The aim of the study is to identify the relevant aspects of numerical analysis of impact of projectiles with soft cores into a package composed of thin flexible plies located on the plastic backing. In order to illustrate the problem, normal impact of 7.62 mm TT projectile into an unclamped package comprising 36 plies of Dyneema SB71 supported on the plastic backing was selected. The problem was solved with the use of the finite element method (FEM) with the explicit integration scheme (central difference method) of motion equations in the matrix form. Based on the conducted numerical computations, it was revealed that obtaining the extreme deformations of a projectile soft core and the backing material in Lagrangian description requires employment of adaptive methods. The proposed R-adaptive method performs its role but must be used carefully due to the mass loss which may appear during calculations.
Background: Recoarctation (reCoA) of the aorta is a common complication after the Norwood procedure. Untreated, it can lead to failure of the systemic ventricle and death. The main goal of the study is to defi ne risk factors of reCoA after the Norwood procedure in hypoplastic left heart syndrome (HLHS). Methods: We retrospectively analyzed the pre-, intra- and postoperative data of 96 successive patients who underwent the Norwood procedure between 2007 and 2011. In case of reCoA balloon angioplasty was performed. We analyzed and compared the data of the patients with reCoA and without reCoA using the StatSoft STATISTICA™ 10 soft ware. Results: ReCoA was noted in 23 patients (33.3%). Th is complication was diagnosed 95.1 days (49–156 days) on the average aft er the Norwood procedure. Balloon angioplasty successfully allowed for decreasing the mean gradient across the site of the narrowing from the average 27.5 mmHg to the average 9.7 mmHg (p = 0.008) and enlarged the neo-isthmus by the average of 2 mm (p <0.05). Th e risks factors seemed to be the diameter of the ascending aorta OR = 7.82 (p = 0.001), atresia of the mitral valve OR = 7.00 (p = 0.003) and atresia of the aortic valve — OR = 6.22 (p = 0.002). Conclusion: Balloon angioplasty seems to be an eff ective intervention in case of reCoA. A low diameter of the native ascending aorta (≤3mm) and the presence of atresia of the mitral and/or aortic valve should intensify the vigilance of a cardiologist in the search for signs of reCoA of the aorta.