Validation of synthesized central pressure waveform in Patients with an infrarenal aortic aneurysm before and after endovascular repair

Abstract

BackgroundAbdominal aortic aneurysm (AAA) disease is mainly treated by endovascular aneurysm repair (EVAR), which shows short-term advantages in terms of lower morbidity and mortality compared to open repair. Long-term outcome seems te be inferior with regard to survival. This could partly be explained by a change in dynamics of the aortic wall, including aortic central pressure (CP) waveforms, induced by the endograft (Figure). Arterial stiffness is predictive of cardiovascular disease but has not been investigated in AAA-patients. We investigated if CP and Augmentation index (AIX) can be calculated correctly in AAA-patients.MethodsNon-invasive and invasive waveform recordings and CP- and stiffness-calculations were performed simultaneously before and after EVAR. Non-invasive radial artery waveforms were recorded, from which CP was estimated by SphymoCor (Atcor Medical, Sydney, Australia). Invasive pressure measurements were performed with a fluid-filled catheter in the infrarenal aorta. A generalized ascending-to-abdominal aorta transfer function (GTFAA) was used to estimate CP from the invasively measured abdominal aorta pressure-waveform, which served as reference for the non-invasively estimated CP. From the CP waves, systolic pressure and AIX were computed.ResultsThe difference between the invasive and non-invasive peak CP showed a bias of 23.9 mmHg (limits-of– agreement: −37.2:85.0) before and a bias of 0.4 (−32.6:33.4) after implant. Mean AIX (SD) was −30.7(11.2) and −38.9(31.2) before and after implant, respectively.ConclusionSynthesizing CP with non-invasive measurements in combination with the use of a GTF in patients with AAA is feasible especially after EVAR. Differences in CP and AIX could be explained by differences in AAA-morphology or an error in phase unwrapping, which are currently investigated in-vitro and in-vivo (NCT01220245).