Time Constants of Cardiac Function and Their Calculations

Xufang Bai1, *, Quan Wang2
1 University of Ottawa Heart Institute, Ottawa, ON, Canada
2 Quan Wang, Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, MB, Canada

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© Bai and Wang; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario, K1Y 4W7, Canada; Tel: 613-761-5000; Fax: 613-761-4695; E-mail:


Left ventricular diastolic time constant, Tau, is the most established index to describe left ventricular diastolic function. However, the lack of a practical method for the measurement of Tau has been an uncomfortable reality which formerly kept all but a few researchers from making use of it. Recently, the non invasive calculation of Tau in an echo lab was accomplished through formulas developed by universal mathematical method. Tau was first suggested by the fact that left ventricular diastole is an active process, and we can therefore predict that there must be some other time constants which can be used to describe other active movement of ventricular muscles during isovolumic period. Similar mathematical manipulation was employed to develop formulas for “the other Tau(s)”. Such Tau(s) represent new sets of indexes useful for the description of cardiac function. They are expected to be the most established indices given the fact Tau is revealing the power of ventricular muscles without interference from either preload or afterload.

Keywords: Tau, cardiac function, left ventricular diastolic time constant..