Introduction: Hypoplastic Left Heart Complex (HLHC) is characterized by a mitral (MV) or aortic (AoV) valve z-score < -2, antegrade flow in the ascending aorta, ductal dependency, possible coarctation or aortic arch hypoplasia, and no significant valvar or subvalvular stenosis (Tchervenkov 2000). The z-scores of the valves are the leading features; therefore the algorithm of the z-score-calculation has a fundamental impact. However, in all HLHC-publications different equations were used. The aim of the study was to evaluate and apply existing z-score-calculations in HLHC.
Method: The literature dealing with z-score-calculations and HLHC were compared. An own cohort of 10 newborns diagnosed with a HLHC was evaluated.
Results: Five different methods are published for z-score-calculation of the MV and AoV. The correlation between the different regression equations is vague. In our cohort, the maximal z-values of the MV and AoV were -3,7/ -4,4 using the equations published by Zilberman 2005 and Petterson 2008 but -8,5/ -7,5 while using the formula published by Dauberney 1999, indicating a high standard error. The z-score-formulas published by Kirklin 1985 and Serraf 1999 used either not echo-derived or m-mode-derived normal values which results in an overestimation of the z-value.
Conclusion: The MV and AoV z-scores calculated with different equations vary enormously. Comparing patients with HLHC is therefore not possible when using different methods. The published z-score-calculation-algorithms from Zilberman and Petterson seem to be the most appropriate to use in HLHC. The database project hypoplastic left heart syndrome (Tchervenkov) should implement a uniform use of z-score-calculation in HLHC.