Source: https://patents.google.com/patent/US20050059962?oq=6272333
Timestamp: 2018-03-22 16:20:26
Document Index: 77047934

Matched Legal Cases: ['art 802', 'art 802', 'art 802', 'art 802', 'art 802', 'art 802', 'art 802', 'art 802', 'art 802']

US20050059962A1 - Ablation catheter with tissue protecting assembly - Google Patents
Ablation catheter with tissue protecting assembly Download PDF
US20050059962A1
US20050059962A1 US10660820 US66082003A US2005059962A1 US 20050059962 A1 US20050059962 A1 US 20050059962A1 US 10660820 US10660820 US 10660820 US 66082003 A US66082003 A US 66082003A US 2005059962 A1 US2005059962 A1 US 2005059962A1
US7569052B2 (en )
FIG. 32A and 32B show representative lesion patterns in a left atrium that may be formed using the system of FIG. 1; and
The internal electrode 350 is carried at a distal end 352 of a support member 354, which is fixedly secured within the lumen 332 of the catheter member 302 by cross bars 355 or similar structures. In an alternative embodiment, the electrode 350 can be carried by a structure (not shown) fixedly secured to the distal end 306 of the catheter member 302. In a further alternative embodiment, the electrode structure 310(1) does not include the cross bars 355, and the support member 354 is slidable within the lumen 332. This has the benefit of allowing the support member 354 to be removed from the interior 334 of the body 330, thereby allowing the body 330 to collapse into a lower profile. The interior electrode 350 is composed of a material that has both a relatively high electrical conductivity and a relatively high thermal conductivity. Materials possessing these characteristics include gold, platinum, platinuim/iridium, among others. Noble metals are preferred. A RF wire 360 extends through the lumen 332 of the catheter member 302, and electrically couples the internal electrode 350 to the electrical connector 362 on the handle assembly 320 (see FIG. 3). The support member 354 and/or the electrode structure 310 may carry temperature sensor(s) (not shown) for sensing a temperature of a liquid inflation medium 338 during use.
Larger pore diameters, typically used for blood microfiltration, can also be used for ionic transfer. These larger pores, which can be seen by light microscopy, retain blood cells, but pennit passage of ions in response to the applied RF field. Generally, pore sizes below 8 um will block most blood cells from crossing the membrane. With larger pore diameters, pressure driven liquid perfusion, and the attendant transport of macromolecules through the pores 370, is also more likely to occur at normal inflation pressures for the body 330. Still larger pore sizes can be used, capable of accommodating formed blood cell elements. However, considerations of overall porosity, perfusion rates, and lodgment of blood cells within the pores of the body 330 must be taken more into account as pore size increases.
The tube 339 is slidably secured to the sealer 341. This has the benefit of allowing the delivery tube 339 to be removed from the interior 334 of the body 330, thereby allowing the body 330 to collapse into a lower profile. In this case, the sealer 341 has a shape and size configured to prevent delivered medium 338 from escaping from the interior 334 of the body 330, while allowing the tube 339 to slide therethrough. Alternatively, if a slidilg arrangement between the tube 339 and the body 330 is not required or desired, the delivery tube 339 can be secured to the proximal end of the body 330.
As FIGS. 8-10 show, the electrode structure 310 can include, if desired, a normally open, yet collapsible, interior support structure 340 to apply internal force to augment or replace the force of liquid medium pressure to maintain the body 330 in the expanded geometry. The form of the interior support structure 340 can vary. It can, for example, comprise an assemblage of flexible spline elements 342, as shown in the electrode structure 310(2) of FIG. 8 (expanded geometry) and FIG. 9 (collapsed geometry), or an interior porous, intenvoven mesh or an open porous foam structure 344, as shown in the electrode structure 310(3) of FIG. 10. The interior support structure 340 is located within the interior 334 of the body 330 and exerts an expansion force to the body 330 during use. Alternatively, the interior support structure 340 can be embedded within the wall of the body 330. The interior support structure 340 can be made from a resilient, inert material, like nickel titanium (commercially available as Nitinol material), or from a resilient injection molded inert plastic or stainless steel. The interior support structure 340 is preformed in a desired contour and assembled to form a three dimensional support skeleton.
Refer to FIGS. 14-18, the stabilizer 400 and the portion of the ablation catheter 104 in association with the stabilizer 400 will now be described. As shown in FIGS. 14 and 15, one embodiment of a stabilizer 400(1) includes a shroud 402 that is secured to the distal end 306 of the catheter member 302. The shroud 402 circumscribes at least a portion of the expandable-collapsible body 330, thereby substantially preventing ablation energy from dissipating to surrounding tissues beyond the target tissue to be ablated. The stabilizer 400(1) futher comprises a plurality of vacuum ports 407 (here, four) associated with a distal edge 405 of the shroud 402, and a plurality of respective vacuum lumens 404 longitudinally extending within a wall of the shroud 402 in fluid communication with the vacuum ports 407. The stabilizer 400(1) includes an optional temperature sensing element 414, such as a thermocouple or thermistor, secured to the shroud 402. The temperature sensing elements 414 may be used to monitor a tissue temperature.
As shown in FIG. 16, the stabilizer 400(1) optionally includes support wires 430, which are partially embedded within the wall of the shroud 402 and partially within the wall of the catheter member 302. The support wires 430 can be made from a resilient material, such as metal or plastic. Nitinol is particularly preferred. In one embodiment, the support wires 430 are prefomied to have a shape that is substantially rectilinear. In this case, the shroud 402 will remain substantially in its collapsed configuration until pushed to open into an expanded configuration by the expandable-collapsible body 330 when the body 330 is expanded. Such configuration has the benefit of allowing the electrode structure 310 to assume its collapsed configuration more easily. If the support wires 430 are made stiff enough, the electrode structure 310 together with the stabilizer 400(1) can assume their collapsed configurations without the use of the sheath 300. In this case, the sheath 300 is optional and the ablation catheter 104 does not include the sheath 300. In an alternative embodiment, the support wires 430 are preformed to have a bent shape that flares away from a centerline 432 at the distal end 306 of the catheter member 302. In this case, the stabilizer 400(1) will assume a collapsed configuration when resided within a lumen of a sheath 300, and will have a tendency to open into the expanded configuration when it extends distally from the sheath 300. Such configuration has the benefit of allowing the electrode structure 310 to assume its expanded configuration more easily.
The electrode structure 310(7) does not include an expandable-collapsible body, but rather a rigid cap-shaped electrode 460 mounted to the distal tip of the catheter member 462. The electrode structure 310(7) further comprises a RF wire 468 that is electrically coupled between the electrode 460 and the electrical connector 362 on the handle assembly 461. The RF wire 468 extends tlrough a lumen 466 of the catheter member 462. The stabilizer 400(4) includes one or more vacuum lumens 470 (in this case, two) embedded within the wall of the catheter member 462. The distal ends of the vacuum lumens 470 terminate in vacuum ports 472, and the proximal ends of the vacuum lumens 470 are in fluid communication with the vacuum port 408 on the handle assembly 461.
It should be noted that the ablation device that can be used with the system 100 should not be limited to the embodiments of the ablation catheters 104(l)-104(4) discussed previously, and that other ablation devices known in the art may also be used. For examples, ablation catheters such as modified versions of those described in U.S. Pat. Nos. 5,800,432, 5,925,038, 5,846,239 and 6,454,766 B1, can be used with the system 100.
FIG. 27A shows an embodiment of a mapping catheter 700(1) that may be used with the system 100 for sensing signals on a surface of a heart. The mapping
catheter 700 includes an actuating sheath 712 having a lumnen 713, and a catheter member 708 slidably disposed within the lumen 713 of the sheath 712. The catheter member 708 comprises a proximal end 709 and a distal end 710, and an electrode array structure 702 mounted to the distal end 710 of the catheter member 708. The electrode array structure 702 includes a plurality of resilient spline elements 704 , with each spline element 704 carrying a plurality of mapping electrodes 706. Each of the spline elements 704 further includes a vacuum port 716 coupled to the vacuum 732 (shown in FIG. 1) via a lumen (not shown) carried within the spline element 704. The vacuum ports 716 are configured to apply a vacuum force to stabilize the array structure 702 relative to tissue as the mapping electrodes 706 sense electrical signals at the tissue. The number of spline elements 704 and electrodes 706 may vary, but in the illustrated embodiment, there are eight spline elements 704, with four mapping elements 706 on each spline element 704. The array 702 is configured to assume an expanded configuration, as shown in FIG. 27A, when it is outside the sheath 712. The size and geometry of the array 702 are configured such that the array 702 can at least partially cover the epicardial surface of a heart when it is in its expanded configuration. Because the mapping catheter 700(1) is not configured to be steered through vessels, as in the case with conventional mapping catheters, the array 702 can be made relatively larger to carry more mapping electrodes 706. The array 702 is also configured to be brought into a collapsed configuration by retracting the array 702 (i.e., proximally moving a handle 714 secured to the probe 708) into the lumen of the sheath 712 (FIG. 27B).
In the illustrated method, the mapping catheter 700(l) is configured to sense electrical signals at an exterior surface of the heart 802. Performing signal sensing on the exterior of the heart 802 is beneficial in that the physician can readily move the mapping catheter 700(1) around the heart 802 to obtain data at different locations on the heart 802. Once a target site is determined, it can then be marked with a biocompatible surgical ink, which can be visualized by a conventional imaging device. For example, surgical ink can be delivered through an orifice of a catheter to mark the target site. Performing signal sensing on the exterior of the heart 802 also reduces the risk of blocking a blood vessel and/or puncturing a vessel associated with mapping procedures that require a catheter steered through vessels. Alternatively, instead of performing signal sensing on the exterior of the heart 802, a suitable mapping catheter may be inserted through a vein or artery, steered to an interior of the heart 802, and be used to map electrical signals from within the heart 802 using a conventional method. In an alternative embodiment, the determination of the location of the target tissue is determined using a conventional method in a separate procedure before the operation.
By placing the ground catheter 106(2) within the heart 802, the path of the current delivered by the electrode structure 310 is shorter, i.e., RF energy is directed from the electrode structure 310, across the target tissue, and to the electrode elements 636 of the ground catheter 106(2), thereby efficiently forming a transmural lesion 808 at the target tissue. Such configuration also allows the target tissue to be ablated without a significant dissipation of RF eneigy to adjacent tissues.
FIGS. 33A to 33C show representative lesion patterns formed inside the right atrium based upon these landmarks. FIG. 33A shows a representative lesion pattern L that extends between the superior vena cava (SVC) and the tricuspid valve annulus (TVA). The lesion L can be created in a quasi-bipolar maimer by directing ablation energy to the ablation catheter 104 placed at the LA, while the ground catheter 106 is placed inside the LV or the RV. In an alternative embodiment, the positions of the ablation catheter 104 and the ground catheter 106 maybe exchanged.
an ablative element mounted to the distal end of the elongate member; and
a protective element mounted to the distal end of the elongate member, wherein the protective element at least partially covers the ablative element.
4. The medical probe of claim 2, wherein the cage assembly comprises a ring element that coaxially surrounds and is slidable relative to the elongate member.
5. The medical probe of claim 4, wherein one of the proximal end and the distal end of the cage assembly comprises the ring element, and the other of the proximal end and distal end is fixedly secured to the elongate member.
6. The medical probe of claim 5, wherein the proximal end of the cage assembly comprises the ring element, and the distal end of the cage assembly is fixedly secured to the elongate member.
7. The medical probe of claim 5, wherein the distal end of the cage assembly comprises the ring element, and the proximal end of the cage assembly is fixedly secured to the elongate member.
8. The medical probe of claim 1, further comprising a sleeve having a lumen in which the elongate member is slidably disposed.
9. The medical probe of claim 1, wherein the protective element has an expanded configuration when outside the lumen of the sleeve, and a collapsed configuration when inside the lumen of the sleeve.
10. The medical probe of claim 1, wherein the protective element is made from an electrically non-conductive material.
11. The medical probe of claim 1, wherein the protective element comprises a braided or woven structure.
12. The medical probe of claim 1, further comprising a handle assembly secured to a proximal end of the elongate member.
13. The medical probe of claim 12, wherein the handle assembly comprises a steering mechanism.
14. The medical probe of claim 1, wherein the elongate member is a catheter member.
15. The medical probe of claim 1, wherein the ablative element is an electrode.
16. The medical probe of claim 1, further comprising:
an additional ablative element mounted to the distal end of the elongate member; and
an additional protective element mounted to the distal end of the elongate member, the additional protective element at least partially covering the additional ablative element.
17. The medical probe of claim 1, further comprising:
an additional ablative element mounted to the distal end of the elongate member, wherein the protective element at least partially covers the ablative element and the additional ablative element.
18. The medical probe of claim 1, wherein the protective element completely covers the ablative element.
19. A method of treating tissue in a body, comprising:
inserting an ablative element in the body;
placing the ablative element adjacent the tissue; and
maintaining a distance between the ablative element and the tissue using a protective catheter element that circumscribes at least a portion of the ablative element.
20. The method of claim 19, wherein the ablative element is carried at a distal end of an elongate member, and the inserting comprises inserting the distal end of the elongate member into the body.
21. The method of claim 19, wherein the protective catheter element comprises a cage assembly.
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