To the Editor:

We thank Dr Marino for his thoughtful comments regarding our report, “Impact of Diastolic Dysfunction Grade on Left Atrial Mechanics Assessed by Two-Dimensional Speckle Tracking Echocardiography.” As Dr Marino correctly points out, the estimation of conduit function from left atrial volume curves may not be entirely accurate. This is because we did not take into the consideration the conduit volume during diastole. Nevertheless, the evaluation of conduit function, as defined in our study, has also been used in previous studies. In addition, the calculation of conduit volume assessed using magnetic resonance imaging and echocardiography, as described in previous studies, seems to be tedious and time consuming and thus is not routinely performed in daily clinical practice.

Importantly, because two-dimensional speckle-tracking analysis of left ventricular volumes is possible from the same apical four-chamber data sets used for the calculation of left atrial volume, two-dimensional speckle-tracking echocardiography has the potential to calculate conduit volumes ( Figure 1 ). Further studies are required to establish the accuracy and clinical usefulness of this technology for the calculation of conduit volumes. This measurement is physiologically important but is often ignored in studies assessing left ventricular mechanics.

Calculation of conduit volumes using two-dimensional speckle-tracking echocardiography. If changes visualized in a single apical four-chamber view are accurately reflective of true volumetric changes regardless of chamber shape, and if it is possible to optimize images of both the left ventricle and the left atrium in a single scan plane, simultaneous two-dimensional speckle tracking of both the left ventricular and left atrial walls from the same apical four-chamber view is theoretically possible. From these recordings, left ventricular volume (LVV) and left atrial volume (LAV) curves were generated as a function of time. Left atrial conduit volume (LACV) was defined as [LVV( t ) − LVVmin] − [LAVmax − LAV( t )], where LVVmin is minimal LVV (at end-systole), LAVmax is maximal LAV (near end-systole), and LVV( t ) and LAV( t ) are LVV and LAV at time t . This formula was subsequently rewritten as LACV = [LVV( t ) + LAV( t )] − (LVVmin + LAVmax). If only peak LACV is measured, this formula can be further simplified to (LVVmax − LVVmin) − (LAVmax − LAVmin), which is identical to stroke volume of the LV − (LAVmax − LAVmin).

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