Non-invasive Determination of Aortic Mechanical Properties and Their Effects on Left Ventricular Function Following Endovascular Abdominal Aneurysm Repair

Abstract

Background: Increased pulse-wave velocity (PWV) entails elevated arterial stiffness and is associated with adverse cardiovascular outcomes. Previous studies have shown PWV increases following endovascular aneurysm repair (EVAR). Animal models suggest elevated PWV following endograft deployment occurs in conjunction with decreased aortic compliance and increased aortic impedance. This could lead to unwanted effects on left ventricular (LV) function. This study evaluates the early implications of EVAR on aortic mechanics and associated LV function. Materials and methods: Prospective observational study of elective EVAR for abdominal aneurysm. Transesophageal echocardiography was used to acquire LV flow and function, as well as images of the ascending aorta. Speckle tracking echocardiography (STE) software analysis allowed for determination of aortic volume change throughout the cardiac cycle. Aortic mechanics (including compliance, impedance and reflected wave analysis) and left-ventricular function (including cardiac output, hydraulic load and diastolic function) were measured pre- and post-endograft deployment. Results: Endograft deployment resulted in no significant increase in aortic impedance. It did alter the timing of reflected waves in the aorta, with a greater positive wave being reflected during systole. This increased the hydraulic load on the LV with corresponding statistically non-significant trends for decreasing cardiac output and LV diastolic function. Discussion: STE represents an emerging imaging modality for aortic biomechanical assessment. The increased PWV seen following EVAR may not reflect the same aortic biomechanical pathophysiology as in the non-surgical population with measures of increased arterial stiffness. The stiffer endograft does not appear to acutely increase aortic impedance, though it does alter the timing of reflected waves which may have negative effects on LV function.