Anomalies of mitral subvalvar apparatus include various types of anomalies of papillary muscles and chordae tendineae. Direct insertion into the anterior mitral leaflet and fusion to the ventricular septum of the anomalous papillary muscle or chordae tendineae are common types of these anomalies. Anomalous papillary muscles or chordae, especially those that are inserted directly into the mitral leaflets, play a role in augmenting left ventricular outflow obstruction by restricting mobility of the leaflets and/or tethering them toward the septum, thus narrowing the left ventricular outflow tract.

An uncommon anomalous papillary muscle/chordae was incidentally found in a 38 year old woman with transient ischaemic attack, who underwent transthoracic and transoesophageal echocardiography to evaluate a possible embolic source including patent foramen ovale. Transthoracic echocardiography showed the thick anomalous chordae tendineae was arising from the accessory papillary muscle at the anterior free wall, and inserting into the left ventricular outflow septum, without involving the mitral leaflet (panels A–C). The mitral valve leaflet or annulus were not involved in this anomalous apparatus and there was no left ventricular outflow obstruction throughout the cardiac cycle. Patent foramen ovale was not found by agitated saline contrast, and there was no sign of an intracardiac embolic source in this patient. The neurologist decided to initiate anticoagulation treatment and the patient has been doing well without further vascular events, although the relation between the cerebral vascular event and this uncommon anomalous subvalvar apparatus is not clear.

Transthoracic (TTE) and transoesophageal (TOE) echocardiograms. (A) Parasternal short axis view. Accessory papillary muscle is seen at the left ventricular anterior free wall, just anterior to the anterolateral papillary muscle (arrow). (B) Parasternal modified long axis view by TTE. (C) Long axis view by TOE. Thick anomalous chordae tendineae (arrows) arises from the accessory papillary muscle and attaches to the left ventricular outflow septum after crossing the left ventricle without creating left ventricular outflow obstruction. Ao, aorta; LA, left atrium; LV, left ventricle; LVOT, left ventricular outflow tract; RV, right ventricle.