Endovascular Pressure Measurements: Validation with a Pulsatile Flow Model and Haemodynamic Assessment of Brain AVMs

Abstract

Intravascular pressure measurements for several types of endovascular catheters were obtained in an in vitro model to validate the pressure readings obtained during the interventional procedures of brain AVM embolization. An experimental model was used where the beat rate, flow and pressures were as close as possible to the average human values of interest. It is shown that the corrections increase with the decreasing inner diameter of the catheter used and with increasing vascular pressure. We have also shown that there were no differences between measurements made with the catheter in the direction of flow or against it. An average pressure reading corrections for the various microcatheters to compensate the readings obtained during in vivo monitoring is presented. The haemodynamic assessment of 81 brain AVMs was performed using the endovascular measurement of arterial pressure in 389 feeding arteries during embolization. Mostly, the feeders' arterial median pressure was half the systemic arterial pressure but there was a wide variability of AV shunts in brain AVMs not only from one brain AVM to another but also within the same brain AVM. Measurement of arterial feeder pressure is an inexpensive, quick and accurate tool to evaluate the type of AV shunts within brain AVM.

Figure 1

Overall setup of the experimental pulsatile model.

Figure 2

Variation of the average pressure measured in the microcatheter as a function of the distance from the carrier tip.

Figure 3

Pressure reading for each microcatheter as a function of the pressure in the carrier.

Figure 4

Pressure difference between the readings taken with the microcatheter and the carrier as a function of the pressure in the carrier.

Figure 5

Total pressure differential values histogram.

Figure 6

Mean Brain AVM pressure differential values histogram and normal curve.

Figure 7

Total and Mean brain AVM pressure differential grade distribution.

Figure 8

Type of brain AVM arterial feeders catheterized. Perforator vert-basperforator artery branch of the vertebro-basilar system; Cortical vert-bascortical artery branch of the vertebro-basilar system;Perforator carotid-perforator artery branch of the internal carotid artery; Cortical Carotid-cortical artery branch of the internal carotid artery.