A guide catheter includes an outer guide having an open lumen and a longitudinal pre-stress line extending between a distal end and a proximal end of the outer guide. The outer guide has a longitudinal stiffness that facilitates transmission of forces and prevention of kinking during steering of the outer guide within cardiac vasculature and structures. An inner guide has an open lumen and is movably displaceable within the open lumen of the outer guide. At least a distal end of the outer guide and inner guide are dimensioned for passage into the patient's coronary sinus. A guide handle is connected to the proximal end of the outer guide and includes a longitudinal pre-stress line separable into at least two sections such that guide handle separation splits the outer guide along the longitudinal pre-stress line at the proximal end of the outer guide.