In 1930, Katz et al. first published a study describing a suction phenomenon in an in-vitro preparation of an isolated beating turtle ventricle. They showed that the early-diastolic volume increase of the ventricle coincides with a pressure fall, which is consistent with the concept of suction. He concluded that contraction and relaxation alters the elastic state of the ventricle between two limits (end-systolic and -diastolic), and proposed a suction effect produced by elastic recoil. This view represented a paradigm change, as filling was previously considered the result of atrial pressure. If suction is defined according to Katz, i.e. filling during pressure decay, then it is observed in all ejecting hearts, regardless of contractility, end-systolic volume or filling pressure. This type of suction corresponds to what early physiologists may have called the ventricular filling 'vis a fronte': a filling mechanism generated by the heart. It constitutes a suction effect relative to the filling reservoir. It can occur as a result of both, elastic recoil and relaxation.