This invention relates generally to medical devices, and more particularly to methods and apparatus for catheter devices that demand less skill for their manipulation inside a body.
Human vasculature possesses a highly branched structure. To place an ultrasound intracardiac probe into position within the heart, the imaging transducer is placed into a catheter and inserted into the vasculature, commonly through the leg or arm. Directing a catheter through the body's vascular network and into the heart necessitates having both the ability to visualize the vascular structure in real time and also the ability to steer the catheter tip in a desired direction. Careful steering of the cardiac tip is needed to avoid puncturing vascular walls.
A catheter contains a complex series of strings or wires attached to its tip at one end and to knobs on a handle at the other, opposite end. Careful turning of the knobs can pull the catheter tip in a desired direction, thereby allowing the catheter to be steered in that direction. A physician responsible for inserting the catheter must simultaneously insert and steer the catheter while monitoring the location of the catheter tip fluoroscopically.
An ultrasound intracardiac catheter probe must be directed through vasculature and into a heart to be placed in the appropriate location for imaging. The placement is accomplished by steering the catheter tip as the catheter is inserted within the vascular system. This steering is generally done using a series of wires or cords attached to the catheter tip and controlled manually from the catheter handle as the catheter is inserted into (for example) an artery or vein in a leg of a patient. The location of the catheter during insertion is followed fluoroscopically. A physician requires much skill to move the catheter tip into position without damaging the vasculature or heart walls.
In one aspect, the present invention therefore provides a catheter apparatus. The catheter apparatus includes a catheter having an electroactive polymer inside. The electroactive polymer is configured to control either or both shape and/or direction of the catheter in a vessel as the electroactive polymer is electrically activated. The apparatus further includes a computer which may be denoted as a “control computer.” The computer includes a memory and a processor configured to store vascular information and determine voltages to be applied to activate the electroactive polymer to steer the catheter to a desired site after it is inserted into a body. Also included is an electrical source responsive to the computer and configured to apply the determined voltages to the electroactive polymer.
In another aspect, the present invention provides a method for imaging an organ of a body. The method includes imaging a vascular system of the body, digitizing and storing vascular information obtained from the imaging in a control computer, and using the control computer to apply voltages to an electroactive polymer in a catheter in accordance with the stored vascular information to steer the catheter to a desired site after it is inserted into the body. (Fluoroscopy and digital fluoroscopy are examples of vascular imaging systems.)
In yet another aspect, the present invention provides a catheter apparatus that includes a catheter having an electroactive polymer inside. The electroactive polymer is configured to control either shape and/or direction of the catheter in a vessel as the electroactive polymer is electrically activated. The apparatus further includes a contact sensor configured to sense contact with a vessel wall or an organ wall. Also included is a control computer responsive to the contact sensor and configured to utilize an electrical source to immediately electrically activate the electroactive polymer to change shape or direction of the catheter upon the contact sensor sensing contact with a vessel wall or an organ wall.
It will be appreciated that various configurations of the present invention provide methods and apparatus having or using catheters with very small, if any, width beyond those of prior art catheters. Catheters are easily controlled and can be automatically controlled by computer in some configurations.
In some configurations of the present invention, a catheter tip is steered using a plurality of electroactive polymer bundles along a length of the catheter. Electroactive polymers change their size in response to an electrical voltage and are sometimes referred to as “artificial muscles.” A series of electroactive polymers formed as cords and attached to electrical leads along the catheter can be made to independently stretch or shrink in response to an applied voltages, resulting in bending or steering of the catheter in a desired direction. For example, in some configurations of the present invention, the vascular system is imaged using a contrast agent fluoroscopic method. The vascular information obtained is digitized and stored in a control computer. The computer then applies voltages to a catheter tip in accordance with the stored vascular information to steer the catheter to a desired site after it is inserted into the body. Thus, the skill and dexterity required to steer the catheter is substantially reduced, as the steering is entirely, or at partially, performed under automatic electronic control.
Also in some configurations, a series of cords that are formed from or that comprise electroactive polymers plus appropriate electrical connectors is placed within an intravascular catheter. A voltage is applied to individual electrical connections to individual cords using, for example, a touch panel or any other suitable electronic control and/or pointing device. As voltages are varied, the cords change shape accordingly. By varying the voltages applied to individual cords, the shape of the cords change shape, thereby steering a tip of the catheter in a desired direction.
Some configurations of the present invention have more than one set of electroactive polymer sets and controls along the length of the catheter. In these configurations, the shape of the catheter can be varied more than in those configurations in which guide wires are attached to the catheter tip.
Also, in some configurations, the shape of a vascular network through which the catheter is to be inserted is accurately ascertained using digitized x-ray fluoroscopic methods and contrast agents. Coordinates representing the shape of the vascular network are digitized and used by a “control computer” to generate electrical signals that control the location of the catheter during insertion. Thus, much of the skill required in known catheterization techniques can be supplied by the computer rather than the physician. Also, some configurations include a location sensor at the tip of the catheter to aid a computer in steering the catheter tip.
A contact sensor is provided in some configurations of the present invention for sensing contact with walls of the heart or vasculature. Upon contact, the contact sensor generates an electrical signal that is detected by the control computer. Once contact with the vasculature is detected, the computer or other control device causes a voltage change on an electroactive polymer cord that results in the catheter tip immediately changing shape slightly to avoid or prevent damage to cardiac or vessel walls.
In some configurations and referring to
Also in some configurations, catheter 12 further comprises a contact sensor 32 configured to sense contact with a wall 34 of a vessel 16 wall or wall 36 of an organ 38. Computer 18 is responsive to contact sensor 32 and is configured to utilize electrical source 30 to immediately electrically activate electroactive polymer 14 to change the shape and/or direction of catheter 12 upon contact sensor 32 sensing contact with a vessel wall 34 or an organ wall 36.
Referring to
In some configurations and referring to
Some configurations of apparatus 10 have a plurality of separately controllable cords 40 along all or a portion of the length of catheter 12.
In many configurations, a contrast enhanced tip (“location sensor”) 48 is provided at tip 50 of catheter 12. This tip is imagable with fluorscopy during catheter insertion into the vasculature and aids the control computer in determining correct catheter placement.
To provide images inside body 28, catheter 12, in some configurations, includes an ultrasound imaging transducer 52 and/or an optical imaging transducer 54.
In some configurations and referring to flow chart 100 of
In some configurations, to image 102 a vascular system 56 of body 28 , a contrast agent is used to fluoroscopically image vascular system 56.
Electroactive polymer 14 is, in some configurations, configured to change at least one of shape or direction of catheter 12 when electrically activated, and catheter 12 further comprises a contact sensor 32 configured to sense contact with a vessel wall 34 or an organ wall 36. For example, contact sensor 32 generates a signal that is sent to control computer 18 whenever contact is made. Control computer 18 is used to immediately activate electroactive polymer 14 to change shape or direction of catheter 12 upon contact sensor 32 sensing contact with a vessel wall 34 or an organ wall 36. More than one contact sensor 32 can be used to determine the orientation of tip 50 with respect to vessel wall 34 or organ wall 36.
In some configurations, catheter 12 has a plurality of cords 40 therein that are comprised of electroactive polymer 14, and the method further includes electrically controlling each cord 40 to adjust the shape and/or direction of catheter 12.
In some configurations, a touch panel 44 is utilized to control a voltage applied to each cord 40 to manually steer catheter 12.
Catheter 12 has a plurality of separately controllable cords 40 along its length in some configurations, so that some method configurations further comprise separately controlling each controllable cord 40.
An ultrasound imaging transducer 54 or an optical imaging transducer 56 located at a tip 50 of catheter 12 is used in some method configurations of the present invention to produce an image.
In some configurations of the present invention and again referring to
It thus be appreciated that various configurations of the present invention can be provide with very small, if any, width beyond those of prior art catheters. Moreover, configurations of the present invention are easily controlled and can be automatically controlled by computer in some configurations.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.