Abstract 14692: Assessment of Pulmonary Vascular Volume and Lung Perfusion in Patients with Hypoplastic Left Heart Syndrome in Fontan Circulation Using Cardiovascular Magnetic Resonance Imaging
Introduction: Data from catheter angiography indicate that children with Hypoplastic Left Heart Syndrome (HLHS) in Fontan circulation have hypoplastic central pulmonary arteries. Therefore we utilized novel MRI techniques to assess pulmonary vascular volume and lung perfusion in a cohort of HLHS patients and lung healthy controls.
Methods: 31 children with HLHS (4.9±2.3 yrs) and 8 lung healthy controls (9.8±6.4 yrs) were studied. A modified contrast-enhanced dynamic MR-angiography sequence was used to assess pulmonary vascular and total volume of the right and left side of the lung. With use of dedicated software we measured the lung volume, relative pulmonary vascular volume, the rate of parenchymal contrast enchancement (“up-slope”), as well as the parenchymal mean transit time (MTT) in order to assess pulmonary vascular status and perfusion. Standardised cardiopulmonary exercise testing on a treadmill was performed in all patients and compared to a cohort of pediatric volunteers.
Results: The indexed pulmonary total lung volume and the relative vascular volume (in percent) in HLHS were significantly reduced compared to the control group (634±105 vs. 945±274 ml/m², p<0.05; 6.5±3.7 vs. 9.5±2.4 %/m², p<0.05). Lung perfusion in children with HLHS was also impaired compared to healthy children (MTT: 10.8±2 vs. 6.7±3 s, p<0.01; Up-slope: 0.32±0.24 vs.1.12±0.305 s-1m-²; p<0.01). Relative vascular volume correlated significantly with oxygen-uptake measured by standard spirometry (Spearman's r=0.78; p<1e-4). There were no differences of the right and the left side of the lungs within the two groups.
Conclusions: Advanced MRI methods enable the assessment of pulmonary perfusion in HLHS patients in Fontan circulation. HLHS patients have a reduced total lung volume, pulmonary vascular volume, and an impaired lung perfusion, compared to controls. The reduced vascular volume in HLHS patients appears to be an important limiting factor for pulmonary function. The clinical significance of these findings for the Fontan circulation needs to be evaluated by long-term follow-up.
- © 2011 by American Heart Association, Inc.