A laboratory model of the aortic root flow including the coronary arteries

Abstract

Cardiovascular flows have been extensively investigated by means of in vitro models to assess the prosthetic valve performances and to provide insight into the fluid dynamics of the heart and proximal aorta. In particular, the models for the study of the flow past the aortic valve have been continuously improved by including, among other things, the compliance of the vessel and more realistic geometries. The flow within the sinuses of Valsalva is known to play a fundamental role in the dynamics of the aortic valve since they host a recirculation region that interacts with the leaflets. The coronary arteries originate from the ostia located within two of the three sinuses, and their presence may significantly affect the fluid dynamics of the aortic root. In spite of their importance, to the extent of the authors’ knowledge, coronary arteries were not included so far when modeling in vitro the transvalvular aortic flow. We present a pulse duplicator consisting of a passively pulsing ventricle, a compliant proximal aorta, and coronary arteries connected to the sinuses of Valsalva. The coronary flow is modulated by a self-regulating device mimicking the physiological mechanism, which is based on the contraction and relaxation of the heart muscle during the cardiac cycle. Results show that the model reproduces satisfyingly the coronary flow. The analysis of the time evolution of the velocity and vorticity fields within the aortic root reveals the main characteristics of the backflow generated through the aorta in order to feed the coronaries during the diastole. Experiments without coronary flow have been run for comparison. Interestingly, the lifetime of the vortex forming in the sinus of Valsalva during the systole is reduced by the presence of the coronaries. As a matter of fact, at the end of the systole, that vortex is washed out because of the suction generated by the coronary flow. Correspondingly, the valve closure is delayed and faster compared to the case with no coronary flow

Fluid Flow and Structural Numerical Analysis of a Cerebral Aneurysm Model

“…Flow phantoms basically consist of models that mimic vascular geometry for flow analysis (rigid flow phantoms) and flow analysis and arterial wall deformation (flexible flow phantoms). These biomodels were produced in silicone rubber, as they allow optical access to the flow and also reproduce the physiological compliance of the artery [16,17]. In its manufacture, materials whose biomechanical behavior is close to the real biological material were used [18].…”

Effects of Pulsatile Frequency of Left Ventricular Assist Device (LVAD) on Coronary Perfusion: A Numerical Simulation Study

“…To analyze the frequency characteristics of the coronary system, the coronary circulation model was constructed from 3 main components: the coronary artery, the arteriolar resistance, and the myocardial vessels [ 24 , 25 ], as shown in Figure 1B . The coronary flow originates from the aorta root and flows into the vein [ 26 ]. The arteriolar resistance R AR is mainly responsible for hyperemia and baseline conditions.…”

Including coronary ostia in patient-specific 3D models of the whole aortic valve apparatus, derived from TEE, for biomechanical simulations

“…Regarding our patient-specific geometric model based on echocardiographic images, below we describe a semiautomated process for obtaining the parameters and building the geometry of a new model that considers leaflet asymmetry, interleaflet triangles and the aortic sinus together with thickness parameters; it also takes into account the curvature of the ascending aorta, the LVOT, the coronary ostia and a small portion of the coronary artery. The inclusion of these parameters is justified on the basis that they may significantly affect biomechanical behavior and fluid dynamics of the aortic root [36]. Figure 1: A) the AV apparatus in 3D.…”