Objectives: Pulmonary valve replacement or reconstruction (PVR) is considered to be an effective therapy to reduce right ventricular (RV) dilatation in patients with tetralogy of Fallot (ToF). However, little is known about the remodelling of RV compartments (right ventricular outflow tract (RVOT) and RV corpus) after PVR. Therefore, our aim was to investigate separately the right ventricular compartments before and after PVR with MRI.
Methods: Twenty five patients with ToF (median age: 17.7; 5.3- 48.2 years) underwent PVR for pulmonary insufficiency and RV dilatation. MRI was performed before (median 0.5 year) and after surgery (median 1.8 years).
We used an in-house software for segmental analysis of the RV. The method provides an automatic contour detection algorithm for the determination of the RV blood volume and enables the user to segregate the blood volume of the RVOT and RV corpus based on anatomic landmarks and to generate volume-time-curves over a cardiac cycle. End diastolic (EDVi) and end systolic (ESVi) times were normalized to the patient´s RR times.
Results: After PVR we measured a significant reduction in RV volumes (EDVi: pre: 155.0 mL/m2, post: 121.3 mL/m2; p = 0.015 and ESVi: pre: 96.5 mL/m2, post: 62.2 mL/m2; p = 0.001) and a significant increase of RV ejection fraction (pre: 39%, post: 46%; p = 0.003).There was a significant reduction in RVOT volumes (EDVi pre: 21.0 mL/m2, post: 9.1 mL/m2; p = 0.001 and ESVi: pre: 15.0 mL/m2, post:11.9 mL/m2; p = 0.019). There was also a significant reduction in RV muscular corpus EDVi: pre: 102.2 mL/m2, post: 87.3 mL/m2; p = 0.015, but not in ESVi: pre: 63.3 mL/m2, post: 57.9 mL/m2; p = 0.078).
From RV time-volume curves we derived delay times in RV EDVi to RVOT EDVi before (0.91- 1.0) and after (0.92–1.0) PVR. RV-RVOT ESVi delay was significantly reduced after PVR (pre: 0.44–0.54; post: 0.44–0.48; p < 0.01). The change in QRS duration was not significantly different (pre PVR: 150 milliseconds; post PVR: 140 milliseconds; p = 0.98).
Conclusion: After PVR in ToF patients we have observed significant RV volume reduction and decrease in RV-RVOT ESVi delay. Segmental analysis of the RV compartments showed that the RVOT as well as the RV corpus (not affected by the operation) have improved, indicating the beneficial effects of the operation for the entire RV. Separate analysis of RV compartments may clarify the optimal point in time for reoperation.
