Isovolumetric contraction
= Isovolumetric contraction
During this stage of the <cardiac cycle>, the ventricular inlet and outlet valves are both closed. Ventricular volume is fixed at its end-filling value $V^+$, while increasing <ventricular elastance> raises <pressure> as $p_{LV}=E_{LV}(t)(V^+-V_0)$. Arterial and venous pressures remain approximately fixed when the stage is short relative to their systemic resistance–compliance times.