Aneurysm Sac Pressure Monitoring: Effect of Pulsatile Motion of the Pressure Sensor on the Interpretation of Measurements

Abstract

Purpose:

To determine the effect of pulsatile motion of graft-attached pressure sensors on the accuracy of aneurysm sac pressure measurement.

Methods:

Pressure inside a pressure box was measured with a sensor attached to a stent-graft (Sensor_graft) facing a sensor in fixed position (Sensor_box). Maximum inter-sensor variation of Sensor_graft and Sensor_box was determined in static experiments. Experiments with pulsatile circulation were performed with a compliant and a noncompliant stent-graft at 120/80 mmHg and 160/95 mmHg. Pressure measurements in the box were repeated after the box pressure was increased from 0 to 120 mmHg. Sensor_graft motion was measured by ultrasound. Measurements with Sensor_graft were compared to those with Sensor_box using Pearson correlation coefficients to determine the concordance between the sensors.

Results:

The maximum inter-sensor variation was 4 mmHg. Increased box pressure induced progressive pulsatile graft and sensor motion during all experiments. During the experiments with the compliant graft at systemic pressures of 120/80 and 160/95 mmHg, the maximum inter-sensor variation was exceeded at box pressures of 65 and 75 mmHg, respectively. The sensor motion at these box pressures was 214±2.70 μm and 210±0.93 μm, respectively. Measurements of Sensor_graft were higher than Sensor_box, up to 13 mmHg at a box pressure of 120 mmHg. The Pearson correlation coefficients during these experiments were 0.99 and 1.00 (p<0.001), respectively. In the experiments with the noncompliant graft, the maximum inter-sensor variation was not exceeded, and sensor motion was only 7±0.46 μm and 26±1.48 μm, respectively. The Pearson correlation coefficient during these experiments was 1.00 (p<0.001).

Conclusion:

Pulsatile sensor motion can influence the accuracy of pressure measurement. More compliant grafts are more susceptible to this phenomenon. Despite false high pressure measurements, stent-graft-attached pressure sensors seem appropriate to follow pressure trends in the aneurysm sac.