Abnormalities of right ventricular long axis function after atrial repair of transposition of the great arteries

Background-While volume derived global indices of right ventricle (RV) func tion are frequently abnormal after the Mustard procedure, the mechanism for these abnormalities is poorly understood. RV muscle fibres are predominant ly arranged longitudinally and thus indices derived in the long axis may be tter describe RV function. Methods-20 survivors of the Mustard operation were studied (age 7.8-37.3 ye ars, median 14.2 years). Long axis recordings from the apical four chamber view were obtained with the M mode cursor positioned through the lateral an gle of the tricuspid valve annulus. M mode traces were recorded on paper an d later digitised to derive total atrioventricular ring excursion, peak len gthening rate, and peak shortening rate. These data were averaged and compa red with control data for the normal RV and left ventricle (LV). Results-RV total atrioventricular ring excursion was lower than that for th e RV (p < 0.0001) or LV (p < 0.005) of controls. Peak lengthening rate was lower than the normal RV (p < 0.0001) and LV (p < 0.0001) rates. Furthermor e, peak shortening rate was less than that of normal RV (p <less than> 0.00 01) and normal LV (p < 0.005) controls. Conclusion-Systemic RV long axis function is notably reduced compared with that of either the normal subpulmonary RV or the systemic LV. This presumab ly reflects the response of the predominantly longitudinally arranged myoca rdial fibres to increased afterload. However, such measurements may provide a more sensitive marker for progressive changes in global function during long term follow up.