Medtronic Model #6971-58). No loss of capture or sensing function has been encountered eight months following initial implantation. It is felt that the softer, stronger urethane permitted compression and resulted in a radiographic suggestion of a fractured lead, but lead integrity does not seem to have compromised. Although (his may be an inconsequential radiographic finding, it could lead to an inappropriate lead removal unless it is properly interpreted. (PACE, Vol. 4, November-December, 1981)     

Chronic Atrial Lead Explantation Using a Staged Percutaneous Laser and Open Surgical Approach

We report a staged approach to the explantation of a passive fixation atrial lead 4 years after implantation in a patient with extracardiac J wire protrusion. The body of the lead, from the venous entry site to the proximal electrode, was freed from extensive fibrous binding using an investigational Excimer laser lead extraction sheath. The distal end and J wire were freed and the lead was removed at thoracotomy. This staged approach offered a safe and effective method for the removal of a heavily fibrosed chronic endocardial lead.     

Impact of Transvenous Lead Position on Active-Can ICD Defibrillation: A Computer Simulation Study

Optimizing lead placement in transvenous defibrillation remains central to the clinical aspects of the defibrillation procedure. Studies involving superior vena cava (SVC) return electrodes have found that left ventricular (LV) leads or septal positioning of the right ventricular (RV) lead minimizes the voltage defibrillation threshold (VDFT) in endocardial lead→SVC defibrillation systems. However, similar studies have not been conducted for active-can configurations. The goal of this study was to determine the optimal lead position to minimize the VDFT for systems incorporating an active can. This study used a high resolution finite element model of a human torso that includes the fiber architecture of the ventricular myocardium to find the role of lead positioning in a transvenous LEAD→can defibrillation electrode system. It was found that, among single lead systems, posterior positioning of leads in the right ventricle lowers VDFTs appreciably. Furthermore, a septal location of leads resulted in lower VDFTs than free-wall positioning. Increasing the number of leads, and thus the effective lead surface area in the right ventricle also resulted in lower VDFTs. However, the lead configuration that resulted in the lowest VDFTs is a combination of a mid-cavity right ventricle lead and a mid-cavity left ventricle lead. The addition of a left ventricular lead resulted in a reduction in the size of the low gradient regions and a change of its location from the left ventricular free wall to the septal wall.     

The impact of the right ventricular lead position on response to cardiac resynchronization therapy

Introduction: Left ventricular (LV) lead placement to the latest contracting area (concordant LV lead) is associated with better response to cardiac resynchronization therapy (CRT) compared to a discordant LV lead. However, the effect of the right ventricular (RV) lead site on CRT response is unclear. We investigated the relationship of the RV and LV lead positions on CRT response. Methods: In 131 CRT patients, the LV lead was positioned preferentially in a lateral or posterolateral vein and the RV lead to either the RV septum (RVS, n = 55) or RV apex (RVA, n = 76). The latest site of contraction was determined with two‐dimensional speckle tracking radial strain imaging and patients had a concordant LV lead position if pacing the latest segment, and discordant if not. Response was defined as ≥15% reduction in LV end systolic volume (LVESV) at 6‐month follow‐up. Results: There were no significant differences in mean reduction of LVESV at follow‐up (RVS vs RVA: ?23.3 ± 16% vs 22.1 ± 18%, P = 0.70) or rate of responders (58.2% vs 57.9%, P = 0.97) between the two groups. In patients with a concordant LV lead (n = 71), the response rate was significantly higher than those with a discordant lead (76.1% vs 36.7%, P < 0.001). There were no differences in outcomes in patients with a concordant or discordant LV lead according to the RV lead location. Conclusion: The extent of LV reverse remodeling following CRT is not related to the RV lead position, but is significantly higher in patients with a concordant LV lead. (PACE 2011; 34:467–474)     

Late Manifestation of Coronary Sinus and Left Atrial Perforation of a Left Ventricular Pacemaker Lead at Extraction

A 56‐year‐old man presented for lead extraction of a left ventricular (LV) lead that had been deactivated due to hiccups and of a right ventricular (RV) lead with a high threshold. Pus was noted upon entering the pocket. The right atrial and RV leads were extracted, but traction on the LV lead caused ischemia and was not performed. An echocardiogram demonstrated the lead in the left atrium and a robotic‐assisted thoracotomy was used to remove the lead that had unroofed the coronary sinus, gone into the left atrium, and perforated through the free wall into the pericardium.     

Evaluation of Electrocardiographic Leads for Detection of Atrial Activity (P Wave) in Ambulatory EGG Monitoring: A Pilot Study

The usual lead systems for ambulatory ECG monitoring (AECG) used in the evaluation of arrhythmias is a modified bipolar V-1 and V-5. A comparison of various lead systems to enhance the detection of atrial activity (p waves) has not been reported. We evaluated various surface lead systems in 12 subjects comparing p waves recorded at 20 mm/mV and 50 mm/sec. We compared p wave area, amplitude, and duration from modified bipolar V1 and V5 as well as seven nonstandard leads recorded on a AECG monitor. Of the seven nonstandard leads, a vertical sternal lead, with the negative pole just below the suprasternal notch and the positive pole at the xiphoid process, had the largest area (1.46 +/- 0.65 mm2), and also had a greater area than the standard V1 (0.88 +/- 0.45 mm) and V5 (1.06 +/- 0.49 mm2) lead system (P less than 0.01). We conclude that the bipolar vertical sternal lead system provides a larger p wave area than seven nonstandard bipolar lead systems and the two standard lead systems currently used in AECG monitoring. Replacement of the modified bipolar V1 lead with a vertical sternal lead should improve the recognition of atrial activity and, therefore, enhance the diagnosis of cardiac arrhythmias.