Apparatus and methods are provided for providing access to a body lumen, e.g., to deliver a pacing lead within a patient's heart. The apparatus includes a tubular member including a proximal end, a distal end sized for insertion into a body lumen, and a lumen extending therebetween. An elongate member extends from the distal end of the tubular member. An expandable sheath extends along at least a portion of the elongate member, the sheath being expandable from a contracted condition to facilitate insertion into a body lumen, and an enlarged condition wherein the sheath at least partially defines a lumen communicating with the tubular member lumen. A stylet or other shaped element is insertable into the elongate member for changing a shape of at least a distal tip of the elongate member, e.g., for accessing side branches extending from a body lumen, e.g., within a patient's coronary venous system.