Patent Description:
Cardiac arrhythmias, such as atrial fibrillation (AF), occur when regions of cardiac tissue abnormally conduct electric signals to adjacent tissue. This disrupts the normal cardiac cycle and causes asynchronous rhythm. Certain procedures exist for treating arrhythmia, including surgically disrupting the origin of the signals causing the arrhythmia and disrupting the conducting pathway for such signals. By selectively ablating cardiac tissue by application of energy via a catheter, it is sometimes possible to cease or modify the propagation of unwanted electrical signals from one portion of the heart to another.

<CIT> describes electrophysiologic (EP) catheters, and in particular EP catheters for mapping and/or ablation in the heart. The disclosure is directed to a catheter having a basket-shaped electrode assembly with a high electrode density. The basket-shaped electrode assembly may have a plurality of spines, such as up to twelve, each with a plurality of electrodes, such as up to sixteen. The distal ends of the plurality of spines are joined at a distal hub, all of which are fashioned from a single piece of superelastic material.

Many current ablation approaches in the art tend to utilize radiofrequency (RF) electrical energy to heat tissue. RF ablation can have certain rare drawbacks due to operator's skill, such as heightened risk of thermal cell injury which can lead to tissue charring, burning, steam pop, phrenic nerve palsy, pulmonary vein stenosis, and esophageal fistula. Cryoablation is an alternative approach to RF ablation that can reduce some thermal risks associated with RF ablation but may present tissue damage due to the very low temperature nature of such devices. Maneuvering cryoablation devices and selectively applying cryoablation, however, is generally more challenging compared to RF ablation; therefore, cryoablation is not viable in certain anatomical geometries which may be reached by electrical ablation devices.

Some ablation approaches use irreversible electroporation (IRE) to ablate cardiac tissue using nonthermal ablation methods. IRE delivers short pulses of high voltage to tissues and generates an unrecoverable permeabilization of cell membranes. Delivery of IRE energy to tissues using multi-electrode catheters was previously proposed in the patent literature. Examples of systems and devices configured for IRE ablation are disclosed in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

Regions of cardiac tissue can be mapped by a catheter to identify the abnormal electrical signals. The same or different catheter can be used to perform ablation. Some example catheters include a number of spines with electrodes positioned thereon. The electrodes are generally attached to the spines and secured in place by soldering, welding, or using an adhesive. Furthermore, multiple linear spines are generally assembled together by attaching both ends of the linear spines to a tubular shaft (e.g., a pusher tube) to form a spherical basket. Due to the small size of the spines and the electrodes, however, adhering the electrodes to the spines and then forming a spherical basket from the multiple linear spines can be a difficult task, increasing the manufacturing time and cost and the chances that the electrode fails due to an improper bond or misalignment. What is needed, therefore, are devices and methods of forming an improved basket assembly that can help to reduce the time required for manufacturing the basket assembly, alternative catheter geometries, and alternative electrode shapes and sizes in general.

A medical probe is presented including an expandable basket assembly coupled to a distal end of a tubular shaft. The basket assembly includes a cloverleaf cutout structure at its distal end and spines extending proximally from the cloverleaf structure and coupling to the tubular shaft. The cloverleaf structure includes a sinusoidal-like member extending from one spine to an adjacent spine in a direction around the longitudinal axis. Dimensions of the sinusoidal-like member can be configured to provide a lateral stiffness of the expandable basket assembly within a predetermined range and a maximum peak stress during retraction of the expandable basket assembly into an intermediate catheter such that the maximum peak stress is less than a predetermined threshold. The cloverleaf structure includes one or more side connectors to connect two or more distal facing portions of the cloverleaf structure to one another to increase the strength of the distal end of the spine and prevent breakage.

An example expandable basket assembly for a medical probe, according to the invention, includes a plurality of spines extending along a longitudinal axis from a proximal central proximal spine portion to a distal spine portion. The distal spine portion defines a cloverleaf structure disposed radially around the longitudinal axis. The cloverleaf structure defines a central cutout with a central area disposed about the longitudinal axis. The cloverleaf structure includes a sinusoidal-like member extending from one spine to an adjacent spine in a direction around the longitudinal axis. The sinusoidal-like member includes a plurality of distal facing portions, a plurality of proximal facing portions, and at least one side connector connecting two adjacent distal facing portions to one another.

The sinusoidal-like member may extend around (a) a first virtual circle having a first open area of approximately <NUM>% that of the central area, the first virtual circle having its center located at a first distance to the longitudinal axis, (b) a second virtual circle having a second open area of approximately <NUM>% of the first open area, the second virtual circle having its center located at a second distance smaller than the first distance to the longitudinal axis, (c) a third virtual circle having a third open area approximately equal to the first open area, the third virtual circle having its center located at a third distance approximately equal to the first distance to the longitudinal axis, and (d) a fourth virtual circle encircling the sinusoidal-like member comprises an area approximately <NUM> times greater than the central area and each of the first and third virtual circle is located at a first distance from the central axis while the second virtual circle is located at a second distance of approximately half that of the first distance. The at least one side connector may separate the first and third open areas from the central area.

The at least one side connector may include two or more side connectors.

Portions of the sinusoidal-like member may be tangential to a virtual sphere with its center disposed substantially on the longitudinal axis so that distal edges of the cutout extend a general direction towards the proximal portion.

The expandable basket assembly may include a coating covering the sinusoidal-like member and a central cutout circumscribed by the sinusoidal-like member.

Each of the spines may include at least one retention member extending generally transverse to the spine.

The at least one retention member may include a bow shaped member.

The at least one retention member may include two bow shaped members disposed in opposite direction and transverse to a longer length of each spine.

The at least one retention member may include first and second sets of retention members spaced apart along the spines. The first set may include two bow shaped members disposed in opposite direction and transverse to a longer length of each spine. The second set may include two bow shaped members disposed in opposite direction and transverse to a longer length of each spine so that each electrode is captured between the first and second sets of retention members.

The at least one side connector may have a width ranging from approximately <NUM> to approximately <NUM> and a length ranging from approximately <NUM> to approximately <NUM>.

The plurality of spines may be configured to form an approximately oblate-spheroid basket assembly when in the expanded form.

An example medical probe according to the invention includes a tubular shaft including a proximal end and a distal end. The tubular shaft extends along a longitudinal axis of the medical probe. The medical probe further includes an expandable basket assembly coupled to the distal end of the tubular shaft. The basket assembly includes a plurality of spines extending along a longitudinal axis from a proximal central proximal spine portion to a distal spine portion. The distal spine portion defines a cloverleaf structure disposed radially around the longitudinal axis. The cloverleaf structure defines a central cutout with a central area disposed about the longitudinal axis. The cloverleaf structure includes a sinusoidal-like member extending from one spine to an adjacent spine in a direction around the longitudinal axis. The sinusoidal-like member includes a plurality of distal facing portions, a plurality of proximal facing portions, and at least one side connector connecting two adjacent distal facing portions to one another.

The sinusoidal-like member may extends around (a) a first virtual circle having a first open area of approximately <NUM>% that of the central area, the first virtual circle having its center located at a first distance to the longitudinal axis, (b) a second virtual circle having a second open area of approximately <NUM>% of the first open area, the second virtual circle having its center located at a second distance smaller than the first distance to the longitudinal axis, (c) a third virtual circle having a third open area approximately equal to the first open area, the third virtual circle having its center located at a third distance approximately equal to the first distance to the longitudinal axis, and (d) a fourth virtual circle encircling the sinusoidal-like member comprises an area approximately <NUM> times greater than the central area and each of the first and third virtual circle is located at a first distance from the central axis while the second virtual circle is located at a second distance of approximately half that of the first distance. The at least one side connector may separate the first and third open areas from the central area.

The medical probe may include a plurality of electrodes, each electrode of the plurality of electrodes comprises a body defining a hollow portion extending through the body of the electrode so that a spine can be inserted into the hollow portion and retained by the at least one retention member. The at least one side connector comprises two or more side connectors.

The medical probe may include a plurality of electrically insulative jackets each disposed between a respective spine of the plurality of spines and a respective electrode, thereby electrically isolating the respective electrode from the respective spine.

The at least side connector may have a width ranging from approximately <NUM> to approximately <NUM> and a length ranging from approximately <NUM> to approximately <NUM>.

The medical probe may include a wire disposed inside a respective jacket the plurality of electrically insulative jackets, the wire is electrically connected to the respective electrode.

The plurality of spines may be configured to form an approximately spherically-shaped basket assembly when in the expanded form.

The central cutout approximates a central circle with the central area. The cloverleaf structure may be disposed within a fourth circle with its center on the longitudinal axis so that portions of the cloverleaf close to the center circle is spaced apart along the longitudinal axis with respect to portions of the cloverleaf close to the fourth circle thereby defining a concave cloverleaf structure.

The cloverleaf structure may be concave with its center extending towards the proximal central spine portion of the basket to approximate a concave surface disposed about the longitudinal axis.

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>%.

As used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment. In addition, vasculature of a "patient," "host," "user," and "subject" can be vasculature of a human or any animal. It should be appreciated that an animal can be a variety of any applicable type, including, but not limited thereto, mammal, veterinarian animal, livestock animal or pet type animal, etc. As an example, the animal can be a laboratory animal specifically selected to have certain characteristics similar to a human (e.g., rat, dog, pig, monkey, or the like). It should be appreciated that the subject can be any applicable human patient, for example. As well, the term "proximal" indicates a location closer to the operator or physician whereas "distal" indicates a location further away to the operator or physician.

As discussed herein, "operator" can include a doctor, surgeon, technician, scientist, or any other individual or delivery instrumentation associated with delivery of a multi-electrode catheter for the treatment of drug refractory atrial fibrillation to a subject.

As discussed herein, the term "ablate" or "ablation", as it relates to the devices and corresponding systems of this disclosure, refers to components and structural features configured to reduce or prevent the generation of erratic cardiac signals in the cells by utilizing non-thermal energy, such as irreversible electroporation (IRE), referred throughout this disclosure interchangeably as pulsed electric field (PEF) and pulsed field ablation (PFA). Ablating or ablation as it relates to the devices and corresponding systems of this disclosure is used throughout this disclosure in reference to non-thermal ablation of cardiac tissue for certain conditions including, but not limited to, arrhythmias, atrial flutter ablation, pulmonary vein isolation, supraventricular tachycardia ablation, and ventricular tachycardia ablation. The term "ablate" or "ablation" also includes known methods, devices, and systems to achieve various forms of bodily tissue ablation as understood by a person skilled in the relevant art.

As discussed herein, the terms "bipolar" and "unipolar" when used to refer to ablation schemes describe ablation schemes which differ with respect to electrical current path and electric field distribution. "Bipolar" refers to ablation scheme utilizing a current path between two electrodes that are both positioned at a treatment site; current density and electric flux density is typically approximately equal at each of the two electrodes. "Unipolar" refers to ablation scheme utilizing a current path between two electrodes, wherein a first electrode experiences a high current density and high electric flux density and is positioned at a treatment site, and a second electrode experiences comparatively lower current density and lower electric flux density and is positioned remotely from the treatment site.

As discussed herein, the terms "biphasic pulse" and "monophasic pulse" refer to respective electrical signals. "Biphasic pulse" refers to an electrical signal including a positive-voltage phase pulse (referred to herein as "positive phase") and a negative-voltage phase pulse (referred to herein as "negative phase"). "Monophasic pulse" refers to an electrical signal including only a positive or only a negative phase. Preferably, a system providing the biphasic pulse is configured to prevent application of a direct current voltage (DC) to a patient. For instance, the average voltage of the biphasic pulse can be zero volts with respect to ground or other common reference voltage. Additionally, or alternatively, the system can include a capacitor or other protective component. Where voltage amplitude of the biphasic and/or monophasic pulse is described herein, it is understood that the expressed voltage amplitude is an absolute value of the approximate peak amplitude of each of the positive-voltage phase and/or the negative-voltage phase. Each phase of the biphasic and monophasic pulse preferably has a square shape including an essentially constant voltage amplitude during a majority of the phase duration. Phases of the biphasic pulse are separated in time by an interphase delay. The interphase delay duration is preferably less than or approximately equal to the duration of a phase of the biphasic pulse. The interphase delay duration is more preferably about <NUM>% of the duration of the phase of the biphasic pulse.

As discussed herein, the terms "tubular" and "tube" are to be construed broadly and are not limited to a structure that is a right cylinder or strictly circumferential in cross-section or of a uniform cross-section throughout its length. For example, the tubular structures are generally illustrated as a substantially right cylindrical structure. However, the tubular structures may have a tapered or curved outer surface without departing from the scope of the present disclosure.

The term "temperature rating", as used herein, is defined as the maximum continuous temperature that a component can withstand during its lifetime without causing thermal damage, such as melting or thermal degradation (e.g., charring and crumbling) of the component.

The present disclosure is related to systems, methods or uses and devices which utilize end effectors including electrodes affixed to spines. Example systems, methods, and devices of the present disclosure may be particularly suited for IRE ablation of cardiac tissue to treat cardiac arrhythmias. Ablative energies are typically provided to cardiac tissue by a tip portion of a catheter which can deliver ablative energy alongside the tissue to be ablated. Some example catheters include three-dimensional structures at the tip portion and are configured to administer ablative energy from various electrodes positioned on the three-dimensional structures. Ablative procedures incorporating such example catheters can be visualized using fluoroscopy.

Ablation of cardiac tissue using application of a thermal technique, such as radio frequency (RF) energy and cryoablation, to correct a malfunctioning heart is a well-known procedure. Typically, to successfully ablate using a thermal technique, 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. Typically, for an ablation procedure using a thermal technique, the electropotentials and the temperatures are measured before, during, and after the actual ablation.

RF approaches can have risks that can lead to tissue charring, burning, steam pop, phrenic nerve palsy, pulmonary vein stenosis, and esophageal fistula. Cryoablation is an alternative approach to RF ablation that can reduce some thermal risks associated with RF ablation. However maneuvering cryoablation devices and selectively applying cryoablation is generally more challenging compared to RF ablation; therefore, cryoablation is not viable in certain anatomical geometries which may be reached by electrical ablation devices.

IRE as discussed in this disclosure is a non-thermal cell death technology that can be used for ablation of atrial arrhythmias. To ablate using IRE/PEF, biphasic voltage pulses are applied to disrupt cellular structures of the myocardium. The biphasic pulses are non-sinusoidal and can be tuned to target cells based on electrophysiology of the cells. In contrast, to ablate using RF, a sinusoidal voltage waveform is applied to produce heat at the treatment area, indiscriminately heating all cells in the treatment area. IRE therefore has the capability to spare adjacent heat sensitive structures or tissues which would be of benefit in the reduction of possible complications known with ablation or isolation modalities. Additionally, or alternatively, monophasic pulses can be utilized.

Electroporation can be induced by applying a pulsed electric field across biological cells to cause reversable (temporary) or irreversible (permanent) creation of pores in the cell membrane. The cells have a transmembrane electrostatic potential that is increased above a resting potential upon application of the pulsed electric field. While the transmembrane electrostatic potential remains below a threshold potential, the electroporation is reversable, meaning the pores can close when the applied pulse electric field is removed, and the cells can self-repair and survive. If the transmembrane electrostatic potential increases beyond the threshold potential, the electroporation is irreversible, and the cells become permanently permeable. As a result, the cells die due to a loss of homeostasis and typically die by programmed cell death or apoptosis, which is believed to leave less scar tissue as compared to other ablation modalities. Generally, cells of differing types have differing threshold potential. For instance, heart cells have a threshold potential of approximately <NUM> V/cm, whereas for bone it is <NUM> V/cm. These differences in threshold potential allow IRE to selectively target tissue based on threshold potential.

The solution of this disclosure includes systems and methods for applying electrical signals from catheter electrodes positioned in the vicinity of myocardial tissue, preferably by applying a pulsed electric field effective to induce electroporation in the myocardial tissue. The systems and methods can be effective to ablate targeted tissue by inducing irreversible electroporation. In some examples, the systems and methods can be effective to induce reversible electroporation as part of a diagnostic procedure. Reversible electroporation occurs when the voltage applied with the electrodes is below the electric field threshold of the target tissue allowing cells to repair. Reversible electroporation does not kill the cells but allows a physician to see the effect of reversible electroporation on electrical activation signals in the vicinity of the target location. Example systems and methods for reversible electroporation is disclosed in <CIT>.

The pulsed electric field, and its effectiveness to induce reversible and/or irreversible electroporation, can be affected by physical parameters of the system and biphasic pulse parameters of the electrical signal. Physical parameters can include electrode contact area, electrode spacing, electrode geometry, etc. examples presented herein generally include physical parameters adapted to effectively induce reversible and/or irreversible electroporation. Biphasic pulse parameters of the electrical signal can include voltage amplitude, pulse duration, pulse interphase delay, inter-pulse delay, total application time, delivered energy, etc. In some examples, parameters of the electrical signal can be adjusted to induce both reversible and irreversible electroporation given the same physical parameters. Examples of various systems and methods of ablation including IRE are presented in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

To deliver pulsed field ablation (PFA) in an IRE (irreversible electroporation) procedure, electrodes should contact the tissue being ablated with a sufficiently large surface area. As described hereinbelow, the medical probe includes a tubular shaft including proximal and distal ends, and a basket assembly at the distal end of the tubular shaft. The basket assembly includes a single unitary structure. The unitary structure can include a plurality of linear spines formed from a planar sheet of material or tube stock and one or more electrodes coupled to each of the spines. The plurality of linear spines can converge at a central spine intersection including one or more cutouts. The cutouts can allow for bending of each spine such that the spines form an approximately spherical or oblate-spheroid basket assembly. It is noted that the cutouts (in various configurations described and illustrated in the specification) allows the basket to be compressed into a much smaller form factor when undeployed (or undergoing a retraction into a delivery sheath) without buckling or plastic deformation.

<FIG> is a schematic, pictorial illustration of a medical system <NUM> including a medical probe <NUM> and a control console <NUM>, in accordance with an embodiment of the present invention. Medical system <NUM> may be based, for example, on the CARTO® system, produced by Biosense Webster Inc. of <NUM> Technology Drive, Suite <NUM>, Irvine, CA <NUM> USA. In embodiments described hereinbelow, medical probe <NUM> can be used for diagnostic or therapeutic treatment, such as for performing ablation procedures in a heart <NUM> of a patient <NUM>. Alternatively, medical probe <NUM> may be used, mutatis mutandis, for other therapeutic and/or diagnostic purposes in the heart or in other body organs.

Medical probe <NUM> includes a flexible insertion tube <NUM> and a handle <NUM> coupled to a proximal end of the tubular shaft. During a medical procedure, a medical professional <NUM> can insert probe <NUM> through the vascular system of patient <NUM> so that a distal end <NUM> of the medical probe enters a body cavity such as a chamber of heart <NUM>. Upon distal end <NUM> entering the chamber of heart <NUM>, medical professional <NUM> can deploy a basket assembly <NUM> approximate a distal end <NUM> of the medical probe <NUM>. Basket assembly <NUM> can include a plurality of electrodes <NUM> affixed to a plurality of spines <NUM>, as described in the description referencing <FIG>, <FIG>, <FIG>, <FIG> hereinbelow. To start performing a medical procedure such as irreversible electroporation (IRE) ablation, medical professional <NUM> can manipulate handle <NUM> to position distal end <NUM> so that electrodes <NUM> engage cardiac tissue at a desired location or locations. Upon positioning the distal end <NUM> so that electrodes <NUM> (disposed on an extension structure <NUM>) engages cardiac tissue, the medical professional <NUM> can activate the medical probe <NUM> such that electrical pulses are delivered by the electrodes <NUM> to perform the IRE ablation.

The medical probe <NUM> can include a guide sheath and a therapeutic catheter, wherein the guide sheath includes the flexible insertion tube <NUM> and the handle <NUM> and the therapeutic catheter includes the basket assembly <NUM>, electrodes <NUM>, and a tubular shaft <NUM> (see <FIG>). The therapeutic catheter is translated through the guide sheath so that the basket assembly <NUM> is positioned in the heart <NUM>. The distal end <NUM> of the medical probe <NUM> corresponds to a distal end of the guide sheath when the basket assembly <NUM> is contained within the flexible insertion tube <NUM>, and the distal end <NUM> (of the tube <NUM>) corresponds to a proximal portion (<FIG>) of the basket assembly <NUM> when the basket assembly <NUM> is extended from the distal end of the guide sheath. The medical probe <NUM> can be alternatively configured to include a second handle on the therapeutic catheter and other features as understood by a person skilled in the pertinent art.

In the configuration shown in <FIG>, control console <NUM> is connected, by a cable <NUM>, to body surface electrodes, which typically include adhesive skin patches <NUM> that are affixed to patient <NUM>. Control console <NUM> includes a processor <NUM> that, in conjunction with a tracking module <NUM>, determines location coordinates of distal end <NUM> inside heart <NUM>. Location coordinates can be determined based on electromagnetic position sensor output signals provided from the distal portion of the catheter when in the presence of a generated magnetic field. Location coordinates can additionally, or alternatively be based on impedances and/or currents measured between adhesive skin patches <NUM> and electrodes <NUM> that are affixed to basket assembly <NUM>. In addition to being used for recording ECG signals or acting as location sensors during a medical procedure, electrodes <NUM> may perform other tasks such as ablating tissue in the heart.

As described hereinabove, in conjunction with tracking module <NUM>, processor <NUM> may determine location coordinates of distal end <NUM> of tube <NUM> inside heart <NUM> based on impedances and/or currents measured between adhesive skin patches <NUM> and electrodes <NUM>. Such a determination is typically after a calibration process relating the impedances or currents to known locations of the distal end has been performed. While embodiments presented herein describe electrodes <NUM> that are preferably configured to deliver IRE ablation energy to tissue in heart <NUM>, configuring electrodes <NUM> to deliver any other type of ablation energy to tissue in any body cavity is considered to be within the scope of the present invention. Furthermore, although described in the context of being electrodes <NUM> that are configured to deliver IRE ablation energy to tissue in the heart <NUM>, one skilled in the art will appreciate that the disclosed technology can be applicable to electrodes used for mapping and/or determining various characteristics of an organ or other part of the patient's <NUM> body.

Processor <NUM> may include 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 be programmed to perform one or more algorithms and uses circuitry <NUM> and circuit <NUM> as well as features of modules to enable the medical professional <NUM> to perform the IRE ablation procedure.

Control console <NUM> also includes an input/output (I/O) communications interface <NUM> that enables control console <NUM> to transfer signals from, and/or transfer signals to electrodes <NUM> and adhesive skin patches <NUM>. In the configuration shown in <FIG>, control console <NUM> additionally includes an IRE ablation module <NUM> and a switching module <NUM>.

IRE ablation module <NUM> is configured to generate IRE pulses including peak power in the range of tens of kilowatts. In some examples, the electrodes <NUM> are configured to deliver electrical pulses including a peak voltage of at least <NUM> volts (V). The medical system <NUM> performs IRE ablation by delivering IRE pulses to electrodes <NUM>. Preferably, the medical system <NUM> delivers biphasic pulses between electrodes <NUM> on the spine. Additionally, or alternatively, the medical system <NUM> delivers monophasic pulses between at least one of the electrodes <NUM> and a skin patch.

In order to prevent blood coagulation, system <NUM> supplies irrigation fluid (e.g., a normal saline solution) to distal end <NUM> of tube <NUM> and to the proximal area of basket assembly <NUM>. It is noted that irrigation fluid can be supplied through the flexible insertion tube <NUM>. Control console <NUM> includes an irrigation module <NUM> to monitor and control irrigation parameters, such as the pressure and the temperature of the irrigation fluid. It is noted that while the preference for the exemplary embodiments of the medical probe is for IRE or PFA, it is within the scope of the present invention to also use the medical probe separately only for RF ablation (unipolar mode with an external grounding electrode or bipolar mode) or in combination with IRE and RF ablations sequentially (certain electrodes in IRE mode and other electrodes in RF mode) or simultaneously (groups of electrodes in IRE mode and other electrodes in RF mode).

Based on signals received from electrodes <NUM> and/or adhesive skin patches <NUM>, processor <NUM> can generate an electroanatomical map <NUM> that shows the location of distal end <NUM> in the patient's body. During the procedure, processor <NUM> can present map <NUM> to medical professional <NUM> on a display <NUM>, and store data representing the electroanatomical map in a memory <NUM>. Memory <NUM> may include 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 include a touchscreen that can be configured to accept inputs from medical professional <NUM>, in addition to presenting map <NUM>.

<FIG> is an illustration of a perspective view of a medical probe <NUM> including a basket assembly <NUM> in an expanded form when unconstrained, such as by being advanced out of an insertion tube lumen at a distal end <NUM> of an insertion tube <NUM>. Probe <NUM> may include a contact force sensor <NUM> to determine contact force of the spines against cardiac tissues. Details of the contact force sensor are shown and described in US Patent Application Publication No. <CIT>.

It should be noted that the medical probe <NUM> illustrated in <FIG> lacks the guide sheath illustrated in <FIG>. In the expanded form <FIG>, spines <NUM> bow radially outwardly and in the collapsed form (not shown) the spines <NUM> are arranged generally along a longitudinal axis <NUM> of insertion tube <NUM>. In <FIG>, a plurality of electrically insulative jackets <NUM> is provided so that each jacket can be disposed between a respective spine <NUM> of the plurality of spines and a respective electrode <NUM> of the plurality of electrodes, thereby electrically isolating the plurality of electrodes from the plurality of spines.

As shown in <FIG>, basket assembly <NUM> includes a plurality of flexible spines <NUM> that are formed at the end of a tubular shaft <NUM> and are connected at both ends. During a medical procedure, medical professional <NUM> can deploy basket assembly <NUM> by extending tubular shaft <NUM> from insertion tube <NUM> causing basket assembly <NUM> to exit insertion tube <NUM> and transition to the expanded form. Spines <NUM> may have elliptical e.g., circular, or rectangular that may appear to be flat cross-sections, and include a flexible, resilient material e.g., a shape-memory alloy such as nickel-titanium, also known as Nitinol forming a strut as will be described in greater detail herein. As shown in <FIG>, <FIG> and <FIG>, basket assembly <NUM> has a proximal portion <NUM> and a distal end <NUM>. The medical probe <NUM> can include a spine retention hub <NUM> that extends longitudinally from a distal end of tubular shaft <NUM> towards distal end <NUM> of basket assembly <NUM>. As described supra, control console <NUM> includes irrigation module <NUM> that delivers irrigation fluid to basket assembly <NUM> through tubular shaft <NUM>.

Turning to <FIG>, the plurality of flexible linear spines <NUM> converge at a central spine intersection <NUM> that is also disposed on a longitudinal axis <NUM> defined by the spines <NUM>. In some examples central spine intersection <NUM> can include one or more cutouts <NUM> that allow for bending of the spines <NUM> when each spine respective attachment end <NUM> is connected to the spine retention hub <NUM>, described in more detail below.

As shown herein, electrodes <NUM> positioned on spines <NUM> of basket assembly <NUM> can be configured to deliver ablation energy RF and/or IRE to tissue in heart <NUM>. Additionally, or alternatively, the electrodes can also be used to determine the location of basket assembly <NUM> and/or to measure a physiological property such as local surface electrical potentials at respective locations on tissue in heart <NUM>. The electrodes <NUM> can be biased such that a greater portion of the one or more electrodes <NUM> face outwardly from basket assembly <NUM> such that the one or more electrodes <NUM> deliver a greater amount of electrical energy outwardly away from the basket assembly <NUM> i.e., toward the heart <NUM> tissue than inwardly.

Examples of materials ideally suited for forming electrodes <NUM> include gold, platinum and palladium and their respective alloys. These materials also have high thermal conductivity which allows the minimal heat generated on the tissue i.e., by the ablation energy delivered to the tissue to be conducted through the electrodes to the back side of the electrodes i.e., the portions of the electrodes on the inner sides of the spines, and then to the blood pool in heart <NUM>.

Referring to <FIG>, basket assembly <NUM> of medical probe <NUM> is shown without the insulative sleeve <NUM> or associated wirings to electrodes <NUM> being disposed inside sleeve <NUM> to show the novel underlying basket structure <NUM>. Basket <NUM> includes a single unitary structure that includes a plurality of spines <NUM> formed from a cylindrical tube stock (<FIG>) and treated to cause the spines <NUM> to bias radially outward. The material for the spine <NUM> can be nitinol, cobalt chromium, stainless steel, titanium, or combinations hereof.

Referring to <FIG>, the spine retention hub <NUM> can be inserted into the tubular shaft <NUM> and attached to the tubular shaft <NUM>. Spine retention hub <NUM> can include a cylindrical member <NUM> including a plurality of relief lands <NUM>, multiple irrigation openings <NUM> to allow outflow of irrigation fluid into a volume defined by the basket spines, and hub end <NUM>. Relief lands <NUM> can be disposed on the outer surface of cylindrical member <NUM> and configured to allow a portion of each spine <NUM>, such as each spine attachment end <NUM>, to be fitted into a respective relief land <NUM> of retention hub <NUM> also known as a coupler for a contact force sensor <NUM>. The attachment end <NUM> can be a generally linear end of the spine <NUM>. The attachment end <NUM> can be configured to extend outwardly from the spine retention hub <NUM> such that the basket assembly <NUM> is positioned outwardly from the spine retention hub <NUM> and, consequently, outwardly from the tubular shaft <NUM>. In this way, the spine <NUM> can be configured to position the basket assembly <NUM> distally from the distal end of the tubular shaft <NUM> and distal from the distal end of the insertion tube <NUM> when the basket assembly <NUM> is deployed. Reference electrode <NUM> can be disposed on the projection <NUM> or on the hub end surface <NUM>. It should be noted that hub <NUM> in effect can have multiple functions: (<NUM>) to retain the spine legs proximally; (<NUM>) allow hub <NUM> (as well as the basket assembly <NUM>) to be connected to distal tube <NUM>; (<NUM>) to function as a fluid diverter for irrigation fluid delivered through distal tube <NUM>; and (<NUM>) provide a reference electrode <NUM>.

Referring to <FIG>, a sectional view of the basket assembly <NUM> is shown cut-away to show the spines <NUM> disposed inside jackets <NUM> with wiring <NUM> running along the spines <NUM> and extending through the jacket <NUM> to connect with the electrode <NUM> via connection point (e.g., solder pad) <NUM>. <FIG> shows a perspective view of an opaque jacket <NUM> through which wirings <NUM> can be seen to extend through jacket <NUM> to respective connection points <NUM> of electrodes <NUM>. It should be noted that the connection point <NUM> is not required to be disposed inside the lumen <NUM> of electrode <NUM> but can be outside lumen <NUM> as long as the connection point does not interfere with tissue contact of the electrode <NUM>.

Referring to <FIG>, in a preferred embodiment, electrode <NUM> is about <NUM> to about <NUM> long with a width from about <NUM> to about <NUM> wide and a height of about <NUM> to about <NUM>. The lumen <NUM> may have a negative surface area of about <NUM>-squared to about <NUM>-squared. The lumen <NUM> is not placed at the geometrical center but is rather offset lower so that the center <NUM> of lumen <NUM> is more towards the flat bottom surface <NUM>. This arrangement ensures that more of the top surfaces <NUM> and <NUM> of electrode <NUM> is above the lumen <NUM> than below lumen <NUM>.

Referring to <FIG>, electrode <NUM> can be located substantially in place with respect to spine <NUM> by way of a retention member <NUM> formed integrally with the spine <NUM>. As illustrated in <FIG>, i each of the spines <NUM> can include at least one retention member <NUM> extending generally transverse to the spine <NUM>. To allow for insertion of the spine <NUM> through lumen <NUM> (<FIG>) of electrode <NUM>, each spine <NUM> can be bisected with a central spine member <NUM> so that empty space <NUM> is provided to allow retention member <NUM> to bend inwardly towards the central spine member <NUM>. The shape of retention member <NUM> can be of any shape as along as such shape serves to allow the member <NUM> to be compressed for insertion into lumen <NUM> of electrode <NUM> and once released to prevent movement of electrode <NUM> with respect to the retention member <NUM>. In one embodiment, the at least one retention member <NUM> is shaped in a bow-like configuration with a center of such bow extending away from a periphery of spine <NUM>. In a preferred embodiment, the at least one retention member <NUM> for each electrode <NUM> may include two bow shaped members <NUM> disposed in opposite direction and transverse to a longer length <NUM> of each spine <NUM>.

In the configuration shown in <FIG>, the at least one retention member may have first 220a, 220b and second sets 220c, 220d of retention members <NUM> spaced apart along the spines. The first set includes two bow shaped members 220a, 220b disposed in opposite direction and transverse to a longer length <NUM> of each spine <NUM> and the second set includes two bow shaped members 220c, 220d disposed in opposite direction and transverse to a longer length <NUM> of each spine <NUM> so that each electrode <NUM> is captured between the first and second sets of retention members 220a, 220b and 220c and 220d.

<FIG> shows the spine structure 38a as formed from a tube stock. It is also within the scope of this invention for the spine structure 38a to be formed form a flat sheet stock, cut and heat treated to achieve the spheroidal basket shape shown herein. The spine structure 38a illustrated in <FIG> can be compressed longitudinally and the spines <NUM> can expand radially to form the basket shape spine structure illustrated in <FIG> of basket assembly <NUM> illustrated in <FIG>.

<FIG> and <FIG> show the distal portion <NUM> (<FIG>) in which the distal portion <NUM> of basket assembly <NUM> of medical probe <NUM> can be considered as being flattened between two flat sheets of glass. In this viewing configuration, it can be seen in <FIG> that distal portion <NUM> defines a structure <NUM> resembling a cloverleaf and hence structure <NUM> will be referred hereafter as a "cloverleaf". As before, basket <NUM> in <FIG> and <FIG> has a plurality of spines <NUM> extending along the longitudinal axis <NUM> from a proximal central proximal spine portion <NUM> to a distal spine portion <NUM>.

In <FIG>, the distal spine portion <NUM> defines a cloverleaf structure <FIG>, <NUM> disposed radially around the longitudinal axis <NUM>. Each clover cutout <NUM> is aligned along radial axis A, B, C, D, E and F extending orthogonally from axis <NUM> so that the plurality of spines <NUM> extend from the proximal central spine portion <NUM> in an equiangular pattern such that respective angles between respectively adjacent spines are approximately equal. While the preferred embodiment includes six spines, it is within the scope of the invention to have any number of spines from four to twelve.

Of note is that the cloverleaf structure <NUM> also defines a central cutout C0 with a negative or empty area A0 disposed about the longitudinal axis <NUM>. In particular, the cloverleaf structure <NUM> can be delineated by the following structures: a sinusoidal-like cloverleaf member <NUM> extending from one spine <NUM> to an adjacent spine <NUM> in a direction e.g., counterclockwise, or clockwise around the longitudinal axis <NUM>. This characteristic of the sinusoidal structure <NUM> can be seen in <FIG> with for example, spine <NUM> located on radial axis A. Starting from this spine <NUM> on axis A, a sinusoidal-like cloverleaf member <NUM> is configured so that it meanders as indicated by dashed line <NUM> around a portion of the cutout <NUM> having a negative or open first area A1 which can be approximated by circle R1. As used herein, the term "open area" means the absence of any solid structure to define an empty space. This first open area A1 is approximately <NUM>% that of the central area A0. For convenience, the first open area A1 can be approximated by the first virtual circle R1 that has its center located at a first distance L1 to the longitudinal axis <NUM>. Continuing in <FIG>, the sinusoidal cloverleaf member <NUM> meanders in a counter-clockwise direction from axis A to axis F around a second open area A2 towards an adjacent spine <NUM> located on axis F. For convenience, the second open area A2 can also be approximated to a second virtual circle R2 having a second open area A2 of approximately <NUM>% of the first open area A1. It is noted that the second virtual circle may have its center of radius R2 located at a second distance L2 smaller than the first distance L1 to the longitudinal axis <NUM>. Continuing towards axis F in <FIG>, the sinusoidal cloverleaf member <NUM> meanders dashed line <NUM> around a third open area A3 which for convenience is approximated by third virtual circle with radius R3. The third virtual circle has its center for radius R3 located at a third distance L3 to the central axis <NUM> that is greater than L2 and approximately equal to the first distance L1. Once the sinusoidal cloverleaf member <NUM> crosses axis F, the structural nomenclatures repeat again with another first open area A1 on the other side of axis F closer to axis E on which sinusoidal cloverleaf member <NUM> meanders as referenced by dashed line <NUM> towards next spine <NUM> located on axis E. Sinusoidal cloverleaf member <NUM> may include a plurality of distal facing portions <NUM> and a plurality of proximal facing portions <NUM>. Additionally, as shown in <FIG>, <FIG>, <FIG>, and <FIG>, <FIG>, and in accordance with the invention, the sinusoidal cloverleaf member <NUM> includes at least one side connector <NUM> connecting two adjacent distal facing portions <NUM> to one another. Each of the side connectors <NUM> may have a width W1 ranging from approximately <NUM> to approximately <NUM> and a length L4 ranging from approximately <NUM> to approximately <NUM>. The one or more connectors <NUM> may separate the first open area A1 and third open area A3 from the central area A0.

In <FIG>, a width T0 of the spine <NUM> can be from <NUM> to <NUM> while the sinusoidal member <NUM> has a maximum width T1 of about ½ of the width of T0 with a minimum width T2 of about <NUM>/<NUM> of spine width T0. A width T3 proximate the spine axis (A, B, C, D, E or F) is about the same as the maximum with T1. The central area A0, approximated by radius R0, is approximately <NUM>-squared, the fourth virtual circle C4 may have an area approximately <NUM> times greater than the central area A0. Each of the first and third virtual circle R1 and R3 is located at a first distance L1 of approximately <NUM> from the central axis <NUM> while the second virtual circle R2 is located at a distance L2 of approximately ½ that of the first distance L1.

Preferably, the plurality of spines <NUM> can be made from a material including nitinol, cobalt chromium, stainless steel, titanium, and combinations or alloys hereof. Each electrode <NUM> can be made of a material selected from stainless steel, cobalt chromium, gold, platinum, palladium, and alloys hereof.

The inventors have devised the cloverleaf structure <NUM> in order to allow the basket assembly <NUM> to be compressed from a maximum diameter of the basket of approximately <NUM> to fit within an <NUM>-<NUM> French sheath without buckling or causing permanent plastic deformation to the spines <NUM> at any part of the basket assembly <NUM>. In an alternative embodiment, if the number of spines is increased the size of the sheath may be increased to up to <NUM> French to accommodate the additional spines. By virtue of this design, the inventors have been able to compress the basket into a sheath and deploy for full expansion for at least <NUM> times without any physical sign of buckling.

Referring back to <FIG>, it is noted that the sinusoidal-like cloverleaf member <NUM> is configured so that a portion of cloverleaf member <NUM> is tangential to the central circle C0 proximate a location between any two radial axes on which two neighboring spines <NUM> are located. For example, with spine <NUM> on radii axis A neighboring spine <NUM> on axis B, the sinusoidal cloverleaf member <NUM> is tangential to the open circle C0 at a location bisecting the two radial axis A and B by a line Q1 connected to the central axis <NUM>. This tangential characteristic of the sinusoidal cloverleaf member <NUM> around the open area A0 is repeated for any two adjacent spines <NUM> as spine <NUM> on axis B and spine <NUM> on axis C and so on for all of the bisecting axes Q1, Q2, Q3, Q4, Q5, Q6. The bisecting axes Q1, Q2, Q3, Q4 correspond to peaks of the sinusoidal cloverleaf member <NUM> and the radial axes A, B, C, D, E, F correspond to troughs of the sinusoidal cloverleaf, wherein peaks of the sinusoidal member are closer to the central axis <NUM> and troughs are further from the central axis <NUM>.

Another notable feature of the basket structure <NUM> is a concavity <NUM> of the distal central portion <NUM> (<FIG>) that can be seen with reference to <FIG> and <FIG>. In <FIG>, it can be seen that the cloverleaf structure <NUM> is bent so that its open center <NUM> is contiguous to a plane defined by central circle C0 and spaced apart by a gap G with respect to a plane defined by the fourth virtual circle C4 encircling the cloverleaf structure <NUM>. The concavity is indicated by a virtual circle <NUM> and a dashed line <NUM> representing the compound curvature generated by the cloverleaf structure <NUM> about the central axis <NUM>.

<FIG> illustrates the electrode <NUM> an end front view and <FIG> illustrates the same electrode from a top-down perspective view of electrode <NUM>, in accordance with an embodiment of the present invention. Each electrode <NUM> is fabricated from a biocompatible electrically conductive material, such as platinum, palladium, iridium or gold and alloys of such metals. Each end (one shown in <FIG>) of electrode <NUM> is provided with generally flat lands <NUM> surrounding a lumen <NUM> with curved outer surfaces <NUM> surrounding the lands <NUM>. Electrode <NUM> has a tissue facing surface with a generally flat top surface <NUM> with curved outer perimeter <NUM> surrounding the generally flat top surface <NUM>. The lumen <NUM> (i.e., a hollow through opening) extends along longitudinal axis <NUM> therethrough. In addition to the tissue contacting outer surface, each given electrode <NUM> has an inner surface <NUM> defined by its lumen <NUM> on which spine <NUM> can be inserted through the lumen <NUM>. Electrical wire or electrical trace <NUM> (<FIG>, sufficiently sized to deliver current pulses of at least <NUM> amps) can be connected to a connection point on the electrode (outside or inside surface). Preferably, wire <NUM> is electrically connected to a connection point <NUM> on the inside surface <NUM> of lumen <NUM>. The cross-section of the electrode can be ovoid, trapezoidal, or substantially ovoid or trapezoidal shape as shown in <FIG>.

<FIG> is a perspective view of another example basket assembly 38b of a medical probe in an expanded form and including a coated distal end <NUM>. The distal end <NUM> includes an atraumatic coating <NUM> configured to reduce likelihood of tissue damage due to pressure of the distal end <NUM> of the basket assembly 38b against tissue. The coating <NUM> covers the sinusoidal-like member <NUM> and covers the central cutout A0 circumscribed by the sinusoidal-like member <NUM>. The coating <NUM> can be applied to alternative configurations of basket assembly 38b as understood by one skilled in the art to reduce likelihood of tissue damage due to pressure of the distal end <NUM> of the basket assembly 38b against tissue. The coating <NUM> may be particularly suited for basket assembly structures having an open distal end. The coating <NUM> may also be particularly suited for basket assembly structures having struts or structures with edges positioned at the distal end of the basket assembly.

<FIG> illustrates the spine structure as formed from a tube stock and including the coating <NUM> at the distal end. The coating <NUM> preferably includes a polymeric material. The coating <NUM> can be applied to the basket assembly 38b by dipping the distal end <NUM> in a liquid polymer and curing the polymer to form a flexible membrane. The distal end <NUM> can be dipped when the basket assembly is in an expanded form as illustrated in <FIG>, when the basket assembly is collapsed to a tubular shape similar to as illustrated in <FIG>, or at a partially expanded state between the states illustrated in <FIG>. The distal end <NUM> can be expanded to the expanded form as illustrated in <FIG> as the coating <NUM> is cured to take its final shape.

<FIG> illustrates a perspective view of a distal end <NUM> of another example basket assembly 38c of the medical probe in an expanded form and including a coating 45a with a central opening <NUM>. The central opening <NUM> may allow for the basket assembly 38c to be easier to collapse compared to the coating <NUM> illustrated in <FIG>.

Claim 1:
An expandable basket assembly (<NUM>) for a medical probe (<NUM>), comprising:
a plurality of spines (<NUM>) extending along a longitudinal axis (<NUM>) from a proximal central proximal spine portion to a distal spine portion, the distal spine portion defining a cloverleaf structure (<NUM>) disposed radially around the longitudinal axis, the cloverleaf structure defining a central cutout (C0) with a central area (A0) disposed about the longitudinal axis, the cloverleaf structure comprising:
a sinusoidal-like member extending from one spine to an adjacent spine in a direction around the longitudinal axis, the sinusoidal-like member comprises a plurality of distal facing portions (<NUM>), a plurality of proximal facing portions (<NUM>), and characterised in that the cloverleaf structure further comprises
at least one side connector (<NUM>) connecting two adjacent distal facing portions to one another.