Guide catheters for facilitating implantation of cardiac leads for applying electrical stimulation to and/or sensing electrical activity of the heart through one or more electrodes positioned at an implantation site within a heart chamber or cardiac vessel adjacent a heart chamber. Such a cardiac lead has low torqueability and pushability through a pathway to enable attachment of the cardiac lead at the implantation site. The catheter body comprises a delivery lumen to introduce a small diameter cardiac lead and a guide lumen to receive a guide tool to locate the catheter body distal end at the implantation site. The small diameter lumen within a small diameter guide tube extends distally from the delivery exit port of the delivery lumen. The catheter body is shaped to bias the delivery lumen exit port toward the heart.