Ventricular function and cardiac reserve in contemporary Fontan patients

Background/objective Total cavopulmonary connection (TCPC) has been the preferred treatment for patients with univentricular hearts. Current TCPC-techniques are the intra-atrial lateral tunnel (ILT) and the extracardiac conduit (ECC). We aimed to determine ventricular function during rest and stress, and to compare results for both techniques and for left (LV) versus right ventricular (RV) dominance. Methods 99 patients, aged 12.5 ± 4.0 years underwent echocardiography and magnetic resonance imaging (MRI), and 69 patients underwent stress MRI. Results Echocardiography showed impaired systolic and diastolic function. MRI parameters were comparable between ILT and ECC at rest. During dobutamine there was a decrease in end-diastolic volume (EDVi) (91 ± 21 vs. 80 ± 20 ml/m² p < 0.001). Ejection fraction (EF) and cardiac index (CI) during dobutamine were lower for ILT patients (59 ± 11 (ILT) vs. 64 ± 7% (ECC), p = 0.027 and 4.2 ± 1.0 (ILT) vs. 4.9 ± 1.0 L/min/m² (ECC), p = 0.006), whereas other parameters were comparable. TEI-index was higher in ILT-patients (0.72 ± 0.27 (ILT) vs. 0.56 ± 0.22 (ECC), p = 0.002). Diastolic function was frequently impaired in patients with a dominant RV (67% (RV) vs. 39% (LV), p = 0.011). Patients with dominant LV's had smaller end-systolic volume (ESVi) (40 ± 13 (LV) vs. 47 ± 16 (RV) ml/m², p = 0.030) and higher EF (55 ± 8 (LV) vs. 49 ± 9 ml/m² (RV), p = 0.001) and contractility (2.3 ± 0.8 (LV) vs. 1.9 ± 0.7 mm Hg/ml/m² (RV), p = 0.050) during rest and higher EF during dobutamine (63 ± 8 (LV) vs. 58 ± 10 ml/m² (RV), p = 0.043). Conclusion Ventricular function is relatively well preserved in modern-day Fontan patients. With dobutamine stress there is a decrease in EDVi. ECC patients have higher CI and EF during stress. Patients with a dominant RV have lower systolic, including impaired contractility, and diastolic function.

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