The Z scores value of cardiac structure by preoperative echocardiography in children with tetralogy of Fallot

Objective To evaluate the value and clinical application of cardiac structure Z scores in children with preoperative tetralogy of Fallot (TOF) by echocardiography. Methods Considering the result of 31 patients who underwent echocardiography in Shenzhen Children’s Hospital before TOF repair from January 2011 to September 2013, the median age was 10 months (range: 3 days to 14 years). Other 31 normal children were selected as normal control group with age- and sex-matched, the median age was 10 months (range: 6 days to 13 years). Echocardiographic measurements included the diameter of right ventricular outflow tract (RVOT), pulmonary valve diameter (PVD), left pulmonary artery diameter (LPAD), right pulmonary artery diameter (RPAD), pulmonary valve peak velocity (PV-Vmax), tricuspid annulus diameter (TVD), mitral annulus diameter (MAD), left ventricular end-diastolic volume (LVEDV) and left ventricular mass (LVmass). Shenzhen Children’s Hospital pediatric echocardiography normal reference values and the regression equation are applied to obtain the forecast average, and using the Z-score formula into the standard value (Z = [M-y]/). Results There was no significant difference in body surface area between the TOF group and control group (P>0.05). Compared with control group, the true value of RVOT reduced significantly in TOF group, its Z-score showed negative values increase (-4.87±1.86 vs 0.33±0.93, t=-13.90, P 0.05), but the Z scores of TOF were significantly reduced than the control group (0.25±0.78 vs 0.76±0.65, t=-2.75; -0.92±1.94 vs 0.03±1.01, t=-2.41; -0.83±1.59 vs 0.67±0.69, t=-4.71; all P 0.05). For the Z scores of PV-Vmax, there were no significant difference between transannular patch surgery and pulmonary valve-sparing repair (8.58±1.20 vs 8.12±1.16, t=1.07, P>0.05). Conclusions The Z scores value of cardiac structure can be used in quantitative analysis of RVOT obstruction and development of left ventricular backward of TOF. The Z score of transannular patch surgery is more lower than pulmonary valve-sparing repair patients. The normalized Z score by body surface area correction is important for the preoperative diagnosis and the surgical planning. Key words: Echocardiography; Z score; Tetralogy of Fallot; Child