Numerical simulation of the flow through venous valve during a Valsalva maneuver

The paper presents the results of a numerical study of the flow in a model of popliteal venous valve during the Valsalva maneuver. During this procedure the increased intrathoracic pressure is transmitted from vena cavae back to venous valves causing venous reverse flow (reflux). The duration of reflux measured by ultrasound method is typically used to diagnose the presence of reflux. Reflux duration longer than 1 s of for deep veins implies valve incompetence. Numerical model of the venous valve of the popliteal vein was built on the basis of clinical data. Non-stationary equations of hydrodynamics and an elastic leaflets movement were solved. The Valsalva maneuver was simulated with the pressure impulse at the inlet boundary. Numerical data were obtained for the velocity field, the duration of the reverse flow, the reflux for different leaflet elasticity, including a healthy valve and a valve with incompetence. For a healthy valve model, the reflux duration was less than 1 s, and for an incompetent valve, it was more than 1 s. It corresponds with the clinical results. The obtained results can be used by phlebologists to improve the ultrasound diagnostics of valve incompetence.