Non-invasive pressure-volume loops show high arterial elastance in children with repaired tetralogy of Fallot.

Background: Children with repaired tetralogy of Fallot (rToF) often have pulmonary regurgitation with right ventricular (RV) dilatation and dysfunction, whereas less is known about the effect on the left ventricle (LV). The aim was to investigate LV haemodynamic variables derived from non-invasive pressure-volume loops in children with rToF and how they compare to controls and previous research on adults.

Materials and methods: Ten children with rToF and pulmonary regurgitation (12 years [10-13], 6 males) and 10 age- and sex-matched healthy controls (12 years [10-14], 6 males) underwent brachial blood pressure in conjunction with cardiac magnetic resonance imaging. Pressure-volume loops were derived by brachial blood pressure together with LV volumes throughout the cardiac cycle in short-axis cine images yielding several haemodynamic variables, including arterial elastance. The RV endocardial border was delineated in end-diastole and end-systole.

Results: Children with rToF and pulmonary regurgitation had larger RV end-diastolic volume (136 [114-156]) than controls (100 [94-112] ml/m²; p = 0.0015) and smaller LV end-diastolic volume (83 [58-91] ml/m²) than controls (101 [92-110] ml/m²; p = 0.002). Arterial elastance was higher in children with rToF (1.5 [1.3-2.7] mmHg/ml) than in controls (1.1 [1.0-1.5] mmHg/ml; p = 0.02). Heart rate was higher in children with rToF (77 [74-81] bpm) than in controls (69 [65-75] bpm; p = 0.027).

Conclusion: Children with rToF had higher arterial elastance and heart rate than controls, likely due to increased sympathetic tone to compensate for impaired LV filling following pulmonary regurgitation. If this contributes to increased risk of adverse cardiovascular and cerebrovascular events remains to be studied.