Computer-aided patch planning for treatment of complex coarctation of the aorta

Between five and eight percent of all children born with congenitally malformed hearts suffer from coarctations of the aorta. Some severe coarctations can only be treated by surgical repair. Untreated, this defect can cause serious damage to organ development or even lead to death. Patch repair requires open surgery. It can affect patients of any age: newborns with severe coarctation and/or hypoplastic aortic arch as well as older patients with late diagnosis of coarctation of the aorta. Another patient group are patients of varying age with re-coarctation of the aorta or hypoplastic aortic arch after surgical and/or interventional repair. If anatomy is complex and interventional treatment by catheterization, balloon angioplasty or stent placement is not possible, surgery is indicated. The choice of type of surgery depends not only on the given anatomy but also on the experience the surgical team has with each method. One surgical approach is patch repair. A patch of a suitable shape and size is sewed into the aorta to expand the aortic lumen at the site of coarctation. At present, the shape and size of the patch are estimated intra-operatively by the surgeon. We have developed a software application that allows planning of the patch pre-operatively on the basis of magnetic resonance angiographic data. The application determines the diameter of the coarctation and/or hypoplastic segment and constructs a patch proposal by calculating the difference to the normal vessel diameter pre-operatively. Evaluation of MR angiographic datasets from 12 test patients with different kinds of aortic arch stenosis shows a divergence of only (1.5±1.2) mm in coarctation diameters between manual segmentations and our approach, with comparable time expenditure. Following this proposal the patch can be prepared and adapted to the patient's anatomy pre-operatively. Ideally, this leads to shorter operation times and a better long-term outcome with a reduced rate of residual stenosis and re-stenosis and aneurysm formation.