Assessing Univentricular Function in Adult Fontan Using 3D Echocardiography

Objective: To determine the accuracy of assessing univentricular function in adult Fontan patients using three-dimensional (3D) volumetric echocardiography. Design: A prospective observational study in an adult Fontan patient cohort. Setting: University Hospitals Birmingham, NHS Foundation Trust. Patients: 26 patients were enrolled in the study all aged over 18 years, possessing the Fontan anatomy, with no contraindications to Cardiac Magnetic Resonance (CMR) imaging and in sinus rhythm. Intervention: All patients underwent transthoracic echocardiography using a Philips EPIQ 7 and X5-1 transducer. End diastolic volume (EDV), end systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) were obtained using two dimensional (2D) and 3D acquisitions. CMR was performed within 3 months according to standard protocols. Outcome Measures: The agreement and correlation between 2D, 3D and CMR derived parameters were determined by Bland and Altman analysis and Pearson’s correlation coefficient method. The inter-observer variability was also assessed for all three modalities. Results: 3D volumetric acquisitions of the single ventricle were feasible in 18/26 (69%) patients. 3D volumes strongly correlated with CMR but with a systematic bias to underestimation: EDV r = 0.66, bias = –47.1 (–109.6 to 15.2); ESV r = 0.82, bias = – 19.4 (–59.9 to 21.1); EF r = 0.73, –1.56 (–18.8 to 15.7) and SV r = 0.32, –27.7 (– 70.2 to 14.7). Inter-observer variability was lowest with CMR, when compared to echocardiographic techniques. The inter-observer variability for 3D when compared with 2D echocardiography was lower across all parameters except EDV. Conclusions: 3D volumes correlate strongly with CMR and may be used for serial assessment of univentricular function. However, 3D volumes on echo are not interchangeable with CMR due to systematic underestimation of volume.