Guide extension catheter

A guide extension catheter for use with a predefined length guide catheter, the guide extension catheter comprising:

• an elongate tube member having a circular cross-section with an outer diameter sized to be insertable through a cross-sectional inner diameter of the guide catheter and defining a coaxial lumen having a cross-sectional inner diameter through which an interventional cardiology device is insertable, wherein a proximal portion of the elongate tube member comprises structure defining a proximal side opening extending for a distance along a longitudinal axis, and accessible from a longitudinal side defined transverse to the longitudinal axis, to receive the interventional cardiology device into the coaxial lumen while the proximal portion remains within a lumen of the guide catheter;
• a push member configured to advance the elongate tube member through the guide catheter, the push member being proximal of and operably connected to the elongate tube member, the push member having a maximal cross-sectional dimension at a proximal portion that is smaller than the outer diameter of the elongate tube member and having a length that when combined with a length of the elongate tube member forms a device length that is longer than the guide catheter, such that when at least a distal portion of the elongate tube member is extended distally of a distal end of the guide catheter, at least a portion of the proximal portion of the push member extends proximally through a hemostatic valve in common with the interventional cardiology device;
• and
• a balloon radially surrounding a portion of the elongate tube member, the balloon comprising an inflatable tube in fluid communication with an elongate lumen configured to provide inflation fluid to, or withdraw inflation fluid from, the balloon.

A method, comprising:

• advancing a distal end of a predefined length guide catheter having a continuous lumen through a blood vessel to an ostium of a coronary artery;
• advancing a distal end of a guide extension catheter through, and beyond the distal end of, the guide catheter, including advancing a push member of the guide extension catheter that is proximal of, operably connected to, and more rigid along a longitudinal axis than an elongate tube member of the guide extension catheter, into the continuous lumen of the guide catheter, the push member having a maximal cross-sectional dimension at a proximal portion that is smaller than a cross-sectional outer diameter of the elongate tube member and having a length such that, when combined with the length of the elongate tube member, a distal end portion of the elongate tube member is extendable through the continuous lumen of the guide catheter and beyond the distal end of the guide catheter while a proximal end of the push member is extendable through a hemostatic valve positioned at a proximal end of the guide catheter,
• the advancement of the push member causing advancement of the distal end portion of the elongate tube member beyond the distal end of the guide catheter while a side opening of the guide extension catheter remains within the continuous lumen of the guide catheter, the side opening extending for a distance along a longitudinal axis of the guide extension catheter and accessible from a longitudinal side defined transverse to the longitudinal axis, the elongate tube member defining a lumen coaxial with the continuous lumen of the guide catheter and having a cross-sectional inner diameter through which an interventional cardiology device is insertable;
• and
• inflating a balloon, which radially surrounds a portion of the elongate tube member, to engage the elongate tube member with an inner surface of the guide catheter, including urging fluid into the balloon to inflate a series of helical windings of the balloon.