Longitudinal mechanics as a component of the left ventricular systolic function in children of the first year of life in the early postoperative period after surgical perimembranous ventricular septal defect closure
Aim. To evaluate left ventricular systolic function in the early postoperative period after surgical perimembranous ventricular septal defect (VSD) closure in children aged <1 year using longitudinal mechanics. Methods. Between 2014 and 2017, we examined 65 children aged 2-11 months with perimembranous VSD (mean diameter = 8.6 ± 1.7 mm) and a pulmonary-to-systemic blood flow ratio of >1.5/1. The longitudinal mechanics of the left ventricle (LV) were assessed using vector velocity imaging. All the children underwent surgical perimembranous VSD closure. Echocardiographic studies were performed preoperatively, immediately postoperatively, and 1 and 20 days postoperatively. Results. In all the children, significant decreases in the LV end-systolic volume index, end-diastolic volume index, stroke volume index (SVI), and ejection fraction (EF) were identified immediately postoperatively when compared with the preoperative findings. One day postoperatively, the LV volume data normalized; however, in 10.8% of the children, the SVI and EF remained impaired. The percentage EF reduction showed weak correlations with the childrens' weights (Rs = 0.3; p = 0.039), aortic cross-clamping durations (Rs = 0.36; p = 0.03), and VSD sizes (Rs = 0.33; p = 0.006). Twenty days postoperatively, the LV volumetric parameters normalized; however, the EF did not reach the initial value. The longitudinal strain and strain rate were reduced preoperatively when compared with normal values. For the prediction of a postoperatively significant EF reduction (<35%), the preoperative LV strain had a sensitivity of 88%, specificity of 98.2%, and cutoff value of -9.2%; the LV strain rate had a sensitivity of 87.8%, specificity of 94.7%, and cutoff value of -0.47 s<sup>-1</sup>. Conclusion. Children aged <1 year with perimembranous VSD showed reductions in the longitudinal mechanics of the LV, reflecting subclinical systolic dysfunction. One day after surgical correction, a transient decrease in LV systolic function was noted in all the children; however, a significantly impaired LV systolic function was noted in 10.8% of the children. Our findings indicate that the longitudinal mechanics of the LV can predict LV systolic dysfunction in the early postoperative period with high sensitivity and specificity.