Noninvasive intrasac pressure measurement and the influence of type 2 and type 3 endoleaks in an animal model of abdominal aortic aneurysm

The objective of this study was to noninvasively detect pressure changes within an excluded aneurysm sac in an animal model of abdominal aortic aneurysm (AAA) and to study the influence of type 2 and 3 endoleaks. A porcine model of AAA that allows for the creation of type 2 and 3 endoleaks was used. A miniaturized pressure monitoring device (3 × 9 × 1.5 mm; Remon Medical Technologies, Caesarea, Israel) was implanted within the surgically created and excluded aneurysm sac. The pressure monitoring device is an ultrasound-based system that allows for pressure measurements in a noninvasive, transcutaneous fashion. In addition, catheter-based pressures were taken within the aorta and directly in the AAA sac. Noninvasive measurements were taken in a transcutaneous fashion between the initial operation and the time of sacrifice, when the type 3 endoleak was created (2 weeks). The median mean arterial pressure was 66 mm Hg (range 55-120 mm Hg; N = 8). The median noninvasive sac pressure with a type 2 endoleak was 48 mm Hg (range 39-90 mm Hg; N = 8) and was almost identical to the catheter-based measurements. Noninvasive pressures could be measured as early as postprocedure day 1. Two animals had follow-up that suggested closure of the type 2 endoleak during the observation period. With the creation of the type 3 endoleak, the catheter and noninvasive sac pressure and waveform changed from a flatline trace to a higher-pressure pulsatile trace (median 54 mm Hg; range 46-81 mm Hg; N = 8), reproducing the arterial pressure and waveform. This is the first study, to our knowledge, that demonstrates the efficacy of a noninvasive, miniaturized pressure monitoring device in identifying pressure changes in an excluded aneurysm sac with type 2 and type 3 endoleaks. This technology holds great promise for follow-up of patients and identification of sac pressure changes after EVAR and may allow a change in the current follow-up strategy.