Vortex formation time: an emerging echocardiographic index of left ventricular filling efficiency?

ARTICLEThe mere existence of the formation number is intriguing since it hints at the possibility that nature uses this time scale for some evolutionary incentives such as optimum ejection of blood from the left atrium to the heart's left ventricle.—Gharib et al .1 About 500 years ago, Leonardo da Vinci conducted a haemodynamic study of the sinus of Valsalva in which he deduced and explained formation of a blood flow vortex.2 Fast forwarding to the present, Gharib et al .1 used an experimental arrangement of a piston producing a wide range of jets and vortex rings alongside those jets by pushing columns of fluid of length L through an orifice with diameter D . They referred to the length-to-diameter ratio, i.e. L / D , as the formation number . While settings with low L / D generated merely a single and rather weak vortex ring, settings with large L / D resulted in a vortex ring that could no longer grow and was followed by a less-efficient fluid transport by a trailing jet.3 The maximum growth of the vortex ring without a trailing jet was observed when the L / D ratio was within a limited value range of 3.6–4.6 for an otherwise wide variety of flow conditions.1 Because …