Response to Letter Regarding Article, “Effect of Chronotropy and Inotropy on Stitch Tension in the Edge-to-Edge Mitral Repair”
We welcome the salient comments by Dasi and colleagues pertaining to our work on the effect of chronotropy and inotropy on leaflet stitch tension in the Alfieri mitral valve repair.1 The authors make sound scientific arguments, and we agree that knowing instantaneous flow rate would enhance our understanding of the true determinants of stitch tension. For this reason, we are setting out to analyze the influence of instantaneous flow (derived as a differential function of left ventricular volume as a function of time) on leaflet tension during the hemodynamic interventions of the current and prior2 experimental protocols. We believe these in vivo data will supplement the elegant in vitro experiments and computational models of Dr Yoganathan’s Georgia Tech Group.3
As to the study at hand, we have amended our original article with revised versions of Figures 2 and 3 to include standard deviation bars so as to address the potential inconsistencies pointed out by Dasi and colleagues. Neither mitral annular area nor stitch tension decreased during diastole as shown in the revised Figure 2 and confirmed by frame-to-frame statistical analysis throughout diastole. Similarly, revised Figure 3 shows that during calcium infusion no significant increase in stitch tension occurred, which again was confirmed by frame-to-frame statistical analysis throughout diastole. The standard deviation error bars were originally omitted for the sake of clarity; we apologize that their omission could lead to alternative interpretations of the data. We hope that these figures and our statistical calculations address these concerns. We hope to present the instantaneous flow data in the future and thank Dasi and colleagues for their insightful commentary that furthers the scientific process.