Biopotential fiber sensor.

UNLABELLED: We have developed a new biopotential fiber sensor (BFS) technology as an alternative to traditional wet-gel Ag/AgCl electrodes in long-term monitoring applications. Biopotential fiber sensor technology uses proprietary method of bonding copper sulfide to the surface of acrylic fibers, thus creating an electrically conductive medium (10(-1) ohms/cm). Surface modified bundles of acrylic fibers form stable biopotential sensors when doped with proprietary ink comprising organic acids and nano particles of Ag and AgCl. Biopotential fiber sensors are characterized by a small footprint 0.1 mm2 and low mass of 0.005 g. Biopotential fiber sensor systems are disposable 1-piece assemblies combining the functions of the electrodes, lead wires and a patient cable. METHODS: The electric performance characteristics of BFS were obtained according to American National Standards Institute/Association for the Advancement of Medical Instrumentation EC-12:2000 standard and compared with Ag/AgCl wet-gel electrodes. The noise characteristics were determined from 250 hours of 3-lead electrocardiographic (ECG) data recorded with BFS over a period of 10 days from healthy volunteers. RESULTS: The BFS direct current offset voltage was 0.11 mV and alternate current impedance at 10 Hz was 22 ohms. The sensors average longevity on the body surface with no detachments was at least 7 days. BFS demonstrated high immunity to motion and electric field-induced artifacts. CONCLUSIONS: Biopotential fiber sensors are well suited for routine long-term ECG monitoring applications because of increased patient comfort through integration of the electrode, lead wire, and a patient cable, which function into one disposable BFS fiber assembly. Biopotential fiber sensor have electrical characteristics comparable to Ag/AgCl wet electrodes. We observed an improved ECG signal quality, reduced frequent electrode detachments, reduced wire clutter and entanglement, and improved sensor adherence to the skin over longer periods of time.

A posterior-based omega-shaped flap vaginoplasty in girls with congenital adrenal hyperplasia caused by 21-hydroxylase deficiency.

OBJECTIVE: To describe a technical modification for constructing a vagina in girls with congenital adrenal hyperplasia caused by 21-hydroxylase deficiency, using a narrower skin base but rich subcutaneous tissue, aiming to obtain both longer and larger vaginal segments with better cosmesis of the external genitalia. PATIENTS AND METHODS: From August 1997 to February 2001, 28 girls (aged 5 months to 17 years) had a neovagina constructed using a posterior-based omega-shaped flap. Twenty-six patients had a low vagina entering into the urogenital sinus and two had a high vagina that entered the urogenital sinus. In those with a high vagina the flap procedure was combined with the Passerini-Glazel technique. All the patients were scheduled for vaginal "calibrations" during the first year after surgery and, according to the result, would then undergo vaginal dilatation. RESULTS: Six children were re-operated; five had plastic surgery to correct genital folds that had regained a scrotal aspect, whereas one with a high vagina developed a urethral stricture, with urinary dribbling and infection, and had the urethra reconstructed. These six children are currently well. No hormone therapy was given to one child for 1 year who is scheduled for further surgery for a re-virilized clitoris. Two patients were lost to follow-up. Up to the last visit, 19 girls had not developed a vaginal stricture and the cosmesis of their external genitalia was deemed good. CONCLUSION: The posterior-based omega-shaped flap enabled both the construction of wider vaginal segments with a low risk of developing stenosis in those with a low vagina, and increased vaginal dimension when associated with the Passerini-Glazel technique for those with a high vagina. However, despite good cosmesis of the external genitalia, the follow-up is too short to confirm whether this technique will meet all the expectations.

Sigmoid reconfigured vaginal construction in children.

PURPOSE: We present a modified technique of sigmoid neovaginal construction in children that protects the sigmoid pedicle from traction, allows easy adjustment of caliber and reorients the mucosal fold in a longitudinal direction. MATERIALS AND METHODS: From 1997 to 2000, 10 genetically male (46 XY) children 1 to 13 years old underwent construction of a neovagina with sigmoid, incorporating the Yang-Monti concept of intestinal reconfiguration. The diagnosis was androgen insensitivity in 7 patients, congenital adrenal hyperplasia in 2 due to 17 alpha-hydroxylase deficiency and 3 beta-hydroxysteroid dehydrogenase deficiency, respectively, and bladder exstrophy in 1 who required sex reassignment. RESULTS: Eight children had an adequate caliber neovagina after an initial period of systematic dilation. In 1 case a relevant stricture required reoperation using the same technique and the outcome was good. In another child a stricture developed in the middle of the reconfigured sigmoid segment and a regular dilation schedule is still being followed after 23 months of followup. CONCLUSIONS: The new sigmoid reconfiguration technique enables the use of smaller dimension intestinal segments and construction of a long vaginal conduit of adequate caliber. Its optimal adequacy for penetration must be assessed in the future after these patients begin sexual activity.

Cardiovascular collapse caused by electrocardiographically silent 60-Hz intracardiac leakage current. Implications for electrical safety.

BACKGROUND: The national standard for safe 60-Hz intracardiac leakage current under a single-fault condition is 50 microA. This standard is intended to protect patients from alternating current (AC) at levels below the threshold for sensation, but the minimum unsafe level for AC in closed-chest humans is not known. To determine this value, we studied 40 patients at testing of implantable cardioverter-defibrillators using a programmable source of 60-Hz AC. METHODS AND RESULTS: We applied AC for 5-second test periods in increasing strengths until ventricular fibrillation (VF) was induced or 1 mA was reached. Two current paths were tested: bipolar, between tip and ring electrodes of a right ventricular pacing catheter, and unipolar, from tip to a remote electrode. We observed a characteristic sequence of 3 responses as AC was increased: (1) intermittent ventricular capture with QRS morphology identical to pacing through the electrodes (minimum value, 20 microA); (2) continuous capture at cycle length 282+/-88 ms (minimum value, 32 microA); and (3) VF persisting after AC termination (minimum value, 49 microA). Continuous capture caused loss of pulsatile arterial pressure and cardiovascular collapse (mean arterial pressure, 32+/-8 mm Hg) for the duration of AC with no ECG evidence of AC stimulation. Thus, the clinical picture was that of hypotensive ventricular tachycardia (VT). The continuous-capture threshold was /=5 seconds should be

Antibodies to ICA512/IA-2 in rodent models of IDDM.

Antibodies to ICA512/IA-2 are a well established marker of human IDDM and can be detected prior to and soon after the onset of insulin dependency. The non-obese diabetic (NOD) mouse and the diabetes-prone BB rat develop spontaneous diabetes as a consequence of T-cell mediated autoimmune destruction of islet beta-cells, but the occurrence of autoantibodies is controversial. We tested sera from NOD mice and BB-rats for anti-ICA512 by a radioimmunoprecipitation assay (RIP). In sequential serum samples from 20 NOD mice, of which 15 developed diabetes, low levels of anti-ICA512 were demonstrable. Anti-ICA512 appeared close to the onset of hyperglycaemia and was usually transient. Non-diabetic NOD mice also produced anti-ICA512, but at a later age and at lower levels than the diabetic NOD mice. In a cross-sectional analysis of sera from BB rats, low levels of anti-ICA512 were present in 11/20 (55%) of non-diabetic-diabetes prone (DP) BB rats, 0/4 (0%) of diabetic DP BB rats, and 1/6 (17%) of diabetes-resistant BB rats. Anti-ICA512 was not detected in rats of other strains, including three Sprague-Dawley rats with streptozotocin-induced diabetes. In both NOD mice and BB rats the anti-ICA512 reactivity was directed to the cytoplasmic domain of the protein. The transient appearance of anti-ICA512 close to the onset of diabetes in NOD mice and the loss of these antibodies after diabetes onset is consistent with the occurrence of anti-ICA512 in human IDDM. Thus in both human IDDM and rodent models, anti-ICA512 is a marker of the impending onset of diabetes and disappears after diabetes onset.

Patient-specific predictions of outcomes in myocardial infarction for real-time emergency use: a thrombolytic predictive instrument.

BACKGROUND: Thrombolytic therapy can be life-saving in patients with acute myocardial infarction. However, if given too late or insufficiently selectively, it may provide little benefit but still cause serious complications and incur substantial costs. OBJECTIVE: To develop a thrombolytic predictive instrument for real-time use in emergency medical service settings that could 1) identify patients likely to benefit from thrombolysis and 2) facilitate the earliest possible use of this therapy. DESIGN: Creation and validation of logistic regression-based predictive instruments based on secondary analysis of clinical data. PATIENTS: 4911 patients who had acute myocardial infarction and ST-segment elevation on electrocardiogram; 3483 received thrombolytic therapy. MEASUREMENTS: Data were obtained from 13 major clinical trials and registries and directly from medical records, including electrocardiograms obtained at presentation. Input variables include presenting clinical and electrocardiography features; predictive models generate probabilities for acute (30-day) mortality if and if not treated with thrombolysis, 1-year mortality rates if and if not treated with thrombolysis, cardiac arrest if and if not treated with thrombolysis, thrombolysis-related intracranial hemorrhage, and thrombolysis-related major bleeding episode requiring transfusion. Together, these models constitute the thrombolytic predictive instrument. RESULTS: The predictive models generated the following mean predictions for patients in the Thrombolytic Predictive instrument Database: 30-day mortality rate, 7.1%; 1-year mortality rate, 10.9%; rate of cardiac arrest, 3.7%; rate of thrombolysis-related intracranial hemorrhage. 0.6%; and rate of other thrombolysis-related major bleeding episodes, 5.0%. They discriminated with between persons having and those not having the predicted outcome; areas under the receiver-operating characteristic (ROC) curve were between 0.77 and 0.84 for the five outcomes. Calibration between each instrument's predicted and observed served rates was excellent. Validation of the predictive instruments of 30-day and 1-year mortality, done on a separate test dataset, yielded areas under the ROC curve of 0.76 for each CONCLUSIONS: After the basic features of a clinical presentation are entered into a computerized electrocardiograph, the predictions of the thrombolytic predictive instrument can be printed on the electrocardiogram report. This decision aid may facilitate earlier and more appropriate use of thrombolytic therapy in patients with acute myocardial infarction.

Estimation of regional end-systolic wall stress during exercise in coronary artery disease.

Estimating left ventricular wall stress has recognized applications, but formulae for global stress cannot be applied to ischemic ventricles. A mathematic method for estimating regional stress in infarcted ventricles has been described. The hypothesis tested was that exercise-induced ischemia increases end-systolic wall stress. Subcostal four-chamber echocardiograms were recorded at rest and during peak symptom-limited exercise in 19 controls and 41 patients with chest pain undergoing coronary arteriography. Centerline regional wall motion and regional end-systolic wall stress were measured at rest and at peak exercise. The normal controls had increased wall motion with exercise, but wall stress remained low. All 32 of the patients with coronary artery disease (> or = 50% diameter narrowing) had wall motion abnormalities with exercise, but the sensitivity of identifying right coronary artery obstructions was poor. Patients with coronary disease had higher regional stress at peak exercise than did the controls. The sensitivity of identifying lesions in all three coronary arteries (0.95 to 1.0) was better than that for wall motion (p < 0.04). The specificity of wall stress needs to be tested in a larger population. Exercise-induced ischemia causes increased regional end-systolic wall stress that reflects its distribution in patients with coronary artery disease. These changes can be measured non-invasively during exercise echocardiography.

Prediction of the infarct-related artery in acute myocardial infarction by a scoring system using summary ST-segment and T-wave changes.

We developed a scoring system to predict the artery responsible for an acute myocardial infarction (AMI) using ST-segment and T-wave changes on the initial electrocardiogram (ECG) using data from 228 patients (development set) with symptoms compatible with AMI and tested in a similar group of 223 patients (test set) from the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI-5) Trial. Using stepwise logistic regression we were able to accurately predict the left anterior descending (LAD), right, or left circumflex (LC) coronary artery as the infarct-related artery using 2 variables: (1) the summation of the ST-segment elevation in leads V1 to V4; and (2) the summation of the T-wave negativity in leads I, aVL, and V5. In the development set, these 2 variables demonstrated respective sensitivity and specificity of 98% and 90% for LAD lesions, 82% and 85% for right narrowings, and 82% and 84% for LC narrowings. In the test set, the sensitivity and specificity were 97% and 95% for LAD lesions, 85% and 86% for right lesions, and 73% and 60% for LC coronary artery lesions. Information easily obtained on the ECG can accurately predict the likelihood of the LAD, right, or LC artery as the infarct-related artery. This may be useful in the decision to administer thrombolytic treatment.

Comparison of electron beam computed tomography scanning and magnetic resonance imaging quantification of right ventricular mass: validation with autopsy weights.

RATIONALE AND OBJECTIVES: We compared, in the same human hearts, the ability of magnetic resonance (MR) imaging and electron beam computed tomography (CT) scanning to accurately quantify the free wall and septal components of right ventricular (RV) mass. METHODS: Eleven hearts extracted at autopsy were subjected to MR imaging and electron beam CT scanning in short-axis projections. Regression analyses of mass determinations obtained by manual planimetry MR imaging and electron beam CT scanning and autopsy weights were performed. RESULTS: RV free wall mass by both MR imaging (53.4 +/- 19.1 g) and electron beam CT scanning (53.9 +/- 20.4 g) correlated well with autopsy weight (57.7 +/- 20.2 g). Regression analysis showed a strong correlation for MR imaging (r = .88, slope = .88, standard error the estimate [SEE] = 7.2 g, p < .001) and electron beam CT scanning (r = .95, slope = .95, SEE = 6.6 g, p < .001). RV septal mass by MR imaging (10.8 +/- 3.5 g) and electron beam CT scanning (7.1 +/- 2.4 g) correlated less well with the autopsy weight (12.5 +/- 6.5 g). Regression analysis showed a fair correlation for MR imaging (r = .45, slope = .83, SEE = 2.05 g, p = .001) and a poor correlation for electron beam CT scanning (r = .46, slope = .17, SEE = 2.25 g, p = .57). CONCLUSION: Both MR imaging and electron beam CT scanning accurately predict RV free wall mass but have difficulty predicting the septal component. Because the septal component constitutes only a small proportion of the total RV mass, determinations of RV mass should be based solely on the free wall component.

The exclusion of women from clinical trials of thrombolytic therapy: implications for developing the thrombolytic predictive instrument database.

The thrombolytic predictive instrument (TPI) was developed to identify those patients most likely to benefit from thrombolytic therapy for acute myocardial infarction as well as to facilitate the earliest possible administration of this treatment. The TPI consists of predictive models derived from clinical data obtained from both clinical trials and data registries. These models are subject to potential bias due to combinations of primary data from different sources. The purpose of this investigation was to assess the influence of gender in developing the TPI database. In this database, there were 1,096 (22%) women and 3,826 (78%) men; only 38% of the women were enrolled in clinical trials, whereas 46% of the men were (p < 0.0001). Within clinical trials, there were few significant eligibility differences between women and men, as the vast majority of patients met eligibility standards for entry in these trials. However, within clinical registries, the women were older (p < 0.0001) and more often had elevated blood pressure on admission (p = 0.002). Multivariate logistic regression indicated that after adjustment for significant predictors of trial inclusion, women were 25% less likely to be included in clinical trials (odds ratio = 0.76, 95% confidence interval = 0.60, 0.96). In order to counter bias introduced by the exclusion of women from clinical trials, the TPI database included patients from non-trial settings. Carefully including patients from clinical registries or non-trial settings may be an important strategy in constructing generally applicable predictive instruments.

Right ventricular mass measurement by electron beam computed tomography. Validation with autopsy data.

RATIONALE AND OBJECTIVES: Validation of right ventricular mass quantitation by electron beam computed tomography in humans has not been performed. The ability of electron beam computed tomography to accurately determine the septal component of the right ventricle also has not been determined. This article addresses both issues. METHODS: Twenty human adult hearts obtained at autopsy were scanned by electron beam computed tomography in a short-axis projection. Planimetry of the right ventricular free wall and septal components of each slice was performed and summed to determine right ventricular mass. These measurements were compared against comparable measurements obtained by autopsy weights of the hearts. RESULTS: Right ventricular free wall weights by electron beam computed tomography (53.9 +/- 18.4 g) correlated well (slope = .92, r = .92, standard error of the estimate = 7.4 g, P < .001) with autopsy weights (55.8 +/- 18.4 g). Right ventricular septal weights by electron beam computed tomography (6.1 +/- 2.3 g) correlated poorly (slope = .04, r = .11, standard error of the estimate = 2.4 g, P = .65) with autopsy weights (13.9 +/- 6.3 g). CONCLUSIONS: Electron beam computed tomography quantitation of right ventricular mass is accurate in humans if only the free wall and not the septal component is utilized.