Calculation of left ventricular relaxation time constant-Tau in patients with aortic regurgitation by continuous-wave Doppler.

Bai X - Open Cardiovasc Med J (2008)

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Figure 2: The curve derived from Eq. (9) shows the relation of (t3-t1)/(t2-t1) and ADP.
Mentions: from this equation we can draw the conclusion that ADP is determined by the ratio of (t3-t1)/(t2-t1) on the ascending limb of aortic regurgitation continuous wave Doppler spectrum. (Fig. 2) Interestingly, when (t1-t3)/(t1-t2)=3 is considered, from Eq. (9), we can find the corresponding result, ADP is around 108 mmHg. When (t3-t1)/(t2-t1)=4, ADP is around 49 mmHg. Which means when ADP is lower, the ascending limb of the aortic regurgitation curve bends more. Further study about this relationship between (t3-t1)/(t2-t1) and ADP must be very exciting and fruitful.

Bottom Line: 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.Similarly, formulas are developed here by pure mathematical derivative to calculate Tau by continuous-wave Doppler in patients with aortic regurgitation.

View Article: PubMed Central - PubMed

Affiliation: Henderson 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.

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