A catheter (10) is adapted for deflection in a narrow tubular region and/or a sharp turn. The catheter has an elongated body (12), a deflection section (14) having a support member adapted for heat activation to assume a trained configuration and a lead wire configured to deliver a current to the support member for heat activation. The support member is constructed of a shape memory alloy, for example nitinol, and the lead wire is adapted to directly heat the support member. Moreover, the catheter may include a thermally insulating layer covering at least a portion of the support member. The trained configuration of the support member extends in a single dimension, in two dimensions or in three dimensions.
