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At least 253 records · Page 14Linked to original sources
PubMed2002

Specific relationship between blood lead and air lead in the crystal industry.

OBJECTIVES: The main objective of the study was to establish the consequences of exposure to crystal dust on blood lead level in workers employed in hand-finishing and grinding crystal pieces. The second objective was to research a relationship between ambient air lead and blood lead. METHODS: A study conducted in eastern France on 131 subjects occupationally exposed to an aerosol containing crystal particles involved personal measurements of atmospheric exposure to lead, determination of blood lead and, by questionnaire, collection of personal data on exposure characteristics, state of health and level of hygiene of survey volunteers. RESULTS: Initial analysis showed that differences in exposure at the workplace corresponded to differences in blood lead in the operators. There was definitely a potential risk of overexposure to lead, but the existence of this risk was not confirmed by level of blood lead concentrations and, moreover, no clinical signs of lead poisoning in the employees exposed were revealed. The existence of a relationship between personal air (PbA) and blood lead (PbB) levels in grinders and polishers was demonstrated. This relationship, of the form log PbB=2.064+0.181 x log PbA, turns out to be different from those provided by previously published models, which were developed from studies conducted in lead-acid battery manufacturing plants and form the basis of national regulations. Thus, chronic exposure at 100 microg/m(3) of lead at a crystal-grinding workshop corresponds to a mean PbB level of 270 microg/l, whereas the recognized models estimate 350 to 500 microg/l. CONCLUSIONS: This study revealed a specific risk for these categories of exposed individuals. The origin of the descriptive model obtained for the lead exposure/ PbB level relationship raises, through the example of lead, the more general problem of the need to take into account differentiation of chemical substances containing the same element in biological monitoring.

Adult↗
PubMed1992

The isotopic composition of lead in man and the environment in Finland 1966-1987: isotope ratios of lead as indicators of pollutant source.

The isotopic composition of lead was determined in samples collected between 1966 and 1987, mainly from the Helsinki area, in emission sources (gasoline, incinerator and lead smelter emissions, coal), air, in samples representing long-term deposition (lichen, soil, lake sediments), and in human tissue. Isotope ratios were determined by thermal ionization mass spectrometry after chemical separation of lead by anion exchange and cathodic electrodeposition. The origin of lead in man and the environment in the Helsinki area was evaluated by using the differences in the measured isotope ratios as an indicator. The mean of the ratio in gasoline (206Pb/207Pb 1.124 +/- 0.026) and the ratios in other emission sources in Helsinki (1.149-1.226) were significantly different. However, the wide range of isotope ratios in gasoline (1.063-1.173) reduced the accuracy when assessing the contribution of the different sources. Lead in air samples from Helsinki (1.123 +/- 0.013) could be attributed to gasoline, as could lead in soil near a highway (1.136 +/- 0.003). By contrast, isotope ratios measured in lichen (1.148 +/- 0.006) indicated considerable amounts of lead from sources with higher 206Pb abundances, evidently industrial sources. The isotope ratios in human liver, lung, and bone from individuals dying between 1976-79 (206Pb/207Pb ratio 1.142 +/- 0.015, 1.151 +/- 0.011, and 1.156 +/- 0.013, respectively) reflect the large lead emissions from the incinerators and lead smelters in the Helsinki area in the 1960s and 1970s. In lake sediment cores a correlation was found between the isotope ratios, lead concentration, and depth. The nonanthropogenic lead of high isotope ratios from bedrock was the major component at depths dated older than 100 years. At the surface of the sediment atmospheric lead prevailed, with ratios similar to those of gasoline, air samples and lichen. In the post-1900 layers, anthropogenic lead made up about 40-95% of the total sedimentary lead.

Bone and Bones↗
PubMed1987

Effect of different levels and periods of lead exposure on tissue levels and excretion of lead, zinc, and calcium in the rat.

Influence of lead on tissue content and urinary excretion of lead, zinc, and calcium in rats was studied following various exposure periods. Weanling male rats were fed a trace mineral-sufficient diet with either 0, 200, 500, or 1000 ppm lead (as acetate) in drinking water for 4, 8, or 12 weeks. Blood lead ranged from 40 to over 100 micrograms/dl; kidney lead was highest at 4 weeks. Urinary lead excretion was highest at 4 weeks and declined with longer exposure. Urinary zinc excretion correlated positively with lead excretion at the lower excretion rates but plateaued at higher lead excretion rates. After 12 weeks exposure at each lead dose employed, decrease zinc concentration was observed in testes, bone, and brain. Plasma, erythrocyte, and kidney zinc were not affected, while pancreas and liver zinc were slightly elevated. Urine calcium was increased significantly only in rats exposed to 1000 ppm, possibly reflecting renal cell damage as determined by elevated renal calcium levels. These results indicate that lead dose is more important than exposure period for determining kidney lead levels, while urinary lead excretion rate is both dose and time dependent. Blood lead clearance values are relatively independent of dose and fall as exposure continues. Essential trace metal balance for zinc, especially, and to a lesser extent for calcium, is affected by the dose and length of chronic lead exposure.

Animals↗
PubMed1984

Biological availability of lead in a paint aerosol. 2. Absorption, distribution and excretion of intratracheally instilled lead paint particles in the rat.

Four groups of rats received by intratracheal instillation (1) a lead chromate paint particulate suspension, (2) lead tetraoxide suspension, (3) lead acetate solution, or (4) saline. Lead-dosed animals received an equivalent dose of 1 mg lead/kg body weight. Distribution of lead was monitored through assays of urine, feces, and tissues (lung, bone, muscle kidney, liver) obtained at post-mortem 5 weeks after exposure. Delta-aminolevulinic acid dehydratase (ALA-D) activity was measured to determine the effect of lead on heme biosynthesis. The vast majority of the dosed lead in the paint matrix remained in the lung. In contrast, in the lead acetate-dosed animals, little remained in the lung, but significant elevations were found in bone and kidney. Blood ADA-D was significantly depressed in the lead acetate-treated animals, but was not significantly different from control animals in the animals dosed with lead paint or lead tetraoxide. These findings suggest that lead chromate in an alkyd resin paint matrix is poorly absorbed from the lung compared with lead acetate and lead tetraoxide.

Absorption↗
PubMed1989

Lead distribution in rats repeatedly treated with low doses of lead acetate.

Male Sprague-Dawley rats were treated with ip injections of lead acetate (10 and 20 mg/kg) at intervals of 1, 2, 4, 8, 12, 16, 20, and 24 weeks. Eight rats from each specified injection group were sacrificed 48 hr after the end of each treatment. Lead was determined in whole blood, plasma, plasma filtrate, saliva, urine, feces, brain, salivary glands, liver, kidney, testes, femur, and fur. In the liver, the concentrations of lead fluctuated; in the salivary glands and the testes, lead levels were low. In the bone, the kidney, and the brain, lead accumulated steadily and reached high levels in bone and renal tissues, but remained low in the brain. Correlation analysis showed a reciprocal relationship between blood-lead and kidney-lead in the rats treated with 10 mg lead acetate/kg (r = 0.898). In the rats treated with 20 mg lead acetate/kg, urine-lead was correlated to kidney-lead (r = 0.820). In both groups of treated rats, fur-lead was correlated to kidney-lead (r = 0.868 and r = 0.905, P less than 0.01) and brain-lead (r = 0.879 and r = 0.946, P less than 0.01).

Animals↗
PubMed2003

Factors affecting EDTA extraction of lead from lead-contaminated soils.

The effects of solution:soil ratio, major cations present in soils, and the ethylenediaminetetraacetic acid (EDTA):lead stoichiometric ratio on the extraction of lead using EDTA were studied for three different Superfund site soils, one rifle range soil, and one artificially lead-contaminated soil. Extraction of lead from the lead-contaminated soils was not affected by a solution:soil ratio as low as 3:1 but instead was dependent on the quantity of EDTA present. Results of the experiments showed that the extraction efficiencies were different for each soil. If sufficiently large amount of EDTA was applied (EDTA-Pb stoichiometric ratio greater than 10), most of the lead were extracted for all soils tested except for a Superfund site soil from a lead mining area. The differences in extraction efficiencies may be due to the major cations present in soils which may compete with lead for active sites on EDTA. For example, iron ions most probably competed strongly with lead for EDTA ligand sites for pH less than 6. In addition, copper and zinc may potentially compete with lead for EDTA ligand sites. Experimental results showed that addition of EDTA to the soil resulted in a very large increase in metals solubility. The total molar concentrations of major cations extracted were as much as 20 times the added molar concentration of EDTA. For some of the soils tested, lead may have been occluded in the iron oxides present in the soil which may affect lead extraction. While major cations present in the soil may be one of the factors affecting lead extraction efficiency, the type of lead species present also play a role.

Cations↗
PubMed1997

The relationship of lead in soil to lead in blood and implications for standard setting.

As part of a soil lead regulation process, this review was conducted to determine the association between lead in soil and established human health effects of lead or validated biomarkers of lead exposure. We reviewed only studies where soil exposure could be distinguished from other sources of lead and whose design could reasonably be used to infer a causal relationship between soil lead and either biomarkers or health effects. No such studies of health effects were found. Studies describing a quantitative relationship between soil lead and blood lead did meet our criteria: 22 cross-sectional studies in areas with polluted soil; and three prospective studies of soil lead pollution abatement trials. The cross-sectional studies indicated that, compared to children exposed to soil lead levels of 100 ppm, those exposed to levels of 1000 ppm had mean blood lead concentrations 1.10-1.86 times higher and those exposed to soil lead levels of 2000 ppm had blood lead concentrations 1.13-2.25 times higher. The prospective studies showed effects within the ranges predicted by the cross-sectional studies. Differences in results between studies were surprisingly modest and likely explainable by random sampling error, different explanatory variables included in data analyses and differences in methods of measuring lead in environmental specimens.

Adolescent↗
PubMed2007

Lead-induced procoagulant activation of erythrocytes through phosphatidylserine exposure may lead to thrombotic diseases.

Lead (Pb) is a ubiquitous heavy metal pollutant in various environmental media, especially in food and drinking water. In human blood, about 95% of lead is associated with erythrocytes, suggesting that erythrocytes could be an important target of lead toxicity in the cardiovascular system. Recent studies suggested that erythrocytes could contribute to blood coagulation via phosphatidylserine (PS) exposure and resultant procoagulant activation. We investigated the effects of lead on the procoagulant activity of erythrocytes using in vitro human erythrocyte and in vivo rat models. In a flow cytometric analysis, lead (Pb2+) enhanced PS exposure on human erythrocytes in a concentration- and time-dependent manner. The concentration of lead (1-5 microM) used in the current investigation is well within the ranges observed in blood from lead-exposed populations. PS exposure by lead appeared to be mediated by increased intracellular calcium levels as shown by 19F-NMR and intracellular ATP depletion. Consistent with these findings, the activity of scramblase, which is important in the induction of PS exposure, was enhanced, whereas the activity of flippase, which translocates exposed PS to inner membrane, was inhibited by lead treatment. Furthermore, lead-exposed erythrocytes increased thrombin generation as determined by a prothrombinase assay and accelerated the coagulation process initiated by tissue factor in plasma. These procoagulant activations by lead were also confirmed in vivo. Administration of lead significantly enhanced PS exposure on erythrocytes and, more importantly, elevated thrombus formation in a rat venous thrombosis model. These results suggest that lead exposure can provoke procoagulant activity in erythrocytes by PS exposure, contributing to enhanced clot formation. These data will provide new insights into the mechanism of lead-induced cardiovascular diseases.

Adolescent↗
PubMed2005

[Is the lead-equivalent suited for rating protection properties of lead-free radiation protective clothing?].

PURPOSE: Currently, lead-free x-ray-protective clothing is classified by the European production standard EN 61 331-3. To evaluate protective effects of lead-free materials according to this standard, the certifying offices as well as customers solely refer to the lead equivalent (LE). The LE of lead-free protective clothing, however, depends on the tube voltage (energy spectrum). Therefore, stating a single value for x-ray-protective clothing does not reveal the protective efficacy for the complete range of energy as applied in clinical practice. Moreover, the method of narrow beam geometry does not account for information on secondary radiation (scattered and fluorescent radiation) generated within the material. Lead-free materials, however, generate large-scale fluorescent radiation, especially for elements with atomic numbers below 60. As a consequence, full-scale secondary radiation of a given material can only be detected with a broad beam setup. MATERIALS AND METHODS: In accordance with IEC 61 331-1, we compared commercially available radiation-protective aprons manufactured with lead-free or partially lead-free materials with aprons manufactured on a lead-oxide basis. In addition to the LE, attenuation ratios and dose-build-up-factors under broad beam-conditions were evaluated. RESULTS: In comparison with lead-oxide materials, protection efficacy of lead-free materials is reduced by up to 70 %, particularly for a tube voltage below 80 kV. Lead-composite materials (partially lead-free materials) are less affected. CONCLUSION: Users and patients wearing lead-free x-ray-protective clothing might unknowingly be exposed to a much larger dose than generally assumed. In the future, radiation protection rating should exclusively refer to the "attenuation ratio", which is based on broad beam geometry and characterizes radiation attenuation much more precisely than the lead equivalent.

Fluorescence↗
PubMed1982

Lead absorption in children of employees in a lead-related industry.

Children can be exposed to lead from a variety of environmental sources. It has been repeatedly reported that children of employees in a lead-related industry are at increased risk of lead absorption because of the high levels of lead found in the household dust of these workers. A case-control study was done in Oklahoma in 1978 to determine whether children of employees in battery manufacturing plant had a higher prevalence of high levels of blood lead than children whose parents were not employed in a lead-related industry. The data obtained indicated that the blood lead levels of the study children were significantly greater than those of the control children. None of the control children had blood lead levels greater than 30 micrograms/dl, while 53% of the exposed children had blood lead levels of greater than 30 micrograms/dl. Trends indicated that the children whose fathers had higher lead exposure at work also had higher blood lead levels. However, the study children whose fathers had good personal hygiene had blood lead levels comparable to the control children. It appeared that only good personal hygiene, i.e., showering, shampooing and changing clothes and shoes before leaving work, was effective for lead containment. The mere changing of clothes and shoes appeared to be inadequate for lead containment.

Child, Preschool↗
PubMed2001

The effects of retained lead bullets on body lead burden.

BACKGROUND: Numerous case reports have demonstrated that lead poisoning with potentially fatal consequences can result from retained lead projectiles after firearm injuries. To assess the impact of retained projectiles on subsequent lead exposure in the population, one cannot rely on self-selected cases presenting with symptoms of lead intoxication. This preliminary study seeks to identify increased lead burden and identify risk factors of elevated blood lead levels for individuals with retained lead bullets. METHODS: Forty-eight patients were originally recruited from gunshot victims presenting for care at the King/Drew Medical Center in Los Angeles, California. An initial blood level was measured for all recruited patients and repeated for the 28 participants available for follow-up, 1 week to 8 months later. Medical history, including a history of prior firearm injuries and other retained projectiles, was taken, along with a screening and risk factor questionnaire to determine other sources of lead (occupational/recreational) to which the patient might have been, or is at present, exposed. The participants also had K-shell x-ray fluorescence determinations of bone lead in the tibia and calcaneus in order to determine past lead exposures not revealed by medical history and risk factor questionnaire. Multivariate models of blood level were made using risk factor and bone lead concentration data. RESULTS: We demonstrated that blood lead tends to increase with time after injury in patients with projectile retention, and that the increase in significant part depended on the presence of a bone fracture caused by the gunshot. CONCLUSION: We encountered evidence suggesting that the amount of blood lead increase in time after injury is also dependent on the tibia lead concentration. There were too few cases in the study to fully test the effects of bullet location, or the interaction of bullet location with bone fracture or bullet fragmentation.

Adolescent↗
PubMed2001

Contribution of lead from calcium supplements to blood lead.

We conducted a case-control study to determine the contribution of lead to blood from consumption of calcium supplements approximating the recommended daily intakes over a 6-month period. Subjects were males and females ages 21 to 47 years (geometric mean 32 years) with a geometric mean blood lead concentration of 2.5 microg/dL. They were subdivided into three groups. One treatment group (n = 8) was administered a complex calcium supplement (carbonate/phosphate/citrate) and the other treatment group (n = 7) calcium carbonate. The control group (n = 6) received no supplement. The lead isotopic compositions of the supplements were completely different from those of the blood of the subjects, allowing us easily to estimate contribution from the supplements. The daily lead dose from the supplements at 100% compliance was about 3 microg Pb. Three blood samples were taken at 2-month intervals before treatment to provide background values, and three were taken during treatment. Subjects in the treatment group were thus their own controls. Lead isotopic compositions for the complex supplement showed minimal change during treatment compared with pretreatment. Lead isotopic compositions in blood for the calcium carbonate supplement showed increases of up to 0.5% in the (206)Pb/(204)Pb ratio, and for all isotope ratios there was a statistically significant difference between baseline and treatment (p < 0.005). The change from baseline to treatment for the calcium carbonate supplement differed from that for both the control group and the group administered the complex supplement. Blood lead concentrations, however, showed minimal changes. Variations in blood lead levels over time did not differ significantly between groups. Our results are consistent with earlier investigations using radioactive and stable lead tracers, which showed minimal gastrointestinal absorption of lead in the presence of calcium (+/- phosphorus) in adults. Even though there is no discernible increase in blood lead concentration during treatment, there are significant changes in the isotopic composition of lead in blood arising from the calcium carbonate supplement, indicating a limited input of lead from diet into the blood. Because calcium carbonate is overwhelmingly the most popular calcium supplement, the changes we have observed merit further investigation. In addition, this type of study, combined with a duplicate diet, needs to be repeated for children, whose fractional absorption of lead is considerably higher than that of adults.

Adult↗
PubMed2002

The effect of interior lead hazard controls on children's blood lead concentrations: a systematic evaluation.

Dust control is often recommended to prevent children's exposure to residential lead hazards, but the effect of these controls on children's blood lead concentrations is uncertain. We conducted a systematic review of randomized, controlled trials of low-cost, lead hazard control interventions to determine the effect of lead hazard control on children's blood lead concentration. Four trials met the inclusion criteria. We examined mean blood lead concentration and elevated blood lead concentrations (> or = 10 microg/dL, > or = 15 microg/dL, and > or = 20 microg/dL) and found no significant differences in mean change in blood lead concentration for children by random group assignment (children assigned to the intervention group compared with those assigned to the control group). We found no significant difference between the intervention and control groups in the percentage of children with blood lead > or = 10 microg/dL, 29% versus 32% [odds ratio (OR), 0.85; 95% confidence interval (CI), 0.56-1.3], but there was a significant difference in the percentage of children with blood lead > or = 15 microg/dL between the intervention and control groups, 6% versus 14% (OR, 0.40; 95% CI, 0.21-0.80) and in the percentage of children with blood lead > or = 20 microg/dL between the intervention and control groups, 2% versus 6% (OR, 0.29; 95% CI, 0.10-0.85). We conclude that although low-cost, interior lead hazard control was associated with 50% or greater reduction in the proportion of children who had blood lead concentrations exceeding 15 microg/dL and > or = 20 microg/dL, there was no substantial effect on mean blood lead concentration.

Air Pollution, Indoor↗
PubMed1999

Impact of diet on lead in blood and urine in female adults and relevance to mobilization of lead from bone stores.

We measured high precision lead isotope ratios and lead concentrations in blood, urine, and environmental samples to assess the significance of diet as a contributing factor to blood and urine lead levels in a cohort of 23 migrant women and 5 Australian-born women. We evaluated possible correlations between levels of dietary lead intake and changes observed in blood and urine lead levels and isotopic composition during pregnancy and postpartum. Mean blood lead concentrations for both groups were approximately 3 microg/dl. The concentration of lead in the diet was 5.8 +/- 3 microg Pb/kg [geometric mean (GM) 5.2] and mean daily dietary intake was 8.5 microg/kg/day (GM 7.4), with a range of 2-39 microg/kg/day. Analysis of 6-day duplicate dietary samples for individual subjects commonly showed major spikes in lead concentration and isotopic composition that were not reflected by associated changes in either blood lead concentration or isotopic composition. Changes in blood lead levels and isotopic composition observed during and after pregnancy could not be solely explained by dietary lead. These data are consistent with earlier conclusions that, in cases where levels of environmental lead exposure and dietary lead intake are low, skeletal contribution is the dominant contributor to blood lead, especially during pregnancy and postpartum.

Adult↗
PubMed1992

Removing lead from bone: clinical implications of bone lead stores.

The chelating agent, CaNa2EDTA, has proven useful for both the diagnosis and treatment of lead poisoning. The EDTA lead-mobilization test has demonstrated the presence of excessive body lead stores when blood concentrations were "normal." The EDTA lead-mobilization test is, however, impractical because it requires injections and timed urine collections. Bone lead measured in biopsy specimens by atomic absorption spectroscopy shows a good correlation with chelatable lead. Over 95% of the body stores of lead are retained in bone with a biological half-life approximating two decades. The half-life of lead in blood, on the other hand, approximates one month. Bone, therefore, provides a good estimate of cumulative lead absorption. In vivo tibial K x-ray fluorescence (XRF) is a safe, specific and reliable technique for the non-invasive measurement of elevated bone lead concentrations. K XRF measures lead to a depth of about 2 cm in cortical bone and is largely independent of geometric factors because lead is measured relative to bone calcium. In vivo tibial K XRF can therefore replace the EDTA lead-mobilization test and bone biopsies for assessing body lead stores and for following the efficacy and endpoint of deleading during chelation therapy.

Bone and Bones↗
PubMedDate not supplied

International perspectives of lead exposure and lead toxicity.

Three approaches have been used to examine how human body burdens of lead depend on different environments: (1) In paleopathologic studies, lead concentrations have been determined in well-preserved human bones or teeth, and pre-pollution samples generally show lead concentrations of about 1% of current levels in industrialized countries. (2) Geographic comparisons of blood-lead concentrations show low levels in, Nepal, Faroe Islands, and Sweden, while high levels occur in Mexico and Malta; average blood-lead levels may vary by a factor of 10 or more. (3) In analytical epidemiology, major exposure sources have been related to lead levels in blood, by either prospective or cross-sectional design. Increased blood-lead concentrations are related to smoking, drinking alcoholic beverages, eating vegetables for dinner, urban residence, and exposure from lead-using industries; average blood-lead values of subgroups within well-defined populations may vary by a factor of 3 or more. The dose-relationships for lead-induced neurotoxicity will depend on the sensitivity of the parameters chosen as indicators of lead exposure and of neurotoxicity. The temporal relationship between lead exposures and the development of deficits must be ascertained. Individual susceptibility and interacting factors must also be taken into account. Differences in addressing these issues impede the comparison between studies. Recently neonatal jaundice has been found to be a risk factor for subsequent neurobehavioral dysfunction in children with a birth weight above 2500 g, but only in children with increased lead exposure. Lead exposure may act in combination with several other factors and result in additive, or synergistic effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Environmental Exposure↗
PubMed1996

Evaluating lead bioavailability data by means of a physiologically based lead kinetic model.

A method of bioavailability estimation is presented in which a physiologically based kinetic model of lead kinetics is fit simultaneously to blood and bone lead concentrations after a period of exposure to dietary lead. Optimization of the simultaneous fit, varying only fractional absorption, gives the best estimate of fractional bioavailability for each treatment group. The analysis was applied to data from three separate studies in which rats were fed for 30 consecutive days purified diets containing lead added as lead acetate, mine waste-contaminated test soils, or mine waste itself. Fractional absorption decreased as lead intake increased, regardless of the source of the lead; but the magnitude of this dose dependence was lead source-dependent. There were no differences in lead absorption by male and female rats when lead intake was expressed per unit body weight. Fractional absorption varied from 4 to 5%, at low exposure rates (1-2 mg lead/kg/day) when lead acetate was added to the diet, to 0.24% at a high exposure rate (24 mg/kg/day) when a mine waste-contaminated test soil was added to the diet. Comparison of the results of this analysis with the results of a more conventional analysis, in which the bone and blood lead concentrations were separately compared with bone and blood lead concentrations in rats given daily injections of lead acetate intravenously for 29 consecutive days, demonstrated that the standard analysis failed to reveal the dose dependence of fractional absorption.

Animal Feed↗
PubMed1988

A single ECG lead in the serial monitoring of ischemic injury and necrosis in patients with acute anterior myocardial infarction: comparison with 49-lead precordial maps and standard ECGs.

To evaluate the single ECG lead with the maximal ST-segment elevation on admission as a modality suitable for monitoring ischemic injury and necrosis, the author correlated the single lead from 49-lead precordial maps and that from the corresponding standard ECGs with the ECG systems from which they derived. A total of 265 pairs of studies (14 per patient) from 20 patients with acute anterior myocardial infarction were used. Serial recordings were done on admission, at 12 predetermined time intervals during hospitalization, and at discharge. The amplitudes of ST-segment elevation, R waves, and Q waves of the single lead and all of the complexes of the corresponding precordial maps or standard ECGs were measured, using the same methodology. The single ECG lead correlated well with the precordial maps and the standard ECG. Although in serial studies the originally selected single lead was not the one displaying the maximal ST-segment elevation in 29% of the studies, it was always located on a locus immediately adjacent to the new lead in the grid recording the maximal ST. Changes in the precordial map or standard ECG were always detected by the corresponding single lead. The single lead from the standard ECG reflected changes in the precordial map, indicating that a precordial map is not necessary on admission for identification of the single lead. Correlations of R waves and Q waves from the single lead and the precordial map or the single lead and the standard ECG were not as good as the ones found for ST-segment elevation, although they provided monitoring of directional changes of the QRS complexes during hospitalization. Thus, a single lead from a precordial map or standard ECG is adequate for monitoring of the magnitude of ischemic injury in patients with acute anterior myocardial infarction. The single lead also provides some information as to the evolution of changes in the precordial QRS complexes associated with infarction and maintains its traditional role of providing surveillance for arrhythmias or conduction abnormalities.

Adult↗