Virtual simulations in planning intravascular treatment of aortic coarctation - a retrospective analysis.

Introduction: A number of studies on using both three-dimensional printing and virtual models in assessment of aortic coarctation have been published, yet none of them uses virtual modelling as a planning tool in a blind retrospective analysis. Aim: Assessment of virtual modelling and virtual reality in planning interventional treatment of aortic coarctation. Material and methods: The study involved computed tomography scans of 20 patients performed prior to interventional treatment of aortic coarctation, which were used to create a virtual three-dimensional model of the aorta in Materialise Mimics. A group of potential stents was modelled in Materialise 3-Matic and complete simulations were assessed in Mimics Viewer using a virtual reality headset in order to choose an optimal stent, which was later compared with the implanted one. Results: In 5 cases identical or very similar stents were proposed, in 12 cases simulations had slight, potentially avoidable misestimations either in stent length or diameter, and in 3 cases differences were more considerable. Overall, in 14 cases the location of the stent was concordant between the simulation and reality and in the remaining 6 cases the simulated stent was located lower than the actual one. Conclusions: The method of computer modelling provided a satisfactory success rate of predicting the possible stents to use during the procedure. Differences in chosen stents may have been caused by individual experience in interventional cardiology, the lack of availability of certain stents in the heart catheterization laboratory, the lack of information about the diameter of the vascular access and differences in dimensions measured on the model, tomography and angiography.

Acute and late obstruction of a modified Blalock-Taussig shunt: a two-center experience in different catheter-based methods of treatment.

Modified Blalock-Taussig (B-T) shunt occlusion results in a sudden reduction of pulmonary vascular perfusion, causing dramatic saturation drop and cyanosis which pose a direct hazard to a child's life. The results of percutaneous local r-tpa infusion, balloon angioplasty and additionally stent implantation in obstructed modified B-T shunts were studied to assess their role as an alternative to a re-do surgery. We outline two pediatric centers' experience (period 2004-2008) regarding the effectiveness of various emergency treatment methods for occlusion or critical stenosis of systemic-to-pulmonary arterial shunts in 23 children. Local r-tpa infusion via catheter was performed in 12/23 patients, balloon angioplasty in 22/23 and additionally stent implantation in 3/23 children. Procedures were successful in 22/23 patients (96%), with an increase in arterial saturation [average: 30%; standard deviation (S.D.) 15%; Shapiro-Wilk test; dependent t-test-P<0.01]. Unrestricted contrast flow was achieved in 18 patients, reduced central flow in three and minimal flow in one child. Neither local nor systemic complications occurred. Our experience demonstrates the possibility of successful early shunt recanalization with the use of local thrombolytic therapy combined with the balloon angioplasty. The presence of old fixed thrombus with neointimal hypertrophy in the shunt constitutes an indication for endovascular stent implantation.