Abstract 17404: New Insights into Mechanisms of Right Ventricular Dysfunction in Tetralogy of Fallot: Regional Post-Systolic Shortening is Associated with Right Ventricular Dysfunction and Dyssynchrony

Abstract

Background Regional right ventricular (RV) dysfunction is recognized as a key determinant of global RV function and outcomes after tetralogy of Fallot repair (rTOF). Regional left ventricular contraction after aortic valve closure (post-systolic shortening; PSS) is an established contributor to ventricular dyssynchrony and inefficiency, but its role in RV dysfunction after TOF repair (rTOF) is unknown.

Methods We studied 50 rTOF patients without RV outflow obstruction in comparison to 50 age and sex-matched controls. Regional RV free wall and septal longitudinal strain were derived by 2D speckle tracking. RV end-systole (pulmonary valve closure), peak strain (maximal strain in a cardiac cycle) and time to peak strain in 6 RV segments were measured. RV global function was assessed by MRI ejection fraction. RV dyssynchrony was calculated as the standard deviation of time to peak strain in 6 RV segments.

Results Patient characteristics are shown in the table. Compared with controls, TOF patients had significantly delayed RV basal (465±60 ms, p<0.001) and mid wall (429±52 ms, p<0.001) peak strain, which occurred well after pulmonary valve closure (Fig). In rTOF, but not controls, heart rate corrected RV basal time to peak strain correlated with regional peak strain (r=-0.4, p=0.006), RV mechanical dyssynchrony (r=0.4, p=0.003), and QRS duration (r=0.4, p=0.009), but not global RV function or peak exercise oxygen consumption.

Conclusion RV PSS is associated with RV regional dysfunction and dyssynchrony in rTOF. Strong but inefficient basal deformation after pulmonary valve closure may contribute to progressive RV dysfunction not amenable to conventional intervention.