Heart valve

The mitral valve separates the left atrium from the left ventricle. In a reservoir model with the atrium incorporated into the venous filling compartment, ideal one-way flow is $Q_v=[p_v-p_{LV}{]}_{+}/R_v$, where $[x{]}_{+}=\max (x,0)$ and $R_v$ is open-valve hydraulic resistance. The positive-part rule prevents reverse flow in this idealization.