Cardiac remodelling following thoracic endovascular aortic repair for descending aortic aneurysms

Abstract

Objectives: Current endografts for thoracic endovascular aortic repair (TEVAR) are much stiffer than the aorta and have been shown to induce acute stiffening. In this study, we aimed to estimate the impact of TEVAR on left ventricular (LV) stroke work (SW) and mass using a non-invasive image-based workflow.

Methods: The University of Michigan database was searched for patients treated with TEVAR for descending aortic pathologies (2013-2016). Patients with available pre-TEVAR and post-TEVAR computed tomography angiography and echocardiography data were selected. LV SW was estimated via patient-specific fluid-structure interaction analyses. LV remodelling was quantified through morphological measurements using echocardiography and electrocardiographic-gated computed tomography angiography data.

Results: Eight subjects were included in this study, the mean age of the patients was 68 (73, 25) years, and 6 patients were women. All patients were prescribed antihypertensive drugs following TEVAR. The fluid-structure interaction simulations computed a 26% increase in LV SW post-TEVAR [0.94 (0.89, 0.34) J to 1.18 (1.11, 0.65) J, P = 0.012]. Morphological measurements revealed an increase in the LV mass index post-TEVAR of +26% in echocardiography [72 (73, 17) g/m2 to 91 (87, 26) g/m2, P = 0.017] and +15% in computed tomography angiography [52 (46, 29) g/m2 to 60 (57, 22) g/m2, P = 0.043]. The post- to pre-TEVAR LV mass index ratio was positively correlated with the post- to pre-TEVAR ratios of SW and the mean blood pressure (ρ = 0.690, P = 0.058 and ρ = 0.786, P = 0.021, respectively).

Conclusions: TEVAR was associated with increased LV SW and mass during follow-up. Medical device manufacturers should develop more compliant devices to reduce the stiffness mismatch with the aorta. Additionally, intensive antihypertensive management is needed to control blood pressure post-TEVAR.

Keywords: Cardiac remodelling; Computational modelling; Stroke work; Thoracic endovascular aortic repair.

© The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Figures

Figure 1:

Patient-specific models of the thoracic aorta and its side branches were constructed from computed tomography angiography data. First, centre lumen lines were selected in each artery. Then, 2-dimensional segmentations were made along the centre lumen line, delineating the vessel walls. The individually segmented arteries were combined through an automated lofting and blending process, completing the 3-dimensional geometry. This geometry was then discretized into a highly refined finite-element mesh.

Figure 2:

Pre-TEVAR and post-TEVAR geometric models for all patients. Finite-element mesh sizes are reported in millions of elements. TEVAR: thoracic endovascular aortic repair.

Figure 3:

Left: distribution of the aortic and the endograft stiffness. Right: reduced order models were attached to the inflow and outflow sections of the 3-dimensional computational model. The parameters of the Windkessel, heart and coronary models were tuned to match the patient-specific flow and the pressure data. The patient-specific left-ventricular elastance function (E(t)) describes the pressure generation in the heart model. In the coronary circulation, extravascular myocardial compression is modelled by broadcasting the left ventricular pressure to each coronary model [16] (orange arrow). TEVAR: thoracic endovascular aortic repair.

Figure 4:

Left ventricular mass measurements from electrocardiographic-gated computed tomography angiography data pre-TEVAR (A) and post-TEVAR (B) in patient 4. TEVAR: thoracic endovascular aortic repair.

Figure 5:

Flow and pressure waveforms for patient 4. AoR: aortic root; BCT: brachiocephalic trunk; DAo: descending aorta; LCA: left coronary artery; LCCA: left common carotid artery; LSA: left subclavian artery; LVOT: left ventricular outflow tract; TEVAR: thoracic endovascular aortic repair.

Figure 6:

Comparison of pre- and post-TEVAR left ventricular pressure–volume loops. Stroke work is increased in all cases. Case-specific observations are discussed in the Supplementary Material. TEVAR: thoracic endovascular aortic repair.

Figure 7:

Positive correlation between the post- to pre-thoracic endovascular aortic repair mass index ratio measured by echocardiography and both SW and the mean BP ratio. BP: blood pressure; SW: stroke work.