Related Experiment Video
Updated: Jun 28, 2026

Noninvasive Determination of Vortex Formation Time Using Transesophageal Echocardiography During Cardiac Surgery
Published on: November 28, 2018
Calculation of left ventricular relaxation time constant-Tau in patients with aortic regurgitation by continuous-wave
1Henderson Research Center, McMaster University, Hamilton, Ontario, L8V 1C3, Canada. xufangbai@yahoo.com
Abstract:
Left ventricular relaxation time constant, Tau, is the best index to evaluate left ventricular diastolic function. The measurement is only available traditionally in catheter lab. In Echo lab, several methods of non-invasive measurement of Tau have been tried since 1992, however almost all the methods are still utilizing the same formula to calculate Tau as in catheter lab, which makes them inconvenient, time-consuming and sometimes not very accurate. A simple method to calculate Tau in patients with mitral regurgitation has been developed just based on Weiss' formula and simplified Bernoulli's equation. Similarly, formulas are developed here by pure mathematical derivative to calculate Tau by continuous-wave Doppler in patients with aortic regurgitation.
Related Concept Videos
Aortic Regurgitation II: Clinical Features and Diagnostic Tests
Aortic Regurgitation I: Introduction
Aortic Regurgitation IV: Nursing Management
Aortic Regurgitation III: Medical Management

