 aneurysm membran septum 1 aneurysm membran septum rare lesion presum develop congenit basi aneurysm origin left ventricl beneath aortic valv bulg ventricl septal leaflet tricuspid valv atrium 2 aneurysm produc symptom ventricular outflow tract obstruct ruptur result septal defect shunt left ventricl atrium ventricl 3 aneurysm membran septum isol abnorm associ congenit cardiac defect aortic valvular insuffici membran septal aneurysm site bacteri endocard thrombu format 4 aneurysm resembl aris membran septum occur complex deform produc endocardi cushion defect angiograph featur diagnost cushion defect recogn 5 presenc septal aneurysm establish angiocardiographi diagnost featur left ventricular angiocardiogram present 