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.
This is the proof:

Weiss’ formula:

P = e(exp)(t /T+B) +C

The derivative of both sides:

dp = e(exp)(t /T+B) (1/T )dt or:

P = e(exp)(t /T+B) +C

The derivative of both sides:

dp = e(exp)(t /T+B) (1/T )dt or:

dp/dt = e(exp)(t /T+B) (1/T )

Since t starts from peak -dp/dt, when t=0, we have:

dp/dt max = e(exp)B (1/T ) = e(exp)B /Tau

Since t starts from peak -dp/dt, when t=0, we have:

dp/dt max = e(exp)B (1/T ) = e(exp)B /Tau

Because e(exp)B is a constant, it means -dp/dt max and Tau share a relationship of one to one correspondence. We can draw the conclusion that -dp/dt max and Tau are equivalent indices in clinical significance.

References:

(1) Kazuhiro Yamamoto. The Time Constant of Left Ventricular Relaxation: Extrication from Load Dependence and overestimation of Functional Abnormality. Circ Heart Fail. 2010;3:178-180.

## No comments:

## Post a Comment