Impedance-gradient electrode reduces skin irritation induced by transthoracic defibrillation.

A new type of disposable external defibrillation electrode has been developed to reduce the skin irritation commonly associated with defibrillation and synchronised cardioversion. This design employs an impedance gradient to reduce the proportion of current delivered to the electrode periphery. The temperature distribution under the new electrode was compared with that of four other types of commercially available electrodes after repeated high-energy biphasic defibrillation discharges to domestic swine.

Self-sealing, large bore arterial punctures: a counterintuitive new phenomenon.

The human femoral artery can bleed dangerously following the removal of a catheter uring cardiac catheterization. In this study, a modified technique of needle insertion, simply inserting the needle bevel-down instead of the standard bevel-up approach, was tested as a means to reduce bleeding after catheter removal. Large bore needle punctures were made in surgically exposed arteries of anesthetized pigs using either a standard technique (45 degree approach, bevel up) or a modified technique (25 degree approach, bevel down).

Electroventilation with monopolar and bipolar intratracheal electrodes.

Unlabelled: Electroventilation is the technique of producing inspiration with stimuli applied to inspiratory muscles by using strategically placed electrodes on or within the body. We conducted studies using the dog to determine the efficacy of monopolar and bipolar intratracheal electrodes for electroventilation. Bipolar electrodes were able to produce an inspired volume greater than a spontaneous tidal volume in all seven dogs, but monopolar electrodes were able to in only three of seven dogs.

Electrophysiological control of ventricular rate during atrial fibrillation.

Thirteen anesthetized canine subjects (17-29 kg) were used to demonstrate that mild cervical left vagal stimulation could control ventricular rate effectively during atrial fibrillation (AF). Two studies are presented. The first study used six subjects to demonstrate the inverse relationship between (manually applied) left vagal stimulation and ventricular excitation (R wave) rate during AF.

Characterization of atrioventricular nodal response to electrical left vagal stimulation.

The dynamic effect of left vagal stimulation on atrioventricular conduction was studied in six isofluorane-anesthetized dogs ranging in weight from 22 to 29 kg. The cervical vagus nerve trunks were left intact and no beta-adrenergic blockade was produced so that any influences of the sympathetic nervous system and autonomic reflex activity could be observed. Atrial pacing was used to control the heart rate while single, short trains of left vagal stimulation were delivered and timed to occur at different instances during the cardiac cycle.