Patent Description:
Pulmonary vein isolation (PVI) is the cornerstone of treating atrial fibrillation, and is used for both Paroxysmal AF (PAF) and Persistent AF (PsAF). However, while the results of PVI for patients with PAF are consistently good, the results for patients with PsAF are much more variable. Thus, some patients with PsAF do well with just PVI, while other patients in the category need more treatment than just PVI.

<CIT> describes a method of creating a lesion in cardiac tissue where the method includes deploying a distal treatment section of an ablation catheter into a heart chamber and manipulating the distal treatment section against the cardiac tissue and into a curved shape that encloses a plurality of vessel entries in the heart chamber. The method further includes commencing a first application of ablation energy from the distal treatment section to the cardiac tissue and halting the first application of ablation energy to the cardiac tissue. The first application of ablation energy causes formation of a first continuous lesion in the cardiac tissue that encloses the plurality of vessel entries.

"The HATCH and CHA2DS2-VASc scores: Prognostic value in pulmonary vein isolation" hypothesizes that both the HATCH and CHA<NUM>DS<NUM>VASc scores may predict failure of Afib ablation.

To date, typically for patients with persistent atrial fibrillation (PsAF), there has not been a tool that categorizes patients with atrial fibrillation as just needing PVI (pulmonary vein isolation), or needing more than just PVI.

The inventors have found that the CHA<NUM>DS<NUM>-VASc score for a patient may be used as a metric for determining whether PVI alone may be sufficient for the patient, or whether more treatment, i.e., further ablation outside of
the pulmonary vein, may be required. (The score is described in detail in the Detailed Description of the Embodiments section below. ) If the patient score is less than a preset value, which depends on the gender of the patient, then PVI alone may be sufficient to treat the atrial fibrillation of the patient. If the patient score is greater than or equal to the preset value, then further treatment, i.e. ablation other than PVI alone, may be necessary to treat the atrial fibrillation.

(It should be noted that the CHA<NUM>DS<NUM>-VASc score is at present used to predict/estimate the risk of stroke in patients with atrial fibrillation. A high score corresponds to a greater risk of stroke, so that typically in this case anticoagulation treatment is required.

In an embodiment a physician ascertains a CHA<NUM>DS<NUM>-VASc score for the patient. The physician then inserts a probe into the patient, and navigates the probe so that a distal end of the probe contacts a pulmonary vein of the patient.

The physician then uses the distal end to apply a suitable energy modality, typically radio-frequency energy or pulsed field ablation (also known as irreversible electroporation), to ablate the pulmonary vein so that pulmonary vein isolation is achieved. The achievement of pulmonary vein isolation is determined by the physician (who may also be the operator of the probe) usually with a mapping probe to detect for the absence of electrical signals conducted between the atrium and the subject vein or by pacing the coronary sinus and detecting entry block of signals. When the CHA<NUM>DS<NUM>-VASc score is less than the preset value referred to above, the physician may cease ablation of the pulmonary vein and withdraw the probe from the vein. When the CHA<NUM>DS<NUM>-VASc score is greater than or equal to the preset value, the physician may need to perform further ablation outside the vein. The physician typically performs the above procedure sequentially on all of the patient pulmonary veins.

<FIG> is a schematic, pictorial illustration of a medical system <NUM> comprising a medical probe <NUM> and a control console <NUM>, and <FIG> is a schematic pictorial illustration of a distal end <NUM> of the medical probe. Probe <NUM> is used as a catheter, and is also referred to herein as catheter <NUM>. Medical system <NUM> may be based, for example, on the CARTO® system, produced by Biosense Webster Inc. of <NUM> Technology Drive, Irvine, CA <NUM> USA. In embodiments described hereinbelow, medical probe <NUM> is used for ablation of tissue in a heart <NUM> of a patient <NUM> (also referred to herein as a subject). Alternatively, medical probe <NUM> may be used, mutatis mutandis, for other therapeutic and/or diagnostic purposes in the heart or in other body organs.

Probe <NUM> comprises an insertion tube <NUM> and a handle <NUM> coupled to a proximal end of the insertion tube. During a medical procedure, a medical professional <NUM> can insert probe <NUM>, via a prepositioned sheath <NUM>, through the vascular system of patient <NUM> so that distal end <NUM> of the medical probe enters a chamber of heart <NUM>. Upon distal end <NUM> entering the chamber of heart <NUM>, medical professional <NUM> can deploy a balloon <NUM>, described in more detail below, that is affixed to distal end <NUM>, and the medical professional can manipulate handle <NUM> to position the balloon in order to engage myocardial tissue at a desired location or locations. Balloon <NUM> is typically formed from bio-compatible material such as polyethylene terephthalate (PET), polyurethane, nylon, or silicone.

In the configuration shown in <FIG>, control console <NUM> is connected, by a cable <NUM>, to body surface electrodes, which typically comprise adhesive skin patches <NUM> that are affixed to patient <NUM>. Control console <NUM> also comprises a processor <NUM> which is coupled to a number of modules, the modules comprising software and/or hardware components. Details and functionality of the modules are described below.

Processor <NUM>, in conjunction with a current tracking module <NUM>, determines location coordinates of distal end <NUM> inside heart <NUM> based on impedances and/or currents measured between adhesive skin patches <NUM> and microelectrodes <NUM> and/or ablation electrodes <NUM> (<FIG>) that are affixed to balloon <NUM> (typically as gold overlaying the balloon). In addition to being used as location sensors during a medical procedure, microelectrodes <NUM> (also referred to herein simply as electrodes) may perform other tasks such as measuring electrical activity of heart <NUM> and/or pacing of the heart.

Alternatively or additionally, processor <NUM> determines location coordinates of distal end <NUM> based on signals received by an electromagnetic (EM) tracking module <NUM>. The signals are generated by a magnetic sensor <NUM> incorporated into a tubular shaft <NUM> of distal end <NUM>, and the sensor generates its signals in response to magnetic fields, transmitted by alternating magnetic field radiators <NUM> positioned beneath patient <NUM>, traversing the sensor.

Processor <NUM> may comprise real-time noise reduction circuitry <NUM> typically configured as a field programmable gate array (FPGA), followed by an analog-to-digital (A/D) signal conversion integrated circuit <NUM>. The processor can pass the signals from A/D circuit <NUM> to another processor and/or can be programmed to determine the location coordinates referred to above.

Impedance and current-based location tracking techniques are described, for example, in <CIT>, <CIT>, and <CIT>. Electromagnetic location tracking techniques are described, for example, in <CIT>, <CIT>, and <CIT>. The methods of location sensing described hereinabove are implemented in the above-mentioned CARTO® system and are described in detail in the patents cited above.

Prior to insertion of probe <NUM> into patient <NUM>, processor <NUM> acquires an electroanatomical map <NUM> of heart <NUM>. Typically data for the map is acquired using a probe other than probe <NUM>, such as a focal catheter which is configured to be both tracked by module <NUM> and to acquire signals from regions of heart chambers contacted by the catheter. An example of a focal catheter is described below with reference to <FIG>. Typically, although not necessarily, processor <NUM> uses the signals to determine local activation times (LATs) of the heart chambers, and incorporates the LATs into map <NUM>. Map <NUM> is stored in a memory <NUM> accessible by processor <NUM>, and during the procedure the processor can present map <NUM> to medical professional <NUM> on a display <NUM>.

During the procedure using probe <NUM>, processor <NUM> may overlay an icon, representing the location of distal end <NUM> (determined as described above) on map <NUM>, so enabling professional <NUM> to track the distal end.

Memory <NUM> may comprise any suitable volatile and/or non-volatile memory, such as random access memory or a hard disk drive. In some embodiments, medical professional <NUM> can manipulate map <NUM> using one or more input devices <NUM>. In alternative embodiments, display <NUM> may comprise a touchscreen that can be configured to accept inputs from medical professional <NUM>, in addition to presenting map <NUM>.

In the configuration shown in <FIG>, balloon <NUM> (shown inflated) is affixed to tubular shaft <NUM> that terminates distal end <NUM>. Balloon <NUM> is configured to extend from sheath <NUM>, and to deploy into a left atrium <NUM> of heart <NUM> so that electrodes <NUM> contact an ostium <NUM> of a pulmonary vein <NUM>. The contact may be verified by any convenient means known in the art, such as by noting a change of impedance between the electrodes and patches <NUM>.

Control console <NUM> also comprises an inflation module <NUM> and an ablation module <NUM>. Ablation module <NUM> is configured to monitor and control ablation parameters such as the level and the duration of ablation power (e.g., radio-frequency (RF) energy) conveyed to ablation electrodes <NUM> from ablation module <NUM>, and module <NUM> typically comprises an RF generator <NUM> for this purpose.

Inflation module <NUM> is configured to monitor and control the inflation of balloon <NUM>. In some embodiments, inflation module <NUM> can use irrigation fluid to inflate balloon <NUM>, and control the inflation of the balloon by controlling a flow rate of the irrigation fluid into the balloon. In these embodiments balloon <NUM> typically comprises multiple small fenestrations (not shown) that allow the irrigation fluid to exit the balloon. These fenestrations are typically <NUM>-<NUM> millimeters in diameter.

As is described herein, probe <NUM> is used to ablate elements of PV <NUM>. However, other methods for processor <NUM> to ablate elements of PV <NUM> are also considered to be comprised within the scope of the present invention. For example, probe <NUM>, with a distal end exemplified by distal end <NUM>, operates as a balloon catheter, while another type of probe, such as a focal catheter, may also be used for the ablation. An example of a medical probe being formed as a focal catheter is provided in <FIG>, as described below.

<FIG> is a schematic pictorial illustration of a distal end <NUM> of a medical probe <NUM>, according to an alternative embodiment. Apart from the differences described below, the operation of distal end <NUM> is generally similar to that of distal end <NUM> (<FIG> and <FIG>), and elements indicated by the same reference numerals in both distal end <NUM> and <NUM> are generally similar in construction and in operation.

In contrast to distal end <NUM> of probe <NUM>, distal end <NUM> of probe <NUM> does not comprise a balloon. Rather distal end <NUM> is formed as a generically cylindrical extension <NUM> of shaft <NUM>. At the distal tip of extension <NUM> an electrode <NUM>, typically in the shape of a cup, is formed to cover the distal tip. Typically one or more other electrodes <NUM>, typically in the form of rings, surround extension <NUM>. As for electrodes <NUM>, electrode <NUM> is configured to operate as an ablation electrode, by being coupled to ablation module <NUM>. In addition, while electrodes <NUM> may also be configured to act as ablation electrodes by being coupled to module <NUM>, they are typically configured to be similar to electrodes <NUM>, i.e., to act as location sensors by being coupled to the current tracking module, and/or to measure electrical activity and/or provide pacing.

It will be understood that with distal end <NUM> probe <NUM> operates as a focal catheter, and the distal end may be tracked using module <NUM>. Alternatively or additionally, distal end <NUM> may comprise a magnetic sensor <NUM>, generally similar to sensor <NUM>, in which case distal end <NUM> may be tracked using EM tracking module <NUM>.

In embodiments, in addition to probe <NUM> or probe <NUM> being used to ablate patient <NUM>, processor <NUM> is coupled to a pulmonary vein isolation (PVI) module <NUM>. Module <NUM>, inter alia, stores a value of a CHA<NUM>DS<NUM>-VASc score for patient <NUM>, and the CHA<NUM>DS<NUM>-VASc score is described below with reference to <FIG>. Other functions of PVI module <NUM> are described with reference to the flowchart of <FIG>.

<FIG> is a schematic diagram illustrating a chart <NUM> of CHA<NUM>DS<NUM>-VASc, as it is presented to physician <NUM> on display <NUM>.

The chart of CHA<NUM>DS<NUM>-VASc illustrates eight conditions of patient <NUM> that physician <NUM> considers, before performing ablation on the patient. Each of the conditions is assumed to be present or absent. If absent, the condition is assigned a value of zero (<NUM>). If present, the condition has a value given by Table I:.

To evaluate the CHA<NUM>DS<NUM>-VASc score for patient <NUM>, the physician totals the values of all the conditions. For example, if patient <NUM> is a <NUM> year old male with diabetes mellitus, the CHA<NUM>DS<NUM>-VASc score is <NUM>.

The physician may enter the value of the CHA<NUM>DS<NUM>-VASc score into PVI module <NUM>, using controls <NUM>. As described in the flowchart of <FIG>, which illustrates steps of an algorithm stored in PVI module <NUM>, the CHA<NUM>DS<NUM>-VASc score is used by the PVI module to determine how ablation of patient <NUM> may to be performed.

The algorithm also uses the gender of patient <NUM>, and the physician may input the patient's gender to processor <NUM> by any convenient means, for instance by using touch screen buttons <NUM> or <NUM>, or by selecting the appropriate button with controls <NUM>.

<FIG> is a flowchart of steps of an algorithm stored in PVI module <NUM>. The algorithm is implemented by processor <NUM>, and comprises steps of a procedure followed for ablation of patient <NUM>, and the description assumes that probe <NUM> with distal end <NUM>, i.e., a balloon catheter, is used for the procedure. However, other probes, such as probe <NUM>, i.e., a focal catheter, may be used, and the use of such other probes is considered to be comprised within the scope of the present invention.

In an initial step <NUM>, physician <NUM> evaluates the CHA<NUM>DS<NUM>-VASc score of patient <NUM>, and stores the score in module <NUM>, as described above with reference to <FIG>. In the initial step the physician also inputs the gender of patient, as described above, to processor <NUM> and the processor uses the patient's gender to assign and record a preset value for the patient. If the patient is male the preset value is assigned to be <NUM>; if the patient is female the preset value is assigned to be <NUM>. The preset value is used in a comparison step <NUM>, described below.

The physician repeats the remaining steps of the flowchart for each pulmonary vein in turn, until all pulmonary veins of the patient have been treated.

In a probe insertion step <NUM>, the physician inserts probe <NUM> into patient <NUM>, and navigates distal end <NUM> until electrodes <NUM> of the distal end are in contact with ostium <NUM> of pulmonary vein <NUM>. The navigation may be performed using current tracking module <NUM> and/or EM tracking module <NUM>, and the contact may be verified as described above, e.g., by observing changes of impedance between electrodes <NUM> and patches <NUM>.

In an ablation step <NUM>, and using a first comparison step <NUM>, the physician uses RF generator <NUM> to ablate a circle around the ostium. While performing the ablations, the physician checks if the pulmonary vein has been isolated. The check for isolation typically comprises measuring changes in impedance of the ablated tissue, and/or observing changes in signals by signal pacing and/or passive signal acquisition. If pacing is used, isolation is indicated if a signal injected on one side of the ablated circle is not observed on the other side. If passive signal acquisition is used, isolation may be indicated if signals that were present before the ablation are no longer present.

If comparison step <NUM> returns negative, the physician continues ablation in step <NUM>.

If comparison step <NUM> returns positive, i.e., the physician has determined that the pulmonary vein is isolated, control continues to a notification step <NUM>, where the physician notifies processor <NUM>, using controls <NUM>, to record isolation.

In a second comparison step <NUM>, the processor checks if the CHA<NUM>DS<NUM>-VASc score of patient <NUM>, stored in PVI module, is less than the preset value recorded in step <NUM>.

If the comparison returns positive, i.e., the score is less than the preset value, then embodiments assume that with this score and the achievement of isolation, no further ablation is necessary. In this case control continues to a withdraw probe step <NUM> where the physician may be recommended to cease ablation and withdraw the probe from the vein because pulmonary vein isolation has been achieved and the score is less than <NUM>. In one embodiment the recommendation is in the form of a notice to the physician, such as a notice <NUM> (<FIG>), that is presented on display <NUM>. If comparison <NUM> returns negative, i.e., the score is the preset value or more, then embodiments assume that even given the achievement of isolation, with this score further ablation outside the pulmonary vein is necessary. In this case control continues to a further ablation step <NUM>, where the physician may be recommended to continue ablation. In one embodiment the recommendation is in the form of a notice to the physician,
such as a notice <NUM> (<FIG>), that is presented on display <NUM>.

The further ablations needed are in proximity to the pulmonary vein, and may include ablation of rotors (e.g. focal triggers having a repetitive activation pattern), ablation to isolate the posterior atrial wall, ablation to isolate the left atrial appendage, and/or ablation of additional locations of arrhythmogenic activity. It will be understood that this list is not comprehensive, and other ablations that may be needed are also considered to be comprised within the scope of the present invention.

Claim 1:
Apparatus for ablating a patient, comprising:
a probe (<NUM>), configured to be inserted into the patient (<NUM>), so as to contact a pulmonary vein (<NUM>) of the patient;
and a processor (<NUM>), configured to:
ascertain a CHA<NUM>DS<NUM>-VASc score for the patient (<NUM>),
apply energy via the probe (<NUM>) so as to ablate the pulmonary vein (<NUM>) until pulmonary vein isolation (PVI) is achieved,
cease ablation of the pulmonary vein (<NUM>) when PVI is achieved and the CHA<NUM>DS<NUM>-VASc score is less than a preset value, and
apply the energy to perform a further ablation when PVI is achieved and the CHA<NUM>DS<NUM>-VASc score is greater than or equal to the preset value,
wherein the preset value is <NUM> if the patient is male, and is <NUM> if the patient is female.