Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart which is of concern. Within the heart, the ability to control the exact position and orientation of the catheter tip is critical and largely determines how useful the catheter is.
Bidirectional catheters have been designed to be deflectable in one direction by one puller wire and in the opposite direction within the same plane by a second puller wire. In such a construction, the puller wires extend into opposing off-axis lumens within the tip section of the catheter. So that the tip section can bend in both directions in the same plane, the puller wires and their associated lumens are located along a diameter of the tip section. For ablation catheters, electrode lead wires are also provided within the distal end and typically, an additional lumen is used to contain the electrode lead wires. For example, U.S. Pat. No. 6,210,407, is directed to a bi-directional catheter comprising two puller wires and a control handle having at least two movable members longitudinally movable between first and second positions. As another example, U.S. Pat. No. 6,171,277 is directed to a bidirectional steerable catheter having a control handle that houses a generally-circular spur gear and a pair of spaced apart rack gears. Each rack gear is longitudinally movable between first and second positions, whereby proximal movement of one rack gear results in rotational movement of the spur gear, and correspondingly distal movement of the other rack gear. Also known is U.S. Pat. No. 6,198,974 which is directed to a bi-directional electrode catheter comprising a control handle. At their proximal ends, two pairs of puller wires are attached to movable pistons in the control handle. Each piston is controlled by an operator using a slidable button fixedly attached to each piston. Movement of selected buttons results in deflection of the tip section into a generally planar “U”- or “S”-shaped curve. Further known is U.S. Pat. No. 5,891,088 directed to a steering assembly with asymmetric left and right curve configurations. Proximal ends of left and right steering wires are adjustably attached to a rotatable cam housed in a control handle. The rotatable cam has first and second cam surfaces which may be configured differently from each other to accomplish asymmetric steering.
Also known are control handles that provide a greater degree of deflection in the catheter tip. For example, U.S. Pat. No. 7,377,906, the entire disclosure of which is hereby incorporated by reference, has increased throw capacity through the use of pulleys around which puller wire travel for minimized offset angle between the puller wire and the longitudinal axis of the control handle while maximizing the travel distance of that puller wire for any given distance traveled by the pulley drawing the puller wire. Suitable tensile puller members are described in U.S. Patent Publication No. 2008/0103520, the entire disclosure of which is also hereby incorporated by reference.
However, it is desirable to provide a control handle that allows user adjustability of the maximum degree of deflection as well as deflection sensitivity of the control handle to user manipulations, as needed for different uses and applications.