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At least 91 records · Page 5Linked to original sources
PubMed1984

Reversible end-of-life indicator leading to erroneous pacemaker replacement-pitfalls of telemetry.

In several modern pacemakers, end-of-life (EOL) is indicated by a single-step rate drop, which is initiated by a voltage-sensitive electronic switch. This switch may also be activated by other causes, such as very short voltage drops, low temperatures, and electrocautery. We report a case in which a Cordis 233 F Sequicor II pulse generator was operating at 51.6 bpm in VOO mode at the time of implantation. As telemetry seemed to indicate that back-up pacing (the EOL indicator in this model) was "off," it was erroneously assumed that the pacemaker was not working properly. The unit was replaced by another impulse generator. At laboratory testing, the pacemaker was within specifications, when back-up pacing was separately programmed off. In conclusion, physicians should be aware of the new phenomenon of reversible EOL indicators, and that they may not rely on telemetry in this respect. Future pacemakers should incorporate a telemetry message which prevents similar misunderstandings.

Equipment Design↗
PubMed1996

Reliability and variability of impedance measured by real-time telemetry.

UNLABELLED: With the aim to detect dysfunction of pacing leads, most present-day pacemakers measure pacing impedance by means of real-time telemetry. The recommended setting for impedance measurement is 5.0 V for pulse amplitude and 0.5 ms for pulse duration. Availability of reliable settings would facilitate impedance measurements during follow-up. The purpose of the present study was twofold: (1) to assess whether telemetrically measured impedance of the studied pacemaker is similar to impedance measured at implantation; and (2) to evaluate whether the pacemaker setting influences telemetrically measured impedance. Sixty-five consecutive patients receiving VVI(R) pacemakers were studied; in all patients, impedance measured at implantation by a pacing system analyzer was compared to measurements obtained telemetrically within 1 day after implantation. In 44 other patients, impedance was determined 3 months after implantation at 60 and 120 ppm (n = 44), twice at 60 ppm (n = 42), and 12 months after implantation at 60 ppm (n = 34). For each measurement, pulse amplitude was programmed to 0.8, 1.6, 2.5, 5.0, and 8.0 V, and pulse duration to 0.05, 0.25, 0.50, and 1.00 ms. Impedance at implantation (606 +/- 113 ohms) did not differ from the data obtained with telemetry (629 +/- 113 ohms; P = NS). Different pacing rates, repeat measurements, and follow-up time failed to show any influence on impedance. Measurement tolerance was < 10% for 15 of 19 studied settings other than 5.0 V and 0.5 ms. CONCLUSION: The studied pacemakers provide reliable data for telemetrically measured impedance. Telemetrical impedance does not necessarily have to be measured at 5.0 V and 0.5 ms. These findings should be considered for measurement and interpretation of real-time telemetry impedance during follow-up.

Aged↗
PubMed1998

Hospital pager systems may cause interference with pacemaker telemetry.

Electromagnetic interference (EMI) is a well-known cause of pacemaker dysfunction. The communication between pacemakers and programmers, enabled by telemetry, is also susceptible to EMI. We have observed that hospital pager systems have the potential to interfere with pacemaker telemetry. Measurements in our pacemaker clinic and in a technical laboratory have shown that inductive pager systems may disturb telemetry in the form of inaccurate battery voltage, current and impedance measurements, disturbances in intracardiac electrogram tracings, or total interruption of telemetric communications. The reason for EMI was an overlap of carrier frequencies of some pacemaker programmers (32-37 kHz) with those of our inductive pager system (36.11 kHz). Radiofrequency pager systems using higher frequencies (in MHZ range) are unlikely to cause such interference. Awareness of this interference potential may have practical implications in choosing the carrier frequencies of inductive hospital pager systems, as well as pacemaker programmers, and in planning the location of pacemaker clinics.

Electromagnetic Fields↗
PubMed1996

Validation of a telemetry system for long-term measurement of blood pressure.

We have used an implanted telemetry system to continuously monitor blood pressure (BP) in three dogs for durations ranging from 28 to 75 wk after implantation. Measurements of BP obtained by telemetry were compared every 3-12 wk, with measurements of BP recorded with a manometer-tipped catheter that was inserted into a femoral artery. Over a wide range of both physiological and pharmacologically manipulated pressures (40-200 mmHg), the values of BP obtained by the two methods were highly correlated (all r > 0.966; all P < or = 0.0001). However, the mean differences between the values obtained by the two systems were different from zero (range +29.6 to -1.5 mmHg; P < or = 0.0001), indicating an offset in the BP values recorded from the implanted system. Furthermore, this offset was dependent on the absolute level of the BP. The findings indicate that, for a period of at least 28 wk and up to 75 wk after implantation, the telemetry system accurately measures acute changes in BP and can reliably measure absolute BP provided that the system is properly validated.

Animals↗
PubMed1999

Telemetry for cardiovascular monitoring in a pharmacological study: new approaches to data analysis.

Radio-telemetry systems offer the ability to measure blood pressure and heart rate in experimental models of hypertension without the stress artifacts induced by some other methods. We therefore aimed to develop improved, nonparametric regression methods for radio-telemetry data and to use these to assess the effects of pharmacological interventions on cardiac and vascular hypertrophy in the stroke-prone spontaneously hypertensive rat. One control group and 5 groups treated either with losartan (alone or in combination with NG-nitro-L-arginine methyl ester [ L-NAME]), perindopril (also alone or in combination with L-NAME), or hydralazine plus hydrochlorothiazide were monitored for 4 weeks. Cardiac hypertrophy was assessed by the left ventricle plus septum weight to body weight ratio and vascular hypertrophy by flow-cytometry analysis of vascular smooth muscle cell polyploidy. Hemodynamic series were split into trend and cyclic components by the seasonal and trend decomposition procedure based on Loess and compared between groups by Loess regression modeling. Systolic and diastolic blood pressures were reduced systematically by losartan and perindopril (P<10(-10)) but to a lesser extent by hydralazine plus hydrochlorothiazide (P<10(-8)), and diurnal variation was reduced in the latter group (P<10(-6)). L-NAME significantly reduced the hypotensive effect only of losartan. Vascular and cardiac hypertrophy were significantly attenuated with losartan or perindopril, but were unchanged with other treatments. The new analysis proposed here identifies differential effects on trends and cyclic variation and associations with regression of end-organ damage for losartan and perindopril compared with hydralazine plus hydrochlorothiazide. The method offers a powerful tool for detailed investigation of radio-telemetry data.

Animals↗
PubMed1992

Staring episodes in children analyzed by telemetry.

Staring episodes in children may be ictal or nonictal, and telemetry helps make this distinction. Twenty-seven children referred to our service for elucidating the nature of their staring spells were studied by telemetry. No staring events were recorded in four children. The staring events were not associated with electroencephalographic (EEG) changes in 12 children. In 11 children, the staring events had EEG accompaniments: four had generalized spike-and-wave changes; three had focal or asymmetrical changes; and four had generalized decrement (desynchronization), which has not been described before as an electrical correlate of staring. EEG video telemetry in this group of patients led to accurate diagnosis and appropriate medical, surgical or behavioral management.

Adolescent↗
PubMed2002

Rate-correction technique for QT interval in long-term telemetry ECG recording in beagle dogs.

The establishment of a new rate-correction method for the QT interval is presented for long-term telemetry ECG recording in free-moving beagle dogs. First, in order to define the QT-RR relation to derive the correction formula, the diurnal variations of the QT and RR intervals and the influencing factors were analyzed, and the QT-RR regression coefficient beta was estimated under various conditions: steady and non-steady states of animal, light and dark periods, and over 24 h. In the results, the diurnal rhythm of the QT interval was synchronized with the RR interval reflecting the physical and emotional states of the animal. The coefficient beta had considerable variation during the day: beta; 0.276 +/- 0.052 (maximum to minimum: 0.495 to 0.153). Thus, it was considered that the ideal rate-correction technique for telemetry ECG requires the selection of a flexible coefficient beta adjusted to the condition of the measurement. Therefore, rate-correction utilizing analysis of covariance estimating the coefficient beta for each dog, was compared with previously proposed formulas which fix the rate-correction coefficient, based on the capacity to dissociate the effects of heart rate on the QT interval. This was then tested by the levels of discrimination apparent in the QT prolongation caused by a class III antiarrhythmic drug, which ranked the formulas on the levels of correction achieved as follows: covariance adjustment > Matsunaga > Van de Water > Bazett. Thus, the rate-correction method utilizing analysis of covariance is proven adequate for data from telemetry ECG recordings.

Analysis of Variance↗
PubMed2002

Development of telemetry system in the common marmoset--cardiovascular effects of astemizole and nicardipine.

The purpose of this study was to evaluate a telemetry system for examining the cardiovascular system in the conscious common marmoset. Parameters obtained were blood pressure, heart rate, respiratory rate, ECG, body temperature and locomotor activity, and these were continuously recorded on a data recorder via the telemetry system and then processed by a computerized system. Diurnal rhythms of blood pressure, heart rate, body temperature and locomotor activity were observed in this system. We studied the effects of astemizole (antihistamine) and nicardipine (Ca2+ channel blocker) on cardiovascular parameters. Astemizole at 30 mg/kg (p.o.) and at 1 to 3 mg/kg (i.v.), prolonged QT interval and induced ventricular extrasystole. Torsades de pointes occurred in one of three cases at 3 mg/kg (i.v.) and 30 mg/kg (p.o.), while it did not affect the blood pressure, respiratory rate and body temperature. Nicardipine at 30 mg/kg (p.o.) caused sustained hypotension and tachycardia. These results demonstrate the usefulness of the telemetry system using the common marmoset for evaluating the cardiovascular effects of drugs under physiological conditions.

Animals↗
PubMed2005

Practical application of guinea pig telemetry system for QT evaluation.

The purpose of this study was to evaluate a telemetry system for examining QT evaluation in the conscious free-moving guinea pig using 10 reference compounds whose effects on human QT interval are well established: 8 positive references (bepridil, terfenadine, cisapride, haloperidol, pimozide, quinidine, E-4031 and thioridazine), and 2 negative references (propranolol and nifedipine). Pharmacokinetic experiments were also performed for the 8 positive references. Telemetry transmitters were implanted subcutaneously in male Hartley guinea pigs, and the RR and QT intervals were measured. All 8 positive references prolonged QTc (QTc = k x QT/RR(1/2)) 10% or more during the 60 min observation period. When the values of the QTc changes were plotted against the serum concentrations, the resulting curves exhibited an anticlockwise hysteresis loop for all 8 references. In guinea pigs treated with haloperidol, changes of the T-wave shape from positive to flat were observed. The 2 negative references did not prolong the QTc. These findings suggest that the present telemetry guinea pig model is useful for QT evaluation in the early stages of drug development, because of the small body size of guinea pigs and their action potential configuration, which is similar to that of humans.

Animals↗
PubMedDate not supplied

Telemetry glucose monitoring device with needle-type glucose sensor: a useful tool for blood glucose monitoring in diabetic individuals.

For continuous monitoring of glucose concentration in ambulant diabetic patients, a telemetry glucose monitoring system with a needle-type glucose sensor has been developed. The system consists of a sensor transmitter (4 X 6 X 2 cm, 50 g) that converts current signals generated in a needle-type glucose sensor to high-frequency audio signals and a receiver that continuously calculates glucose concentrations from the received audio signals. The noise range of a monitoring record with the telemetry system (0.3 +/- 0.04%, mean +/- SEM) was significantly smaller than that with a wire-connected system, the wearable artificial endocrine pancreas (2.5 +/- 0.3%). Postprandial tissue glucose concentration responded well to the plasma glucose concentration, with a time lag of 5 min. Continuous glucose monitoring of five diabetic subjects for 77 +/- 22 h revealed that a significant correlation existed between the subcutaneous tissue glucose concentration and the plasma glucose concentration measured simultaneously in each patient. These data indicate the usefulness of the telemetry glucose monitoring system in strict glycemic control of diabetic individuals.

Autoanalysis↗
PubMed2000

[First experiences in Neural Response Telemetry in patients with Nucleus 24 cochlear implant system].

Nucleus 24 Cochlear Implant System enables bidirectional communication with the implant-telemetry. Information about implant function can be obtained using telemetry. Neural Response Telemetry is a measurement of neural activity in the cochlea as a response to electrical stimulation. Principle of NRT recording, classification of responses and examples of responses obtained in patients implanted in Poznań are presented.

Adult↗
PubMed1999

Video-EEG telemetry: apparent manifestation of both epileptic and non-epileptic attacks causing potential diagnostic pitfalls.

Video-EEG telemetry is often used to support the diagnosis of non-epileptic seizures (NES). Although rare, some patients may have both epileptic seizures (ES) and NES. It is crucially important to identify such patients to avoid the hazards of inappropriate anticonvulsant withdrawal. To delineate the electroclinical characteristics and diagnostic problems in this group of patients, we studied the clinical, EEG and MRI features of 14 consecutive patients in whom separate attacks, considered to be both NES and ES were recorded using video-EEG telemetry. Only two patients were drug-reduced during the telemetry. Most patients had their first seizure (ES or NES) in childhood (median age 7 years; range: 6 months-24 years); 8/14 patients were female. Brain MRI was abnormal in 10/14 patients. Interictal EEG abnormalities were present in all patients; 13/14 had epileptiform and 1/14 only background abnormalities. Over 70 seizures were recorded in these 14 patients: in 12/14 patients, the first recorded seizure was a NES (p < 0.001), and 7 of these patients had at least one more NES before an ES was recorded. Only 3/14 patients had more than 5 NES before an ES was recorded. Recording a small number of apparently NES in an individual by no means precludes the possibility of additional epilepsy. Particular care should be taken, and multiple (> 5) seizure recording may be advisable, in patients with a young age of seizure onset, interictal EEG abnormalities, or a clear, potential aetiology for epilepsy.

Adolescent↗
PubMed1982

[The performance of ECG telemetry in the analysis of rhythm disorders].

630 outpatients and inpatients under rest as well as under conditions of physical loads and psychic stress were examined with the help of a radiobiotelemetry device of own construction, which corresponds to a combination of traditional radiotelemetry and tape storage. In 81.4% of the patients with hitherto unclarified disturbances of the cardiac rhythm telemetry obtained their qualitative clarification. In 50% of all cases with classical angina pectoris symptomatology the ischaemic heart disease was verified by determination of the usual criterias of ECG at the telemetry stripe. Of these 50% only 7 patients had no arrhythmia. In 57.5% of all examined patients with pacemakers of permanent frequency we could prove a considerable parasystoly in load by telemetry. 9 patients with R-demand-pacemakers became evident by triggering defects in load. During the psychoanalytic examination we registered extrasystoles in 25%, apart from this once developed a pancardiac asystolism. The radiobiotelemetry is a valuable completion of the well-known methods of load.

Arrhythmias, Cardiac↗
PubMed1978

PCM telemetry for physiological data.

PCM technology offers significant advantages in the application of telemetry to medical and physiological studies. The requirements for less complicated handling, standardized system layout, improvement of weight, size and power supply by commercial battery modules, as well as different wireless data links are met better by a PCM encoder which was specially developed for physiological applications. The advantages of PCM are illustrated in this paper by relating the experimental requirements to technical specifications for the elements of a telemetry link. A newly designed 8-channel PCM-telemetry system satisfying these requirements is described.

Humans↗
PubMedDate not supplied

Telemetry for the year 2000: meeting the needs of the customer.

As customers of medical technology, all too often we are limited in our equipment selection process by the unwillingness of the vendor to custom-design their equipment to meet our needs. Reductions in capital equipment budgets as well as in operating (salary) budgets will require hospitals to make equipment selections based not only on how the technology can fulfill a patient care need, but also on how the technology can reduce or offset operating costs. The replacement of older telemetry monitoring equipment with state-of-the-art computerized, distributed network display terminals offers a new insight into how telemetry monitoring can better serve the needs of the caregiver, and at the same time contribute to reductions to operating costs. Computerized arrhythmia telemetry monitoring technology has finally advanced to the point where you don't need a full-time person to "monitor the monitor."

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Transcutaneous optical telemetry system with infrared laser diode.

A transcutaneous telemetry system is indispensable when monitoring and controlling the operation of an artificial heart totally implanted inside the body. A telemetry system using light is more useful than radio waves from the viewpoint of electromagnetic interference and power consumption. In this report, a transcutaneous optical coupler consisting of an infrared laser diode (LD) and a PIN photodiode (PINPD) was evaluated, and the transcutaneous optical coupling and information transmission characteristics were evaluated in in vitro experiments. The wavelength and directional angle of the LD used were 830 nm and 9.5 degrees, respectively. With regard to the directional angle of PINPD, the authors found that a PINPD with a larger directional angle allowed for more deviation between the axes optical axes of the LD and the PINPD. It was also found that the transcutaneous coupler had an optimum distance for the permissible deviation to be maximized. The information signals modulated by the phase shift keying (PSK) were transmitted at a rate of 9,600 bps through goat skin 4 mm thick, and demodulated by the phase locked loop (PLL) on the receiving side. As a result, the information signals were demodulated without any errors in deviation within 10.5 mm at a distance of 11 mm. In conclusion, the transcutaneous optical telemetry system using an infrared LD has sufficient characteristics to monitor and control the operation of an artificial heart totally implanted inside the body.

Heart, Artificial↗
PubMed2000

Wireless medical telemetry service. Federal Communications Commission. Final rule.

This document allocates new spectrum and establishes rules for a Wireless Medical Telemetry Service (WMTS) that allows potentially life-critical equipment to operate on an interference-protected basis. Medical telemetry equipment is used in hospitals and health care facilities to transmit patient measurement data, such as pulse and respiration rates to a nearby receiver, permitting greater patient mobility and increased comfort. This action will increase the reliability of medical telemetry equipment.

Government Agencies↗
PubMed1984

Myopotential interference with DDD pacemakers: endocardial electrographic telemetry in the diagnosis of pacemaker-related arrhythmias.

Skeletal myopotentials may inhibit the output of unipolar demand ventricular pacemakers, resulting in protracted episodes of asystole in susceptible patients. The new DDD-mode pacemakers have, in addition to a unipolar ventricular lead, a unipolar atrial lead to enable atrioventricular sequential or atrial synchronous function. During clinical investigation of a new dual-unipolar cardiac pacing system programmed to operate in the DDD mode (Pacesetter AFP models 281 and 283), 6 patients were noted (5 men and 1 woman, aged 22 to 68 years) who manifested paroxysmal acceleration of ventricular pacing rate approaching the maximal tracking rate. Two patients also had abrupt slowing or cessation of ventricular output. With the use of atrial electrographic recordings (obtained with telemetry), the following mechanisms of rate change were found: myopotential tracking, myopotential inhibition, interference-mode asynchronous operation, sudden increases in sinus rate, and pacemaker-mediated reentrant tachycardia. In all patients, reprogramming of the implanted devices, based on telemetered atrial electrography, resulted in disappearance of the arrhythmias and loss of symptoms while maintaining the DDD pacing mode. Thus, several mechanisms of rhythm disturbances are peculiar to dual-chamber cardiac pacing systems that use unipolar electrodes. Endocardial telemetry combined with extensive programming capability offers the best opportunity for proper diagnosis and management of these problems.

Adult↗