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Biomedical subjects

J Mugica

Publications and source records attributed to J Mugica.

At least 19 recordsLinked to original sources
PubMed1992

Noninvasive transcutaneous cardiac pacing: modern instrumentation and new perspectives.

Noninvasive transcutaneous cardiac pacing has evolved from a simple stand alone unit with no ventricular sensing to a complete cardiac arrest resuscitation system combining synchronous pacing and defibrillation capabilities and using a single set of multifunction electrodes. In current instrumentation, four configurations exist including stand alone unit, modular configuration, built-in monitor and recorder, and built-in monitor, recorder and defibrillator. In present day devices, ventricular sensing, extensive programmability, and large surface electrodes are general features. Capture monitoring requires specific integrated electrocardiographic capability. Future developments are expected to involve low threshold electrode technology, integrated mechanical monitoring, and interdevice electrode compatibility.

Cardiac Pacing, Artificial↗
PubMed1992

Is polyurethane lead insulation still controversial?

A controversy arose some 10 years ago over the reliability of polyurethane lead insulation. On the basis of one of the longest standing and largest databanks worldwide, the authors compare the cumulative survival of several thousand polyurethane, standard silastic, and high-performance silastic electrodes as it pertains to the failure criterion described as insulation degradation. With the possible exception of the Medtronic 6972 (Medtronic, Inc.) electrode, polyurethane electrodes have a 100% reliability at 84 months, which is similar to silastic electrodes.

Databases, Factual↗
PubMed1992

Lead failures.

Explore the source record for details and available documents.

Electrodes, Implanted↗
PubMed1990

Effect of different body-exercise modes on the rate response of the temperature-controlled pacemaker Nova MR.

In order to evaluate the effect of different modes of physical exercise on the rate response of the temperature-controlled Nova MR, parameters such as temperature behaviour and correlation of work load to pacing rate were investigated using different types and protocols of stress testing. This study considered 21 patients (age: 66 +/- 12 y). The indications for the Nova MR were AV block (n: 14) and sick sinus syndrome (n: 7). The patients performed two different types of exercise (treadmill n: 13, bicycle n: 14) based on different protocols. We registered the surface ECG, pacing rate, exercise time, and (via data transmission by the RX 2000 programmer) blood temperature and pacing rate. An adequate rate response could be achieved with all the different types of exercise and protocols using more sensitive program settings. The type of stress testing used to adjust or evaluate the Nova MR seems to be secondary, although cycling as compared with treadmill exercise resulted in a slightly weakened reaction of temperature and pacing rate. Our investigations revealed a good correlation between work load and pacing rate independent of the type of stress testing. The initial DIP (48%) is not a constant phenomenon and showed inter- and intraindividual variations. Impressive psychological influences also exhibited an effect on temperature and pacing rate, sometimes preventing a DIP response. During exercise at lower work loads (under 50 watts, shorter than 3-4 min) the rate response of the Nova MR--without any detected DIP--is often delayed due either to a decrease or to a late and flat increase in temperature. An additional fast-reacting sensor could be advantageous in triggering the initial rate response in such cases.

Aged↗
PubMed1989

Pre- and postnatal aminopeptidase activities in the rat brain.

Research concerning the functional role of brain peptides is performed, in part, by studying peptidase enzymes which might be involved in brain peptide processing or inactivation. Aminopeptidase (AP) activity has been proposed as a candidate regulator of the degradation of these peptides. In this paper, changes in Lys- and Leu-aminopeptidase activities in rat brain hemispheres, cerebellum and medulla were examined in 20 day fetuses and one day postnatal subjects. Aminopeptidase activities were studied by measuring the rate of hydrolysis of the artificial substrates Lys- and Leu-2-naphthylamides (fluorimetrically detected in triplicate). Both enzyme activities increase from the last fetal stage up to the first day of birth in all the brain areas examined except for the case of Leu-AP activity in the medulla. It is suggested that these activities play a part in the neurochemical changes that take place during rat brain maturation, possibly by regulating the activity of several neuroactive peptides.

Aminopeptidases↗
PubMed1988

DDD pacing: an effective treatment modality for recurrent atrial arrhythmias.

We performed atrial EP studies (atrial substrate evaluation) on 10 patients. These patients had evidence of paroxysmal, sustained, recurrent atrial arrhythmias (7 men and 3 women with a mean age of 64 +/- 15 years). All patients combined a brady-tachy syndrome; 7 patients had a sick sinus syndrome (SSS) and 3 patients a typical vagally induced atrial arrhythmia. No anti-arrhythmic drug was allowed in 3 patients with SSS, 1 drug failed in 4 patients and the combination of 2 drugs failed in 3 patients during the first to eighth years prior to pacemaker implantation. Atrial substrate evaluation was feasible in all these patients off anti-arrhythmic therapy and showed important abnormalities of atrial loco-regional conduction parameters and long refractory periods (RP). The remarkable point was, in 7 patients, a paradoxical improvement in intra-atrial conduction delay at rapid pacing rate. The DDD pacing mode was chosen in all patients. No technical problem occurred during implantation. Atrial pacing rate was programmed to be slightly higher than the mean diurnal heart rate calculated on Holter monitoring. After implantation, the mean follow-up period was 18 +/- 25 months with an average of one Holter every 4 months during the first 2 years. The 7 patients who improved intra-atrial conduction at rapid pacing rate were controlled without drugs, 2 patients were controlled with 1 drug, and 1 patient with 2 drugs. Atrial pacing in the DDD mode in a selected group of patients prevents paroxysmal and drug-resistant atrial arrhythmias. Atrial substrate evaluation is a sensitive tool for assuring the long-term benefit of atrial pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Clinical experience with new leads.

Recent developments in cardiac pacemaker electrodes have resulted in significant benefits to the group of pacemaker patients as a whole. The results of analysis of 2,818 chronic pacemaker electrodes are presented. These electrodes are divided into major categories according to their particularities: platinum iridium, elgiloy, carbon-tip, anodized platinum and granulated iridium-platinum. All leads were in the ventricular position. The results of acute and chronic threshold measurements reveal that carbon-tipped electrodes appear to have the most favorable overall characteristics. This will have a major influence on long-term pacing practices.

Carbon↗
PubMed1987

Direct diaphragm stimulation.

Direct diaphragmatic stimulation is effective without discomfort to the patient and without muscular fatigue. However, some quadriplegic patients may require synchronous expiratory stimulation in order to obtain complete and permanent respiratory autonomy. Now it will be necessary to undertake further studies of the indications for direct diaphragm stimulation.

Aged↗
PubMed1986

Importance of atrial electrophysiology in the work-up of cerebral ischemic attacks.

Recent data suggest that a large proportion of ischemic strokes are due to embolic phenomena from the heart. Atrial fibrillation appears to be one of the principal causes of embolization. If electrophysiologic parameters are considered as determining factors, the existence of atrial hypervulnerability in patients with embolic strokes is significant, when arrhythmia has been excluded as an etiology. This study suggests that an aggressive approach to early diagnosis and management through electrophysiologic studies might aid in preventing future neurologic attacks.

Adult↗
PubMed1986

Clinical experience with 910 carbon tip leads: comparison with polished platinum leads.

Since 1980, we have implanted 910 carbon tip leads from three different manufacturers. The pacing thresholds from these leads were compared to those of standard polished platinum electrode configurations. Our major findings are that while acute voltage thresholds are not significantly different, two of the three carbon tip leads that we used in the study have statistically lower chronic thresholds then polished platinum leads (p less than or equal to 0.01).

Carbon↗
PubMed1986

The clinical utility of pacemaker follow-up visits.

Because of the increased complexity of modern pacemakers, pacemaker follow-up visits in specialized centers become more and more indispensable. In this study, the results of 15,000 outpatient visits to the cardiac pacing center between the years 1983-1985 are presented. In most cases (92.8%), verification of normal function was made; however, mandatory reprogramming was required in 1.2%, and hospitalization for various reasons was required in 6% of visits. Careful outpatient monitoring of pacemakers is therefore very important for detecting early or late pacemaker complications.

Electrocardiography↗
PubMed1986

Survival and mortality in 3,701 pacemaker patients: arguments in favor of pacemaker reuse.

This study analyzed the results of 3,701 patients implanted with cardiac pacemakers at the Centre Chirurgical du Val d'Or between 1976 and 1981. Two pacemaker populations were compared: those having a new pacemaker and those implanted with a reused pacemaker. There were no statistically significant differences between the two groups, either in terms of indications for implantation or in terms of actuarial survival of patients. In addition, there was no significant change in survival of the pulse generator. The reutilization of pacemakers appeared to be in no way detrimental to patients.

Actuarial Analysis↗
PubMed1985

[Assisted respiration by stimulation of the diaphragmatic muscle. A case].

Direct electrical stimulation of the diagram has resulted in physiological functioning in a quadriplegic patient. Mechanical ventilation could be partly withdrawn with 13-hour periods of "respiration". During the 2-month stay in hospital, 90 hours of respiration were obtained by stimulation. The patient died 8 weeks after the operation.

Aged↗
PubMed1978

Methods for recording intermittent contact signals in demand pacemaker arrhythmias (11 cases).

This report describes some of the various techniques which may be used to demonstrate intermittent and/or incomplete fracture of a pacing lead. Eleven patients treated with an R-wave-inhibited demand pacer showed signs of paroxysmal arrhythmias. Intraoperative recordings of the ventricular electrogram showed the presence of spurious signals mimicking an R-wave. These signals varied from patient to patient but remained morphologically constant when a given technique was used in a given case. The most significant signals were picked up when pacing and recording on the same lead.

Arrhythmias, Cardiac↗
PubMed1977

[Determination of first signs of pacemaker failure. Oscilloscopic study before and after removal].

An oscilloscopic study aimed at determining the first signs of pacemaker failure was carried out in vitro after removal in 95 cases. Using a differential apparatus with a 1 megahertz passing band, the following parameters were measured: interspike interval, amplitude, duration and morphology of the spike. During the course of the study, signs of pacemaker failure were seen in 66 cases. It may be concluded that the interspike interval represents the easiest and most precise measurement, making it possible alone to detect dysfunction in 70 per 100 of cases. However, in 30 per 100 of cases, represented by certain types of pacemaker, its alteration is preceded by a decrease in voltage. Whilst the latter may be precisely and easily measured in vitro, the same does not apply when the pacemaker is in situ and only large changes may be taken to be significant and interpreted in relation to the number of batteries in the model studied. Study of the vectrocardiogram should be added to the measurements mentioned above, any sudden change in axis of the spike being an argument in favour of a fault in the conductor. In the future, measurement of the area of the spike, a reflection of the energy delivered the histogram of the RR intervals giving an idea of the respective durations of function and of inhibition in demand models will provide additional information.

Humans↗