Abstract
Anomalous papillary muscles (PMs), in which the PMs are directly attached to the anterior mitral valve (MV) leaflet, can cause obstruction of the left ventricular outflow tract (LVOT). Accurately diagnosing of anomalous PMs, understanding their pathology, and performing appropriate surgery are essential for relieving LVOT obstruction effectively.A 71-year-old man with hypertrophic obstructive cardiomyopathy was referred to our hospital. Transthoracic echocardiography revealed LVOT obstruction with a peak outflow pressure gradient of 63 mm Hg at rest and 96 mm Hg during the Valsalva maneuver. Furthermore, an anomalous PM was suspected to be the cause of LVOT obstruction. Three- and four-dimensional cardiac computed tomography (CT) images clearly demonstrated that an anomalous PM from the anterior PMs was directly attached to the body of the anterior MV leaflet and that the anomalous PM, together with the thickened ventricular septum, caused a dynamic obstruction of the LVOT. We resected the anomalous PM from the anterior PMs and the subaortic ventricular septum using a transaortic approach.In this case, preoperative three-dimensional and four-dimensional cardiac CT images were effective at revealing the presence of an anomalous PM and its pathology in patient with LVOT obstruction, leading to accurate and smooth surgical procedures and improved patient outcomes. LEARNING OBJECTIVE: •Anomalous PMs are classified by their attachment patterns and appropriate surgical methods are recommended for each type, providing valuable insights for clinical decision-making.•This report emphasizes the significance of 3D and 4D cardiac CT in identifying the causes of LVOTO. This imaging technique provides important information regarding the location of the anomalous PM and dynamic impact, leading to a successful surgical outcome.