Introduction Children with reconstructed aortas performed for palliation in hypoplastic left heart syndrome (HLHS) have reduced aortic distensibility and unfavourable arterial-ventricular coupling. The impact of these changes on ventricular function and cardiovascular functional performance in surviving adults with single ventricular physiology remains unknown.
Methods Cardiac MRI (1.5T) was performed in 10 patients (mean age 19 years ± 2) with HLHS who had undergone aortic reconstruction in childhood, 10 age and gender matched patients with single ventricle physiology but without aortic reconstruction and 10 age and gender matched diabetic controls subjects. Aortic distensibility (defined as (maximum aortic area – minimum aortic area/minimum aortic area)/pulse pressure)) was assessed in the mid ascending aorta throughout the cardiac cycle using steady state free precession imaging and analysed using Matlab software. Congenital patients also underwent routine cardiopulmonary exercise testing (RAMP protocol) to asses parameters of cardiovascular functional performance.
Results Patients with HLHS had reduced aortic distensibility compared with patients with single ventricular physiology and diabetics (2.13 10–3 mmHg ± 1.26 vs. 3.9 10–3 mmHg ± 1.41 vs. 7.3 10–3 mmHg ± 1.38, p < 0.01) Figure 1. There were no differences in univentricular volumes or ejection fraction between HLHS and other single ventricular physiology (EF 55% ± 8 vs. 60 ± 5, p = 0.12). All patients with single ventricular physiology had marked cardiac limitation. Functional restriction was more severe in HLHS although did not reach statistical significance; predicted VO2 max for age and gender 55% ± 18 vs. 60% ± 20 (p = 0.16), reduced cardiac work load 9.27 METS ± 3.6 vs. 10.4 METS ± 3.5 (p = 0.47), VE/VCO2 slope < 35 n = 6 vs. n = 3 (p = 0.68).
Conclusion Adults with reconstructed aortas in hypoplastic left heart syndrome have reduced aortic distensibility and impaired prognostic markers of functional cardiovascular performance before changes in ejection fraction. The potential impact of these findings warrants further study.
- Hypoplastic left heart syndrome
- single ventricle physiology
- exercise capacity
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