Shock Voltage Research Articles

Treatment of catecholamine-sensitive right ventricular tachycardia by endocardial catheter ablation

Endocardial catheter ablation with direct current high voltage shocks was performed in a patient with recurrent syncope due to a catecholamine-sensitive ventricular tachycardia that was drug refractory and occurred in the absence of identifiable heart disease. Pace mapping and catheter activation mapping of the spontaneous and isoproterenol-induced ventricular tachycardia located the tachycardia origin in the right ventricular outflow tract. Ablation dramatically reduced spontaneous ventricular tachycardia and ectopic activity (from 50,000 to <100 ectopic beats/ 24 h). The patient has remained symptom free and without ventricular tachycardia recurrence for 3 years. These observations and review of previous studies suggest that catheter mapping can easily locate the arrhythmia focus in the right ventricular outflow tract and that catheter ablation can be performed at low risk. Catheter ablation is a viable option for the treatment of right ventricular catecholamine-sensitive tachycardias that are unresponsive to antiarrhythmic drugs.

Short-Term Changes of Laboratory Values After Extracorporeal Shock Wave Lithotripsy

AbstractSince the inception of extracorporeal shock wave lithotripsy 9 years ago treatment strategies have changed. Patients currently are receiving larger numbers of higher voltage shock waves. However, upper limits of safety for these treatments have not been established. In an attempt to address this question a comparative study of effects of extracorporeal shock wave lithotripsy on laboratory values between 2 stone centers, Munich and Tucson, using different treatment strategies 3 to 4 years apart was done to identify possible differing effects. Patient stone burdens were similar. However, Tucson patients received almost twice the number of shock waves. Both groups showed a significant decrease in hematocrit (by 8.7 per cent in Munich and 6.4 per cent in Tucson). Both groups had a significant increase in white blood count (14.5 per cent in Munich and 22.7 per cent in Tucson). In addition, both groups had increased serum levels of glutamic oxaloacetic transaminase of 43.3 and 59.7 per cent, respectivel...

Critique of the Dornier HM3 lithotripter as a clinical algesimeter

The power and nociceptive intensity of shock waves generated by the Dornier HM3 extracorporeal shock wave lithotripter (ESWL) are voltage dependent and suited to algesimetry in a controllable voltage range of 8–30 kV. Fidelity of the HM3 as an algesimeter was tested by: 1. (1) In vitro measurements of shock pressure at voltages between 14 and 30 kV were recorded by a force transducer at the point of clinical focus. 2. (2) Unanaesthetized volunteer ( n = 5) assessment and VAS pain scores of shocks in the range of 10–24 kV, yielding highly significant correlations between blinded randomized shock voltage ( r = 0.88), and VAS scores ( r = 0.84). 3. (3) Voltage-tolerance curves generated from 33 ASA class 1 or 2 patients undergoing ESWL treatment under epidural analgesia with 0.125% bupivacaine, fortified with a bolus epidural dose of 100 μg fentanyl if pain arose during treatment. Voltage tolerance was increased by 50% after an epidural bolus of 100 μg fentanyl ( P < 0.001). The respiratory consequences of epidural fentanyl were assessed by changes of respiratory rate and rhythm recorded from capnographic tracings of expired carbon dioxide. This study indicates that the Dornier HM3 system provides a valuable opportunity to conduct precise, quantitative measurements of induced deep truncal pain, as well as the effectiveness and respiratory cost of analgesic interventions directly applicable to the safe management of acute pain.

Short-Term Changes of Laboratory Values after Extracorporeal Shock Wave Lithotripsy: A Comparative Study

Since the inception of extracorporeal shock wave lithotripsy 9 years ago treatment strategies have changed. Patients currently are receiving larger numbers of higher voltage shock waves. However, upper limits of safety for these treatments have not been established. In an attempt to address this question a comparative study of effects of extracorporeal shock wave lithotripsy on laboratory values between 2 stone centers, Munich and Tucson, using different treatment strategies 3 to 4 years apart was done to identify possible differing effects. Patient stone burdens were similar. However, Tucson patients received almost twice the number of shock waves. Both groups showed a significant decrease in hematocrit (by 8.7 per cent in Munich and 6.4 per cent in Tucson). Both groups had a significant increase in white blood count (14.5 per cent in Munich and 22.7 per cent in Tucson). In addition, both groups had increased serum levels of glutamic oxaloacetic transaminase of 43.3 and 59.7 per cent, respectively. However, only the Tucson group showed increases in serum glutamic pyruvic transaminase, lactic dehydrogenase and total bilirubin in 51.5, 40.8 and 46 per cent of the patients, respectively. Further analysis indicated that extracorporeal shock wave lithotripsy was associated with 2 significant short-term changes of blood or serum laboratory values: 1) those presumed to be dilutional from related infusions, rather than extracorporeal shock wave lithotripsy treatments themselves and 2) those presumed to be related to cellular injury after high energy treatments. Elevated serum glutamic pyruvic transaminase, lactic dehydrogenase and total bilirubin values of Tucson patients clearly were related to higher kilovolts and number of shocks or to treatments on the right side. These observations probably resulted from transient trauma to the liver, as well as renal cells.

RNA transfection of Escherichia coli by electroporation

Cells of Escherichia coli were efficiently transfected with Qβ phage RNA by electroporation. A single voltage shock at 6.25 kV/cm with a 25 μF capacitor resulted in an infectivity yield considerably higher than that attained by a lysozyme-EDTA spheroplast method or a CaCl 2 procedure. A linear relationship was found between concentration of the input RNA and yield of the transfectants, over a wide range. Efficiency of the electroporation-mediated transfection (electrotransfection) was increased by addition of certain sodium salts but decreased by preincubation in a Tris buffer containing sucrose.

50 YEARS OF POWER FENCING

The history of high power fencing shows how this New Zealand idea contributed extensively to the profitability of pastoral farming by improving animal control, pasture utilisation and weed control. The development of electrified fencing is traced wth examples of incidents, starting in America in the thirties where it has improved only slightly, while in New Zealand development started in 1936 to become a world leader thanks to the Phillips (Ruakura) low impedance fence. Examples of its benefits are described by quoting farm profitability competition winners. Power fencing continues to become more sophisticated with items like voltage alarms, shock stops and tumblewheels. Keywords: power fencing, pasture improvement, weed control.

Defibrillation Threshold: A Simple and Quantitative Estimate of the Ability to Defibrillate

It has recently been shown that the probability of successful defibrillation as a function of energy has a sigmoidal dose-response relationship. Determination of a defibrillation "dose-response curve" is time consuming and requires multiple defibrillation attempts. On the other hand, determination of a defibrillation threshold is achieved rapidly and would be better suited to study the effect of interventions on the ability to defibrillate patients. We assessed the relationship of defibrillation threshold to the defibrillation "dose-response curve" in twelve open chest, halothane anesthetized pigs. Ventricular fibrillation was induced electrically, and defibrillation was attempted by passing sequential pulse shocks through an indwelling catheter and plaque electrodes. Defibrillation threshold was determined by decreasing the stored voltage of the initial shock until it failed to defibrillate the heart. Five different stored voltage levels distributed around defibrillation threshold were then randomly administered, six times for each level. A "dose-response curve" was obtained for each animal. Defibrillation threshold superimposed on the "dose-response curve" at 76 +/- 7.2 percent (mean +/- SEM) defibrillation success. Energy delivered at 1.5 times average defibrillation threshold was predicted to achieve 100 percent defibrillation success for a single shock in all animals. We conclude that defibrillation threshold provides a simple and quantitative estimate of the ability to defibrillate with a predictable relationship to the "dose-response curve."

Stimulation of the cerebral cortex in the intact human subject

One of the most fertile methods of investigating the brain is to stimulate a part of it electrically and observe the results. So far, however, use of the method in man has been restricted by the necessity of opening the skull surgically to apply the electrodes. Much could be done, both with healthy subjects and with neurological patients, if it were feasible to stimulate through electrodes on the scalp, although the localization of the stimulus on the cortex will always be much less sharp than with electrodes on the brain surface. In an intact man, however, the brain is protected from electricity by the skull and by the scalp, both of which normally offer considerable resistance. Furthermore, the cerebral cortex does not have a particularly low electrical threshold. It is probably for these reasons (despite an occasional contrary claim1) that attempts to stimulate the brain by applying stimuli from conventional stimulators to the scalp have been stopped by pain or have otherwise failed. These obstacles have now begun to yield. Recently, it was found that, on stimulating muscles in the human hand2 without any special preparation of the skin, the effective resistance fell to low values if brief but very high voltage shocks were used. Applying the same technique to the head, it has now proved possible at the first attempt to stimulate two areas of the human cortex, without undue discomfort.

Piezoelectric polymer transducer and its application to acoustics

Piezoelectric polymer has several unique properties compared with conventional piezoelectric materials, namely (1) low acoustic impedance, (2) high flexibility, (3) a relatively low dielectric constant, (4) high breakdown voltage, (5) resistance mechanical and thermal shock. A thin sheet of wide area can be easily produced, and it can be properly given local piezoactivity. At the present stage, polarized stretched films of polyvinylidene fluoride (PVDF) are considered to be most promising in practical use. Various transducers with PVDF films have been developed in the field of acoustics from audio engineering to ultrasonics, such as microphones, headphones, loudspeakers, electromechanical transformers, ultrasonic transducers, and so on. Principles and constructions of these transducers especially for ultrasonics are described including several new constructions which have been recently proposed. Applications of these transducers to electronic devices as well as ultrasonic imaging systems are also described.

Attenuation of ethanol intake by contingent punishment of food-maintained responding

Two food-deprived rats responded under a concurrent fixed-ratio 12 (food) fixed-ratio 1 (8% ethanol) reinforcement schedule in which a tone occurred during every second or every fourth interpellet interval. When ethanol-maintained lever presses during the presence of the tone shifted the food schedule to one in which electric shock punishment occurred, ethanol-maintained responding consistently decreased. The decrease in the frequency of ethanol-maintained responding varied directly with shock voltage from 25 to 100 V, and occurred during intervals with the tone present and absent. These results indicate that ethanol in take may be attenuated by contingent changes in a concurrent food schedule.

Decision as a Function of Attribution and Attributor's Position

Summary In a situation in which both the attributee and the attributor had to choose the level of shock they were to receive in a later session, the attributor made either a high attribution (70 v) or low attribution (30 v) to the attributee and indicated either a high own position (70 v) or low own position (30 v). To vary the attributor on the dimension of trustworthiness, the attribution was either overheard or regular. Thus the experiment had a 2 × 2 × 2 factorial design, with 80 male American undergraduates as the Ss or attributees. The attributees chose a higher voltage of shock in the high attribution condition than in the low attribution condition and also a higher voltage of shock in the high attributor's position condition than in the low attributor's position condition. No other effects were significant.

PUNISHMENT OF AUTOSHAPED KEY‐PECK RESPONSES OF PIGEONS

The effects of different voltages of response-dependent and response-independent electric shock on the frequency of key-peck responses engendered by an autoshaping procedure were studied. In Experiments I and II, each response produced a brief electric shock, and response frequency generally decreased more with higher-voltage shock. Preshock frequencies of responding were generally recovered across successive sessions of relatively low-voltage shock delivery but not at higher shock voltages. The effects of response-dependent and response-independent shock were compared in Experiment III by using a yoked-control procedure in which each pigeon received each type of shock delivery at different times. Response-dependent shock generally produced greater decreases in response frequency. In the final experiment, one response-independent shock per autoshaping trial was scheduled. The number of autoshaped responses per trial was related to shock voltages. These results suggest that response-dependent and response-independent electric shock effectively decrease frequency of autoshaped responses.

Effects of intracranial reward strength on escape threshold

Rats with implanted monopolar electrodes in the lateral posterior hypothalamus were trained for self-stimulation behavior (ICSS). Rats were allowed to self-stimulate in a two-compartment test chamber. Thirty-eight different electrical stimuli were used to maintain ICSS. In one compartment, a foot shock of increasing voltage was administered. It was observed that the voltage of the foot shock required to elicit an escape response increases during ICSS. This attenuation of aversive state was related to the strength of the reinforcing effect elicited by brain stimulation. The reinforcing effect involves two factors of which only one seems to be responsible of the escape threshold modification.

Effect on Breathing of an Electric Shock Applied to the Extremities

Electric shock frequently causes the arrest of breathing. This paper reports on an experimental investigation of this phenomenon. A convulsion is a likely consequence of a high voltage shock applied to the extremities. It is suggested that this convulsion may be reponsible for breathing failure.

Predicted compliance in obedience situations as a function of implied instructional variables

Male college students were asked to predict behavior in a Milgram-type obedience situation. Description of the situation and wording of the measuring instruments provided varying degrees of implications that the hypothetical subject would fully comply. Predicted evaluation of victim by subject, fee demanded for participation, percentage of predictions of non-compliance, and terminal shock voltage were unaffected by the experimental manipulations. 27% predicted completion, and the terminal shock predicted was 196 V.

Time ratio regulation — A new inverter design technique

Silicon controlled rectifiers and time-ratio regulation techniques have been combined in a new power supply to provide increased reliability in railroad-radio service. Because of unusual environmental conditions, railroad locomotive and caboose radio equipment has been plagued with a high failure rate. These conditions include a wide variation in supply voltages, transient voltage surges, vibration, shock and temperature extremes. This paper describes two-way radio equipment that has been designed specifically for greater reliability in service on locomotives and cabooses. In the power supply, silicon controlled rectifiers are used in a new full-wave circuit in which both the pulse width and repetition rate of the stepped waveform are changed in order to maintain constant output voltages. Choke input filters are used to smooth the rectified secondary voltages and produce tine-averaged values of the pulses. Design considerations and performance data are discussed. This design demonstrates the advantages of applying time-ratio regulation and controlled rectifier inverter techniques to railroad vehicular-communication power supplies. These techniques can be extended to D.C. to D.C. power supplies for other applications.

CARDIAC ARRHYTHMIAS FOLLOWING CONDENSER DISCHARGES AND THEIR DEPENDENCE UPON STRENGTH OF CURRENT AND PHASE OF CARDIAC CYCLE.

To improve technics for electrical defibrillation of the heart, an apparatus was constructed for the application of a condenser discharge at any selected phase of the cardiac cycle. With this apparatus 2160 discharges were applied through the intact chests of 240 dogs under thiopental anesthesia. The voltage ranged from 0.5 to 6 kv, the condenser capacity from 0.5 to 100 µF, the total energy from 0.06 to 1800 watts. The associated changes in cardiac rhythm were graded from one (no abnormalities) through two (mild, brief extrasystoles), three (more protracted but fully reversible periods of bigeminy, extrasystoles, block, etc.), four (severe but reversible changes lasting several minutes, usually with fall in blood pressure), to five (severe arrhythmias changing into ventricular fibrillation). The severity of the arrhythmias increased progressively as the voltage was increased, and to a much smaller extent with increases in the total amount of electrical energy. Arrhythmias also were significantly more severe when the shock was delivered during the refractory period (S-T interval) than during the excitable (P interval) stage of the cardiac cycle. Two types of ventricular fibrillation of very different prognosis were revealed. One came on suddenly after low voltage shocks and could easily be terminated by a single adequate defibrillation impulse. The other came on more gradually after high voltages and energies and tended to be irreversible. Observations thus far made indicate that the severity of the arrhythmia following condenser shocks gives an approximate indication of the severity of pathological changes in the heart. Excessive currents could damage the heart to such an extent that myocardial contractions were weak or absent although electrical activity persisted. Therefore the parameters of condenser discharges used for clinical defibrillation should be such that they will produce only the mildest and briefest arrhythmias.

Cable sheath surface discharges and electric shock

ELECTRIC SHOCK HAZARD from the surface of an energized cable is of great importance due to the increasing use of semiconductive jackets. Data were obtained showing the amount of current flowing to ground over a range of “body contact” resistances for nonshielded, metallic-shielded, and “semiconductive” jacketed rubber-insulated cables operating at various voltage levels. The range of currents then was related to known shock sensation levels to assess the amount of hazard involved. A theoretical approach to the voltage rise, surface current, and shock current of cables having different outer surfaces materials helps considerably in understanding the phenomena involved. Calculation of surface voltage rise and current flow can be carried out properly by considering the distributive nature of the cable constants.

Susceptibility of Heart to Electric Shock in Different Phases or the Cardiac Cycle

In connection with an extended series of experiments on the effects of electric shock, the fact has been brought to light that shocks whose duration is a small fraction of the cardiac cycle have a marked difference in their tendency to cause ventricular fibrillation,. depending upon the phase of the cycle in which they occur. The shocks were tripped off by amplified cardiac currents after a controlled delay from a reference point in the electrocardiac cycle. The electrocardiogram together with the shock current and voltage were photographically recorded in time relation on a continuously moving film, which enabled checks to be made on the placement of the shocks in the cardiac cycle. Nearly 800 shocks with 60-cycle current of .03 and .1 second durations were administered to 92 anesthetized sheep in different parts of the cardiac cycle, with currents ranging from 1 to 17 amperes, through the pathway between the right fore-leg and the left hind-leg. A large proportion of the shocks which were given near the...