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PubMed2006

Long-term follow-up of transvenous defibrillation leads: high incidence of fracture in coaxial polyurethane lead.

BACKGROUND: As a result of longer follow-up after implantation of cardioverter defibrillators (ICD), fatigue of the leads has become a concern. The aim of this study was to determine the incidence and clinical presentation of ICD lead failures. METHODS AND RESULTS: The study population consisted of 241 patients with 249 ICD leads who underwent implantation of an ICD with a transvenous lead system. After device implantation, the patients were routinely followed up every 4 months. Five lead failures (2.0%) occurred as an oversensing of artifact during the follow-up period (2.6+/-2.1 years); 4 of those 5 patients received inappropriate shocks and 1 case of lead failure was identified in a patient with frequent episodes of non-sustained ventricular fibrillation. In particular, the right ventricular polyurethane transvenous lead in the Medtronic model 6936 failed in 4 (13%) of 31 cases. Percutaneous lead extraction was not available in all cases, so an additional ICD lead was inserted through the same site of the subclavian vein. CONCLUSIONS: Lead failures may occur 5 years after ICD implantation and polyurethane leads have an especially high incidence of failure. However, there were no follow-up parameters observed that predicted lead failures.

Adult↗

PubMed1998

12-lead ST-segment monitoring vs single-lead maximum ST-segment monitoring for detecting ongoing ischemia in patients with unstable coronary syndromes.

BACKGROUND: 12-lead ECG monitoring of the ST segment is more sensitive than patients' symptoms for detecting ischemia after thrombolytic therapy or catheter-based interventions, but it is unclear whether monitoring of the single lead showing maximum ST deviation would be as efficacious. OBJECTIVE: To determine whether monitoring all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes. METHODS: Continuous 12-lead ST segment monitoring was performed in 422 patients from the onset of myocardial infarction or during balloon inflation in catheter-based interventions until the patient's discharge from the cardiac care unit. Computer-assisted techniques were used to determine (1) which lead showed the maximum ST deviation at the onset of myocardial infarction or during balloon inflation and (2) what proportion of later ischemic events were associated with ST deviation in this lead. RESULTS: The lead with the maximum ST deviation could be determined in 312 patients (74%). The remaining 110 (26%) had non-Q wave infarction without ST deviation or no ST changes during balloon inflation. During 18,394 hours of 12-lead ST monitoring, 118 (28%) of the 312 patients had a total of 463 ischemic events, 80% of which were silent. Of 377 ischemic events in which a maximum ST lead was detected, 159 (42%) did not show ST deviation in this lead (sensitivity, 58%; 95% CI, 53%-63%). Routine monitoring of leads V1 and II showed ST deviation in only 152 of the 463 events (sensitivity, 33%; 95% CI, 29%-37%). CONCLUSIONS: Monitoring of all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes.

Aged↗

PubMed1982

[Determination of lead in hydride form in bone biopsies of patients with long past lead poisoning].

Disturbances in the determination of lead by means of flameless atomic absorption by highly pure CaCl2-solutions were demonstrated. To avoid such disturbances a new method for estimation of lead in bone specimens is introduced. Lead is separated in hydride form by adding NaBH4 to the specimens in an acid solution containing tartaric acid and sodium dichromate in a so called metal-hydride-system and then identified by atomic absorption spectrophotometry. For higher concentrations or for mass spectrometric determination of the lead isotope proportions the lead hydride may also be frozen. The hydride method has been used with the estimation of lead in biopsy specimens from the iliac crests of 14 patients who suffered from nephropathies of unknown origin. In addition flameless AAS was employed and the results were controlled. The lead contents in bone specimens from 13 patients with a long history of occupational exposure to lead varied between 126 mumol/kg (26 micrograms/g) and 1,97 mmol/kg (410 micrograms/g) of dried substance. In five control specimens the corresponding values ranged from 19 mumol/kg (4 micrograms/g) to 87 mumol/kg (18 micrograms/g). These findings suggest that nephropathy results from body burden of lead. Additionally hair specimens and nail clippings from several of the above patients were analysed. Control analyses were carried out. The question of lead release from deposits in bone and the connections between nephropathy and exposure to lead are discussed.

Bone and Bones↗

PubMed1983

Home lead-work as a potential source of lead exposure for children.

Health examinations for lead poisoning were made on 62 family members from 15 families of homes carrying on lead work, such as quench-hardening in a molten lead bath and type-printing, as work at home. The most interesting findings concern the occurrence of cases with an unduly high lead absorption among children, but not among adult family members other than home lead-workers. The home environments of the children with an unduly high lead absorption represented contamination with housedust high in lead contents. The ingestion of the contaminated housedust by hand-to-mouth is probably responsible for the excessive lead exposure of the affected children. The results of the present study suggest that contamination of housedust with lead due to home lead-work constitutes a possible hazardous source of lead exposure for children.

Adolescent↗

PubMed1997

Influence of L-lysine and zinc administration during exposure to lead or lead and ethanol in rats.

Influence of lysine and zinc administration on the lead-sensitive biochemical parameters and the accumulation of lead during exposure to lead or lead and ethanol was investigated in rats. The lead exposure inhibited blood delta-aminolevulinic acid dehydratase (ALAD) activity, increased blood zinc protoporphyrin (ZPP), urinary delta-aminolevulinic acid (ALA), serum glutamic oxalacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), blood and tissue lead levels, and decreased blood and hepatic glutathione (GSH) contents. Some of these effects were enhanced on coexposure to ethanol. The simultaneous administration of lysine and zinc reduced tissue accumulation of lead and most of the lead-induced biochemical alterations irrespective of exposure to lead alone or lead and ethanol. The depletion of endogenous calcium and magnesium owing to lead or ethanol exposure was also prevented by co-administration of lysine and zinc.

Alanine Transaminase↗

PubMed1996

Use of the Centers for Disease Control and Prevention childhood lead poisoning risk questionnaire to predict blood lead elevations in pregnant women.

OBJECTIVE: To assess the accuracy of a questionnaire developed by the Centers for Disease Control and Prevention (CDC), given to pregnant women for identification of children at risk for lead poisoning. METHODS: The study population consisted of all 314 new prenatal patients enrolled in health department clinics in 1990-1992. Lead was measured in venous blood, and patients completed written questionnaires to gather information about lead exposure risk factors. The relationship between elevated maternal blood lead levels (at or greater than 10 micrograms/dL or 0.483 mumol/L) and responses to the CDC questionnaire and other questions were examined using chi 2 statistical analysis. RESULTS: Two hundred ninety-nine women provided responses to questions about lead exposure risk. Thirty-nine women (13%) had elevated blood lead levels. A woman with a positive response to at least one CDC question was more likely to have elevated blood lead than a woman who answered negatively to all four CDC questions (relative risk = 2.39, 95% confidence interval 1.17-4.89; P = .01). Using the CDC definition of high risk ("yes" to at least one question), the questionnaire had a sensitivity of 75.7% and a negative predictive value of 93.1%. A questionnaire that combined housing conditions, smoking status, and high consumption of canned foods had a sensitivity of 89.2% and a negative predictive value of 96.4%. A high prevalence of elevated blood lead in children living with women with elevated blood lead was observed. CONCLUSION: Querying pregnant women about risk factors for lead exposure can aid in assessing prenatal lead exposure risk. The sensitivity and negative predictive value of the CDC questionnaire, when used with high-risk women, are comparable to its reported accuracy in young children.

Centers for Disease Control and Prevention, U.S.↗

PubMed1994

Effect of chelate treatments on kidney, bone and brain lead levels of lead-intoxicated mice.

The effects of chelating agent treatment with meso-2,3-dimercaptosuccinic acid (DMSA), Na2CaEDTA, Na2ZnEDTA, and Na3ZnDTPA on the organ lead levels of lead-loaded mice have been determined. At 1 mmol/kg/day i.p., all caused reductions in the lead levels of the kidney after four injections, but only Na2CaEDTA produced a significant reduction in brain lead. All chelating agents caused significant reductions in kidney and brain lead levels when administered at a daily dose of 1 mmol/kg/day for eight days, but only DMSA reduced the bone lead level. In animals given 50 mg Pb/kg or 100 mg Pb/kg, the administration of Na2CaEDTA or DMSA at 1 mmol/kg/day x 8 produced significant reductions in kidney, bone and brain lead levels, but DMSA produced greater reductions of bone lead in both groups and of kidney lead in the group given 100 mg Pb/kg. An examination of published data describing the effect of chelating agent treatment on brain lead levels indicates that DMSA produces a reduction in brain lead levels under all conditions examined to date.

Animals↗

PubMed1992

Experimental model of lead nephropathy. II. Effect of removal from lead exposure and chelation treatment with dimercaptosuccinic acid (DMSA).

Male Sprague-Dawley rats were exposed to high-dose (0.5%) lead acetate for periods ranging from 1 to 9 months; then lead exposure was discontinued, and animals were sacrificed after 12 months. Controls were pair-fed. Two additional groups of low-dose (0.01%) and high-dose (0.5%) rats were exposed to lead for 6 months, then lead was discontinued and the rats were treated with three 5-day courses of 0.5% DMSA (dimercaptosuccinic acid) over the next 6 months. Controls were rats exposed to lead for 6 months, then removed from exposure for 6 months without receiving DMSA. Low-dose lead-treated rats showed no significant pathological changes with or without DMSA treatment, but exhibited a significant increase in GFR after DMSA. High-dose lead-treated animals showed no functional or pathological changes when lead exposure was discontinued after 1 month. However, when duration of exposure was 6 or 9 months, GFR was decreased and serum creatinine and urea nitrogen were increased as compared to controls. Tubulointerstitial disease was severe. Administration of DMSA resulted in an improvement in GFR and a decrease in albuminuria, together with a reduction in size and number of nuclear inclusion bodies in proximal tubules. However, tubulointerstitial scarring was only minimally reduced. It may be concluded that, except for brief initial exposure, discontinuation of high-dose lead exposure fails to reverse lead-induced renal damage. Treatment with the chelator, DMSA, improves renal function but has less effect on pathological alterations. As GFR improved after DMSA treatment in both low-dose and high-dose lead-treated rats, irrespective of the degree of pathological alterations, it may be concluded that the DMSA effect is most likely mediated by hemodynamic changes.

Acetylglucosaminidase↗

PubMed2001

Longitudinal changes in bone lead concentration: implications for modelling of human bone lead metabolism.

In this study, 539 occupationally exposed subjects received in vivo bone lead measurements using 109Cd excited K X-ray fluorescence (109Cd K XRF). Of these subjects, 327 had previously been measured five years earlier. Measurements were made from both tibia and calcaneus samples, taken to reflect cortical and trabecular bone, respectively. Changes in tibia lead concentration related negatively to initial tibia lead concentration and positively to both lead exposure between the measurement dates and initial calcaneus lead concentration. This finding confirmed and strengthened the interpretation of an earlier study involving fewer subjects. With the larger data set it was possible to examine subgroups of subjects. This showed that people aged less than 40 years had a shorter half-life for the release of lead from the tibia (4.9, 95% CI 3.6-7.8 years) than did those older than 40 (13.8, 95% CI 9.7-23.8 years). Similarly, less intensely exposed subjects (lifetime average blood lead < or = 25 micrograms dL-1) had a shorter tibia lead half-life (6.2, 95% CI 4.7-9.0 years) than those with a lifetime average blood lead > 25 micrograms dL-1 (14.7, 95% CI 9.7-29.9 years). Age and measures of lead exposure were strongly correlated; nevertheless, age matched subgroups with high and low intensity exposures showed clearance rates that were significantly different at the 10% level, with the lower exposure intensity again being associated with the faster clearance. These findings imply that current models of human lead metabolism should be examined with a view to adjusting them to account for kinetic rates varying with age and probably also with exposure level.

Adult↗

PubMed1975

Recovery of blood lead concentration and of red cell 8-aminolevulinic acid dehydrase activity in dogs following return to normal diets after 75 weeks of lead feeding.

Blood lead concentration and red cell delta-aminolevulinic acid dehydrase (ALAD) activity were determined at intervals for eight months after symptom-free dogs, which had received 100 ppm or 500-1000 ppm of lead, by weight, in their diets for 75 1/2 weeks, were returned to a lead-free diet. Statistical treatment of the data disclosed a linear relationship between the logarithm of blood lead concentration or of ALAD activity and the logarithm of time (experimental week) during the recovery period. The calculated regressions predict that recovery of ALAD will occur before recovery of the blood lead concentration. Predicted recovery times depend on the levels selected as those which must be attained for recovery to be complete, as well as on the dosage of lead. The logarithm of the slope of the ALAD recovery regression of the individual dog has a linear relation to the percentage reduction in ALAD due to the lead, the regression accounting for 92% of the variance in the recovery rates. The slope of the blood lead recovery regression has a linear relation to the increase in blood lead for the dogs which received the low lead diet, but not for those which received the high lead diet.

Animals↗

PubMedDate not supplied

Blood lead levels in 2- to 3-year-old children in the Greater Bilbao Area (Basque Country, Spain): relation to dust and water lead levels.

The objectives of this study were to determine blood lead levels in 2-y-old children in the Greater Bilbao Area (Basque Country, Spain) and to compare those levels with the lead content of different media (i.e., house dust, park dust and soil, and water) in the child's environment. Between May and September of 1992, 138 children, aged 2 to 3 y, were studied. All children were attended by pediatricians within the public health-care network, and their parents volunteered for the study. A venous blood sample was drawn from each child and was analyzed for lead level, and the parents answered a questionnaire that addressed the socioeconomic background and habits of the children. The environment was investigated in 42 cases. Blood lead levels exceeded 15 micrograms/dl in 2% of the children, and 14% of the children had levels that exceeded 10 micrograms/dl (geometric mean = 5.7 micrograms/dl [4.7-6.7 micrograms/dl]. Blood lead levels were higher among (a) children whose mothers worked outside the home, (b) children whose fathers had only a primary-level education, and (c) children who lived in houses constructed prior to 1950. The geometrical averages of lead in house dust, park soil, and park dust were 595, 299, and 136 micrograms/g, respectively. Statistically significant linear correlation was found between blood lead level and lead content in park dust, a finding that explained a 9% variation in blood lead level; a subgroup of these children was also found to have a strong linear association between blood lead and lead content in house dust.

Analysis of Variance↗

PubMed2003

Evaluation of a childhood lead questionnaire in predicting elevated blood lead levels in a rural community.

The accuracy of a lead screening questionnaire in predicting elevated blood lead levels was examined in a pediatric practice in a rural part of New York state. A retrospective chart review was used to collect data on children ages 9 to 24 months who presented for well-child visits. Children with both questionnaire and lead level results available in the chart were included in the study (n = 171). The mean blood lead level among all children was 1.6 microg/dl (median = 2.0 microg/dl, range 0 to 24 microg/dl). Four children (2.3%) had elevated lead levels (greater than 10 microg/dl), with levels for two of these children being greater than 20 microg/dl. Although our lead screening questionnaire was expanded from the standard 1991 CDC questionnaire by the inclusion of six additional items, it was not especially useful in predicting elevated blood lead levels above 10 microg/dl. However, the questionnaire exhibited some utility in predicting marked elevations in blood lead levels (over 20 microg/dl). Although results in other geographic areas might differ, the lead questionnaire may have value by enhancing parents' awareness of potential lead hazards in their children's environment and may prove to be more useful in areas of high risk to lead exposure.

Centers for Disease Control and Prevention, U.S.↗

PubMed1977

Lead in enamel and saliva, dental caries and the use of enamel biopsies for measuring past exposure to lead.

Enamel biopsies taken from schoolchildren in a community where exposure to lead was a health hazard were analyzed for lead and fluoride. The children with high enamel lead had significantly higher caries scores than the children with low enamel lead, in spite of the fact that the high lead group also was higher in enamel fluoride. There was no increase in enamel lead with age. The lead in saliva was only a fraction of that in blood. Infants with lead poisoning showed higher saliva lead than a normal infant. The use of the lead in enamel biopsies and in saliva for measuring exposure to lead is discussed.

Adult↗

PubMed1991

Sequential measurements of bone lead content by L X-ray fluorescence in CaNa2EDTA-treated lead-toxic children.

With the development of L X-ray fluorescence (LXRF) to measure cortical bone lead directly, safely, rapidly, and noninvasively, the present study was undertaken to a) evaluate LXRF as a possible replacement for the CaNa2EDTA test; b) quantify lead in tibial cortical bones of mildly to moderately lead-toxic children before treatment; and c) quantify lead in tibial cortical bones of lead-toxic children sequentially following one to two courses of chelation therapy. The clinical research design was based upon a longitudinal assessment of 59 untreated lead-toxic children. At enrollment, if the blood lead (PbB) was 25 to 55 micrograms/dL and the erythrocyte protoporphyrin (EP) concentration was greater than or equal to 35 micrograms/dL, LXRF measurement of tibial bone lead was carried out. One day later, each child underwent a CaNa2EDTA provocative test. If this test was positive, lead-toxic children were admitted to the hospital for 5 days of CaNa2EDTA therapy. These tests were repeated 6 weeks and 6 months after enrollment. Abatement of lead paint hazards was achieved in most apartments by the time of initial hospital discharge. The LXRF instrument consists of a low energy X-ray generator with a silver anode, a lithium-doped silicon detector, a polarizer of incident photons, and a multichannel X-ray analyzer. Partially polarized photons are directed at the subcutaneous, medial mid-tibial cortical bone. The LXRF spectrum, measured 90 degrees from the incident beam, reveals a peak in the 10.5 KeV region, which represents the lead L alpha line.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone and Bones↗

PubMed1991

Sequential measurements of bone lead content by L X-ray fluorescence in CaNa2EDTA-treated lead-toxic children.

Bone and Bones↗

PubMed1997

Lead exposure in Latin America and the Caribbean. Lead Research Group of the Pan-American Health Organization.

As a result of the rapid industrialization of Latin America and the Caribbean during the second half of this century, exposure to lead has become an increasingly important problem. To obtain an estimate of the magnitude of lead exposure in the region, we carried out a survey and a literature search on potential sources of lead exposure and on blood lead concentrations. Sixteen out of 18 Latin American and 2 out of 10 Caribbean countries responded to the survey. Lead in gasoline remains a major problem, although the lead content has decreased in many countries in the last few years. The impact of leaded fuel is more important in urban settings, given their high vehicular density. Seventy-five percent of the population of the region lives in urban areas, and children younger than 15 years of age, the most susceptible group, comprise 30% of the population. Other sources of lead exposure identified in the region included industrial emissions, battery recycling, paint and varnishes, and contaminated food and water. Lead is recognized as a priority problem by national authorities in 72% of the countries that responded to the survey, and in 50% of the countries some legislation exists to regulate the lead content in certain products. However, compliance is low. There is an urgent need for a broad-based coalition between policy makers, industry, workers, unions, health care providers, and the community to take actions to reduce environmental and occupational lead exposures in all the Latin American and Caribbean countries.

Caribbean Region↗

PubMed1999

[Experimental and clinical study to remove lead and to prevent lead damage of kidney with salt of high dose KI].

OBJECTIVE: To study and make a salt prevent lead poisoning. METHODS: SD rats were given 0.25% lead acetate by food intake and were given 10 mg.kg-1.d-1, 20 mg.kg-1.d-1 and 30 mg.kg-1.d-1 potassium iodide from drinking water in respective groups, in order to look for the dose of KI which prevents lead poisoning. The salt to prevent lead poisoning was made, 50 workers were given the salt as to flavouring of daily food intake. PbB, Pbu, ZPP, delta-ALA, NAG(N-acetyl-beta-D-glucosaminidase), RP(Retinol protein) were observed. RESULTS: The dose of KI to prevent experimental lead poisoning of SD rats was 10 mg.kg-1.d-1 by oral intake. People who contacted lead had an increase of urine lead in the third day, and had most urine lead on ninth day after taking the salt with KI. Normal urine lead on the fourth week. Pre- and post-oral intake of the salt with high dose KI, Hb, ZPP, delta-ALA, PbB, NAG and Rp the people mentioned above had the following indexes, (101.2 and 128) g.L-1 (P = 0.05), (33.5 and 7.7) micrograms.g-1 Hb(P < 0.01), (123.12 and 65.35) mumol.L-1 (P < 0.05), (2.123 and 0.85) mumol.L-1 (P < 0.01), (20.9 and 6.7) U.L-1 (P < 0.01), (1.5 and 0.34) mg.L-1 (P < 0.05) respectively. CONCLUSION: The salt with 1% KI may remove lead and prevent lead damage of the kidney.

Adolescent↗

PubMed2005

Prevalence of elevated blood lead levels and evaluation of a lead-risk-screening questionnaire in rural Minnesota.

The objectives of the study reported here were to determine the prevalence of elevated blood lead levels in rural Minnesota and to evaluate a lead-risk-screening questionnaire. Blood lead tests and lead risk questionnaires were obtained for a sample of 1,090 children younger than 48 months of age (72 percent of the eligible population) from three rural counties of west-central Minnesota between September 1, 2001, and August 31, 2002. It was found that overall, 2.4 percent of children in the study had blood lead levels of > or = 10 microg/dL (0.48 micromol/L) (results for capillary and venous tests combined), 0.9 percent had venous blood lead levels of > or = 10 microg/dL, and 0.5 percent of study participants had blood lead levels of > or = 20 microg/dL (0.96 micromol/L). Three risk factor questions, when taken together, predicted 90 percent of blood lead levels of > or = 10 microg/dL and all blood lead levels of > or = 20 microg/dL. The study estimated the prevalence of lead poisoning using a sample of the entire population rather than a clinic-based convenience sample. The authors conclude that targeted screening is an effective way to identify lead-poisoned children in rural areas of Minnesota.

Child, Preschool↗