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PubMed1989

A comparison of serial 49-lead precordial ECG maps and standard 6-lead precordial ECGs in patients with acute anterior Q wave myocardial infarction.

A comparison of 265 pairs of standard ECGs and 49-lead precordial maps in 20 patients with ST-segment elevations in anterior ECG leads on admission who eventually were diagnosed as having suffered an anterior Q wave myocardial infarction was carried out to investigate the diagnostic performance provided by the standard ECG in serial studies. Ten patients received intravenous methylprednisolone and 10 were given placebo on admission, and paired map-standard ECG studies were done. ST-segment elevations were taken as an index of ischemic injury and reduction of R wave amplitude or development of Q waves as a marker of developing necrosis. Methods of measurements and derivation of ECG parameters used in the analysis were the same for the standard ECGs and maps. Comparisons of percent change of five ECG-derived variables between 13 time points and admission, as assessed by the six precordial leads of the standard ECGs and the paired 49-lead maps, were made for the entire data base. A separate analysis to assess the performance of the standard ECG was carried out in a comparison of the methylprednisolone and placebo subgroups. In this latter assessment results of comparisons of the standard ECGs from the treatment and placebo cohorts were similar to the conclusions from the comparisons of the corresponding 49-lead maps. Comparisons for the entire 265 pairs of tracings by the two ECG systems demonstrated that the standard ECG is adequate to monitor quantitatively the ischemic injury and necrosis as reflected by the ECG in serial studies throughout the hospitalization and can be effectively employed in lieu of multilead precordial maps in the evaluation of therapeutic modalities for patients with anterior Q wave myocardial infarction.

Body Surface Area↗

PubMed1993

The effects of lead-resistant pseudomonads on the growth of Triticum Aestivum seedlings under lead stress.

Five Pseudomonad strains, SPb-1, SPb-2, SPb-3, (from a water sample), SPb-4, and SPb-5 (from rhizosphere), which could tolerate lead acetate up to 1000 microm ml(-1), were isolated from an industrially polluted area around Kasoor, Pakistan. Only SPb-5 harbours a lead-resistant plasmid. Triticum aestivum seeds inoculated with strains SPb-4 and SPb-5 were germinated and grown under different concentrations (0, 1, 5, 10, 15 and 20 mM) of lead acetate for ten days. Germination and seedling growth were adversely affected. Poor growth was associated with increased lead content of seedlings. With bacterial inoculation, germination and seedling growth were improved, as compared with non-inoculated treatments. Stimulation in the growth of seedlings was accompanied by a decrease in lead content, as compared with non-inoculated treatments.

Journal Article↗

PubMed1999

Importance of posterior chest leads in patients with suspected myocardial infarction, but nondiagnostic, routine 12-lead electrocardiogram.

Criteria for reperfusion therapy in acute myocardial infarction require the presence of ST elevation in 2 contiguous leads. However, many patients with myocardial infarction do not show these changes on a routine 12-lead electrocardiogram and hence are denied reperfusion therapy. Posterior chest leads (V7 to V9) were recorded in 58 patients with clinically suspected myocardial infarction, but nondiagnostic routine electrocardiogram. ST elevation >0.1 mV or Q waves in > or =2 posterior chest leads were considered to be diagnostic of posterior myocardial infarction. Eighteen patients had these changes of posterior myocardial infarction. All 18 patients were confirmed to have myocardial infarction by creatine phosphokinase criteria or cardiac catheterization. Of the 17 patients who had cardiac catheterization, 16 had left circumflex as the culprit vessel. We conclude that posterior chest leads should be routinely recorded in patients with suspected myocardial infarction and nondiagnostic, routine electrocardiogram. This simple bedside technique may help proper treatment of some of these patients now classified as having unstable angina or non-Q-wave myocardial infarction.

Adult↗

PubMed1995

Frequency content and sex difference of the Frank lead signal-averaged ECG in a population with significant coronary artery disease. Comparison with concurrent 12-lead ECG morphology.

The 12-lead electrocardiogram (ECG) and a 100-beat signal-averaged Frank lead ECG (SAECG) at a sampling rate of 1,000 Hz and with 16-bit resolution were recorded from 52 women and 256 men with significant coronary artery disease presenting for coronary artery revascularization. The QRS portion of each Frank lead was digitally filtered in four bandwidths: 0-10, 10-60, 60-150, and 150-250 Hz. The root-mean-square (RMS) voltage of each filtered signal was calculated as an absolute value and normalized as a percentage of the sum of the four filters, creating 27 variables. Three groups were formed using the presenting 12-lead ECG: N-ECG, ST-ECG, and MI-ECG. Despite variation in 12-lead morphology, concordance was dominant in the RMS values of the SAECG in sex comparisons within and between groups. There was significant sex difference of the RMS values in 6 of the 15 absolute RMS variables within the three groups. Women had no significant between-group difference, and men had a significant between-group differences in five absolute values and one normalized RMS value. P was considered significant at < .05.

Analysis of Variance↗

PubMed2000

Orthogonal leads for the measurement of QT dispersion: a comparison with conventional leads.

To determine the characteristics of QT interval dispersion using orthogonal ECG leads with high paper speed (100 mm/s) and high voltage gain (10 cm/mV) as compared to conventional 12-lead ECG, we measured the QT dispersion in 57 patients at rest and directly after exercise using these two techniques. The measurements were repeated by the same observer and by an independent observer in 29 patients to assess reproducibility. QT dispersion was found to be significantly lower in orthogonal leads than standard lead tracings (24+/-20 ms versus 44+/-17 ms at rest, P<0.001; 29+/-21 ms versus 53+/-27 ms after exercise, P<0.001, respectively). The intrasubject and interobserver reproducibility was better for the orthogonal lead tracings, making this technique a potentially useful tool for future research.

Adult↗

PubMed1997

Standard 12-lead ECG versus special chest leads in the diagnosis of right ventricular myocardial infarction.

The case of a 60-year-old woman with an acute inferior transmural myocardial infarction associated with a right ventricular myocardial infarction provided an opportunity to compare the performance of the 12-lead electrocardiogram (ECG) and the right chest leads in the diagnosis of infarction of the right ventricle. While the right chest leads revealed unequivocal evidence of ischemic injury emanating from the right ventricle, the standard leads II and III showed changes compatible with inferior myocardial infarction; familiarity with vectorial interpretive concepts of ST segment deviations could provide a hint of an associated right ventricular involvement. This report is presented at a time of renewed controversy regarding the necessity of special ECG leads in the diagnosis of acute right ventricular infarction in the routine emergency department environment.

Electrocardiography↗

PubMed2000

Enhancing the hit-to-lead properties of lead optimization libraries

In this paper we address several issues in the design of lead optimization libraries. Multipharmacophore descriptors were first developed in the context of designing diverse compound libraries. One reason for favoring such descriptors is the importance of the pharmacophore hypothesis in understanding the interaction of a compound with a protein target. Allied to this is the proposal that sampling over all potential pharmacophores leads to diversity in a biologically relevant space. We present results in support of this argument and also demonstrate that such methods are applicable to the design of focused libraries where the aim is to design the library toward a known lead or leads. This portability is important because it means that the same descriptors can be used for diverse library design, screening set selection, and focused library design, giving a consistent approach. We also examine the question of designing libraries with improved pharmacokinetic properties and show that it is possible to derive simple and rapidly computable descriptors applicable to the prediction of drug transport properties. Furthermore, these can be applied in the context of library design, although it may be necessary to synthesize libraries in a noncombinatorial manner to obtain the best results. To address this problem, we describe a Monte Carlo search procedure that allows the selection of a near-combinatorial subset in which all library members satisfy the design criteria. We present an example from our own work that illustrates how consideration of calculated log P, molecular weight, and polar surface area in the design of a combinatorial library can lead to compounds with improved absorption characteristics as determined by experimental Caco-2 measurements.

Journal Article↗

PubMed2002

Holo- and hemidirected lead(II) in the polymeric [Pb(4)(mu-3,4-TDTA)2(H2O)2]*4H2O complex. N,N,N',N'-tetraacetate ligands derived from o-phenylenediamines as sequestering agents for lead(II).

The coordinating ability of the ligands 3,4-toluenediamine-N,N,N',N'-tetraacetate (3,4-TDTA), o-phenylenediamine-N,N,N',N'-tetraacetate (o-PhDTA), and 4-chloro-1,2-phenylenediamine-N,N,N',N'-tetraacetate (4-Cl-o-PhDTA) (H4L acids) toward lead(II) is studied by potentiometry (25 degrees C, I = 0.5 mol x dm(-3) in NaClO4), UV-vis spectrophotometry, and 207Pb NMR spectrometry. The stability constants of the complex species formed were determined. X-ray diffraction structural analysis of the complex [Pb4(mu-3,4-TDTA)4(H2O)2]*4H2O (1) revealed that 1 has a 2-D structure. The layers are built up by the polymerization of centrosymmetric [Pb4L2(H2O)2] tetranuclear units. The neutral layers have the aromatic rings of the ligands pointing to the periphery, whereas the metallic ions are located in the central part of the layers. In compound 1, two types of six-coordinate lead(II) environments are produced. The Pb(1) is coordinated to two nitrogen atoms and four carboxylate oxygens from the ligand, whereas Pb(2) has an O6 trigonally distorted octahedral surrounding. The lead(II) ion is surrounded by five carboxylate oxygens and a water molecule. The carboxylate oxygens belong to four different ligands that are also joined to four other Pb(1) ions. The selective uptake of lead(II) was analyzed by means of chemical speciation diagrams as well as the so-called conditional or effective formation constants K(Pb)eff. The results indicate that, in competition with other ligands that are strong complexing agents for lead(II), our ligands are better sequestering agents in acidic media.

Journal Article↗

PubMed2006

Crystal structure of lead(II) acetylacetonate and the structure of the acetylacetone solvated lead(II) ion in solution studied by large-angle X-ray scattering.

The crystal structure of bis(acetylacetonato)lead(II) and the structure of the acetylacetone solvated lead(II) ion in solution have been determined by single-crystal X-ray diffraction and large-angle X-ray scattering (LAXS), respectively. The acetylacetone is deprotonated and acts as a bidentate anionic ligand (acac-) in the solid Pb(acac)2 compound. The lead(II) ion binds four oxygen atoms strongly in a nearly flat pyramidal configuration with Pb-O bond lengths in the range 2.32-2.37 A, and additionally three oxygens from neighboring complexes at 3.01-3.26 A. Acetylacetone acts as a solvent (Hacac) at dissolution of lead(II) trifluoromethanesulfonate forming a pentasolvate with a mean Pb-O bond distance of 2.724(5) A. The 6s2 lone electron pair on the lead(II) ion becomes stereochemically active in the crystalline acetylacetonate complex, while it is inactive in the solvate in solution. The solution was also analysed using IR and 1H NMR spectroscopy.

Journal Article↗

PubMed1990

Transatrial implantation of transvenous pacing leads as an alternative to implantation of epicardial leads.

State-of-the-art pacing modalities are not readily utilized with conventional epicardial pacing lead implantation techniques. A transatrial implantation technique was developed combining a limited surgical approach with transvenous leads. Six patients who were poor candidates for transvenous implants have received DDD or DDDR pacemakers by this approach. The limited surgical approach includes resection of the third or fourth costal cartilage through a small skin incision, reflection of the pleura, and opening of the pericardium. The introducer and transvenous leads are inserted through a right atrial pursestring suture. The leads are positioned in the right ventricle and right atrium using standard fluoroscopic techniques. Through the incision, the subcutaneous tissue pocket is constructed on the right anterior chest wall. The leads are connected to the pacemaker without the need for adaptors or tunneling. There were no procedure-related complications. The magnitude of the surgery and postoperative morbidity are significantly less than for a standard thoracotomy, median sternotomy, and transdiaphragmatic epigastric or subcostal approach. The utility of the transatrial implantation technique is that it allows the use of state-of-the- art bipolar dual chamber pacemakers restoring access to all pacing modalities for those patients not candidates for transvenous implantation.

Adult↗

PubMed1992

Ventricular lead transection and atrial lead damage in a young softball player shortly after the insertion of a permanent pacemaker.

We report a case in which permanent pacemaker implantation using a conventional subclavian approach on the throwing side of an avid softball player resulted in complete transection of the ventricular lead and severe damage to the atrial lead. The site of the lead fracture suggested that both leads were crushed between the clavicle and the first rib as a result of the frequent and repetitive arm movement. This case illustrates the importance of the selection of the correct approach for permanent pacing lead insertion.

Adult↗

PubMed1998

A complication of pacemaker lead extraction: paradoxical embolism of a lead fragment in a leg artery.

Extraction of three chronically implanted pacemaker leads was performed via the implant vein in a 71-year-old man. One of the leads broke in the subclavian scar tissue. The lead fragment migrated into the left peroneotibial trunk artery. Transesophageal echocardiography showed patent foramen ovale associated with right-to-left atrial shunt. This complication of lead extraction is discussed along with the role of echocardiography prior to lead removal.

Aged↗

PubMed2006

VDD lead-lead interaction and atrial oversensing: an acute animal study.

Limited data exist on the utilization of a transvenous A-sense; V-pace/sense (VDD)pacing system with a chronically retained nonfunctioning endocardial V-sense/pace (VVI)pacing lead. In an acute canine model, no atrial oversensing was observed with lead-lead interaction between the VDD lead and the pseudo-retained VVI lead. Undersensing occurred <10% of all beats observed.

Animals↗

PubMed2000

Exchange of pacing or defibrillator leads following laser sheath extraction of non-functional leads in patients with ipsilateral obstructed venous access.

Occlusion of the subclavian or brachiocephalic vein in pacemaker or defibrillator patients prohibits ipsilateral implantation of new leads with standard techniques in the event of lead malfunction. Three patients are presented in whom laser sheath extraction of a non-functional lead was performed in order to recanalise the occluded vein and to secure a route for implantation of new leads. This technique avoids abandoning a useful subpectoral site for pacing or defibrillator therapy. The laser sheath does not affect normally functioning leads at the same site.

Adult↗

PubMedDate not supplied

Role of lead aVR in evaluation of 12-lead electrocardiogram.

Diagnostic information obtained from the evaluation of the unipolar lead aVR in electrocardiography (ECG) is not fully appreciated, and therefore, the lead aVR is often overlooked in the routine evaluation of the 12-lead ECG. Lead aVR may supplement clinical information, aiding in the management of several cardiovascular conditions. The role of the lead aVR in evaluation of various clinical conditions is reviewed.

Antidepressive Agents, Tricyclic↗

PubMed2004

Lead isotopic compositions of environmental certified reference materials for an inter-laboratory comparison of lead isotope analysis.

Lead isotope ratios, viz. 207Pb/206Pb and 208Pb/206Pb, of the commercially available certified reference materials (CRMs) issued in Japan are presented with an objective to provide a data set, which will be useful for the quality assurance of analytical procedures, instrumental performance and method validation of the laboratories involved in environmental lead isotope ratio analysis. The analytical method used in the present study was inductively coupled plasma quadrupole mass spectrometry (ICPQMS) preceded by acid digestion and with/without chemical separation of lead from the matrix. The precision of the measurements in terms of the relative standard deviation (RSD) of triplicated analyses was 0.19% and 0.14%, for 207Pb/20Pb and 208Pb/206Pb, respectively. The trueness of lead isotope ratio measurements of the present study was tested with a few CRMs, which have been analyzed by other analytical methods and reported in various literature. The lead isotopic ratios of 18 environmental matrix CRMs (including 6 CRMs analyzed for our method validation) are presented and the distribution of their ratios is briefly discussed.

Journal Article↗

PubMed1975

Comparison between Wilson's thoracic leads and the telemetrically transmitted lead CM6 in patients with heart diseases during exertion.

In 76 patients suffering from heart diseases and 19 healthy men simultaneously the chest leads V(2), V(4) and V(5) were recorded and the bipolar lead CM(6) (Manubrium sterni-Apex cordis, 6th intercostal space) transmitted telemetrically during increasing exercise load on the bicycle ergometer. The lead CM(6) was most similar to chest lead V(5) with regard to R/S-ratio, ST-depression, form and amplitude of the T-wave, QX-QT-ratio and ST-elevation. ST-depressions of V(5) were found nearly without exception in CM(6), mostly more pronounced. Ascending ST-depressions are more frequent in CM(6) than in V(5), in single patients also ST-depressions with horizontal or downward slope. ST-elevations registrated in V(2) and V(4) are not reliably reproduced in CM(6). It is concluded that the wireless transmission of the bipolar chest lead CM(6) is sufficient for the diagnosis of coronary insufficiency during exercise,

Adult↗

PubMed2001

[Comparative assessment of the left chest EKG leads V7-V9 and bipolar Slapak and Partilla leads in the diagnosis of posterior and posteriobasal myocardial infarction].

The study included 100 patients with acute inferoposterior myocardial infarction consequently admitted to hospital. Both the standard ECG in 12 leads as well as additional V7-V9 and Slapak & Partilla leads were recorded in each patient. Two-dimensional echo at rest was performed to evaluate regional wall motion. The criterion of dividing patients into any MI subgroup was the presence of abnormal Q wave in any system leads. Posterior + inferior MI was found in 88%, limited posterobasal--in 2% and diaphragmal (inferior)--in 10% of patients. Good correlation of Q-wave in II, aVF and S1-S4, V7-V9 and S1-S4 was found. The more abnormal Q waves were revealed in lead systems the more was necrosis size as assessed by echo. We conclude, that additional lead systems are of value in revealing necrosis size and its location in patients with damaged posterior wall.

Electrocardiography↗