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Heart Disease in Pregnancy - part 6

Schematic sơ đồ của tâm thất trái trong bệnh cơ tim phì đại trong tâm thu. Có chiếu của vách ngăn đáy vào đường thoát ra với tâm thu trước chuyển động của van hai lá, mà kết quả trong dòng chảy tắc nghẽn đường tâm thất trái. Tắc nghẽn là năng động, phụ thuộc vào hậu gánh | Hypertrophic cardiomyopathy and pregnancy 175 LVO Gradient Increase lower preload lower afterload contractility preload afterload contractility Figure 13.2 Schematic diagram of the left ventricle in hypertrophic cardiomyopathy during systole. There is projection of the basal septum into the outflow tract with systolic anterior motion of the mitral valve which results in left ventricular outflow tract obstruction. The obstruction is dynamic dependent on the preload afterload and contractility of the heart. By permission of the Mayo Foundation for Medical Education and Research. arterial bed and decreased coronary flow reserve may contribute to these symptoms. Autonomic dysfunction may also occur resulting in inappropriate vasodilatation. A subset of patients have dynamic left ventricular outflow tract obstruction which may be responsible for symptoms3 14 Figure 13.2 . This is caused by severe hypertrophy of the basal septum projecting into the left ventricular outflow tract and secondary systolic anterior motion of the mitral valve. The abnormal mitral valve motion is produced either by a Venturi effect from an increase in velocity sucking the mitral valve into the outflow tract or by drag forces pushing redundant mitral valve leaflets into the outflow tract.15 Secondary mitral regurgitation may be present from distortion of the mitral valve apparatus and contribute further to symptoms. The mitral valve apparatus is almost always abnormal in these patients with anterior displacement of the 176 Chapter 13 papillary muscles which position the mitral valve leaflets so as to contribute further to this outflow tract obstruction.16 It is the young patients with severe outflow tract obstruction who are at highest risk for hemodynamic deterioration during pregnancy. Diagnosis of hypertrophic cardiomyopathy in patients of child-bearing age As young patients with hypertrophic cardiomyopathy are symptom free the diagnosis of hypertrophic cardiomyopathy is primarily made .