Design of a Motion Compensated Tissue Resection Catheter for Beating Heart Cardiac Surgery

Cardiac catheters allow clinicians to minimally invasively interact with the beating heart without stopping the heart or opening the chest. However, the fast motion of the intracardiac structures makes it difficult to modify and repair the tissue in a controlled and safe manner. To enable surgical procedures on the inside of the beating heart, we have developed an ultrasound-guided catheter system that virtually freezes the heart by compensating for the fast cardiac motions. The device presented in this paper is a resection tool that allows the catheter system to cut moving tissue, a key surgical task required for many intracardiac procedures including valve and leaflet repair. The motion tracking system is demonstrated in vivo and the tissue resection tool is evaluated by resecting tissue mounted on a cardiac motion simulator. The motion compensated catheter is shown to greatly improve the resection cut quality on the moving tissue target while reducing the forces experienced by the tissue by almost 80%. INTRODUCTION Physicians and engineers are developing a range of new procedures, drugs, and technologies to treat ailments that can affect the health and function of the human heart. One of the most significant advances in cardiac therapies is the use of cardiac catheters to give clinicians minimally invasive access to the heart via the vascular system. Cardiac catheters are long and thin flexible tubes and wires that are inserted into the vascular system and passed into the heart. Procedures that are now performed using catheters include measuring cardiac physiological function, dilating vessels and valves, and implanting prosthetics and devices [1]. While catheters can perform many tasks inside the heart, they do not yet allow clinicians to interact with heart tissue with the same level of skill as in open heart surgery. A primary reason for this limitation is that current catheters do not have the dexterity, speed, and force capabilities to perform complex tissue modifications on moving cardiac tissue. One such tissue modification that is required to perform many procedures inside the heart, such as mitral valve repair, is tissue resection [2]. Robotic and actuated catheters are a potential solution to the limitations of conventional catheters. Current robotic cardiac catheters, such as the commercially available Artisan Control Catheter (Hansen Medical, Mountain View CA, USA) or CorPath Vascular Robotic System (Corindus Vascular Robotics, Natick MA, USA), allow for teleoperated guidance of a catheter tool inside the heart [3,4]. These devices permit a human operator to control the positioning of a catheter in vivo. However, these actuated catheter technologies do not provide sufficient speeds to allow the catheters end effectors to keep up with the fast motion of intracardiac structures nor do they attempt to directly modify or resect the cardiac tissue [5,6]. Advances have also been made in the area of tissue resection technology. Robot tissue resection is now possible in laparoscopic procedures with the daVinci surgical robotic system (Intuitive Surgical, Sunnyvale, CA, USA). This device allows for the laparoscopic resection of a large range of tissues and organs, including the prostate, lungs, and gastrointestional system [7,8,9]. Tissue resection is also performed minimally invasively without the use of robotics. For example, the transurethral resection of the prostate (TURP) procedure utilizes a restroscope device, such as the Karl Storz Bipolar Restroscope System (Karl Storz Endoscopy-America Inc., El Segundo, CA, USA), to remove tissue from the prostate via the urethra using electrocautary [10]. Another example of minimally invasive tissue resection is atherectomy, a procedure where plaque or tissue is percutaneously removed from a large blood vessel using a catheter device such as the SilverHawk Plaque Excision System (Foxhollow Technologies, Redwood City, CA USA) [11,12]. Although these devices have demonstrated clinical