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PubMed2000

Automatic ectopic beat elimination in short-term heart rate variability measurement.

Our studies deal with fully automatic measurement of heart rate variability (HRV) in short term electrocardiograms. Presently, all existing HRV analysis programs require user intervention for ectopic beat identification, especially of supraventricular ectopic beats (SVE). This makes the HRV measurement in large, e.g. epidemiological studies problematic. In this paper, we present a fully automatic algorithm for the discrimination of the ventricular (VE) and SVE ectopic beats from the normal QRS complexes suited for a reliable HRV analysis. The QRS identification is based on the template matching method. The ectopic beats are identified based on several morphological and timing properties of the electrocardiogram (ECG) signal. The method incorporates several approaches and makes HRV analysis of large numbers of electrocardiograms feasible. It uses the template matching for the basic morphology check of the QRS complex and the P-wave, the timing information to avoid unnecessary ectopic beat checks and to adjust thresholds and it also looks for a special QRS morphology, which is common in VEs. We used a testing set of 69 electrocardiograms selected from a large number of recordings. The selected ECGs contained abnormalities including ectopic beats, right branch bundle block, respiratory arrhythmia, blocked atrial extrasystole, high amplitude and wide T-waves. The evaluation of our method showed a specificity of 0.99, supraventricular ectopic beat sensitivity of 0.99 and ventricular ectopic beat sensitivity of 0.98.

Algorithms↗
PubMed2002

Automatic pattern recognition in ECG time series.

In this paper, a technique for the automatic detection of any recurrent pattern in ECG time series is introduced. The wavelet transform is used to obtain a multiresolution representation of some example patterns for signal structure extraction. Neural Networks are trained with the wavelet transformed templates providing an efficient detector even for temporally varying patterns within the complete time series. The method is also robust against offsets and stable for signal to noise ratios larger than one. Its reliability was tested on 60 Holter ECG recordings of patients at the Department of Cardiology (University of Bonn). Due to the convincing results and its fast implementation the method can easily be used in clinical medicine. In particular, it solves the problem of automatic P wave detection in Holter ECG recordings.

Electrocardiography↗
PubMed1997

Computerized automatic system to obtain inspiration/expiration chest roentgenograms without patient collaboration.

We have developed a computerized automatic X-ray image acquisition system. It consists of conventional pressure and flow transducers connected to a commercial data acquisition card installed in a PC/AT, the card output being connected through a relay to a conventional X-ray system. Signal processing, that has been applied for automatic detection of inspiration and expiration in respiratory signals, allows the X-ray equipment activation at a given moment of the respiratory cycle. Radiographs are thus obtained either in inspiration or expiration at tidal volume on anaestesized experimental animals. The system has also been tested on non-collaborating patients.

Animals↗
PubMed1997

Toxopert-I: knowledge-based automatic interpretation of serological tests for toxoplasmosis.

Primary infection with Toxoplasma gondii, a parasite found in most regions of the world, is asymptomatic in more than 80% of cases. However, primary infection with Toxoplasma gondii in a pregnant woman might cause fetal infection and severe damage. Most cases do not require treatment. This applies to women without any infection (denoted as seronegative) and women who have acquired the infection before conception (denoted as latent). In contrast, women with postconceptual infection require immediate treatment to prevent or ameliorate fetal infection. We have developed an expert system, called Toxoport-I, designed for routine laboratory work, which automatically interprets serological test results of toxoplasma infection. By using the system the clinician can also examine questionable cases by interactively exploring possible results. We used a popular method of designing expert systems applied to medical interpretation and therapy advice, the rule-based one. In order to meet the requirements of automatic interpretation in toxoplasma serology the following characteristics were introduced: the interpretation of sequences of test results, the possibility of excluding inconsistent test results and the adaptability of the knowledge base. A decision graph that covers the different kinds of infections as well as therapy and recommendations for further tests was designed, implemented and was clinically tested by carrying out a retrospective study including 1000 pregnant women. A comparison of Toxoport-I and the clinician's interpretations yielded sensitivity and specificity rates of over 99% each.

Animals↗
PubMed1999

Automatic finite element mesh generation for maxillary second premolar.

Developing three dimensional finite element mesh models for irregular geometric objects requires a large amount of manual efforts, hence limiting the three dimensional approach for dental structure analyses. An automatic procedure which can be used to generate a three dimensional finite element mesh for the maxillary second premolar was developed in this study. Firstly, a embedded second premolar was sliced and scanned parallel to the occlusal surface. A self-developed image processing system was employed to detect the boundaries of different materials within each section. An automatic mesh generation program was used on these boundaries to create tetrahedral elements based on moving nodes of uniform cube approach. Six mesh models of the second premolar with different element sizes using linear and quadratic elements were analyzed. Strain energy and von Mises stresses were reviewed for convergence in the crown regions.

Algorithms↗
PubMed1997

Evaluation of the efficacy of a 3.2% glutaraldehyde product for disinfection of fibreoptic endoscopes with an automatic machine.

The efficacy of 'Cidex Plus' 3.2% alkaline glutaraldehyde was evaluated for the disinfection of fibreoptic endoscopes. The glutaraldehyde concentration in 'Cidex Plus', stored in an automatic machine (Olympus EW-20), remained higher than 2% (2.21%) even after a total of 102 disinfection cycles during 28 consecutive days. The results of the in-vitro study on antimicrobial activity showed that this alkaline glutaraldehyde product had a greater activity against 20 test organisms, including vegetative bacteria, bacterial spores, mycobacteria, and fungi, than 2% glutaraldehyde alone. The presence of 10 or 30% human serum did not appear to affect the activity of glutaraldehyde adversely. Instrument samples made from a variety of materials such as stainless steel, glass, teflon, etc. were not damaged after 168 h of immersion in alkaline glutaraldehyde, although it contained approximately 1.7 times more glutaraldehyde than 2% glutaraldehyde alone. Based on these results, 3.2% alkaline glutaraldehyde is considered to be a more effective disinfectant for fibreoptic endoscopes, with the use of an automatic machine, than 2% glutaraldehyde.

Chemistry, Pharmaceutical↗
PubMed1985

Automatic external defibrillators: clinical, training, psychological, and public health issues.

Automatic external defibrillators (AEDs) will be used by spouses, family members, emergency first-responders, and the citizenry at large. Such use, however, raises a number of clinical, training, psychological, and public health issues. Clinical issues: Is cardiac arrest to be verified by the operator or the AED? Second verification systems, such as breath detectors, produce errors of omission, but greatly expand the pool of potential users. The relative merits of high sensitivity and low specificity in arrest verification must be defined by clinicians relative to the setting and the potential users. AEDs require cessation of basic CPR during their assessment periods; clinicians must determine the tradeoff between long interruption of basic life support and much earlier delivery of countershocks. Training issues: Criteria for those to be trained include consideration of who the patient will be and who the AED operator might be. AEDs pose a familiar adult education problem, that is, acquisition of a new psychomotor skill and retention of that skill for long periods before performance. What are the best teaching techniques? Currently available AEDs have different designs for device-operator interaction. Which design is most likely to assure proper performance during an actual arrest? Psychological issues: What are the psychological effects of learning about, living with, and eventually using an AED? The development of the automatic external defibrillator constitutes the most recent attempt to achieve early defibrillation of patients in cardiac arrest. The potential public health effect of such devices is enormous.

Electric Countershock↗
PubMed1986

Home placement of automatic external defibrillators among survivors of ventricular fibrillation.

We performed a study to determine how many patients at highest risk for an episode of ventricular fibrillation (those who have already survived such an event) are potential candidates for automatic external defibrillator placement and accepting of such a device in their homes. All VF survivors in King County, Washington, during 1984 were screened for possible enrollment in the study. Of 95 survivors of out-of-hospital VF, 63 (66%) were eligible and of 47 patients approached, 38 (81%) agreed to participate in the study. These findings suggest that approximately half (product of 66% and 81% acceptance rate equals 53%) of VF survivors potentially could use automatic external defibrillators.

Electric Countershock↗
PubMed1989

Automatic external defibrillators.

Early electrical therapy for patients with ventricular fibrillation and ventricular tachycardia can result in a significant increase of lives saved from sudden cardiac death. Rapid defibrillation has become a goal of prehospital and emergency department cardiac care, and the use of automatic external defibrillators can aid in reaching this objective. The history, mechanics, and implications of automatic external defibrillators are presented.

Animals↗
PubMed1989

Liquid automatic dishwashing detergents: a profile of toxicity.

The recent introduction of liquid automatic dishwashing detergents (LADDs) has resulted in numerous calls to poison information centers and, subsequently, a large number of referrals to emergency departments. As with their traditional granular counterparts, LADDs contain alkaline builders that contribute to the pH of these products. Exposure to granular automatic dishwashing detergents has been associated with caustic injury similar to the pathology produced by other alkaline corrosives. Do LADDs produce similar toxicity? There is no published information that profiles the toxic manifestations associated with exposure to LADDs. To determine their toxicity, all LADD exposures reported to a regional poison information center over a 12-month period were collected. One hundred ninety-two human exposure cases were reviewed. Pediatric patients accounted for 76% of the exposures; 76% were ingestions, 12% were dermal exposures, and 12% were ocular exposures. Seventy-nine percent of the patients were exposed to a full-strength product, and 21% contacted a dilute product or one that had already been through the dishwashing cycle. Of the patients who ingested a LADD, 91.1% remained asymptomatic, 8.2% had minor symptoms, and only one (0.7%) suffered moderate toxicity. In contrast, 91.3% of all patients who had an ocular exposure developed minor or moderate toxicity (73.9% vs 17.4%). Of dermal exposures, 69.6% were asymptomatic, and those with symptoms were the result of inappropriate use. Overall, 78.7% remained asymptomatic, 18.2% developed minor toxicity, and 3.1% developed moderate toxicity. Small oral and dermal exposures usually do not result in toxicity and do not necessitate referral to an ED. Ocular exposures are associated with a high incidence of at least minor toxicity and require ED evaluation.

Adult↗
PubMedDate not supplied

Automatic and effortful processing in aging and dementia: event-related brain potentials.

Automatic and effortful processes were investigated using event-related brain potentials (ERPs) recorded from moderately impaired subjects with probable Alzheimer's Disease (AD), normal elderly, and normal young controls. The effects of effortful attention on ERPs to loud noises and the effects of stimulus intrusiveness on effortfully elicited ERPs were studied. First, ERPs to task relevant and irrelevant startling noises were compared. Second, ERPs to startling noises and moderate tones were compared when both were targets. The effects of age (young vs. elderly controls) and effects of dementing disease (AD subjects vs. elderly controls) were also assessed. Effortful attention augmented noise-elicited P300 amplitude in elderly subjects, but not in young. Intrusiveness augmented task-relevant P300 amplitude in young subjects, but not in elderly. Neither variable affected P300 amplitude in AD subjects. Thus, effects of age and disease depended on how P300 was elicited: when effortfully elicited, P300 amplitude was affected by disease but not age; when automatically elicited, P300 amplitude was affected by age but not disease. N1 effects differed from P300 effects.

Acoustic Stimulation↗
PubMed2003

[Successful ablation of an automatic rhythm originating from his bundle].

Automatic junctional tachycardias are rare supraventricular tachyarrhythmias observed mainly in infants and children. This arrhythmia has a high mortality rate. We report the case of a 22-month-old infant in which the electrophysiological study disclosed an incessant junctional tachycardia originating from an automatic focus located in the His bundle region. Radiofrequency pulse delivery to the His bundle with controlled progressive heating of this region resulted in a definitive ablation of the ectopic focus without complications.

Bundle of His↗
PubMed1998

[National Registry of Automatic Implantable Defibrillators in 1996].

The results of the Spanish Registry of Automatic Defibrillators implanted between February 1996 and January 1997 are reported. A questionnaire per patient was completed by every implanting physician, in every center. The questionnaire was designed by the Section of Electrophysiology and Arrhythmias of the Spanish Society of Cardiology. The data from 306 automatic defibrillators implanted were reported. The percentage of defibrillators per inhabitant in Spain is close to 1 per 100,000. Eighty-five percent were first implants, while a 13% were replacements. Most of the electrodes used were endocardial. Chronic ischemic heart disease was found in 54% of the patients. Forty-six percent of the patients had syncopal ventricular tachycardia, 31% ventricular fibrillation and 23% sustained monomorphic ventricular tachycardia. The generator pocket was pectoral in 87% of the patients and abdominal in 13%. The implant of the defibrillator was associated with other cardiac surgery in only 3% of the patients.

Aged↗
PubMed1998

Neurogenesis of patterns of automatic ventilatory activity.

Normal respiration, termed eupnea, is characterized by periodic filling and emptying of the lungs. Eupnea can occur 'automatically' without conscious effort. Such automatic ventilation is controlled by the brainstem respiratory centers of pons and medulla. Following removal of the pons, eupnea is replaced by gasping, marked by brief but maximal inspiratory efforts. The mechanisms by which the respiratory rhythms are generated have been examined intensively. Evidence is discussed that ventilatory activity can be generated in multiple regions of pons and medulla. Eupnea and gasping represent fundamentally different ventilatory patterns. Only for gasping has a critical region for neurogenesis been identified, in the rostral medulla. Gasping may be generated by the discharge of 'pacemaker' neurons. In eupnea, this pacemaker activity is suppressed and incorporated into the pontile and medullary neuronal circuit responsible for the neurogenesis of eupnea. Evidence for ventilatory neurogenesis which has been obtained from a number of in vitro preparations is discussed. A much-used preparation is that of a 'superfused' brainstem of the neonatal rat. However, activities of this preparation differ greatly from those of eupnea, as recorded in vitro or in arterially perfused in vitro preparations. Activities of this 'superfused' preparation are identical with gasping and, hence, results must be reinterpreted accordingly. The possibility is present that mechanisms responsible for generating respiratory rhythms may differ from those responsible for shaping respiratory-modulated discharge patterns of cranial and spinal nerves. The importance of pontile mechanisms in the neurogenesis and control of eupnea is reemphasized.

Animals↗
PubMed2003

Signal characteristics of spontaneous facial expressions: automatic movement in solitary and social smiles.

The assumption that the smile is an evolved facial display suggests that there may be universal features of smiling in addition to the basic facial configuration. We show that smiles include not only a stable configuration of features, but also temporally consistent movement patterns. In spontaneous smiles from two social contexts, duration of lip corner movement during the onset phase was independent of social context and the presence of other facial movements, including dampening. These additional movements produced variation in both peak and offset duration. Both onsets and offsets had dynamic properties similar to automatically controlled movements, with a consistent relation between maximum velocity and amplitude of lip corner movement in smiles from two distinct contexts. Despite the effects of individual and social factors on facial expression timing overall, consistency in onset and offset phases suggests that portions of the smile display are relatively stereotyped and may be automatically produced.

Adult↗
PubMed2001

Automatic evaluation of arterial diameter variation from vascular echographic images.

An automatic procedure for accurate arterial diameter evaluation from B-mode images obtained by diagnostic ultrasound systems is presented. It is used for measuring brachial artery dilation following reactive hyperemia induced by forearm ischemia, which is an appropriate parameter to study endothelial function in humans. B-mode images obtained from the diagnostic ultrasound system are acquired on a personal computer as grey intensity fields (pixels). A completely automatic algorithm is then applied and the artery walls are identified by two discrete sets of points. Artery diameter is evaluated by parabolic least-square approximation. The accuracy and extensive range of applicability of the diameter evaluation procedure were demonstrated both by preliminary analytic test cases and in vivo analyses. Reproducibility of the diameter estimate was assessed by in vivo measurements. The proposed procedure permits fast and accurate analysis of large amounts of data, because it requires no action by the operator. It thus represents a valuable tool for assessment of endothelium-dependent vasodilation, especially in large, multicentric clinical trials.

Adult↗
PubMed1998

Automatic three-dimensional reconstruction and characterization of articular cartilage from high-resolution ultrasound acquisitions.

Three-dimensional (3D) high-resolution ultrasonography has proved to be useful for in vitro assessment of cartilage remodeling due to osteoarthritis. The diagnosis is performed by computation of the mean thickness of the cartilage, which reveals hypertrophy or thinning, and by 3D reconstruction of the data, which provides essential information about the size, extent, and localization of the lesion. In both cases, preliminary segmention of the cartilage is necessary. This article proposes an algorithm for automatic segmentation of the cartilage from 3D ultrasonic acquisitions of the rat patella, which includes the detection of the cartilage surface and the cartilage/bone interface. The method was designed on the assumption of regularity and smoothness of the interfaces. The use of a global threshold was sufficient to separate the patella area from the background. The cartilage/bone interface was detected by selection of regions of interest (ROIs) encompassing the interface, followed by the detection of the interface within these ROIs using the graph theory. The method was applied to 162 samples. The detection accuracy was judged to be very good or good in 99% of the cases for the cartilage surface and in 86% of the cases for the cartilage/bone interface. The mean cartilage thickness value in the central part of the patella obtained from the automatic detection method was compared to that obtained manually. The coefficient of correlation between the two measurements was 0.92. These results show that our method is reliable. Thus, fast processing of a large number of acquisitions and a more complete analysis of the cartilage surface become possible.

Aging↗
PubMed2001

Dorsolateral prefrontal cortex activation during automatic auditory duration-mismatch processing in humans: a positron emission tomography study.

This study aimed to identify the neural networks underlying automatic and active auditory deviant detection in six healthy subjects using positron emission tomography. Eight alternating blocks of standard and standard plus duration-deviant tones were presented while subjects performed a visual discrimination task. In an additional four blocks, the subjects then performed an auditory discrimination task on the deviant tones. Actively attending the deviant tones increased regional cerebral blood flow (rCBF) in the superior temporal and inferior frontal gyrus as well as in the superior and medio-frontal gyrus. When performing the visual task and presented with deviant tones, significant increase of rCBF was detected in the caudate nucleus, cerebellum, posterior cingulate, inferior frontal and pre-central gyrus thus indicating automatic extra-pyramidal processing of auditory duration deviants.

Acoustic Stimulation↗