<s>[INST] context: The papillary muscles are connected to the mitral valve leaflets by the chordae tendinae. When there is rupture of the chordae tendinae or the papillary muscle itself, the mitral valve is unable to function properly, resulting in mitral regurgitation. Because this is an acute process, accommodation does not occur, resulting in acute pulmonary edema. Edema predominantly affecting the right upper lobe can be seen if the jet of regurgitant blood is directed into the right superior pulmonary vein, which drains the right upper lobe. The left atrium will enlarge over time in the setting of mitral valve regurgitation due to the increased volume of blood that is directed into the left atrium during systole. However, this change occurs over time and will not be seen in the setting of acute papillary muscle rupture. The left ventricle will enlarge oveime in the setting of mitral valve regurgitation because it receives an increased volume of blood from the left atrium - both the volume of blood returning from the lung as well as the regurgitant volume of blood through the mitral valve. As with left atrial enlargement, left ventricular enlargement will occur over time but will not be seen in the setting of acute papillary muscle rupture. Pericardial effusion can occur in the setting of an acute myocardial infarction due to inflammation of the pericardium. Dressler syndrome, thought to be an autoimmune inflammatory response to myocardial neo-antigens, is not an acute process and, when present, occurs several weeks following a myocardial infarction. However, it is not the most common radiographic manifestation of acute papillary muscle rupture. [/INST] question: What is the MOST common radiographic manifestation of acute papillary muscle rupture? | options: A: Pulmonary edema B: Left atrial enlargement C: Left ventricular enlargement D: Pericardial effusion | answer: A </s>