FIELD OF THE INVENTION

The invention relates to transseptal punches.

BACKGROUND OF THE INVENTION

Defects in the left atrium are common, and cause a variety of ailments, including atrial fibrillation, mitral valve prolapse, and atrial appendage thrombosis. These defects can be treated with minimally invasive procedures, with catheters inserted into the atrium. The left atrium must be approached from the right atrium, with catheters navigated through the vena cava and through the fossa ovalis, which is a thin wall between the right and left atrium. The fossa ovalis must be punctured to allow passage of catheters into the left atrium. To puncture the fossa ovalis, surgeons use a transseptal punch, which is also referred to as a Brockenbrough needle. The Brockenbrough needle is a long, very slender punch which is curved at its distal end. This curvature is important as it facilitates operation of the punch.

In a typical procedure in which access to the left atrium is obtained transseptally through the right atrium, a surgeon delivers a Mullins guide catheter into the right atrium, and then delivers a transseptal punch through the Mullins guide catheter to the right atrium. The transseptal punch (and usually an integral obturator or dilator) is navigated through the Mullins guide catheter with a stylet disposed within the punch. At this point the distal tip of the transseptal punch is disposed within the distal end of the Mullins guide catheter. After confirming that the punch is properly located and oriented, the surgeon then withdraws the stylet completely, and withdraws the Mullins guide catheter a short distance to expose the tip of the transseptal needle, and then pushes the transseptal punch through the fossa ovalis. After the transseptal punch has pierced the fossa ovalis and entered the left atrium, the surgeon pushes the Mullins guide catheter over the punch so that the distal tip of the Mullins guide catheter resided in the left atrium. The surgeon then removes the punch entirely from the Mullins guide catheter. After the Mullins guide catheter tip is disposed within the left atrium, the surgeon can deliver any desirable catheter or device to the left atrium through the Mullins guide catheter.

The transseptal punch, which is curved, is forced through the generally straight Mullins guide catheter. This may result in skiving or carving of small slivers of plastic from the inside of the Mullins catheter. Any slivers of plastic scraped from the catheter may be deposited in the right or left atrium, and subsequently cause injury to the patient.

SUMMARY OF THE INVENTIONS

The devices and methods described below provide for a robust steering mechanism for a steerable Brockenbrough needle, or transseptal punch. The transseptal punch comprises two tubes, one disposed within the other. The inner tube extends a short distance beyond the distal tip of the outer tube to provide the penetrating tip of the punch. The outer tube has a region of enhanced flexibility at its distal end, which establishes a deflectable or “steerable” segment. The inner tube is fixed to the outer tube at a point just distal to the deflectable segment. The inner tube, in a region corresponding to the deflectable segment, is split by a longitudinally extending slot. The deflectable segment can be forced to bend by pulling the inner tube proximally relative to the outer tube, (or pushing the outer tube relative to the inner tube). The longitudinally oriented slot in the inner tube provides flexibility needed for deflection, while preventing collapse of the outer tube. A proximal hub, which is fixed to both the inner tube and the outer tube, is operable to pull the inner tube distally relative to the outer tube (or push the outer tube relative to the inner tube). Use of the steerable transseptal punch avoids the skiving problems of prior art transseptal punches.

