Efektivitas Island Flap Rotation Technique sebagai Metode Baru Operasi Jantung pada Kasus Regurgitasi Mitral Berat Degeneratif Lesi P2 : Kajian terhadap Koaptasi Katup, Gradien dan Residual Regurgitasi. = The Effectivity of Island Flap Rotation Technique as a New Method of Cardiac Surgery in Severe Degenerative Mitral Regurgitation with P2 Lesions: A study of Valve Coaptation, Gradient and Residual Regurgitation.