Intrasac Pressure Waveforms After Endovascular Aneurysm Repair (EVAR) are a Reliable Marker of Type I Endoleaks, but not Type II or Combined Types: An Experimental Study

Abstract Purpose To ascertain the nature of the pressure wave transmitted through aneurysm thrombus and the changes produced after endovascular repair and the development of type I and II endoleaks. Methods A 25 mm Talent endovascular graft was deployed in a latex model of an abdominal aortic aneurysm, which was incorporated in a pulsatile flow unit. The graft was surrounded by thrombus analogue to simulate conditions in vivo. Pressure waveforms in the sac were captured over 5 s at 1000 Hz in these settings: (i) no endoleaks (baseline), after introduction of (ii) type I (iii) type II and (iv) combined type I and II endoleaks. The arterial blood pressure settings used were 140/100 and 130/90 mmHg, denoted the high and low settings, respectively. ANOVA in Minitab 13 was applied for statistical analysis. Results Pulsatile waveforms were transmitted through the thrombus. Intrasac pressure after stent-grafting reduced to 110/107, 99/96 mmHg ( p p p Conclusions Intrasac pressure waveforms following EVAR are easily defined following a type I endoleak. Waveforms obtained following type II endoleak simulation resemble the baseline waveform in an attenuated form. Intrasac pressures are, therefore, a reliable marker for type I, but not a type II endoleak. In the case of a combined endoleak, the type I endoleak waveform effectively masks that of the type II. Intrasac thrombus faithfully transmits intrasac pressures.