Three-Dimensional Analysis of the In Vivo Motion of Implantable Cardioverter Defibrillator Leads

Better understanding of the lead curvature, movement and their spatial distribution may be beneficial in developing lead testing methods, guiding implantations and improving life expectancy of implanted leads. Objective The aim of this two-phase study was to develop and test a novel biplane cine-fluoroscopy-based method to evaluate input parameters for bending stress in leads based on their in vivo 3D motion using precisely determined spatial distributions of lead curvatures. Potential tensile, compressive or torque forces were not subjects of this study. Methods A method to measure lead curvature and curvature evolution was initially tested in a phantom study. In the second phase using this model 51 patients with implanted ICD leads were included. A biplane cine-fluoroscopy recording of the intracardiac region of the lead was performed. The lead centerline and its motion were reconstructed in 3D and used to define lead curvature and curvature changes. The maximum absolute curvature Cmax during a cardiac cycle, the maximum curvature amplitude Camp and the maximum curvature Cmax@amp at the location of Camp were calculated. These parameters can be used to characterize fatigue stress in a lead under cyclical bending. Results The medians of Camp and Cmax@amp were 0.18 cm−1 and 0.42 cm−1, respectively. The median location of Cmax was in the atrium whereas the median location of Camp occurred close to where the transit through the tricuspid valve can be assumed. Increased curvatures were found for higher slack grades. Conclusion Our results suggest that reconstruction of 3D ICD lead motion is feasible using biplane cine-fluoroscopy. Lead curvatures can be computed with high accuracy and the results can be implemented to improve lead design and testing.

Who to Test? A Retrospective Study of Lead Testing in High-Risk Children

Background Nearly all pediatric patients in our setting meet high-risk criteria for lead exposure based on screening recommendations and guidelines. Implementation of screening and testing has been inconsistent. Objective To assess the utility and efficacy of performing universal lead testing between ages 1 and 5 at an urban academic pediatric practice. Methods Retrospective review of patients with routine lead testing between 2010 and 2015. Key variables included demographics, serum lead level, and behavioral diagnoses. Results A total of 6597 serum lead levels from 3274 patients were reviewed. Forty-seven samples (0.7%) from 24 patients (0.7%) were elevated. Of the 24 patients with elevated lead, 75% were identified at age 1 or 2. Sixty-seven percent of patients with first elevated lead level at age 3 or older had a diagnosis of developmental delay. Conclusion Routine testing of high-risk patients yielded minimal specificity in identifying elevated lead levels, especially in patients older than 3 years and without developmental delay.

Effects of Individual and Neighborhood Characteristics on Childhood Blood Lead Testing and Elevated Blood Lead Levels, A Pennsylvania Birth Cohort Analysis

Background: Despite declining lead exposure among U.S. children, childhood blood lead level (BLL) undertesting and elevation remains a public health issue. This study explores the impacts of maternal, infant, and neighborhood characteristics on the receipt of lead testing and having elevated BLLs (EBLLs) among children under age two. Methods: Pennsylvania infants born in 2015 and 2016 were followed to 24 months. Birth certificate data were linked to 2015 through 2018 blood lead surveillance data and neighborhood data on household income, poverty, and the burden of houses built before 1970. Generalized linear mixed models were used to examine the individual and neighborhood characteristics independently and/or interactively affecting the likelihood of lead testing and of having EBLLs. Results: A total of 48.6% of children were tested for BLLs, and 2.6% of them had confirmed EBLLs. The likelihood of lead testing and of having EBLLs among non-Hispanic black children was respectively 7% and 18% higher than white children. Children born to mothers with the lowest educational attainment (<high school), with self-payment as a payment source for delivery, and without WIC enrollment were at higher risk of undertesting. Children living in neighborhoods of the lowest quartile of household income and the highest quartile of poverty and old housing were more likely to have EBLLs. Different neighborhood characteristics modified the associations between some individual factors (such as race/ethnicity, payment source for delivery, and WIC enrollment) and the odds of undertesting and of having EBLLs. Conclusion: This cohort analysis provides more accurate estimates of lead screening rates and the percentages of EBLLs than cross-sectional analysis. Some maternal and infant demographics significantly impact the risk of undertesting and of having EBLLs, and some of the effects vary across different neighborhood characteristics. These findings can help lead prevention programs to target screening and treatment resources to children with specific characteristics.

Twiddler’s syndrome with occult lead insulation damage in a child with epicardial pacemaker leads

We present a rare case of incidentally diagnosed Twiddler’s syndrome in a child 7 years after implantation of a dual-chamber pacemaker system with epicardial leads. During revision, an insulation defect of the ventricular lead was evident, despite unremarkable prior pacemaker lead testing. The lead was repaired and a new generator was suture-fixated to prevent re-occurrence of generator manipulation.

Policy Changes and Child Blood Lead Levels by Age 2 Years for Children Born in Illinois, 2001–2014

Objectives. To evaluate how lowering the blood lead level (BLL) intervention threshold affects childhood lead testing policy. Methods. We geocoded 4.19 million Illinois lead testing records (2001–2016) and linked to 2.37 million birth records (2001–2014), data on housing age, industrial emissions, and roads. We used multinomial logistic regression to determine predictors of BLLs of 10 micrograms per deciliter (µg/dL) or greater, 5 to 9 µg/dL, and 4 µg/dL. Results. We found that 2.2% of children had BLLs of 10 µg/dL or greater, 8.9% had BLLs of 5 to 9 µg/dL, and 5.7% had BLLs of 4 µg/dL. Pre-1930 housing was associated with more than 2- to 4-fold increased relative risk of BLLs above all thresholds. Housing built in 1951 to 1978 was associated with increased relative risk of BLLs of 5 to 9 µg/dL (relative risk ratio [RRR] = 1.14; 95% confidence interval [CI] = 1.06, 1.21) but not with increased relative risk of BLLs of 10 µg/dL or greater (RRR = 0.99; 95% CI = 0.84, 1.16). At a given address, previous BLLs of 5 to 9 µg/dL or BLLs of 10 µg/dL or greater were associated with increased risk of BLLs of 5 to 9 µg/dL or BLLs of 10 µg/dL or greater among current occupants by 2.37- (95% CI = 2.20, 2.54) fold and 4.08- (95% CI = 3.69, 4.52) fold, respectively. Conclusions. The relative importance of determinants of above-threshold BLLs changes with decreasing intervention thresholds. Public Health Implications. States may need to update lead screening guidelines when decreasing the intervention threshold.

P2859Low rates of mechanical failures of silicone-polyurethane copolymer-coated ICD leads: 11 years prospective follow-up

Background High rates of ICD lead mechanical failures (insulation abrasion and conductor fracture) resulted in FDA recalls and substantial design modifications. Most subsequent reports of lead failures of newer generation leads are based upon modest-sized, retrospective cohorts with relatively brief follow-up and may be unreliable. Following lead modifications (including silicone-polyurethane copolymer insulation coating), in 2007, one manufacturer established 3 prospective registries, and engaged a university-based methods center to independently review the registries, to adjudicate all reports of lead failures and to independently analyze lead survival. Up to 11 years of follow-up is now available. Purpose To adjudicate all reports of leads inactivated because of possible mechanical failure and to independently calculate rates of mechanical failure overall and by specific type. Methods Manufacturer expert staff confirm each lead inactivation by site interrogation. Following formal algorithms which incorporate lead testing and remote monitoring, they designate all-cause mechanical failure (fracture; insulation abrasion; failure at crimp, bond or weld; or uncertain) based upon the finding of electrical noise, very low or very high or rapidly rising impedance or alternatively they designate non-mechanical dysfunction (e.g. no impedance criteria but elevated thresholds, over or under sensing). The results of returned product analyses are incorporated when available (31%). The methods center receives electronic data transfers twice yearly, reviews all documentation, adjudicates all instances of possible lead failure, assigns probable cause (by 2 electrophysiologists) and conducts independent analyses of lead survival. Results 10,866 patients (73% male, mean age 65.9 yr., LVEF 29.3%, NYHA class II or III 89%) with 11,132 leads had follow-up of 4.6 yr. (median) and 11 yr. (maximum) (Aug 31, 2018). Lead follow-up was censored at the time of lead inactivation, death/transplant or administrative withdrawal. Of leads enrolled, there were 26.6% still in follow-up and of those not the status was 7.4% inactivated, 29.5% death or transplant, 33.8% administrative withdrawal and 3.7% reason missing. Following adjudication, there were 156 all-cause mechanical failures (1.40% total, 0.29%/yr.). Rates of cause-specific mechanical failures were: fracture 1.02% total, 0.22%/yr.; insulation abrasion 0.28% total, 0.06%/yr.; miscellaneous/uncertain 0.12% total, 0.02%/yr.; and externalized conductors 0%. Life-table rates of freedom from lead failure by 11 years were: all-cause mechanical failure 95.9%, conductor fracture 97.0%, insulation abrasion 99.1%, mechanical failure other/uncertain type 99.9%, and externalized conductors 100%. Conclusions Up to 11 yr prospective follow-up of silicone-polyurethane-coated ICD leads with independent adjudication and analyses of events shows low rates of all-cause mechanical failure and no externalized conductors. Acknowledgement/Funding Abbott