Durability and validity of a remote, miniaturized pressure sensor in an animal model of abdominal aortic aneurysm.

PURPOSE: To investigate whether a remote, miniaturized pressure sensor could maintain calibration and function through organized thrombus over an extended period in a porcine model of abdominal aortic aneurysm (AAA).
METHODS: Six adult pigs had an AAA surgically created and excluded. A sensor zeroed to atmospheric pressure was placed within the aneurysm sac and another within the suprarenal aorta of each animal. Pressure measurements were taken at the initial operation and then on a weekly basis over 2 months. The aortic sensors were correlated to an intra-arterial pressure catheter at the initial operation and at the time of sacrifice. Back-table sensor correlation with atmospheric pressure was done at the time of explantation.
RESULTS: Three animals died during the follow-up period. Five animals were available for 6-week follow-up, of which 3 survived for the complete 8-week protocol. Two of the surviving animals had an intra-aortic sensor. All 5 aneurysm sac sensors functioned throughout the experimental period. At the time of sacrifice, the sacs contained a large amount of organized thrombus in which the sac sensors were deeply embedded. The 3 aortic sensors also functioned throughout the course of the experiments. The pressures correlated within 5 mmHg to the catheter-based measurements taken at the initial operation and at the time of sacrifice. Comparison to atmospheric pressure revealed no calibration offset in any sensor.
CONCLUSIONS: This chronic implantation study demonstrates the durability of a remote, miniaturized pressure sensor within a surgically created aneurysm sac as well as the suprarenal aorta of a porcine AAA model. There was no calibration offset in any of the sensors, and they remained valid at explantation. We believe that this is further evidence of the potential applicability of this sensor for clinical use.