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At least 1,135 records · Page 63Linked to original sources
PubMed1995

Automatic quantification of ejection fraction from gated myocardial perfusion SPECT.

UNLABELLED: We have developed a completely automatic algorithm to quantitatively measure left ventricular ejection fraction (LVEF) from gated 99mTc-sestamibi myocardial perfusion SPECT images. METHODS: The algorithm operates in the three-dimensional space and uses gated short-axis image volumes. It segments the left ventricle (LV), estimates and displays endocardial and epicardial surfaces for all gating intervals in the cardiac cycle, calculates the relative left ventricular cavity volumes and derives the global EF from the end-diastolic and end-systolic volume, all without operator interaction. The algorithm for measuring LVEF was tested in 65 clinical patients undergoing 16-interval and 8-interval rest-gated SPECT and validated against first-pass radionuclide ventriculography. RESULTS: Automatic segmentation and contouring of the LV was successful in 65/65 (100%) of the studies. Agreement between EFs measured from 8-interval gated SPECT and EFs calculated from first-pass data was high (y = 2.44 + 1.03x, r = 0.909, p < 0.001, s.e.e. = 6.87). Agreement between EF values measured from 16-interval and 8-interval gated SPECT was excellent (y = -2.7 + 0.97x, r = 0.988, p < 0.001, s.e.e. = 2.65), the latter being on average lower by 3.71 percentage points. CONCLUSION: Our automatic method is rapid and highly agrees with conventional radionuclide measurements of EF, thus providing clinically useful additional information to complement myocardial perfusion studies.

Algorithms↗
PubMedDate not supplied

[Automatic analysis of electrocardiograph signals in the diagnosis of myocardial infarct].

At present the work of automatization of the processes of the ECG analysis for diagnosing myocardial infarction with the help of computer technique is going forward on an ever broader scale. For an automatic identification of the focal changes syndrome on the ECG, which in the clinical practice is considered to be tantanount to myocardial infarction, the use of a special diagnostic device (SDD) is proposed. The SDD are comparatively cheap and simple in operation. The process of diagnosing provides for utilization of medical experience, but, at the same time, eliminates shortcomings inherent in systems that reproduce the physicians' manipulations in establishing the diagnosis of myocardial infarction with the help of an electrocardiogram. The choice of the SDD was made by stimulating it with an all-purpose computer. The results of clinical trials of the SDD conducted at specialized clinics bear proof to great possibilities of the automatic electrocardiographic diagnostics.

Acute Disease↗
PubMed1995

Children's associative learning: automatic and deliberate encoding of meaningful associations.

Three experiments were conducted examining 10- and 11-year-old children's deliberate and automatic encoding of meaningful associative relationships on a paired-associate learning task. Subjects in Experiment 1 were presented pairs of related and unrelated words under deliberate memorization and item-specific incidental-learning conditions. Cued-recall performance was superior with related relative to unrelated pairs under both instructional conditions, suggesting that the encoding of an association between items occurred automatically with meaningfully related words. In Experiment 2, it was found that execution of a verbal elaboration strategy required more time with unrelated than with related pairs, suggesting greater ease of elaboration strategy execution with related materials. Experiment 3 monitored strategy use online using a think-aloud procedure. Cued-recall performance was superior with related pairs when subjects used rehearsal. In contrast, elaboration produced equivalent levels of recall with both types of items, but subjects executed the strategy successfully more often with related than with unrelated pairs. These findings are discussed in terms of the role of automatic processes and the effort demands of strategy execution in children's strategy use.

Attention↗
PubMed1994

[A study of automatic activity and morphology of guinea-pig aortic vestibule].

The automatic activity of aortic vestibule was studied in 82 guinea-pig heart preparations with intracellular microelectrode. Spontaneous activity could be recorded in 16 preparations (19.5%), while in 61 preparations (74.4%) automatic activity could be induced by electrical stimulation. Of these preparations, they were all found a very small region below the right and the poster valves, the response showed a slow and low rising phase and a marked spontaneous depolarization in phase 4. The response could be blocked by Mn2+ and nifedipine. Outside of the specialized valve region, all recorded vestibule action potentials pertain to the fast type. Light and electron microscopic examination showed that the structure of the specialized local aortic vestibule region was similar to that of ordinary myocardium possessing slow automatic activity instead of the ordinary ventricular musculature.

Action Potentials↗
PubMed1994

The diagnostic significance of real sinus node automaticity depression in symptomatic sinus bradycardia.

Atrial overdrive pacing was performed, before and after autonomic blockade, in 42 consecutive patients (32 males and 10 females, mean age 46 +/- 11 years) with symptomatic sinus bradycardia. Patients were divided into two groups: Group I, 23 patients (mean age 43 +/- 8 years) with normal intrinsic heart rate (IHR) and normal intrinsic corrected sinus node recovery time (intrinsic CSNRT < 425 ms) and Group II, 19 patients (mean age 49 +/- 13 years) with abnormal intrinsic sinus node automaticity identified after autonomic blockade by abnormal IHR and/or by abnormal intrinsic CSNRT (> 425 ms). In addition to sinus cycle length, IHR, maximal CSNRT and sinoatrial conduction time (SACT) the real sinus node automaticity depression (SAD) was also evaluated, calculated after autonomic blockade (intrinsic CSNRT-SACT). Not all patients with an abnormal IHR showed abnormally prolonged CSNRT and not all patients with normal IHR had normal CSNRT. Among Group I (normal IHR) in 19 patients the real SAD was < 300 ms, while among Group II in 8 of 11 patients showing abnormal IHR the real SAD was > 300 ms. The abnormal value of SAD (> 300 ms) observed not only in patients with abnormal IHR and/or abnormally prolonged intrinsic CSNRT but also in several patients with normal IHR, increases the sensitivity of testing and may allow to detect even latent organic sinus node dysfunction. In conclusion, a synopsis of IHR, intrinsic CSNRT and intrinsic SACT with real SAD may be useful to estimate more accurately the degree of the impairment of intrinsic sinus node automaticity helping to differentiate the organic sinus node dysfunction from the autonomic one.

Adult↗
PubMed1993

[Long-term results of implantable automatic defibrillator in 43 patients. Analysis of predictive factors of the first electric shock].

In order to identify patients who will receive an electric shock after implantation of an automatic fibrillator, the relationship between the time to the first shock and clinical and paraclinical characteristics were studied in 43 patients treated at the Lyon Cardiological Hospital between July 1987 and September 1991. The age of the patients was 49.5 +/- 16 years (mean + SD). Eighty two percent of patients were men and the average left ventricular ejection fraction was 38.5 +/- 16.8%. Four patients died in the peri-operative period. The average follow-up of the survivors was 22 months. During this period, 21 patients (53.8%) received an appropriate electric shock. Three patients died. The causal role of a malignant ventricular arrhythmia is discussed in one case. A second patient, who never had automatic fibrillation, died of cardiac failure. Finally, the third patient died of non-cardiac pathology. The 22 month actuarial survival rate was 86%. The probability of receiving an appropriate electric shock was 60%. Analysis of clinical and paraclinical features identified left ventricular dysfunction (ejection fraction less than 38%) and cardiac symptoms (Stage III dyspnoea of the NYHA classification) as being associated with earlier electric shocks. This association was even more clear cut in the group of patients with previous myocardial infarction. Therefore, patients with implantable automatic defibrillators for malignant ventricular arrhythmias receive appropriate electric shocks in over 50% of cases. Patients with symptoms of cardiac failure and low ejection fraction are particularly exposed especially when they have previous myocardial infarction.

Actuarial Analysis↗
PubMed1993

Thallium-201 lung uptake: comparison of an automatic and a manual method of ROI drawing.

An automatic method for ROI drawing to measure 201TI lung uptake after stress testing in planar and tomographic myocardial perfusion imaging, was compared with the more commonly used manual method. A linear correlation in the lung/heart ratio (LHR) and lung washout (LWO) data, obtained in planar and SPECT images with the two methods, was found. Pearson's correlation coefficient between the automatic and manual methods was highly significant both for LHR and for LWO. For LHR we found a high linear correlation between the two methods in the planar anterior (r = 0.71, p < 0.001), SPECT anterior (r = 0.84, p < 0.001), and SPECT LAO (r = 0.96, p < 0.001) views. The analysis of LWO data showed a good linear correlation for the planar anterior (r = 0.84, p < 0.001), SPECT anterior (r = 0.66, p < 0.005) and SPECT LAO (r = 0.79, p < 0.001) views. Furthermore, comparison by the student's t test of the averages of the LHR and LWO values obtained in the same views but with different methods was performed. The advantages and the critical issues associated with the automatic method are discussed; it appears to be quick and easy to perform and to be equivalent to the more time-consuming method based on a manual definition of left lung ROI.

Adult↗
PubMed1993

[The automatic implantable cardioverter-defibrillator for prevention of sudden heart death in children and adolescents].

Little experience exists with the automatic implantable cardioverter-defibrillator in the pediatric population. Since 1990, an automatic implantable cardioverter defibrillator was implanted in four young patients (mean age 15.8 years, mean body weight 53.3 kg) with life-threatening ventricular tachyarrhythmias at our institution. In three patients, a cardiac anomaly was evident (dilated cardiomyopathy, status post Rastelli operation for complex transposition of the great arteries, status post atrial switch for transposition of the great arteries), the last patient had a normal cardiac anatomy. Indications for implantation were resuscitation from documented hypotensive ventricular tachycardia in one patient and recurrent syncope of suspected cardiac origin in the remaining three patients. At preimplantation electrophysiological study, all four patients had inducible ventricular tachycardia and/or ventricular fibrillation. At implantation of the cardioverter defibrillator in the operating theatre, the ventricular tachyarrhythmias were again induced and terminated reliably by the device. After a mean follow-up of 13 months, three of the four patients had appropriate discharges without syncope or resuscitation. The automatic implantable cardioverter-defibrillator appears to be a feasible and effective therapy also in pediatric patients for prevention of sudden cardiac death due to ventricular tachyarrhythmias.

Adolescent↗
PubMedDate not supplied

Do we know enough to introduce semi-automatic defibrillation by ambulancemen in Belgium?

The application of semi-automatic external defibrillators by ambulancemen or emergency medical technicians is in the U.S.A. accepted as a substantial progress in the treatment of out-of-hospital sudden death. A retrospective estimation of the percentage of patients registered by the Belgian Cardio-Pulmonary-Cerebral-Resuscitation study group between 1983 and 1987 that could benefit from early defibrillation yielded a gain in good survival of 1% for the whole population. In 1991 a prehospital semi automatic external defibrillation program was started as a feasibility study in several two-tiered emergency physician staffed systems with an ongoing registry of cardiac arrest events. For Bruges and Ghent there was a non-significant increase in prolonged survival in the ventricular fibrillation subgroups with respectively 4.7% and 5.1% since the introduction of the semi-automatic external defibrillators. Apparent differences between our emergency medical systems and e.g. Seattle, such as the number of 1st tier units covering the population and a short delay between 1st and 2nd tier might account for a lack of a statistically significant improvement so far.

Belgium↗
PubMed1993

[Clinical study on judgement of brain death by the nasopharyngeal lead with the aid of an automatic EEG analysis system].

We investigated the relationship between scalp electroencephalogram (EEG) and nasopharyngeal EEG using Automatic EEG Analysis System in 10 patients with the age between 17 and 66 who were clinically presumed brain death because of flat line EEG and loss of auditory brainstem response (ABR). Among 10 patients, nasopharyngeal lead EEG showed low voltage and slow waves of 10-20 microV in 4 cases and flat line EEG in 6 cases. However, Automatic EEG Analysis system-assisted analysis of EEGs recorded on a magnetic tape revealed that equivalent electric potentials in the scalp EEG from these patients were smaller than those of healthy volunteers, but those in the nasopharyngeal EEG from all patients showed low voltage within the range of distribution in normal volunteers (delta:6, theta 1:6, theta 2:2, alpha 1:1, alpha 3:10, beta 1:6 in 10 cases). The present results show that in addition to the routine scalp EEG, it is clinically useful to employ simple and easy nasopharyngeal lead EEG method and to analyze data using Automatic EEG Analysis System for the judgement of brain death.

Adolescent↗
PubMed1993

Automatic detection of K-complexes: validation in normals and dysthymic patients.

A model-based automatic K-complex (Kc) detector was applied to all-night single-channel sleep electroencephalographic (EEG) recordings from normal and dysthymic patients. The performance of the detector was analyzed in the two groups, and the differences obtained were discussed. The results showed that the detection rate of Kc in the normal group was around 92% through all stages of non-rapid eye movement (NREM) sleep, but with high numbers of "false" positives in stage 4 NREM, which reached 57%. In the dysthymic patients "true" detection included 85% of the Kc, but the percentage of "false" positives dropped to 25% in stage 4 NREM. Most of the "false" detections in the normal group were due to sharp delta activity during slow wave sleep (SWS). The results in the patient group were expected, because sleep in dysthymics showed a reduction in SWS when compared to normals. The behavior and automatic artifact rejection mechanisms of the detector are briefly presented. The model-based Kc detector performed significantly better than other automatic detectors described in the literature; it was found to be a useful tool for routine sleep EEG studies.

Adult↗
PubMed1995

[The automatic, beat-to-beat determination of the QT interval and analysis of its spontaneous variability under basal conditions].

OBJECTIVES: An analysis is made of the automatic beat-by-beat measurement of QT and other intervals related to ventricular repolarization. The variability pattern of these intervals is investigated in normal subjects at rest, along with their relation to RR cycle variability. MATERIAL AND METHODS: The electrocardiographic signals (LII) from 11 normal subjects (mean age 31 +/- 10 years) were recorded over 5 min and processed by applying specific algorithms to determine beat-by-beat the RR, QT, RT, QTm and RTm intervals (Tm = peak of T wave). An analysis was made of the variability of these intervals in the time (standard deviation, variation coefficient, difference between maximum and minimum values) and frequency domains (spectral analysis applying the Fourier transform). RESULTS: The differences between the automatic measurements and those performed by two observers (n = 110) were respectively -1.3 +/- 6.4 and -3.7 +/- 6.5 ms for QT, - 1.0 +/- 1.4 and -1.0 +/- 2.3 ms for QTm, -0.3 +/- 1.4 and -0.2 +/- 1.8 ms for RTm, and 0.7 +/- 6.5 and -2.8 +/- 10.3 ms for RT. The QT and RT intervals exhibited greater variability (SD = 6 +/- 1 ms) than QTm and RTm (SD = 3 +/- 1 ms, p < 0.0001). These differences persisted on comparing the corresponding variation coefficients. The differences between the maximum and minimum measurements were 45 +/- 24 ms for QT and RT, the values being significantly less in the case of QTm (21 +/- 26 ms, p < 0.05) and RTm (20 +/- 27 ms, p < 0.05). In the frequency domain, the high- (HF) and low-frequency (LF) band energies were low in the series formed by the ventricular repolarization intervals, and the LF band normalized amplitude was significantly lower than in the RR series. There were no significant differences in the frequencies of the maximum values of the LF and HF bands of the RR series with respect to the QT series. The correlations between the RR intervals and the subsequent repolarization intervals obtained in each subject were not significant in 7 of the 11 subjects studied. CONCLUSIONS: The automatic beat-by-beat determination of the ventricular repolarization intervals is precise, particularly when considering the intervals defined by the T wave peak. Repolarization variability during the sinus rhythm at rest is small, and is not linearly related to modifications of the previous RR interval. Neurovegetative and humoral influences are postulated to explain QT variations. The neurovegetative and humoral influences that regulate cardiac cycle and ventricular repolarization variability at rest, are found to be quantitatively different.

Adult↗
PubMed1995

[Automatic determination for bone morphometry using a computed image analyzer].

An image analyzer which combines a digitizer and a computer is widely employed in bone histomorphometrical evaluation. With this method, however, all regions of determination are traced manually so that considerable time is consumed when many preparations are measured. To resolve this problem, we have developed an automatic program for rapid and quantitative measurement of many bone histomorphometrical parameters using a computed color image analyzer. The bone volume (BV), tissue volume (TV), osteoid surface (OS), and the bone surface (BS) of rat tibia metaphysis were measured by this automatic method, and by the manual method using an image analyzer. The correlation coefficient between both methods in measuring BV/TV was 0.98 and in measuring OS/BS was 0.96. The reproducibility and accuracy of both methods for these parameters were similar. The time required for the automatic method was much shorter than that for the manual method. Various parameters of the tibial metaphysis, lumbar vertebral body, and femoral mid-diaphysis in ovariectomized rat (Fischer) measured by this method were in good agreement with values reported previously.

Animals↗
PubMed1995

Effects of automatic blood volume control over intradialytic hemodynamic stability.

Due to the crucial role of hypovolemia in the genesis of dialysis-induced hypotension, we have evaluated whether the automatic control of the intradialytic blood volume (BV) decrease along a preset trajectory might be beneficial to the hemodynamic stability during treatment. Five frequently hypotensive HD patients were studied and a 3-period-protocol (A1-B-A2) was adopted, each period lasting 6 sessions per patient. During the B periods the patient BV decrease was kept along a predefined profile, thanks to an automatic system with a retroactive control of both the ultrafiltration rate (UFR) and dialysate conductivity (DC); instead, during the A periods, conventional HD was performed, with linear UFR and constant DC, inducing a spontaneous decrease in BV. The intradialytic BV behaviour was much more stable during the B-periods (-10.2 +/- 1.4% by the end of the treatment) than during the A1 (-11.2 +/- 3%) and A2 periods (-11.5 +/- 2.5%). Only one dialysis-hypotension episode was observed during the B periods, compared to 8 and 5 during the A1 and A2 periods, respectively (p < 0.05). The automatic control of the BV changes during dialysis could improve the intra-treatment cardiovascular stability in critically-ill patients.

Biofeedback, Psychology↗
PubMed1996

A new automatic cardiac output control algorithm for moving actuator total artificial heart by motor current waveform analysis.

A new automatic cardiac output control algorithm for an implantable electromechanical total artificial heart (TAH) was developed based on the analysis of motor current waveform without using any transducer. The basic control requirements of an artificial heart can be described in terms of three features: preload sensitivity, afterload insensitivity, and balanced ventricular output. In previous studies, transducers were used to acquire information on the hemodynamic states for automatic cardiac output control. However, such a control system has reliability problems with the sensors. We proposed a novel sensorless automatic cardiac output control algorithm (ACOCA) providing adequate cardiac output to the time-varying physiological demand without causing right atrial collapse, which is one of the critical problems in an active filling device. In vitro tests were performed on a mock circulatory system to assess the performance of the developed algorithm and the results show that the new algorithm satisfied the basic control requirements of the cardiac output response.

Algorithms↗
PubMed1996

Mental retardation and the acquisition of automatic processing.

The acquisition of automatic processing in persons with and without mental retardation was examined. In Experiment 1, subjects viewed slides of objects to determine whether a pictured object belonged to a designated target category. There was an effect of search set size for both groups that decreased and eventually disappeared with practice. This result reflected the acquisition of automatic processing. Also, evidence of automaticity was observed with less practice for subjects without relative to subjects with mental retardation. In Experiment 2, subjects searched for the presence of a designated target shape in arrays containing two, three, or four shapes. Results were essentially the same. Implications of these results for the development of cognitive skills by persons with mental retardation were discussed.

Adolescent↗
PubMed1996

Vibration reduction on hand-held grinders by automatic balancing.

By automatically balanced hand hold grinders, vibrations are reduced to at least half and thereby reducing the estimated risk for vibration injuries by a factor of four. Simultaneously less grinding disc consumption and better grinding results are obtained. Vibration from grinders originates mainly from unbalance in the grinding wheel. Grinding wheels are low price products. With uneven distribution of mass and coarse tolerances. This gives rise to out-of-balance, which changes as the wheel wears. By fitting an automatic balancer, that consists of steel balls contained in a cylindrical ball race on the shaft of the grinder, unbalances will be compensate for in the machine during grinding. The time it takes for an automatic balancer to stabilize is only a few tenths of a second. When grinding, the balancer is stable, even during substantial changes in speed. The technique is applicable to almost all grinding machines on the market and the first grinders using the technique have just been put on the market.

Cumulative Trauma Disorders↗
PubMedDate not supplied

[Automatic monitoring of the myoelectric activity of the small intestine in peritonitis].

To monitor small intestinal myoelectrical activity in patients with peritonitis, the authors used direct electromyography. While processing the electromyograms, they calculated the frequency and amplitude of complexes, the standard deviation of complex duration, the amplitude of spike potentials and spike activity. Data on 41 patients were analyzed by using statistical methods. Normal value ranges and their variations in good- and poor- prognosis peritonitis were established. The findings were used to develop an automatic system which may enter an electromyogram, process it in automatic and semi-automatic modes, store the numbered curve and calculations in special files, construct a chart of the power spectrum density of a signal by the fast Fourier transform.

Electromyography↗