Non-invasive measurement of left ventricular diastolic time constant (Tau)

The Good, the Bad and the Ugly

1993, Dr Nishimura put his hand on Tau.  In the Table 1 (Comparison of Catheter-Derived and Doppler-Derived Variables for 120 Beats in 15 Patients), his measurement is Tau=58ms, (v1-t3)=48ms. 15 years later, I published the Tau formula Tau=1.2(t1-t3). Here comes a miracle: 58=1.2x48. Dr Nishimura has to command the profound respect of us, how such an accurate measurement is possible! In the meantime, my formula is also validated objectively. Now this formula is integrated into Mindray’s Echo machines sold all over the world except North America. This is the Good.

1992, Dr Thomas developed a Tau formula at Harvard. 5 years later, it was “validated” by Dr Scalia and the paper was published in Circulation. The scientific discovery path is destined to be bumpy as Cicero reminds us “any man can make mistakes…”. This time the marriage of Harvard and Circulation doesn’t guarantee win-win cooperation. This method is incorrect with logic flaws. Playing with the Google Scholar, you will find nobody used this formula to calculate Tau in the whole year in 2019. This is the Bad.

I believe I found the right way to calculate Tau, please let me know if I am wrong. Researchers based on my Tau formula found it hard to get their paper published due to the Harvard method. This is the Ugly. 

Only retraction of Dr Scalia's paper will set Tau free. 

Mindray had just launched a high-end ultrasound machine DC80, which is the first Tau-measurable ultrasound machine in the world.

A Small Step in Math, A True Stride in Cardiology

With the progress of Doppler and modern computer technology, I believe that only a few RBCs’ leaking will be needed to give us a much understandable and clear regurgitation curve. Theoretically, merely a short part of the curve is enough to calculate the Tau. As long as we are allowed to choose 3 points from within the definition field, we can use the updated formulas to proceed. Let’s assume the 3 points are a (v_a, t_a), b (v_b, t_b) and c (v_c, t_c) from left to right. The updated formulas are:

All Tau(s) Calculation Formulas

"The beauty of nature lies in her simplicity."

--- Dr Quan Wang

-dp/dt max is equivalent to Tau

Recently, an editorial (1) from Circulation Heart Failure claimed “Tau derived from the monoexponential model is less dependent on loading conditions than peak -dp/dt and has been used as a reliable index for LV relaxation in many clinical and experimental studies.”

I think –dp/dt max and Tau are the SAME in terms of clinical significance.

CAAM, a clinical call for help from the echo engineers.

Accurate measurement of time intervals is critically important for successful Tau calculation. Garbage in, garbage out. But don't hesitate to move forward. We just need something like computer aided accurate measurement, CAAM. I figured out this word. :)