Abstract: Described herein are devices, methods and kits for assessing and/or enhancing the accessibility of a subvalvular space of a heart, accessing the subvalvular space of the heart (e.g., to provide access for one or more other devices), and/or positioning one or more devices in the subvalvular space of the heart. The devices described herein may, for example, comprise catheters that may be used to manipulate one or more chordae tendineae, diagnostic catheters having different sizes and/or shapes (e.g., different curvatures), guide catheters having different sizes and/or shapes (e.g., different curvatures), and visualization catheters. In some variations, the devices, methods, and/or kits may be used to visualize a target site, such as a subannular groove of a heart valve. In certain variations, the devices, methods, and/or kits may be used to manipulate chordae tendineae to provide additional space in a ventricle of a heart (e.g., enhancing the accessibility of the ventricle).