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Impact of coronary tortuosity on the artery hemodynamics

Buradi Abdulrajak, Mahalingam Arun

Biocybernetics and Biomedical Engineering

2020

Vol. 40, no. 1

126--147

The presence of tortuosity in coronary artery (CA) affects the local wall shear stress (WSS) which is an influencing hemodynamic descriptor (HD) for the development of atherosclerotic sites. To conduct a morphological parametric study in coronary arteries (CAs), several idealized tortuous artery models were obtained by varying three morphological indices namely, curvature radius (CR), distance between two bends (DBB) and the angle of bend (AoB). Computational fluid dynamics methodology with multiphase mixture theory is used to explore the effect of coronary tortuosity on various WSS based hemodynamic descriptors (HDs) namely, time-averaged WSS, oscillatory shear index, time-averaged WSS gradient, endothelial cell activation potential and the relative residence time that are used to determine the vulnerable locations for the onset of thrombosis and atherosclerosis. Our findings suggest that all the tortuosity morphological indices, CR, DBB and AoB have significant influence on the distributions of various HDs and hemodynamics. It is also observed that atherosclerosis prone sites were witnessed at the inner artery wall at downstream regions of the bend section 1 and bend section 2 in all the tortuous artery models studied and found to increase as the CR and DBB were reduced however, found to increase as the AoB is increased. Hence, severe coronary tortuosity in CAs with small CR, small DBB and higher AoB may have lower WSS zones at inner bend sections which promote atherosclerosis plaque progression. The analysis obtained from this multiphase blood flow study can be employed potentially in the clinical assessment on the severity of atherosclerosis lesions as well as in understanding the underlying mechanisms of localization and formation of atherosclerotic plaques.

Biventricular pacemaker synchronization: A numerical cardiocirculatory model application to reproduce in vivo data

Di Molfetta A., De Lazzari C., Ferrari G., Moscariello F., Aguzzi G., Fresiello L., Darowski M., Trivella M. G., Alessandri N

Biocybernetics and Biomedical Engineering

2010

Vol. 30, no. 1

3-15

Cardiac Resynchronization Therapy (CRT) seems to be the most encouraging treatment to limit the damages of ventricular remodelling in patients with moderate-severe cardiac insufficiency. Mathematical modelling of the cardiovascular system is a tool potentially useful to understand how the Biventricular Pacemaker (BPM) must be synchronised during CRT. In this work a computer simulator reproduces clinical data measured, on different patients affected by asynchronous ventricular contraction, before and after CRT. Three patients, affected by asynchronous ventricular contraction, were monitored before and after biventricular stimulation through CRT. Measured and simulated data were compared. Results show that the software simulator can well reproduce in vivo data. Besides, simulated results from BPM together with drug therapy are in accordance with literature data. Numerical modelling could be a useful tool to optimize the BPM synchronization.

Interaction between left ventricle mechanics and myocardial blood flow

Trivella M. G., Pelosi G., Neglia D., L'Abbate A.

Biocybernetics and Biomedical Engineering

2008

Vol. 28, no. 1

3-16

The interaction between coronary circulation and left ventricular mechanics has been studied in animal models as well as investigated in humans. Here we review the results of experimental studies performed at the Institute of Clinical Physiology: the separate contribution of preload and after load on coronary pressure-flow, pressure-volume and volume-flow relationships; single beat as well as averaged instantaneous loops, both during autoregulation and under maximal vasodilation. We then present the results of animal studies on estimate of functional microvascular architecture and its relationship with myocardial blood flow heterogeneity. Finally, we report on clinical applications performed in various models of left ventricular dysfunction as myocardial ischemia, hypertrophic cardiomyopathy, dilated cardiomyopathy and secondary hypertrophy, aimed at investigating the interaction between coronary flow and abnormal left ventricular mechanics.