FIELD OF THE INVENTION

This invention relates to remotely controlled steering and navigation of medical devices through a subject anatomy with a remote navigation system for interventional medicine, where a first medical device in the form of a remotely steered deflectable sheath is used to assist with the steering of a second medical device in the form of a mapping catheter or an ablation catheter. The second medical device is itself be steered by the same remote navigation system, possibly with a different mode of actuation. More generally, the deflectable sheath could be used as a guide or conduit to place a variety of other medical devices in a desired region of a subject anatomy.

BACKGROUND OF THE INVENTION

In recent years minimally invasive interventional procedures have benefited from the development of remote navigation systems with different forms of actuation that can assist with a variety of minimally invasive interventional medical procedures and permit faster procedures with reduced exposure to X-ray radiation. For instance, a commercial example is the Niobe© magnetic navigation system manufactured by Stereotaxis, Inc. of St. Louis, Mo., USA. This system consists of a set of magnets in a procedure room together with control hardware and software and a user interface; the user interface is available in an adjoining control room for comfortable operation by the user, and the magnetic navigation system is integrated with an X-ray system to receive X-ray image data from the latter. Since this remote navigation system can be operated and controlled from a control room outside the procedure room, X-ray radiation exposure to physicians operating the system is eliminated to a large extent, and the arrangement permits the performance of an interventional medical procedure in most part from outside the procedure room. Procedures are generally faster since the physician can perform the procedure in a more comfortable setting while the device actuation is done by the system, and X-ray exposure to the patient as well is significantly reduced.

Generally, the remote navigation system may be interfaced or integrated with a localization system that determines the spatial location of a medical device within a subject anatomy, permitting the possibility of automatically steering and navigating the medical device to a desired set of target locations using closed loop feedback control. An example of an interventional medical device localization system is the CARTO® Electrophysiology localization system manufactured by Biosense-Webster, Inc. of Diamond Bar, Calif. that localizes various catheter and sheath devices incorporating location sensors and/or electrodes for applications in Electrophysiology. Another example of a localization system is the EnSite NavX™ system manufactured by St. Jude Medical of St. Paul, Minn. The spatial location information can be used for example to direct an ablation catheter device automatically to a series of locations.

Cardiological interventional procedures can benefit greatly from the use of such an integrated system. In the clinical application of interventional cardiac electrophysiology, a catheter-based medical procedure is performed to record electrical activity over the interior (endocardial) heart surface, permitting visualization of electrical activity and any abnormalities or arrhythmias if they exist. Subsequently, a catheter-based ablation procedure (where the ablation catheter is a primary medical device) is performed to ablate and isolate regions of the endocardial surface that function as sources of abnormal electrical activity. This type of procedure can take a long time when performed manually and requires a significant level of skill on the part of the interventional physician. In this context, a remotely operated medical navigation system can offer significant benefits especially if at least a part of the procedure can be efficiently automated, leading to reduced procedure time, reduced X-ray exposure for both physician and patient, and reduced discomfort to physician and patient.

In many cases in Electrophysiology ablation procedures, it is important for the catheter to have a sufficient amount of contact with the endocardial surface. The ablation energy is delivered by means of Radio Frequency (RF) power, and this energy delivery process is optimal when there is good contact between the ablation catheter tip and the endocardiac wall; such a configuration ensures that the RF energy is delivered directly to the tissue surface, with minimal dissipation into the blood pool. Accordingly, various means of measuring contact force have been reported on in the literature. In the context of a remote navigation system, it is useful to have a methodology to ensure that a good level of wall contact is present at the ablation catheter tip. In some cases, certain endocardial locations can be difficult to access depending on the particular subject anatomy. The present invention describes a method and apparatus for ensuring both easier access to a desired target location, and once accessed, applying sufficient contact at the desired target location.

While the literature and art in the area of RF catheter ablation discusses methods to measure contact force, there is an unmet need for generally being able to control and drive at least two devices, one supporting the other, in order to optimize contact with the endocardial surface. This invention is intended to address this need by disclosing methods and apparatus for navigating multiple medical devices from a single remote navigation system that actuates both devices. In the present invention, an interventional deflectable sheath device is steered and controlled by the remote navigation system either by manual operation from a user interface or in automated manner. A second medical device is passed through the deflectable sheath device and is also steered and controlled from the remote navigation system. The second medical device could be for instance a localized ablation catheter. Given a desired target location for the ablation catheter to access, and that may be selected for example from an electroanatomical map, the present invention describes methods of driving the deflectable sheath to automatically provide an optimal spatial configuration from which the ablation catheter device can access the target with good contact. Thus, both medical devices, sheath and catheter, are controlled by the remote navigation system to optimize contact.

There are at present no methods that implement such generalized control of multiple medical devices for optimal contact from a single remote navigation system. The disclosure of the present invention provides methods for achieving such objectives.

SUMMARY OF THE INVENTION

The present invention relates to methods of remotely controlling steering and navigation of multiple medical devices through a subject anatomy with an interventional remote navigation system in order to generate good quality contact with desired targeted tissue surface in the subject anatomy. According to the methods taught in the present invention, a first medical device in the form of a deflectable sheath whose deflection can be controlled from the remote navigation system is remotely steered by the remote navigation system. The remote navigation system generally configures and positions the deflectable sheath device by actuating deflection, rotation and insertion/retraction degrees of freedom. Given a desired target location that a user desires to access in a subject anatomy, the remote navigation system runs a computational model to determine an optimal configuration of the deflectable sheath device and drives its placement such that the distal tip of the sheath is aimed approximately at the target while maintaining a pre-defined distance from the target. The pre-defined distance can incorporate a safety distance as well as a margin of sufficient distance that allows the navigation and placement of a second medical device in the form of an ablation catheter that is passed through the lumen of the deflectable sheath.

The deflectable sheath device is driven by passing it though a drive mechanism (such as the Vdrive™ unit manufactured by Stereotaxis, Inc. of St. Louis, Mo.) where rotations of appropriate catheter handle regions are generated by suitable gripping/clamp mechanisms driven by drive motors. These rotations can result in rotations of the catheter shaft and deflections of the deflectable sheath distal portion generated by pull-wires inside the catheter. Likewise, catheter insertion/retraction is generated mechanically by translation of the gripping mechanisms over a length range, again driven by a suitable drive motor and appropriate motion transmission mechanisms. Further details of such drive mechanisms for remote device manipulation are disclosed in US patent application 2009/00105645, “Apparatus for selectively rotating and/or advancing an elongate device”, and US patent application 2010/0298845, “Remote manipulator device”, attached here for reference.

The process of automatically configuring the deflectable sheath device could be implemented based on the computational model together with positional feedback from the motors driving the configuration of the sheath device in one preferred embodiment. In an alternate preferred embodiment, the deflectable sheath can have electrodes on its distal portion that can be localized spatially with a localization system. In this latter case localization data for the tip electrodes can be used as positional feedback and the control algorithm to use feedback to adaptively drive the sheath configuration until it is actually positioned as intended. In still another preferred embodiment, the ablation catheter that passes through the lumen of the deflectable sheath is localized, for example with data from a suitable sensor placed in the distal tip of the catheter. In this embodiment, the catheter is positioned with its distal tip at or just beyond the distal tip of the deflectable sheath, and localization data (position and orientation) from the catheter device is used as input to a feedback-controlled navigation scheme to configure the deflectable sheath.

The computational model for the sheath can determine configurational degrees of freedom for the sheath in order to satisfy the constraints of pointing the distal tip of the sheath at a desired target location while maintaining a given pre-defined distance from it. These constraints are posed as a mathematical problem according to the teachings of the present invention and a solution is determined computationally. If the constraints are not satisfiable in exact manner, a “closest” solution can be determined for the sheath configuration that is as optimal as possible. For exemplary purposes, the disclosure herein treats the case of a (first) deflectable sheath device that it is desired to point at the target location to the best extent possible, while a (second) medical device in the form of a mapping/ablation catheter is passed through the lumen of the sheath. Both devices are driven from a single remote navigation system, while the steering modality generally could be different for the two devices; thus the first device (deflectable sheath) could be actuated mechanically, while the second device (ablation catheter) could be steered magnetically. The ablation catheter device can itself be steered using closed loop feedback control methods that have been disclosed previously (for example, in US Patent application number 2005/0020911, “Efficient closed loop feedback navigation”). Furthermore a range of other actuation schemes could be used, and likewise a larger multiplicity of devices could be deployed in the clinical application and controlled according to the teachings of the present invention, without departing from the scope of the present invention.

