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At least 577 records · Page 32Linked to original sources
PubMed1976

[Significance of risk factors of functional disorders of pacemakers (author's transl)].

In spite of increasing reliability of pacemakers and expensive electronic monitoring systems unforeseen disorders of the regular stimulation of the heart cannot be prevented with certainty. Criteria are given by which the individual risk of the carrier of a pacemaker can be determined, so that the degree of danger can be foreseen. Individual methods of monitoring and in particular checking intervals adapted to the risk are suggested.

Aged↗
PubMed1977

The lithium iodide--powered cardiac pacemaker. Clinical experience with 250 implantations.

A long-life cardiac pulse generator powered by the lithium-iodide fuel cell is described and our experience with 250 implantations is documented. The compact, hermetically sealed pulse generator unit is easily implanted, is reliable, and is well accepted by patients. There have been no pacemaker-related deaths and only minimal morbidity. There was a single instance of electrical circuit failure of the pulse generator early in our experience; however, to date, after 15.9 months' average follow-up representing 3.988 patient months of cardiac pacing, there have been no battery failures and no further electrical component failures. The pulse generator unit is now guaranteed by the manufacturer for 6 years. We believe that the lithium-iodide powered pacemaker represents a significant advance in pacemaker generator technology and is recommended for long-term cardiac pacing.

Bioelectric Energy Sources↗
PubMed1993

Performance comparison among children fitted with myoelectric and body-powered hands.

Seventy-six children with unilateral below-elbow amputation were fitted in random sequence with a myoelectric (MYO) and a body-powered (BP) prosthetic hand of identical size, shape, and glove color. Subjects ranged from six to 17 years, nine months and included 67 children with congenital limb deficiency and nine who sustained traumatic amputation. After training, each child wore each hand for three months. On the form board test requiring only prosthetic use, subjects took 13.7% longer with the MYO and committed more errors with the MYO, specifically in dropping objects and delaying their grasp and release. Object displacement, the most common error, occurred nearly as often with BP as MYO. MYO was minimally faster on a test of ten practical activities designed for bimanual prehension. Card playing was 39.8% faster with BP, whereas donning socks, cutting paper, and bandage application were 27.8%, 12.5%, and 10.9% faster with MYO. Performance with both hands was rated as decidedly poorer than normal quality. No major clinically important differences were found in the comparison of performance.

Activities of Daily Living↗
PubMed1996

In vitro testing of a left ventricular assist device. Study of the effect of its control strategy on energetic relationships inside the left ventricle.

In this study an original left ventricular assist device is tested on an open loop modular physical circuit reproducing Starling's law of the heart to set an optimal control strategy for heart recovery. It is assumed that the goals of the assistance are reduction of oxygen consumption, external work and improvement of cardiac mechanical efficiency. The assistance is evaluated by the position of a working point on the characteristic surfaces of the ventricle defined by peripheral resistance, atrial pressure and selected variables pertaining to energy (pressure-volume area, external work and cardiac mechanical efficiency). In this frame an optimal assistance for heart recovery is a compromise among different requirements corresponding to a restricted set of control parameters values: driving pressure PZB = 35 kPa and timing values T1 and T2 (systole beginning and systole ending in relation to QRS complex and cardiac cycle duration T) T1 = 0.55.T and T2 = 0.73.T.

Bioelectric Energy Sources↗
PubMed1977

[Bioelectric activity in cases of childhood masturbation].

In a total of forty-five cases of masturbation practiced by children EEG derivations were made before, during, and after anticonvulsive treatment. The results obtained confirm the clinical experience showing that the observed seizure-like phenomena have no relation whatever to forms of epilepsy.

Action Potentials↗
PubMed1977

[Influence of static muscle tension on acoustically evoked brain potentials, changes in skin resistance and bioelectric muscle activity].

Auditory evoked brain potentials (AEP), galvanic skin responses (GSR) and auditory evoked bioelectrical muscular responses were recorded in 16 male human subjects during voluntary isometric contraction of m. triceps brachii dexter. The electromygraphically controlled strength of muscular innervation corresponded to 20, 30, 40 and 50% of the maximal voluntary contraction. The trials were organized according to a change-over design. The following results could be obtained: The stepwise increase of the strength of muscular innervation effected an increase of the mean amplitude of auditory evoked EMG responses. The N1-P2 amplitudes of the AEP decreased with increasing strength of muscular innervation. The mean amplitude of the auditory evoked galvanic skin response was not changed significantly by the strength of muscular innervation, however, the spontaneous changes in galvanic skin resistance increased monotonously. Habituation effects were evident regarding amplitudes of AEP and GSR. The results indicate that muscular activity affects sensory information processing.

Acoustic Stimulation↗
PubMedDate not supplied

In vivo studies of an implantable energy convertor for skeletal muscle powered cardiac assist.

A device that harnesses the mechanical energy of skeletal muscle contracting in a linear configuration has been implanted in goats. This energy convertor transforms muscle work to hydraulic energy that could drive a variety of cardiac assist devices. The device is mounted with a rib clamp and plate affixed to the sternum by cortical bone screws. A transcutaneous hydraulic line carries a silicon based working fluid to an external system that controls the muscle load. In 60 to 70 kg goats, the latissimus dorsi insertion was reattached to the energy convertor. A Telectronics myostimulator with intramuscular electrodes stimulated the latissimus dorsi. In acute implants, hydraulic pressures in excess of 150 psi were obtained. Chronic implantation of the device allowed system evaluation in the conscious unanesthetized animal. Two weeks after implant, hydraulic pressures in excess of 200 psi were obtained and energy transferred to the external loading system exceeded 1 J per contraction. Six weeks after implant, the device continued to cycle freely. These initial results are very promising and suggest an implantable energy convertor is feasible. Development of an energy convertor is an important step toward tether-free skeletal muscle powered cardiac assist devices.

Animals↗
PubMed1976

Automatic control of the artificial heart.

An automatic control system has been developed to balance and control the output of an artificial heart. The system consisted of 2 linked negative feedback loops. The left ventricle was controlled by a Servo-Stroke Optimizer, which insured complete filling and full stroke operation of the left pump with each beat and changed the beat rate in accord with changes in aortic pressure. The right ventricle was controlled by a Servo-Variable Systolic Duration unit, which changed the stroke of the right ventricle to maintain the left atrial pressure within a preset band. In the initial animal studies, control pressures (aortic and left atrial pressure) were obtained from implanted transducers. More recently, a method has been devised whereby the control pressures were obtained from specific points on the left air line pressure wave, obviating the need for implanted transducers. The control system has been evaluated in a mock circulatory loop and in 9 calves with implanted artificial hearts. The system has provided balance of the 2 implanted ventricles and changes in flow rate in response to changes in peripheral resistance. The need for an operator to make manual adjustment to the power units has been considerably reduced. Further studies are indicated to evaluate the function of the control system in animals performing moderate-to-maximal exercise. Furthermore, the ultimate benefits of full stroke operation vs fill limited mode operation remain to be delineated.

Animals↗
PubMed1976

Coating evolution with an implantable biological battery.

A cathode of smooth platinum in a right endoatrial position and an anode of Domal magnesium were used to construct a hybrid bioelectric battery designed to power a pacemaker. In use the cathode is gradually covered by a coating consisting of a crystalline layer and a layer of connective tissue. This coating is responsible for the system change in the reduction process at the cathode level: the transfer from an oxygen to a hydrogen system. This system change causes a voltage drop in the bioelectric battery. This paper deals with oxygen diffusion across the tissue layer, as well as with various spectral and chemical analyses. A high level of calcium and phosphorus in the different analyses carried out seems to show that the presence of these elements is related to the coating of the cathode. The effect on the formation of the coating of the position of the cathode is also discussed.

Animals↗