We thank Kong et al. for their interest in our recent work, and we provide a response to their question as follows. After acquiring multiple consecutive single-beat three-dimensional full-volume data sets (HMQ mode with EPIQ 7G; Philips Medical Systems, Andover, MA), it is important to note that the current version of the fully automated quantification software (HeartModel) works only for the first cardiac cycle. To analyze left heart chamber parameters throughout whole data sets, it is necessary to trim data sets that encompass a single cardiac cycle from the first beat to the last beat. Specifically, we use the “trim left” and “trim right” rotary knob to make adjustments so that the left green vertical line on the electrocardiogram on the screen of the ultrasound machine coincides with the R wave, and the right green vertical line coincides with the next R wave. We then store each data set individually. Although this takes time, each three-dimensional image during a single cardiac cycle provides the heart rate at the lower right corner of the screen ( Figures 1 and 2 ). Thus, we calculated the RR interval as 60,000 divided by the heart rate in each image. Finally, we are not sure whether a similar approach could be used with other ultrasound vendors that have the capability for single-beat three-dimensional full-volume data set acquisition.
