Toward optimizing a preshaped catheter and system parameters to achieve single lead DDD pacing.

P wave electrogram amplitudes and atrial stimulation thresholds were determined in eight Hanford miniature swine using a preshaped catheter with an "S" curve in the SVC, and a major lobe in the atrium to enhance electrode contact with the atrial wall. The catheter was designed for pacing and sensing in the DDD mode. P wave amplitudes were also ascertained with two commercially available VDD leads and compared to the data from the experimental catheters.

A new atrial lead with improved stability and P-wave detection.

A new segmented polyether polyurethane atrial pacemaker lead has been developed and tested acutely and chronically in dogs. This lead was constructed so that its tip could quickly and accurately be positioned in close proximity to the S-A node and provide long-term stability without the use of active fixation devices such as tines or screws. The acute intrinsic P-wave potentials seen at the S-A node area (9.

The effects of electrode position on the detection of the transvenous cardiac electrogram.

Adequate sensing of the cardiac electrogram is a necessary requisite for all demand cardiac pacemakers. In order to define better the effects of position of the sensing electrode on the ability of the pacer to detect the electrogram, a specially designed lead system with a movable, large surface area (50 mm2) proximal ring electrode and a small surface area distal tip electrode was placed transvenously in 12 mongrel dogs. As the sensing electrode was moved away from the right ventricular apex, there were slight but insignificant decreases in R wave amplitude.

Endotracheal intubation: an easy way to establish a patent airway in rabbits.

Endotracheal intubation of rabbits was accomplished by inserting a polyethylene catheter into the trachea through a guide needle which had been inserted into the trachea caudal to the larynx. The catheter was advanced cranially until it emerged from the mouth. The catheter then was used as a guide on which the tracheal tube was advanced.