A method of preventing ingress of material into the left atrium of a heart includes providing a delivery sheath, advancing the sheath distal end through an opening between the right atrium and the left atrium of the heart, providing an expandable cage, delivering the expandable cage to the left atrium, and expanding the expandable cage within the left atrium. The expandable cage includes a proximal end, a distal end, and a plurality of supports extending therebetween. The expandable cage also includes a first membrane provided at its proximal end and a second membrane provided at its distal end. The expandable cage has a collapsed configuration so that it can be received within the lumen of the delivery sheath, and an expanded configuration for deployment within the heart. When expanded, the first membrane is positioned at an opening between the left and right atria of the heart, and the second membrane is positioned at the ostium of the left atrial appendage. The first membrane substantially prevents passage of blood between the atria and the second membrane prevents passage of embolic material from the left atrial appendage into the left atrium of the heart.