Cast of Complex Congenital Heart Malformation in a Living Patient
Magnetic resonance imaging data of a 20-year-old male patient was used to produce, to the best of our knowledge, the first cast model of a beating heart. Imaging was performed at the German Heart Institute Berlin, Department of Congenital Heart Disease and Pediatric Cardiology; data were transferred to the Department of Medical and Biological Informatics (German Cancer Research Center, Heidelberg). The patient had the diagnoses of dextrocardia, atrial and visceral situs inversus, L-looped ventricles, and L-malposition of the great arteries, with a large perimembranous ventricular septal defect and pulmonary atresia.
A 3D whole-heart, navigator-corrected MRI data set with nearly isotropic voxel size was acquired with a 1.5-T scanner (Philips Intera CV) during free breathing. The data set consisted of 175 slices with a resolution of 1.8 mm (0.7×0.7×0.9 mm). The following sequence parameters were used: ECG gating; axial slice orientation; single phase; field of view, 320; matrix, 304; repetition time, 4.6 ms; echo time, 2.3 ms; flip angle, 100°; sensitivity encoding factor, 2.2; T2 preparation pulse (echo time, 50 ms)(Brittain); and fat saturation. The epicardium was segmented semiautomatically with a software tool developed at our institution. Automatic endocardial and endoluminal border detection was performed by interactively choosing a gray scale threshold within the volume defined by the epicardial border. A virtual surface model (Figure 1 and the Data Supplement Movie) was created that included only connected structures. From these data, a cast (Figure 2) was made with the laser sintering technique (Weihbrecht, Wolpertshausen). In contrast to stereolithographic techniques in which the initial material used to make the model is fluid, requiring artificial support structures, laser sintering hardens nylon powder, which enables even very delicate structures to be manufactured.
The cast (Figure 2) allowed excellent comprehension of the complex cardiac anatomy with a more explicit understanding of 3D structures than provided by the corresponding computer model (Figure 1). It is expected to be invaluable for diagnosis, treatment planning, and patient education and as a reference during repeated surgery.
Dr Nagel has received research funding from Philips Medical Systems and has served on the speakers’ bureaus of, received honoraria from, consulted for, and/or served on the advisory boards of Bracco and Amersham. The other authors report no conflicts.
The online-only Data Supplement, which contains a movie, can be found at http://circ.ahajournals.org/cgi/content/full/112/24/e356/DC1.