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PubMed2002

Lead poisoning among young children in Russia: concurrent evaluation of childhood lead exposure in Ekaterinburg, Krasnouralsk, and Volgograd.

The Gore-Chernomyrdin Commission encouraged a binational collaboration to evaluate pediatric lead poisoning in Russia. The study evaluated children in three Russian cities: Krasnouralsk, a small city with minimal traffic centered around a copper smelter; and Ekaterinburg and Volgograd, both of which are large cities with multiple factories and heavy vehicular traffic. This project was the first international use of portable blood lead analysis instruments. In each city, at least 90% of children attending selected neighborhood kindergartens participated. We selected kindergartens on the basis of their proximity to industrial areas and major traffic corridors. We obtained capillary blood samples and analyzed for lead content and hemoglobin (Hgb) levels in the field, and collected environmental samples (i.e., indoor dust, tap water, play area soil, and interior and exterior paint) and analyzed for each participating school and in the homes of about 10% of the children who had elevated blood lead levels (BLLs; greater than or equal to 10 microg/dL). We calculated all age-, sex-, and city-specific geometric means using generalized estimating equations to account for covariance within kindergartens, and used multivariate logistic regression models to identify variables predictive of elevated BLLs. Overall, 23% of study children had elevated BLLs and 2% were anemic, defined as Hgb < 11 g/dL. Krasnouralsk had the highest geometric mean BLL (10.7 microg/dL), the highest percentage of children (60%) with elevated BLLs, and the highest percentage of anemic children (4%). All soil samples in Krasnouralsk had detectable lead levels. Volgograd was the only city that had paint samples with elevated lead levels. We found apparent city-specific differences in the percentages of children with elevated BLLs. Lead-contaminated soil and dust, which can result from lead-based automotive fuel and from lead-related industrial emissions, appear to be the most important routes of lead exposure of those evaluated in this study. Elevated lead levels found in paint samples from Volgograd may indicate old undercoats of lead-based paint that could represent a regionally rather than nationally important source of exposure.

Anemia↗
PubMed1994

Lead alters the immunogenicity of two neural proteins: a potential mechanism for the progression of lead-induced neurotoxicity.

Some heavy metals have been suspected of playing a role in the pathogenesis of nervous system diseases such as multiple sclerosis, amyotrophic lateral sclerosis, and Alzheimer's disease. In these disorders, autoantibodies against neural proteins are evident at some stage of the disease. Lead is known to affect both the immune and nervous systems. Work in our laboratory has shown that lead exposure leads to the production of autoantibodies against neural proteins, including myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP). We hypothesize that lead aggravates neurological disease by enhancing the immunogenicity of nervous system proteins, including MBP and GFAP. To test this hypothesis, lead-altered protein was prepared by incubating MBP or GFAP with lead acetate for 24 hr. On days 0, 14, and 28, mice received inoculations with either saline, native protein, or lead-altered protein. Anti-MBP and anti-GFAP, isotypes IgM and IgG, were measured in sera by ELISA on day 38. Sera of mice treated with lead-altered MBP had statistically higher anti-MBP IgG titers than both control and native MBP-immunized mice. An analogous response was seen in mice immunized with lead-altered GFAP. Supernatants from lectin-stimulated splenocytes were also examined for antibody titers and for interleukin 2 (IL-2) and interleukin 6 (IL-6) levels. A significant increase in IL-6 production was seen in mice immunized with lead-altered MBP but not with lead-altered GFAP. No changes were observed in the IL-2 levels of mice immunized with either lead-altered protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1998

Interaction of blood lead and delta-aminolevulinic acid dehydratase genotype on markers of heme synthesis and sperm production in lead smelter workers.

The gene that encodes gamma-aminolevulinic acid dehydratase (ALAD) has a polymorphism that may modify lead toxicokinetics and ultimately influence individual susceptibility to lead poisoning. To evaluate the effect of the ALAD polymorphism on lead-mediated outcomes, a cross-sectional study of male employees from a lead-zinc smelter compared associations between blood lead concentration and markers of heme synthesis and semen quality with respect to ALAD genotype. Male employees were recruited via postal questionnaire to donate blood and urine for analysis of blood lead, zinc protoporphyrin (ZPP), urinary coproporphyrin (CPU), and ALAD genotype, and semen samples for semen analysis. Of the 134 workers who had ALAD genotypes completed, 114 (85%) were ALAD1-1 (ALAD1) and 20 (15%) were ALAD1-2 (ALAD2). The mean blood lead concentrations for ALAD1 and ALAD2 were 23.1 and 28.4 microg/dl (p = 0.08), respectively. ZPP/heme ratios were higher in ALAD1 workers (68.6 vs. 57.8 micromol/ml; p = 0.14), and the slope of the blood lead ZPP linear relationship was greater for ALAD1 (2.83 vs. 1.50, p = 0.06). No linear relationship between CPU and blood lead concentration was observed for either ALAD1 or ALAD2. The associations of blood lead concentration with ZPP, CPU, sperm count, and sperm concentration were more evident in workers with the ALAD1 genotype and blood lead concentrations >/= 40 microg/dl. The ALAD genetic polymorphism appears to modify the association between blood lead concentration and ZPP. However, consistent modification of effects were not found for CPU, sperm count, or sperm concentration.

Adult↗
PubMed1999

The effect of dust lead control on blood lead in toddlers: a randomized trial.

BACKGROUND: Contaminated household dust is believed to be a major source of exposure for most children with elevated blood lead levels. To determine if a vigorous dust clean-up effort would reduce this exposure we conducted a randomized controlled field trial. METHODS: We randomized 113 urban children between the ages of 6 and 36 months: 56 children to a lead dust intervention composed of maternal education and biweekly assistance with household cleaning and 57 children to a control group. Household cleaning was done by two trained lay workers who focused their efforts on wet mopping of floors, damp-sponging of walls and horizontal surfaces, and vacuuming with a high-efficiency particle accumulating vacuum. Household dust lead levels, child blood lead levels, and maternal knowledge of lead poisoning and sources of exposure were measured before and after the intervention. RESULTS: Ninety-nine children were successfully followed for 12 +/- 3 months: 46 children in the lead group and 53 children in the control group. Age and blood lead were similar in the two groups at baseline and averaged 20 months and 12.0 micrograms/dL, respectively. Blood lead fell 17% in the intervention group and did not change among controls. Household dust and dust lead measures also fell significantly in the intervention group. Children in homes cleaned 20 or more times throughout the year had an average blood lead reduction of 34%. CONCLUSIONS: Regular home cleaning, accompanied by maternal education, is a safe and partially effective intervention that should be recommended for the large majority of lead-exposed children for whom, unfortunately, removal to lead-safe housing is not an option.

Air Pollution, Indoor↗
PubMed2002

Factors affecting lead leaching from microwavable plastic ware made with lead-containing pigments.

Although food contact polymers do not normally contain lead, it is suspected that lead may be leached from some microwavable plastic ware items made in Thailand with lead-containing pigments. The purpose of this study was to examine relationships with regard to lead leached from microwavable plastic ware. Four factors were studied: pH, heat level, extraction time, and number of repeated extractions. A total of 243 samples of microwavable plastic ware items locally manufactured in Thailand were used. This study used three pH values (3.5, 4.5, and 6.5) and three heat levels (levels 3, 6, and 9 [170, 500, and 850 W, respectively]). Acetic acid was used both as the extracting agent and for adjusting the pH. Samples were collected at each level at 1, 3, and 5 min, and the amount of leached lead was measured with an atomic adsorption spectrometer. The results of this study show that pH, heat, and extraction time affected the amount of lead leaching from microwavable plastic ware. The amount of lead leaching increased with decreasing pH but increased with increasing heat level and extraction time. On the basis of these three factors, the results of this study indicate that the pH of the extractant (r = -0.592, P < 0.01), the heat level of extraction (r = 0.293, P < 0.01), the extraction time (r = 0.226, P < 0.01), and the number of extractions (r = -0.153, P < 0.01) are related to lead leaching from microwavable plastic ware. The relationship between the pH of the extractant, the heat level of extraction, and the extraction time significantly moderated lead leaching from microwavable plastic ware (R2 = 0.511, P < 0.001). For all factors, the amount of lead leaching was lower than the permissible level of 1 mg/liter specified by the Minister of Public Health. In conclusion, a combination of high acid, prolonged heating, and extraction time accelerated the amount of lead leaching from microwavable plastic ware, but the incidence of lead leaching was negligible.

Acetic Acid↗
PubMed2001

Distribution of blood lead levels in schoolchildren in selected Cape Peninsula suburbs subsequent to reductions in petrol lead.

OBJECTIVE: To determine blood lead levels among children attending schools in selected Cape Peninsula suburbs, and to assess the impact of a reduction in the lead content of petrol. DESIGN: A cross-sectional analytical study of children's blood lead levels and associated risk factors. SETTING: Selected inner city, suburban, and peri-urban schools in the Cape Peninsula, expected to have differing levels of environmental exposure to lead. SUBJECTS: Grade 1 schoolchildren for whom prior written parental consent had been obtained, and who were present at school on the day of the study. OUTCOME MEASURES: Blood lead levels (microgram/dl), associated with a wide range of potential risk factors. RESULTS: Median blood lead levels in suburbs varied from 14 to 16 micrograms/dl, the lowest levels occurring in the peri-urban suburb and the highest in the inner city suburb. Within the inner city suburb of Woodstock, variations in mean blood lead concentrations among schools were substantial, varying from 13 to 19 micrograms/dl. Overall, no change occurred in blood lead levels in this suburb subsequent to the lowering of the lead content of petrol. CONCLUSION: Every effort should be made in South Africa to control sources of lead in the urban environment. The study will serve as a useful baseline against which to measure the impact on blood lead levels of further actions which have been taken to promote the use of lead-free petrol in South Africa.

Child↗
PubMed1980

Increased lead absorption in inner city children: where does the lead come from?

Pica for lead-containing paint has been questioned as the principal mechanism for the widespread moderately elevated blood lead levels (30 to 80 microgram/100 ml) in inner city children. This study explored the hypothesis that lead-contaminated household dust is a major source of lead for these children; hand contamination and repetitive mouthing is the proposed mechanism of ingestion. Forty-nine inner city children with blood lead 40 to 70 microgram/100 ml were matched with 50 children with blood lead less than or equal to 29 microgram/100 ml from the same inner city environment. House dust lead and lead on hands were found in significantly greater quantity among experimental subjects. Other factors differed between groups; lead content of peeling paint, soil lead, and pica affected more experimental than control children, but did not account for more than 50% of experimental cases. The cause of moderate blood lead elevation is multifactoral: no single source accounted for all children with elevated levels. However, lead contamination of house dust and hands appears to be a major factor in this condition.

Child, Preschool↗
PubMed1995

Blood lead levels and anemia in lead exposed workers.

The effects of lead on haematological parameters were studied in 51 occupationally exposed individuals comprising of 27 lead furnace workers, 24 lead pellet handlers and 20 healthy age and service matched controls. Blood lead levels were estimated by atomic absorption spectrometer AAS-180-80 and haematological parameters by Technicon H.1 system. The lead furnace workers had highest blood lead levels (median 71.20 ug/dl, range 21.2-171.10 ug/dl) and low Hb (median 106 g/l, range 73-144 g/l) as compared to healthy subjects (median lead levels 29.80 ug/dl, range 10.20-54.10 ug/dl and Hb median 135 g/l, range 101-153 g/l). The workers handling pellets had moderately increased blood lead levels (median 45.50 ug/dl, range 8.50-130.6 ug/l) and low Hb (median 114 g/l, range 74-158 g/l). The furnace exposed workers had higher blood lead levels and low Hb compared to the lead pellet handlers. TRBC, Hct, MCV, MCH and MCHC did not reveal any significant difference in all groups. It is concluded that chronic lead exposure causes normocytic normochromic anaemia and shows a dose response relationship between lead levels and severity of anemia.

Adult↗
PubMed1998

Lipopolysaccharide and interleukin-6 enhance lead entry into cerebellar neurons: application of a new and sensitive flow cytometric technique to measure intracellular lead and calcium concentrations.

The distribution of intracellular ionized lead (Pb) and calcium in dissociated cerebellar cells of ten-day-old mice was measured by flow cytometry. There are no fluorescent probes specific for lead, whereas commonly used fluorescent calcium indicators bind heavy metals with greater affinity than they do calcium, which impedes discrimination of lead- and calcium-induced fluorescence changes. Therefore, we developed a method to determine [Pb2+]i and [Ca2+]i by employing a combination of the calcium indicator fluo-3 and the heavy-metal chelator TPEN. Using these methods, we studied the effects of multiple in vivo exposure (five subcutaneous injections over 10 days) to lipopolysaccharide (LPS, 100 ng/g), recombinant mouse interleukin-6 (IL-6, 5 ng/g) and/or inorganic lead (lead, 2.5 micrograms/g) on lead and calcium concentrations. Control cells had [Cai] of 112 nM. Lead exposure alone had little effect on [Ca2+]i and resulted in a mean [Pb2+]i of about 7 pM, and did not alter cell volume. A significant fraction of cells (about 44% of living cells) from animals treated with lead plus LPS were swollen, as determined by analysis of the light scattering pattern, and there was a small increase in the number of dead cells, identified with the nucleic acid stain, 7-aminoactinomycin. While [Ca2+]i was not significantly increased in animals treated with either only LPS or IL-6, lead and calcium concentrations were increased in animals exposed to lead and LPS or IL-6 in both the non-swollen and swollen cells, with a mean value of (Pb2+)i of 32 pM and (Ca2+)i of 155 nM in cells not swollen. Electrophysiological analysis showed that LPS injections caused decreases in the membrane potential of endothelial cells of the blood-brain barrier (BBB) and lead potentiated the effect of LPS. IL-6 mimicked the effects of LPS, but was less potent. Thus these experiments indicate a synergistic interaction between lead and cytokines on biophysical properties of both neurons and endothelial cells of the BBB.

Animals↗
PubMed1991

The effects of thiamin on lead metabolism: whole body retention of lead-203.

The effects of thiamin on the whole body retention of led were evaluated in CD-1 mice treated intragastrically or intraperitoneally while exposed to a single dose of lead acetate (100 micrograms) containing 100 mu Ci lead-203. They were administered thiamin (25 or 50 mg/kg body wt.), calcium ethylenediamine tetraacetic acid (CaEDTA) (50 mg/kg body wt.) or their combination in pretreatment or posttreatment regimens for 13 days. Both pre- and posttreatment with thiamin reduced the lead retention compared to the untreated lead-exposed mice, although the different patterns of lead retention were observed. The combined pretreatment (thiamin 50 mg/kg and CaEDTA) and the CaEDTA treatment alone reduced the whole body retention of lead most effectively. Thiamin, CaEDTA and the combined treatments decreased the absorption of lead-203 and the biological half-life of retained lead-203 following oral or intraperitoneal lead exposure. The reduced absorption and enhanced excretion of lead associated with thiamin administration may have therapeutic application for the treatment of lead poisoning.

Absorption↗
PubMed1983

Enzymes involved in the biosynthesis of glycoconjugates. A UDP-2-acetamido-2-deoxy-D-glucose: beta-D-galactopyranosyl-(1 leads to 4)-saccharide (1 leads to 3)-2-acetamido-2-deoxy-beta-D- glucopyranosyltransferase in human serum.

A 2-acetamido-2-deoxy-beta-D-glucopyranosyltransferase (N-acetylglucosaminyltransferase) that catalyses the transfer of 2-acetamido-2-deoxy-D-glucose from UDP-2-acetamido-2-deoxy-D-glucose to terminal nonreducing beta-D-galactosyl residues in disaccharides, oligosaccharides, glycoproteins, and glycolipids has been detected in human serum. The preferred acceptors are those with beta-D-galactosyl residues linked (1 leads to 4) to the subterminal sugar residue. Activity is greatest when the second sugar residue is 2-acetamido-2-deoxy-D-glucose but beta-D-Galp-(1 leads to 4)-D-Glc and beta-D-Galp-(1 leads to 4)-D-Man are also good acceptors. Compounds with beta-D-galactosyl groups linked (1 leads to 3) to 2-acetamido-2-deoxy-D-glucose are relatively poor acceptors and beta-D-Galp-(1 leads to 6)-D-GlcNAc is inactive. Oligosaccharides substituted with an L-fucose unit on the beta-D-galactosyl unit or on the adjacent sugar residue failed to accept 2-acetamido-2-deoxy-D-glucose. Similarly, glycoproteins with L-fucose or sialic acid substituents are less effective acceptors before removal of these sugars to expose more beta-D-galactosyl end-groups. The transferred 2-acetamido-2-deoxy-beta-D-glucopyranosyl residue is cleaved from the enzymic reaction products by the N-acetyl-beta-D-glucosaminidase from Jack beans. Methylation analysis of the products of 2-acetamido-2-deoxy-D-glucosyl transfer to N-acetyllactosamine [beta-D-Galp-(1 leads to 4)-D-GlcNAc] and lactose [beta-D-Galp-(1 leads to 4)-D-Glc] revealed that the terminal, nonreducing D-galactosyl group in both these acceptors had been 3-O-substituted with 2-acetamido-2-deoxy-D-glucose. Hence, the enzyme in human serum catalyses, in the presence of Mn2+, the reaction UDP-GlcNAc + beta-D-Galp-(1 leads to 4)-R leads to beta-D-GlcpNAc(1 leads to 3)-beta-D-Galp-(1 leads to 4)-R + UDP and is a UDP-2-acetamido-2-deoxy-D-glucose: beta-D-galactopyranosyl-(1 leads to to 3)-2-acetamido-2-deoxy-beta-D-glucopyranosyltransferase.

Carbohydrate Conformation↗
PubMed1994

Prediction of isolated first diagonal branch occlusion by 12-lead electrocardiography: ST segment shift in leads I and aVL.

OBJECTIVES: This study was performed to determine electrocardiographic (ECG) features that could distinguish first diagonal branch occlusion from left anterior descending coronary artery occlusion. BACKGROUND: The ECG findings associated with first diagonal branch obstruction have not previously been compared with those of left anterior descending coronary artery obstruction. METHODS: The ECG findings in 34 patients with isolated diagonal branch occlusion (group 9) were compared with those in 20 patients with occlusion at site 6 (group 6) and 20 with occlusion at site 7 (group 7), according to American Heart Association classification. This study had a power > 80% to detect a 50% difference between groups at a probability value of 0.05. RESULTS: ST segment elevation was observed in leads I and aVL for all group 9 patients, in 80% (p < 0.05) of group 6 patients for lead I and 90% for lead aVL and in 50% (p < 0.01) of group 7 patients for lead I and 55% (p < 0.01) for lead aVL. Similarly, there was a higher incidence of abnormal Q waves and inverted T waves in leads I and aVL in group 9 than in groups 6 and 7. In contrast, group 9 showed a significantly lower incidence of ST segment elevation (3.4%), abnormal Q waves (3.0%) and inverted T waves (0%) in lead V1 than group 6 (80%, 40% and 90%, respectively) and group 7 (75%, 60% and 70%, respectively) (p < 0.01 for each). Multivariate analysis revealed that abnormalities in leads I and aVL, combined with a normal lead V1 (and V6), provided good criteria for distinguishing isolated diagonal branch occlusion from left anterior descending coronary artery occlusion. CONCLUSIONS: Isolated diagonal branch occlusion more frequently caused ECG abnormalities in leads I and aVL and less frequently caused changes in the precordial leads compared with left anterior descending coronary artery obstruction, indicating that leads I and aVL represent myocardium perfused by the diagonal branch.

Adult↗
PubMed2003

Additional electrocardiographic leads in the ED chest pain patient: right ventricular and posterior leads.

In the evaluation of the patient with chest pain, the 12-lead electro cardiogram is a less-than-(ECG) perfect indicator of acute myocardial infarction (AMI), particularly when used early in the course of the acute ischemic event; this relative insensitivity for AMI results from many different issues, including a less-than-optimal imaging of certain areas of the heart. It has been suggested that the sensitivity of the 12-lead ECG can be improved if 3 additional body surface leads are used in selected individuals. Acute posterior (PMI) and right ventricular myocardial infarctions are likely to be underdiagnosed, because the standard lead placement of the 12-lead ECG does not allow these areas to be assessed directly. Additional leads frequently used include leads V(8) and V(9), which image the posterior wall of the left ventricle, and lead V(4R), which reflects the status of the right ventricle. The standard ECG coupled with these additional leads constitutes the 15-lead ECG, the most frequently used additional lead ECG in clinical practice. The use of the additional leads might not only confirm the presence of AMI, but also provide a more accurate reflection of the true extent of myocardial damage.

Aged↗
PubMed2006

Assessment of QT-measurement accuracy using the 12-lead electrocardiogram derived from EASI leads.

The purpose of the present study is to assess QT-interval measurements from the EASI 12-lead electrocardiogram (ECG) as compared with the standard 12-lead ECG. The QT interval was automatically determined in simultaneously recorded standard and EASI 12-lead ECGs, using a validated wavelet-based delineator. The agreement between the 2 sets of measurements was quantified both on a lead-by-lead basis and a multilead basis with global definitions of QRS onset and T-wave end. The results show that the agreement between QT-interval measurements from the 2 lead systems is acceptable, with negligible mean differences and with correlation coefficients ranging from 0.91 to 0.98 depending on the lead studied. Although the SD shows a clear dependence on the selected lead (ranging from 9.2 to 26.4 milliseconds), differences are within the accepted tolerances for automatic delineation. In a few patients, large differences were found, mainly because of changes in morphology present in both lead systems. QT intervals measured by the multilead approach were considerably more stable than single-lead measurements and resulted in a much better agreement between the 2 lead systems (correlation coefficient, 0.98; QT difference, 1.1 +/- 9.8 milliseconds). Thus, the EASI 12-lead ECG may be used for reliable QT monitoring when the multilead delineation approach is adopted.

Diagnosis, Computer-Assisted↗
PubMed1993

Assessing the diagnostic value of an ECG containing leads V4R, V8, and V9: the 15-lead ECG.

STUDY OBJECTIVES: To assess sensitivity, specificity, and odds ratios of ECG findings on leads V4R, V8, and V9 for acute myocardial infarction. DESIGN: Prospective, two-stage cohort study. SETTING: A 660-bed university-affiliated community hospital. TYPE OF PARTICIPANTS: One hundred forty-nine admitted patients with suspected myocardial infarction or unstable angina. INTERVENTIONS: Standard 12-lead ECG followed immediately by V4R, V8, and V9. MEASUREMENTS: Initial ECG findings of ST-segment displacement, Q waves, T-wave inversion, and eligibility for thrombolytic therapy. RESULTS: Major abnormalities (ST-segment deviation, T-wave inversion, Q waves) were found on the extra three leads in 28.9% (43 of 149) of patients. Sensitivity of ST-segment elevation for acute myocardial infarction on 12 versus 15 leads increased from 47.1% to 58.8%, respectively, with no decrease in specificity. McNemar's pair-matched analysis for ST-segment elevation on myocardial infarction subgroup showed an association of ST elevation with the 15-lead ECG (P < .05). An eightfold increase in the odds of detecting ST elevation was found (90% confidence interval, 1.42 to 14.58); 22% of patients negative for ST elevation on 12 leads were positive on 15 leads. Analysis of ECG criteria for thrombolytic therapy presenting uniquely on extra leads showed an increased sensitivity from 35.3% to 44.1% on 12 versus 15 leads, respectively; there was a sixfold increase in the odds of meeting ECG thrombolytic therapy criteria (90% confidence interval, 0.34 to 11.66); 13.5% of patients not meeting criteria on 12 leads did so on 15 leads. CONCLUSION: The 15-lead ECG provides increased sensitivity and odds of detecting ST-segment elevation in acute myocardial infarction patients with no loss of specificity; its use may expand the selection of thrombolytic therapy candidates and provide a fuller ECG description of the extent of myocardial injury and necrosis.

Aged↗
PubMed1990

Survival of implantable pacemaker leads. The Implantable Lead Registry.

Early polyurethane leads were reported to have a high incidence of materials failure. In 1979 a six-center registry was begun. By October 31, 1989, 7,311 leads had been registered and lead longevity was calculated by individual manufacturer, cumulatively for all manufacturers and for individual leads. Each lead was registered at implant and at removal from service as having been removed for materials failure or for unrelated reasons. Calculations were made for 23 models and for a total of three manufacturers with more than 100 leads implanted. Four thousand seven hundred and sixty three leads (65.1%) were from Medtronic; 2,177 (29.8%) from Cordis; 297 (4.1%) from Intermedics; and 77 (1.0%) were from all others. The 10-year cumulative survival of Medtronic leads was 96.6 +/- 0.4%; for Cordis leads it was 99.9 +/- 0.1% and for Intermediates leads 97.7 +/- 0.9%. Three lead models registered over 100 units and had poorer survival at 5 years than the remainder of all manufacturers' experience. They were #6972 (n = 107) with 78.6 +/- 4.5%; #6991U (n = 294) with 90.6 +/- 1.9%; and #4012 (n = 288) with 97.3 +/- 1.5%. Other possibly failed models did not achieve statistical significance. It can be anticipated that a lead which survives to the seventh year will have prolonged longevity as thereafter additional failures are uncommon.

Electrodes, Implanted↗
PubMed1993

Long-term performance of epimyocardial pacing leads in adults: comparison with endocardial leads.

The long-term performance of epimyocardial pacing leads in children is well established, but few studies have analyzed the performance in adults. This issue has clinical relevance in view of the increased use of epimyocardial leads with implantable cardioverter defibrillator and antitachycardia pacing systems. We analyzed 93 epimyocardial pacing "systems" (121 leads: 65 unipolar, 28 bipolar) in adult patients (age 57 +/- 16 years), implanted since January 1980. Two different models were studied: Medtronic 4951 "Stab-on" (n = 35) and Medtronic 6917/6917A "Screw-in" (n = 58). A control group was created by randomly matching each epimyocardial system with two endocardial leads, according to age and year of implant. Epimyocardial and endocardial leads were followed-up for 44 +/- 35 and 43 +/- 35 months, respectively (P = NS). Freedom from failure for epimyocardial leads was 0.91 (95% Confidence Interval [95% CI] = 0.82 to 0.96) at 5 years, and 0.91 (95% CI = 0.69 to 0.98) at 10 years. No difference was found between the two analyzed models. Freedom from failure for endocardial leads was 0.97 (95% CI = 0.93 to 0.99) and 0.90 (95% CI = 0.61 to 0.97) at 5 and 10 years, respectively. Epimyocardial leads had a significantly poorer short-term survival than endocardial leads, secondarily to earlier "technique related" failures (P = 0.03; relative risk 3.0; Wilcoxon test). However, overall long-term performance was similar to endocardial leads. Epimyocardial pacing leads, meticulously implanted and tested, have a long-term performance similar to endocardial pacing leads.

Electrodes, Implanted↗
PubMed2005

Long-term performance of screw-in atrial pacing leads: a randomized comparison of J-shaped and straight leads.

OBJECTIVE: In this prospective, randomized, control study we compared performance of J-shaped (JL) and straight atrial leads (SL) with active (screw-in) fixation mechanism, over a 5-year follow-up period. SUBJECTS AND METHODS: A total of 208 consecutive patients were randomized for implantation with a Medtronic 4568 JL model (n = 103) versus a Medtronic 4068 SL model (n = 105), and all lead-related measurements and complications were recorded. RESULTS: Lead-related complications occurred in JL and SL with similar frequency (6% and 9%, respectively, P = 0.45). Lead dislodgment occurred in 8 (7.8%) cases in SL versus none in JL (P = 0.004). Lead malfunction and excessive pacing thresholds without macrodislodgment occurred more frequently in JL (11; 10.7%) than in SL (4; 3.8%), P = 0.055. Lead material failure (insulation break) occurred only once in SL at the 5-year checkup. Most complications occurred during the first year after implantation. Other events occurred in both leads with similar frequency and included: death in 39 and 35, loss of follow-up in 8 and 6, and development of atrial fibrillation in 9 and 15 patients, respectively. Of those who completed follow-up, lead impedance and pacing threshold increased significantly in both groups. P wave decreased in SL but not in JL. CONCLUSION: More dislocations occurred in SL, but were counterbalanced by more lead malfunctions and excessive pacing thresholds in the JL group. Both leads demonstrated minor deterioration in electrical measurements during follow-up, with only 1 case of lead material failure in SL. Overall, both groups demonstrated favorable lead performance throughout follow-up.

Aged↗