Vortex formation time as an index of left ventricular filling efficiency: comparison between children volunteers and patients with tetralogy of Fallot.

Background: Vortex formation time (VFT) had been considered a useful marker for assessing diastolic performance. the VFT assessment of diastolic function using four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) has not been used in repair of tetralogy of Fallot (rTOF) patient. The aims of this study were as follows: (I) establish reference ranges for VFT measurements in healthy children and adolescents using 4D flow CMR imaging; and (II) analyze VFT parameters to assess diastole dysfunction in rTOF patients group.
Methods: We acquired the CMR data was of 62 healthy participants (aged 6-18 years; male: 40, female: 22) and 20 patients with rTOF (aged 10-13 years; male: 15, female: 5) using 4D flow and cine sequence in routine chamber view. The VFT was calculated based on comparison of different algorithms from cine measurements (VFT _volume ) and 4D flow measurements (VFT _blood ). Then, VFT measurements were compared to subject peak filling rate (PFR), age, and cardiac mass using simple linear regression and multiple regression analyses. Data were also categorized according to age for VFT and cardiac functional assessment comparisons between 3 age groups (Group 1: 6-9 years; Group 2: 10-13 years; Group 3: 14-18 years). The correlation of VFT and cardiac function parameters were analyzed in the rTOF group.
Results: Normal mean value of VFT _volume and VFT _blood were 4.25±0.92 and 3.77±1.11 in healthy children participants. The VFT _volume was correlated with VFT _blood (r=0.61, P<0.001). There was a moderately significant correlation between VFT _volume and PFR (r=0.46, P<0.001) and between VFT _blood and PFR (r=0.47, P<0.001), age (r=0.41, P=0.002) and left ventricular (LV) mass (r=0.48, P<0.001). Multiple regression analyses demonstrated that VFT _volume was independently associated with PFR (T=2.239; P<0.05) and VFT _blood (T=4.361; P<0.001). There was a significant difference in VFT _volume between healthy controls and rTOF patients (5.44±1.93 vs. 4.27±0.88, P=0.018).
Conclusions: The VFT measurements showed that the LV that had appropriate space to form the optimal vortex ring in normal children and adolescents aged 6-18 years old. The VFT _volume could potentially be helpful in improving our understanding of LV diastolic dysfunction in rTOF patients.
Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-22-67/coif). All authors report technical assistance from Gaston Vogel and Qiuchen Wang (Pie Medical Imaging Corporation Netherlands), and statistical assistance from Tingfan Wu (GE Healthcare). The authors have no other conflicts of interest to declare.
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