ABSTRACT
A theoretical model is presented for growth and remodeling in the developing embryonic heart. The model is a thick-walled tube composed of two layers of orthotropic pseudoelastic material. The analysis includes stress and strain dependent volumetric growth, with changes in material properties specified to reflect the evolving structure of the heart wall. For use in model validation, experimental measurements of ventricular opening angles are reported for 3-4-day old chick embryos under control and pressure overload conditions. Owing to changes in residual stress in the overloaded heart, the opening angle decreased from 31 +/- 10 degrees to -8 +/- 12 degrees (mean +/- SD) within 12 h and then increased slightly. The opening angle at 12 h was significantly less than the control value. With an appropriate choice of parameters, the model yields reasonable agreement with these and other published opening angle data, as well as with temporal changes in lumen radius, wall thickness, epicardial strains, and pressure-volume curves during development before and after birth.
Subject(s)
Heart Ventricles/embryology , Heart Ventricles/growth & development , Mechanotransduction, Cellular/physiology , Models, Cardiovascular , Ventricular Remodeling/physiology , Animals , Blood Pressure , Chickens , Computer Simulation , Culture Techniques , Elasticity , Stress, MechanicalABSTRACT
Acute mesenteric ischemia is an infrequent abdominal emergency. The 90% mortality of this affection is related to a delayed diagnosis. The mesenteric ischemia and the mesenteric infarction are two different pathologic stages characterized by two different treatment and prognosis. Superior mesenteric artery embolism is the most frequent cause of mesenteric ischemia. According a difficult clinical diagnosis and the necessity of an early diagnosis we suggest an aggressive attitude. All the patients presenting risk factors and an abdominal pain must have a mesenteric angiography. The purpose of the angiography is diagnostic and therapeutic. The aim of surgery in case of mesenteric ischemia is to restore a normal vascularisation. In spite of this attitude the prognosis of this affection remain poor.
