1348455 - CMR reference values of right ventricular volumes, mass and function in patients with hypoplastic left heart syndrome

The survival rate after the Norwood operation for hypoplastic left heart syndrome (HLHS) has steadily improved and this makes it possible that an increasing number of children is reaching the final stage of Fontan circulation. However, there is concern about the function of the systemic right ventricle (RV) and that ventricular dysfunction may progress over time. CMR has established itself as the gold standard for serial assessment of systemic RV performance but due to the lack of standardised RV normal values for HLHS patients, the interpretation of RV volumetric data in these patients remains difficult. Therefore, the aim of this retrospective study was to close this gap by establishing CMR reference values for the systemic RV in HLHS patients.

Methods:

CMR scans of 177 children, adolescents and young adults (age range 1.6 to 25.2 years, 119 males) with HLHS were retrospectively evaluated. Short axis stacks covering the systemic RV from the base to the apex were used to measure RV end-diastolic and end-systolic volumes (RVEDV, RVESV) as well as stroke volume (RVSV), ejection fraction (RVEF), cardiac output (CO), cardiac index (CI) and end-diastolic myocardial mass (RVEDMM). RV volumes and myocardial mass were indexed to body surface area (RVEDVi, RVESVi, RVSVi, RVEDMMi) and height (RVEDV/H, RVESV/H, RVSV/H, RVEDMM/H) and patients were devided into three age groups. Furthermore, reference graphs and tables were created with the LMS-method.

Results:

Average measurements for patients from 1-7 years (n=65, 40 males):
RVEDV 70.1±25.6 ml, RVEDVi 105.8±34.0 ml/m², RVEDV/H 69.4±22.3 ml/m, RVESV 34.4±16.2 ml, RVESVi 52.0±23.1 ml/m², RVESV/H 34.0 ±14.9 ml/m, RVSV 35.6±8.2 ml, RVSVi 53.9±15.8 ml/m², RVSV/H 35.4±10.5 ml/m, RVEF 51.8±8.6 %, RVEDMM 32.1±11.2 g, RVEDMMi 48.0±13.2 g/m², RVEDMM/H 31.6±8.7 g/m, CO 3.0±1.0 l/min, CI 4,6±1.4 l/min/m².

Average measurements for patients from 8-13 years (n=56, 40 males):
RVEDV 104.4±32.7 ml, RVEDVi 98.8±25.4 ml/m², RVEDV/H 77.0±20.4 ml/m, RVESV 51.3±19.9 ml, RVESVi 48.3±15.8 ml/m², RVESV/H 37.7±12.6 ml/m, RVSV 53.0±15.8 ml, RVSVi 50.4±13.3 ml/m², RVSV/H 39.2±10.4 ml/m, RVEF 51.4±7.1 %, RVEDMM 49.3±16.9 g, RVEDMMi 47.3±14.3 g/m², RVEDMM/H 36.8±11.3 g/m, CO 4.1±1.3 l/min, CI 3.9±1.1 l/min/m²

Average measurements for patients from 14-25 years (n=56, 39 males):
RVEDV 192.9±72.0 ml, RVEDVi 115.1±37.9 ml/m², RVEDV/H 113.8±37.8 ml/m, RVESV 104.9±59.9 ml, RVESVi 62.4±34.0 ml/m², RVESV/H 61.6±32.8 ml/m, RVSV 88.0±26.1 ml, RVSVi 52.7±12.7 ml/m², RVSV/H 52.3±13.8 ml/m, RVEF 48.8±9.3 %, RVEDMM 84.1±31.8 g, RVEDMMi 49.8±15.9 g/m², RVEDMM/H 49.4±16.4 g/m, CO 6.5±1.9 l/min, CI 3.9±1.0 l/min/m².

Reference graphs and tables will be provided.

Conclusion:

We were able to define CMR reference values of RV volumes and function for HLHS patients. These data might be useful for the assessment and interpretation of CMR scans in these patients and for future research in this field.