Impact of pulmonary valve replacement on left ventricular rotational mechanics in repaired tetralogy of Fallot

Abstract

Background: In repaired tetralogy of Fallot (rTOF), abnormal left ventricular (LV) rotational mechanics are associated with adverse clinical outcomes. We performed a comprehensive analysis of LV rotational mechanics in rTOF patients using cardiac magnetic resonance (CMR) prior to and following surgical pulmonary valve replacement (PVR).

Methods: In this single center retrospective study, we identified rTOF patients who (1) had both a CMR ≤ 1 year before PVR and ≤ 5 years after PVR, (2) had no other intervening procedure between CMRs, (3) had a body surface area > 1.0 m² at CMR, and (4) had images suitable for feature tracking analysis. These subjects were matched to healthy age- and sex-matched control subjects. CMR feature tracking analysis was performed on a ventricular short-axis stack of balanced steady-state free precession images. Measurements included LV basal and apical rotation, twist, torsion, peak systolic rates of rotation and torsion, and timing of events. Associations with LV torsion were assessed.

Results: A total of 60 rTOF patients (23.6 ± 7.9 years, 52% male) and 30 healthy control subjects (20.8 ± 3.1 years, 50% male) were included. Compared with healthy controls, rTOF patients had lower apical and basal rotation, twist, torsion, and systolic rotation rates, and these parameters peaked earlier in systole. The only parameters that were correlated with LV torsion were right ventricular (RV) end-systolic volume (r = - 0.28, p = 0.029) and RV ejection fraction (r = 0.26, p = 0.044). At a median of 1.0 year (IQR 0.5-1.7) following PVR, there was no significant change in LV rotational parameters versus pre-PVR despite reductions in RV volumes, RV mass, pulmonary regurgitation, and RV outflow tract obstruction.

Conclusion: In this comprehensive study of CMR-derived LV rotational mechanics in rTOF patients, rotation, twist, and torsion were diminished compared to controls and did not improve at a median of 1 year after PVR despite favorable RV remodeling.

Keywords: Feature tracking; Magnetic resonance imaging; Pulmonary valve replacement; Rotational mechanics; Tetralogy of Fallot; Torsion; Twist.

Fig. 1

Schematic illustrating rotational mechanics. L is the length between the basal and apical slices

Fig. 2

Peak systolic rotational parameters in repaired tetralogy of Fallot (rTOF) patients prior to pulmonary valve replacement (n = 60) compared to controls (n = 30). The circles represent the mean rotational parameters with standard deviation

Fig. 3

Rotational parameters over the cardiac cycle. a A representative control subject with counterclockwise apical rotation and clockwise basal rotation. b A representative repaired tetralogy of Fallot patient with the most common pattern of reduced apical and basal rotation with normal rotation direction. c A representative repaired tetralogy of Fallot patient with the second most common pattern of reversed basal rotation and normal direction but reduced apical rotation

Fig. 4

Peak systolic rotational parameters in repaired tetralogy of Fallot patients pre- and post-pulmonary valve replacement (n = 60). The circles represent the mean rotational parameters with standard deviations. P > 0.05 for all