To evaluate the value and clinical application of cardiac structure Z scores in children with preoperative tetralogy of Fallot (TOF) by echocardiography.

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]/).

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). PVD, LPAD and RPAD reduced significantly in TOF group, those Z scores showed a negative value increase (-4.15±2.93 vs 0.11±0.85, t=-7.76; -1.35±2.38 vs 0.66±1.17, t=-4.24; -1.47±2.03 vs 0.59±1.04, t=-4.94; all P<0.05). While PV-Vmax increased significantly, and it’s Z score showed a positive value increase (8.38±0.19 vs 0.24±0.98, t=29.50, P<0.05). TVD of TOF patients was slightly larger than the control group (P= 0.10), but the Z score was significant greater than the control group (1.00±1.17 vs 0.29±0.52, t=3.06, P<0.05). MV-D, LVEDV and LVmass of TOF patients were slightly decreased than the control group (all 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). The Z scores of RVOT, PVD, LPAD and RPAD had no significant difference between transannular patch surgery and pulmonary valve-sparing repair patients (-4.89±2.03 vs -4.84±1.67, t=-0.08; -4.73±3.49 vs -3.34±1.75, t=-1.31; -1.88±2.54 vs -0.62±2.00, t=-1.49; -1.89±1.90 vs -0.84±2.15, t=-1.41; 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).

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.