Impact of Coronary Bifurcation Morphology on Wave Propagation

The branching pattern of the coronary vasculature is a key determinant of its function and plays a crucial role in shaping the pressure and velocity waveforms measured for clinical diagnosis. However, although multiple scaling laws have been proposed to characterize the branching pattern, the implications they have on wave propagation remains unassessed to date. To bridge this gap, we have developed a new theoretical framework by combining the mathematical formulation of scaling laws with the wave propagation theory in the pulsatile flow regime. This framework was then validated in multiple species using high-resolution Cryomicrotome images of porcine, canine and human coronary networks. Results demonstrate that the forward well-matchedness (no reflection for pressure/flow waves travelling from the coronary stem towards the microcirculation) is a salient feature in the coronary vasculature, and this result remains robust under many scenarios of the underlying pulse wave speed distribution assumed in the network. This result also implies a significant damping of the backward traveling waves especially for smaller vessels (radius <0.3 mm). Furthermore, the theoretical prediction of increasing area ratios (ratio between the area of the mother and daughters vessels) in more symmetric bifurcations found in the distal circulation was confirmed by the experimental measurements. No differences were observed by clustering the vessel segments in terms of transmurality (from epicardium to endocardium) or perfusion territories (left anterior descending, left circumflex and right coronary artery).