Routine, direct measurement of aortic pressure in the conscious rabbit

A method for preparation and application of an indwelling catheter for measurement of aortic pressure in conscious rabbits is described. The catheter is generally reliable for periods longer than one month and requires little interference with the normal circulation. The system utilizes coiled polyethylene tubing which has a tapered tip covered with silicone rubber tubing and, at its exterior end, a Velcro matrix for skin healing. The catheter tip is pulled into the abdominal aorta with a trocar, directed caudally. The exterior end is run subcutaneously to the nape of the neck. In 19 rabbits prepared by this method, mean pressure was determined to be 68 +/- 2 mm Hg and pulse pressure was 29 +/- 1 mm Hg two weeks after implantation. The catheters remained patent in 17 rabbits at the time of sacrifice, 12 to 120 days later. In an in vitro sweep-frequency test, maximal resonance of the catheter system was found to lie between 12-14 Hz, at which point the measured pressure amplitude exceeded control by 12.5%.