Fluid Dynamics of a Partially Collapsible Stenosis in a Flow Model of the Coronary Circulation

Abstract

The influence of passive vasomotion on the pressure drop-flow (delta P-Q) characteristics of a partially compliant stenosis was studied in an in vitro model of the coronary circulation. Twelve stenosis models of different severities (50 to 90 percent area reduction) and degrees of flexible wall (0 to 1/2 of the wall circumference) were inserted into thin-walled latex tubing and pressure and flow data were collected during simulated cardiac cycles. In general, the pressure drop increased with increasing fraction of flexible wall for a given flow rate and stenosis severity. The magnitude of this effect was directly dependent upon the underlying stenosis severity. The diastolic delta P-Q relationship of severe, compliant models exhibited features of partial collapse with an increase in pressure drop at a decreasing flow rate. It is concluded that passive vasomotion of a normal wall segment at an eccentric stenosis in response to periodic changes in intraluminal pressure causes dimensional changes in the residual lumen area which can strongly affect the hemodynamic characteristics of the stenosis during the cardiac cycle. This mechanism may have important implications for the onset of plaque fracture and the prediction of the functional significance of a coronary stenosis based on quantitative angiogram analysis.

Influence of hemodynamic conditions on fractional flow reserve: parametric analysis of underlying model

“…Coronary stenosis pressure drop-flow velocity relations in vivo show the same behavior (14,40). Obviously, the exact shape of the curve depends on detailed geometric and biomechanical properties of the stenosis (24,42), but the quadratic component between pressure gradient and flow is a fundamental characteristic.…”

Effect of Varying Hemodynamic and Vascular Conditions on Fractional Flow Reserve: An In Vitro Study

“…The wall of the stenosis geometry was assumed to be rigid in the in vitro experiment. A rigid wall approximation compared with a compliant wall model is expected to provide a conservative estimate (limiting case) of pressure drop, as seen in hyperemia; however, further in vitro experiments with compliant stenosis models are needed for comparison.…”

Relation between functional stenosis and tissue characterization of intermediate coronary plaques in patients with stable coronary heart disease

“…Thus, both functional stenosis and tissue characteristics may be directly linked to clinical outcome. On the other hand, the pressure drop increased with increasing fraction of flexible wall for a given flow rate in an in vitro study [8]. We therefore hypothesized that there is an association between the tissue characteristics of coronary plaque and functional stenosis in patients with stable coronary heart disease.…”