Patent Description:
Ablation of cardiac tissue has been used to treat cardiac arrhythmias. Ablative energies are typically provided to cardiac tissue by a tip portion which can deliver ablative energy alongside the tissue to be ablated. Some of these catheters administer ablative energy from various electrodes located on three-dimensional structures. Ablative procedures incorporating such catheters may be visualized using fluoroscopy.

Ablation catheters with expandable energy-delivery elements are previously known from <CIT>, <CIT> and <CIT>.

While the specification concludes with claims, which particularly point out and distinctly claim the subject matter described herein, it is believed the subject matter will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which:.

More specifically, "about" or "approximately" may refer to the range of values ±<NUM>% of the recited value, e.g., "about <NUM>%" may refer to the range of values from <NUM>% to <NUM>%.

Ablation of cardiac tissue to correct a malfunctioning heart is a well-known procedure for implementing such a correction. Typically, to successfully ablate, cardiac electropotentials need to be measured at various locations of the myocardium. In addition, temperature measurements during ablation provide data enabling the efficacy of the ablation to be measured. Pulmonary vein isolation (PVI) is a technique using a balloon to form a circumferential lesion in the pulmonary veins via a balloon end effector which applies heat ablation via electrodes mounted on the outer surface of the balloon or by cryogenic cooling fluid pumped inside the balloon. With cryogenic cooling, the very low temperature of the cryofluid causes the balloon outer surface to adhere strongly to the cardiac tissues (i.e., the sticky icicle effect) such that a seal is formed between the balloon surface and the tissues. With electrical ablation, there is no icicle effect and hence the operator must apply constant pressure to the balloon to ensure good contact despite the pumping of blood through the veins.

We have devised a balloon type medical catheter <NUM> that can be used for pulmonary vein isolation via electrical ablation (radiofrequency or irreversible electroporation). As shown in <FIG>, catheter <NUM> is made of two parts extending along a longitudinal axis L-L: a handle assembly 100A and end effector 100B. Handle assembly 100A includes handle <NUM> provided at a proximal location (proximal being nearest to the operator) with a rotatable wheel <NUM> that rotates a worm wheel to allow for pinion to translate at least one or more puller wires. The handle <NUM> also include a pusher or puller member <NUM> that allows for an actuator shaft <NUM> disposed inside the catheter shaft <NUM> to be translated along the longitudinal axis L-L. End effector 100B includes the catheter shaft in the form of a tubular member <NUM> extending from the proximal handle 100A or a proximal portion 10A to a distal portion 10B along a longitudinal axis L-L. Mounted in the tubular shaft <NUM> are magnetic location sensing coils <NUM> (dual axes or triple axes coils) and mounted on the shaft <NUM> are impedance electrodes <NUM> that can be used in conjunction with magnetic sensing coils <NUM> to provide location information of the electrodes <NUM> (and therefore the location of tubular shaft <NUM>). Techniques for location sensing with magnetic coils <NUM> and impedance electrodes <NUM> are well known in the art and will be discussed in context with reference to <FIG>.

Disposed partially inside the tubular member <NUM> is an actuator shaft <NUM> designed to be movable relative to tubular member <NUM> along axis L-L via pusher <NUM>. Attached to the distal end <NUM> of actuator <NUM> is first balloon <NUM> connected to the distal end <NUM> via a first balloon distal portion <NUM> coupled to the actuator shaft distal end <NUM>. The first balloon <NUM> is coupled to a slidable coupler <NUM> disposed proximal to the distal end <NUM>. The first balloon has a first balloon proximal portion <NUM> coupled to the slidable coupler so that there is no movement between first balloon proximal portion <NUM> and the coupler <NUM>. A second balloon <NUM> is provided proximal to the coupler <NUM>. The second balloon has a second balloon proximal portion <NUM> coupled to the tubular member <NUM> and a second balloon distal portion <NUM> coupled to the slidable coupler <NUM>. In this exemplary embodiment, the actuator shaft may include a through passage to allow for a guidewire <NUM> to extend through tubular member <NUM> all the way to the handle <NUM>.

Referring to the inset of <FIG>, it can be seen that the coupler <NUM> is used to connect the first balloon <NUM> and the second balloon <NUM> while allowing the coupler <NUM> to be slidable along axis L-L on actuator shaft <NUM>. It should be noted that coupler <NUM> has a coupler body <NUM> with an opening <NUM> extending along the longitudinal axis through the coupler body <NUM>. The through opening <NUM> allows for movement of the coupler body <NUM> relative to the actuator shaft <NUM> and provide a sealing fit or sliding seal <NUM> between the coupler body <NUM> with the actuator shaft <NUM>.

First balloon <NUM> has its proximal portion <NUM> captured between a ring retainer <NUM> and the outer surface of coupler <NUM>. That is, the first balloon <NUM> is physically connected to the slidable coupler with a coupling ring <NUM> disposed over a proximal end portion <NUM> of the first balloon <NUM> and the coupler body <NUM> of the slidable coupler <NUM> so that the proximal end portion of the first balloon is captured between the coupling ring <NUM> and the coupler body <NUM>. Once the retainer <NUM> is placed over the balloon distal portion <NUM>, the retainer <NUM> can be connected to the coupler body <NUM> via adhesive bonding or mechanical crimping. The distal portion <NUM> of first balloon can be captured between the actuator shaft and a retainer nosepiece <NUM> which may have a similar configuration to retainer ring <NUM> so that nosepiece <NUM> can be crimped or bonded via adhesive to the actuator shaft. Second balloon <NUM> has its distal portion <NUM> captured between ring retainer <NUM> and the outer surface of coupler <NUM> and connected to the coupler via adhesive or mechanical retention techniques. The proximal portion <NUM> of second balloon <NUM> is captured inside the tubular member <NUM> via a suitable retention technique e.g., adhesives or polymer reflow). Retainer rings <NUM> as well as nose piece <NUM> can be electrically connected (via electrical traces or wires disposed in actuator shaft) to a.

The coupler <NUM> can be coupled to at least one puller wire 60A and configured to be movable relative to shaft <NUM> such that the coupler <NUM> is forced to slide along actuator shaft <NUM>. That is, as the at least one puller wire 60A is retracted towards the proximal portion of the tubular member <NUM>, the slidable coupler <NUM> translates relative to the actuator shaft <NUM>. While two puller wires are shown diametrically disposed for symmetry, only one wire is necessary to allow for translation of the coupler <NUM>. The puller wire 60A or 60B can be insert molded bonded to the coupler <NUM>.

As noted earlier, actuator shaft <NUM> includes a first passage <NUM> to allow insertion of a guide wire <NUM> into the first passage <NUM> and a second passage <NUM> generally parallel with the first passage <NUM> to allow fluid <NUM> to flow through the second passage <NUM> and exit through at least one peripheral port <NUM>. The second passage <NUM> is connected to an irrigation pump with its own valve to control flow of fluid into second passage <NUM> and out into the second balloon. Also built into the actuator shaft is a third passage <NUM> to allow fluid flow to the first balloon <NUM> independently of fluid flow to the second balloon <NUM>. The third passage <NUM> is also connected to the irrigation pump via its own valves to control flow of fluid into third passage <NUM> and balloon <NUM>. As shown in <FIG>, the first and second passages are separated by divider block <NUM> that extends all the way back to respective valves (not shown) of the second and third passageways. The second and third passages allow for independent inflation of the balloons as will be discussed later with respect to the modes of operation.

With reference to <FIG>, actuator <NUM> has an outer diameter OD20 as measured diametrically between its outer surfaces that is slightly less an inside diameter ID52 of inside surface 52A. Disposed between this gap, indicated as "t" is a suitable seal <NUM> such as a solid type of lubricant coating that ensures a substantial sliding seal between the actuator shaft <NUM> and the coupler inside surface 52A. In the preferred embodiment, the thickness of "t" for the sliding seal <NUM> is approximately <NUM>-<NUM> microns in the form of a coating <NUM> on the on an outer surface 20A of the actuator shaft <NUM>. The thickness t should be a thickness t greater than a difference of an outside diameter of the actuator shaft OD20 and an inside diameter ID52 of the coupler body <NUM>. Alternatively, or in addition thereto, a coating <NUM> can be disposed on an inside surface 52A of the coupler body <NUM> having a thickness t greater than a difference of an outside diameter of the actuator shaft and an inside diameter ID52 of the coupler body <NUM>. Alternatively, the coating <NUM> can be eliminated and instead, the actuator shaft can be made of a lubricious material e.g., Teflon with the outer diameter OD20 being substantially the same or slightly larger than the inside diameter ID52 of coupler body <NUM> so that a sufficiently tight seal can be formed between the actuator shaft <NUM> and the coupler body <NUM> while still allowing for movement of coupler <NUM> relative to actuator shaft <NUM>. In yet another variation where the outside diameter OD20 of actuator shaft is the same or less than the inside diameter ID52 of coupler body <NUM>, at least one O-ring receiving groove can be formed on the inside surface of the coupler, as shown in <FIG> to receive O-ring 60A. A second O-ring groove can also be provided to receive a second O-ring 60B.

The balloon can be assembled as follows. The actuator shaft <NUM> is inserted into the second balloon <NUM>, coupler <NUM> (with retainer rings <NUM> mounted on coupler <NUM>) and first balloon <NUM> with these components mounted on a jig (not shown) to ensure the correct spacings between the balloons and coupler. Once the correct spacings are made, the proximal portion <NUM> of second balloon <NUM> can be bonded to tubular shaft <NUM>. Retainer ring <NUM> is bonded to the distal portion <NUM> of second balloon <NUM> and the coupler <NUM> while the other retainer ring <NUM> is bonded to the proximal portion <NUM> of first balloon <NUM>. The nosepiece can be used to bond the distal portion <NUM> of first balloon to a distal portion of actuator shaft <NUM>.

Referring to <FIG>, it can be seen that the second balloon <NUM> may have a plurality of electrodes 80A-80E disposed on an outer surface <NUM> of the second balloon <NUM>. In an exemplary embodiment, the second balloon may have eight to ten electrodes disposed equiangularly about the longitudinal axis on the outer surface <NUM> of the second balloon. In yet another embodiment shown in <FIG>, the first balloon <NUM> may include a plurality of electrodes 90A-90F disposed on an outer surface <NUM> of the first balloon. In <FIG>, the first balloon <NUM> includes a plurality of electrodes 90A-90J disposed on an outer surface <NUM> of the first balloon and the second balloon <NUM> also includes a plurality of electrodes 80A-80J disposed on an outer surface <NUM> of the second balloon <NUM>. It should be noted that pores <NUM> can be provided through the balloon surface to allow irrigation fluid to escape out of the balloon as a way to irrigate the electrode during ablation. In <FIG>, each balloon may have eight to twelve electrodes such as the ten-electrode configuration described and illustrated in <CIT>.

In the preferred example of <FIG>, the first balloon does not have any electrodes (and therefore no pores <NUM> are provided) while ablation electrodes are provided on the second balloon <NUM> with pores for irrigating the electrodes.

<FIG> illustrate at least three configurations that can be achieved by the invention. In <FIG>, the first balloon <NUM> is shown slightly inflated with the second balloon <NUM> deflated to illustrate the ability of the inventive concept to utilize independent inflation. In the intended use, the first balloon <NUM> (slightly inflated with the actuator shaft fully extended to its maximum length Lmax would be inserted into a pulmonary vein to a sufficient length inside the pulmonary vein and inflated slightly (<FIG>) to ensure the correct insertion length into the pulmonary vein. The insertion length can be determined via impedance measurement with the magnetic location sensors <NUM> and via impedance measurement of electrodes <NUM>, nosepiece <NUM> and the retainer rings <NUM> so that when the second balloon is inflated all of the electrodes <NUM> on the second balloon would have good contact with the pulmonary vein before electrical energy is applied. A discussion on magnetic sensors <NUM> with impedance electrodes <NUM>, <NUM> and <NUM> are provided with reference to <FIG>.

Once the first balloon <NUM> is positioned at the desired position, the tubular shaft <NUM> can be remain stationary while the first balloon <NUM> is fully inflated via port 28B to its maximum diameter. As the first balloon is inflated, the length of the first balloon <NUM> shortens causing the actuator shaft <NUM> to retract with respect to the coupler <NUM>. Once fully inflated, the first balloon <NUM> will remain locked to the walls of the pulmonary vein PV. At this time, the second balloon can be inflated with fluid <NUM> via port 28A (independent from port 28B. Due to porosity of the balloon, some fluid <NUM> will escape the interior of second balloon <NUM>. The operator can adjust the size of second balloon <NUM> by holding tube <NUM> stationary while retracting shaft <NUM>. Because the first balloon <NUM> does not have pores, inflation pressure remains constant and therefore its maximum outer diameter ODlmax remains constant, adjustment of the shaft <NUM> proximally causes the slidable coupler <NUM> to automatically adjust proximally shortening the longitudinal length of second balloon <NUM> thereby increasing its diameter to a maximum diameter of OD2max. At this juncture, the operator can apply ablation energy (as illustrated and described in relation to <FIG>) to the electrodes <NUM> on the second balloon <NUM>'. Once the ablation is completed, the first balloon <NUM> can be deflated, shown here in <FIG> with fluid being evacuated from the ports 28B. The second balloon <NUM> can remain inflated so that impedance measurement to assess the effectiveness of the ablation can be performed. Alternatively, the second balloon <NUM> can also be deflated at the same time as the first balloon <NUM>.

<FIG> illustrates a prototype in a different sequence of inflation as another technique that can be utilized by one skilled in the art. In <FIG>, the first balloon <NUM> is not inflated to allow for entry into a small model of the pulmonary vein PV in <FIG>. The second balloon <NUM> can be slightly inflated as the first balloon approaches the PV. In <FIG>, the first balloon <NUM> is fully inside the PV while the second balloon <NUM> is now presenting its equator (and therefore ablation electrodes <NUM> [not shown]) for ablation of the entrance to the pulmonary vein PV. At this stage, the second balloon <NUM> can be inflated first then the first balloon <NUM> can be inflated next to ensure securement of the second balloon to the PV. Alternatively, the first balloon <NUM> can be inflated first and the second balloon <NUM> can be inflated next and thereafter ablation energy can be delivered to the electrodes as described in <FIG>.

<FIG> is pictorial illustration of a mapping system <NUM>, in accordance with an exemplary mode of the present disclosure. The system shown here includes a catheter shaft <NUM> configured to be inserted into a body part (e.g., a chamber of a heart <NUM>) of a living subject (e.g., a patient <NUM>). A physician <NUM> navigates the end effector 100B described and illustrated herein to a target location in the heart <NUM> of the patient <NUM>, by manipulating a deflectable segment of the end effector. Patient <NUM> is placed in a magnetic field generated by a pad containing multiple magnetic field generator coils <NUM>, which are driven by a unit <NUM>. The magnetic field generator coils <NUM> are configured to generate respective alternating magnetic fields, having respective different frequencies, into a region where a body-part (e.g., the heart <NUM>) of a living subject (e.g., the patient <NUM>) is located. The magnetic coil sensors <NUM> are configured to output electrical signals responsively to detecting the respective magnetic fields. For example, if there are nine magnetic field generator coils <NUM> generating nine respective different alternating magnetic fields with nine respective different frequencies, the electrical signals output by the magnetic coil sensors <NUM> will include components of the nine different frequency alternating magnetic fields. The magnitude of each of the magnetic fields varies with distance from the respective magnetic field generator coils <NUM> such that the location of the magnetic coil sensors <NUM> may be determined from the magnetic fields sensed by the magnetic coil sensors <NUM>. Therefore, the transmitted alternating magnetic fields generate the electrical signals in sensors <NUM>, so that the electrical signals are indicative of position and orientation of the magnetic coil sensors <NUM>. It is noted that the magnetic coil sensors can be triple-axis-sensor to measure three different axes of orientation.

In some exemplary modes, the processing circuitry <NUM> uses position-signals received from the electrodes <NUM> or body surface electrodes <NUM>, and the magnetic sensor <NUM> to estimate a position of the assembly 100B inside a body part, such as inside a cardiac chamber. In some exemplary modes, the processing circuitry <NUM> correlates the position signals received from the electrodes <NUM> and <NUM> with previously acquired magnetic location-calibrated position signals, to estimate the position of the assembly 100B inside the body part. The position coordinates of the electrodes <NUM> may be determined by the processing circuitry <NUM> based on, among other inputs, measured impedances, voltages or on proportions of currents distribution, between the electrodes <NUM> and the body surface electrodes <NUM>.

The method of position sensing using current distribution measurements and/or external magnetic fields is implemented in various medical applications, for example, in the Carto® system, produced by Biosense Webster Inc. (Irvine, California), and is described in detail in <CIT>, <CIT>, <CIT>,<CIT>,<CIT>,<CIT>, <CIT>, <CIT>, and <CIT>, in <CIT>, and in U. Patent Application Publications shown here <CIT> and shown here <CIT>.

The Carto®<NUM> system applies Active Current Location (ACL) which is a hybrid current-distribution and magnetic-based position-tracking technology. In some exemplary modes, using ACL, the processing circuitry <NUM> estimates the positions of the electrodes <NUM>. In some exemplary modes, the signals received from the electrodes <NUM>, <NUM> are correlated with a current-to-position matrix (CPM) which maps current distribution ratios (or another electrical value) with a position that was previously acquired from magnetic location-calibrated position signals. The current distribution ratios are based on measurements of the body surface electrodes <NUM> of current flowing from the electrodes <NUM> to the body surface electrodes <NUM>.

In some exemplary modes, to visualize catheters which do not include a magnetic sensor, the processing circuitry <NUM> may apply an electrical signal-based method, referred to as Independent Current Location (ICL) technology. In ICL, the processing circuitry <NUM> calculates a local scaling factor for each voxel of the volume in which catheters are visualized. The factor is determined using a catheter with multiple electrodes having a known spatial relationship, such as a lasso-shaped catheter. However, although yielding accurate local scaling (e.g., over several millimeters), ICL is less accurate when applied to a volume of a whole heart chamber, whose size is in the order of centimeters. The ICL method, in which positions are calculated based on current distribution proportions can have errors and may yield a distorted shape of the assembly 100B, due to the non-linear nature of the current-based ICL space. In some exemplary modes, the processing circuitry <NUM> may apply the disclosed ICL method to scale ICL space and the assembly 100B shape into a correct one, based on known smaller scale distances between electrodes 80A-80J.

Processing circuitry <NUM>, typically part of a general-purpose computer, is further connected via a suitable front end and interface circuits <NUM>, to receive signals from body surface-electrodes <NUM>. Processing circuitry <NUM> is connected to surface-electrodes <NUM> by wires running through a cable <NUM> to the chest of patient <NUM>. The catheter 100A includes a connector <NUM> disposed at the proximal end 100A of the insertion tube <NUM> for coupling to the processing circuitry <NUM>.

In some exemplary modes, processing circuitry <NUM> renders to a display <NUM>, a representation <NUM> of at least a part of the catheter 100a and an anatomical map or body-part, (e.g., from a mapping process or from a scan (e.g., CT or MRI) of the body-part previously registered with the system shown here), responsively to computed position coordinates of the insertion tube <NUM> and the electrodes 80A-80J on the ablation balloon.

Processing circuitry <NUM> is typically programmed in software to carry out the functions described herein. The software may be downloaded to the computer in electronic form, over a network, for example, or it may, alternatively or additionally, be provided and/or stored on non-transitory tangible media, such as magnetic, optical, or electronic memory. The system shown here may also include a memory <NUM> used by the processing circuitry <NUM>. By virtue of the components and system described and illustrated herein, a method of operating a balloon type ablation effector can be achieved, however, this method itself is not claimed. The non-claimed method can be achieved with an end effector having a tubular member <NUM> extending from a proximal portion 10A to a distal portion 10B along a longitudinal axis L-L with an actuator shaft <NUM> extending from inside the tubular member <NUM> to an actuator shaft distal end <NUM>, the actuator shaft having a plurality of fluid ports. The end effector 100B includes a first balloon <NUM> comprising a first balloon distal portion <NUM> coupled to the actuator shaft distal end <NUM> and a first balloon proximal portion <NUM> coupled to a slidable coupler <NUM>. The end effector <NUM> also includes a second balloon <NUM> comprising a second balloon proximal portion <NUM> coupled to the tubular member <NUM> and a second balloon distal portion <NUM> coupled to the slidable coupler <NUM>. The steps in the non-claimed method include extending the actuator shaft in a distal direction to a maximum length of the actuator shaft relative to the tubular member; inflating at least one of the first and second balloons with fluid via fluid ports so the first balloon reaches a first balloon outer diameter and the second balloon reaches a second balloon diameter increasing the second balloon outer diameter of the second balloon to a maximum outer diameter and decreasing the first balloon outer diameter of the first balloon by retraction of the coupler body relative to the tubular shaft.

Other steps include increasing the first balloon outer diameter to a maximum outer diameter by retraction of the actuator shaft along the longitudinal axis towards the proximal portion of the tubular shaft.

The teachings, expressions, embodiments, examples, etc. described herein should not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may be combined should be clear to those skilled in the art in view of the teachings herein.

Claim 1:
A balloon type medical apparatus (<NUM>) comprising:
a tubular member (<NUM>) extending from a proximal portion to a distal portion along a longitudinal axis;
an actuator shaft (<NUM>) extending from inside the tubular member to an actuator shaft distal end;
a first balloon (<NUM>) comprising a first balloon distal portion coupled to the actuator shaft distal end and a first balloon proximal portion coupled to a slidable coupler (<NUM>);
a second balloon (<NUM>) comprising a second balloon proximal portion coupled to the tubular member and a second balloon distal portion coupled to the slidable coupler (<NUM>), in which the slidable coupler includes:
a coupler body (<NUM>) with an opening (<NUM>) extending along the longitudinal axis through the coupler body, the opening configured to allow movement of the coupler body relative to the actuator shaft and provide a sealing fit between the coupler body with the actuator shaft.