Patent ID: 7747334

Claim:
An electrical lead assembly for a left ventricle of the heart, the lead assembly comprising: a lead with a lead body having a proximal unbiased region and a continuously deflectable preformed curvature extending from the unbiased region, the lead body further having a stiff proximal portion, a flexible distal portion that is more flexible than the stiff proximal portion, and a transition portion between the flexible distal portion and the stiff proximal portion, the flexible distal portion including a distal tip of the lead body, the continuously deflectable preformed curvature curved in one direction through a single plane, the lead having a lumen extending through the lead body, the lumen having a distal end and a proximal end and a first length from the distal to the proximal end, the lead further having a conductor extending through at least a portion of the lead body and an electrode disposed on the distal portion of the lead body and electrically coupled to the conductor, wherein a portion of the stiff proximal portion extends into the continuously deflectable preformed curvature such that the stiff proximal portion provides support to at least a portion of the continuously deflectable preformed curvature; and a stylet that is sized to fit within the lumen, the stylet having a proximal portion, a distal portion with increased flexibility relative to the proximal portion, and a second length from a distal end to a proximal end of the stylet, the second length being at least as long as the first length; wherein the stylet distal portion has a first stiffness and the lead body distal portion has a second stiffness, the first stiffness being sufficiently stiff relative to the second stiffness to straighten the continuously deflectable preformed curvature from a first curved configuration to a second curved configuration when the stylet distal end is positioned in the lumen adjacent the lead body distal end, wherein the first and second curved configurations are shaped to facilitate access to branch vessels of the coronary sinus.