Global and Regional Right Ventricular Function and Deformation in Children with Hypoplastic Left Heart Syndrome (HLHS) Assessed by MR-Feature Tracking

Aim: Recent echocardiographic studies expressed concerns about a decline of 2D echo strain rate of the systemic RV in HLHS during the staged palliation. Therefore, the aim of the study was to detect early preceding changes in deformation parameters in HLHS patients after bidirectional (BCPC) and total cavopulmonary connection (TCPC) utilizing novel MRI myocardial feature tracking techniques.

Methods: Two-dimensional anatomical 4-chamber gradient echo cine MRI were recorded in a total of 25 HLHS patients (Group A: BCPC, n = 14; age: 2.6 ± 0.4 years; Group B: TCPC, n = 11; age: 4.6 ± 1.5 years) for feature tracking as part of a comprehensive cardiac MR-study to determine load dependent and independent contraction parameters. End systolic longitudinal and radial strains and strain rates were calculated using a novel postprocessing software “QStrain” (Version 2.0, Medis Medical Imaging Systems, Leiden, the Netherlands).

Results: All patients were in a good clinical state (NYHA class I) without relevant tricuspid regurgitation. All obtained images could be analyzed. Global ventricular ejection function was in a normal range in both groups (A vs. B: 56.9 ± 4.9% vs. 53.6 ± 8.2%). Heart rate was similar in both groups (87 ± 11 vs. 78 ± 10 bpm). There was no significant difference between the groups for global longitudinal strain (LS: −13.2 ± 2.6% vs. −13.9 ± 2.3%; p = 0.34), strain rate (LSR: −0.16 ± 0.16 s−¹ vs. −0.02 ± 0.20 s−¹; p = 0.06), radial strain (RS: 32.7 ± 16.7% vs. 27.9 ± 21.0%; p = 0.54) and strain rate (RSR: 0.11 ± 0.27 s−¹ vs. −0.04 ± 0.35 s−¹; p = 0.27). Regression analysis also showed that age had no significant effect on global strain and strain rate. But segmental analysis showed a significant difference in regional longitudinal strain in both groups with lower strain in the septal segments (p < 0.001). Inter- and intra-observer variability was good and averaged 8% and 5%, respectively, overall for the combined RV segments.

Conclusion: The quantification of myocardial strain and strain rate in single right ventricles is feasible and reproducible using conventional clinical four-chamber gradient echo cine MR images. Global deformation parameters, including load independent strain rate, and load dependent function parameters showed no decline from BCPC to TCPC palliation indicating that the RV copes well with the different conditions. However, regional segmental RV wall analysis showed a specific contraction pattern with lower longitudinal strain in the septal segments.