Steerable catheter having a single gear drive bidirectional control handle

A bidirectional steerable catheter comprises an elongated, tubular catheter body having at least one lumen extending therethrough. A tip section comprising flexible tubing having at least two lumens extending therethrough is fixedly attached to the distal end of the catheter body. A control handle is mounted to the proximal end of the catheter body. The control handle comprises a generally-hollow handle housing having inside and outside surfaces and a generally tubular core extending longitudinally within the housing. A generally-circular spur gear is rotatably mounted within the handle housing, the spur gear having teeth about its outer circumference. First and second pistons are slidably mounted on diametrically opposed sides of the spur gear and at least partially in surrounding relation to the tubular core within the handle housing. Each piston has an interior edge generally facing the interior edge of the other piston and comprises a series of teeth along its interior edge that engage the teeth of the spur gear so that proximal movement of one piston results in rotational movement of the spur gear and distal movement of the other piston. A longitudinally movable thumb control is fixedly attached to the first piston and accessible from outside the handle housing. The catheter further comprises first and second puller wires having proximal and distal ends. Each puller wire extends from the control handle, through a lumen in the catheter body and into a lumen in the tip section. The distal end of each puller wire is fixedly attached to the tip section. The proximal end of the first puller wire is anchored to the first piston, and the proximal end of the second puller wire is anchored to the second piston. Proximal movement of the thumb control relative to the handle housing results in proximal movement of the first piston and first puller wire relative to the handle housing and catheter body, which results in deflection of the tip section in the direction of the lumen into which the first puller wire extends. Distal movement of the thumb control relative to the handle housing results in distal movement of the first piston, causing proximal movement of the second piston and puller wire relative to the handle housing and catheter body, which results in deflection of the tip section in the direction of the lumen into which the second puller wire extends.