In a physically more stringent concept, suction is defined as filling at negative LV transmural pressure. According to this definition, the ventricular wall performs work to pull blood into the cavity. There are two important conditions for such a suction event. First, the end-systolic volume must be lower than the volume of elastic ventricular equilibrium, otherwise no elastic energy would be stored. Second, early diastolic relaxation must be quick enough to allow restoring forces to prevail over the vanishing active forces. The process of suction lasts until the equilibrium volume is reached. Atrial pressure then stretches the ventricle to a volume where a force balance between filling pressure and ventricular passive stress impedes any further flow (diasthasis). Diasthasis volume is probably higher than the elastic equilibrium volume, which is a ventricular material property. Because LV filling itself very quickly abolishes any negative transmural pressures, and the equilibrium volume of the LV is probably small, suction according to this definition has been measured almost exclusively under particular circumstances, such as in nearly empty ventricles (e.g. artificially low afterload), during artificial absence of filling, or during inotropic stimulation.