Biomedical subjects

S Solingen

Publications and source records attributed to S Solingen.

4 recordsLinked to original sources

PubMed1994

Transmyocardial impedance during single and multiple internal ventricular defibrillation shocks.

Little is known about the transmyocardial impedance during internal ventricular defibrillation. In a canine model, using high rate on-line digitization, random shock delivery, and titanium electrodes, we determined the relationship among voltage, current, and impedance, delivered energy, and defibrillation success within the individual and within successive defibrillation shocks. Impedance decreased with repeated defibrillation in 10 of 11 dogs. Impedance always increased during trapezoidal discharges, whereas voltage decreased. Impedance was lower with high energy-voltage shocks in all dogs. Visually, voltage and current waveform did not show a phase shift. There was no difference in the total energy delivered and the energy converted into heat by the resistive part of the impedance. With a formula valid only for resistive loads, the capacitance of the defibrillator was calculated to be within the measurement accuracy and tolerance of the factory-provided value of 132 microF. Polarization voltage was consistently observed. Thus the transmyocardial impedance during defibrillation is primarily resistive, nonlinear voltage dependent, and declines with successive shocks. Defibrillation success was not influenced by these phenomena.

Animals↗

PubMed1991

Acute effects of intravenous propafenone on the internal ventricular defibrillation threshold in the anesthetized dog.

In 10 treated and 2 control dogs, the short-term effects of intravenous propafenone (2 mg/kg/10 minutes, followed by 1 mg/min [n = 2] or 25 micrograms/kg/min [n = 8]) on the internal ventricular defibrillation energy requirements (DER) were investigated. Multiple stored energy levels were randomly tested and the percent successful defibrillation was plotted against the stored energy, and the raw data were fit by logistic regression. The energy at 50% (E50) and 80% (E80) defibrillation success increased after propafenone by a mean of 75% (8.4 +/- 2.4 to 14.7 +/- 5.9 joules, p less than or equal to 0.05) and 59% (11.1 +/- 3.5 to 17.6 +/- 6.7 joules, p less than or equal to 0.05), respectively. Plasma propafenone levels ranged from 778 to 2554 ng/ml (1495 +/- 592 ng/ml) at the beginning to 833 to 2193 ng/ml (1297 +/- 389 ng/ml) at the end of the defibrillation trials. Two dogs served as controls and received Ringer's solution instead of propafenone and showed the temporal stability of the preparation. In conclusion, intravenous propafenone increases the internal ventricular DER in this canine model. This may have important clinical implications in patients with automatic implantable cardioverter-defibrillators (AICDs) receiving concomitant antiarrhythmic drug therapy and in patients undergoing therapy with intravenous propafenone.

Animals↗

PubMed1988

A 32 key keyboard for the HP PDMS.

The keyboard remains the primary human interface device for existing patient data management systems. The standard bedside keyboard for the Hewlett-Packard PDMS has 16 keys which are used for both numeric data entry and multiple functions, accessed by shift key combinations. We have designed and constructed a 32 key keyboard which speeds single keystroke access to all PDMS functions. The new keyboard is backwards compatible and requires no PDMS software changes. A 32 key keyboard offers many advantages for use with the HP PDMS. The device presented is backwards compatible with the vendor's keyboard and requires no software changes. This keyboard could serve as an updated functional replacement for thousands of keyboards now in use.

Computer Systems↗

PubMed1988

Electrical safety during electrophysiological testing.

This report describes the inadvertent induction of non-sustained atrial and ventricular arrhythmias due to the malfunction of a programmable cardiac stimulator. The malfunction occurred when line power resumed after a brief municipal power outage ("blackout") during an invasive electrophysiological study. The stimulator spontaneously delivered very high frequency pulses through the electrode catheter to the myocardium which resulted in atrial and ventricular arrhythmias. During bench testing, the stimulator delivered a continuous train of high frequency output pulses (greater than or equal to 1 mA) when line voltage resumed normal level after it had dropped below 65 VAC. Electrical safety during electrophysiological testing requires a stimulator design which is immune to altered operating conditions, and which shuts down if abnormal operating or output conditions are detected.

Arrhythmias, Cardiac↗