Abstract:
The present invention is of systems, devices, and methods for cryogenic treatment of cardiac arrhythmia. More particularly, the present invention is of cryoprobes cooled by Joule-Thomson cooling and having particularized shapes of treatment heads, adapted and adaptable to specific loci of treatment of cardiac arrhythmia. The present invention is further of cryogenic methods for treating cardiac arrhythmia comprising three successive stages of cooling.

Description:
FIELD AND BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to systems, devices, and methods for cryogenic treatment of cardiac arrhythmia. More particularly, the present invention relates to cryoprobes cooled by Joule-Thomson cooling and having particularized shapes of treatment heads, adapted and adaptable to specific loci of treatment of cardiac arrhythmia. The present invention further relates to cryogenic methods for treating cardiac arrhythmia comprising three successive stages of cooling.  
           [0002]    Atrial fibrillation is the most common cardiac arrhythmia. Prevalence of atrial fibrillation increases with age, with two cases per thousand at the age of 20-35, increasing to thirty per thousand between the ages of 55 and 60, and to from eighty to a hundred per thousand by age 80.  
           [0003]    Thus, at least 4% of the population suffers from atrial fibrillation, and more than 70% of the sufferers are over 65 years old.  
           [0004]    Patients with atrial fibrillation have a five-fold increased risk of stroke when compared with normal individuals.  
           [0005]    Research has shown that pharmacological approaches to atrial fibrillation have, at one year of treatment, only about 50% success.  
           [0006]    In atrial fibrillation and in cardiac arrhythmias in general, pathological electrically transmissive pathways exist within myocardial tissues.  
           [0007]    Surgical treatment of arrhythmias seeks to destroy those pathways, thereby preventing transmission of aberrant electrical impulses, and thereby preventing non-synchronized atrial and ventricular contractions.  
           [0008]    Popular techniques for treating arrhythmia include methods of cutting or burning lesions in myocardial tissue, preventing electrical conduction therein.  
           [0009]    U.S. Pat. No. 6,161,543 to Cox et. al. presents several well-known and widely used techniques, in particular the “MAZE” method.  
           [0010]    Currently the MAZE III operation is the most effective treatment of atrial fibrillation, known to have the best long-term success rate. The MAZE procedure pioneered by J. Cox and colleagues creates lines of conduction block that interrupt all potential macro reentrant circuits and cure the atrial fibrillation. The MAZE  3  procedure involves the excision of the atrial appendages, isolation of the pulmonary veins and fragmentation of the atrium, to destroy, and prevent the re-formation of, re-entrant circuits.  
           [0011]    The Maze procedure, however, is difficult to execute, and requires a major intervention with consequent complexities of management and often difficult recoveries.  
           [0012]    Indeed, all treatment procedures requiring open chest surgery, and particular procedures requiring open-heart surgery and/or heart-lung machine support, are relatively difficult, dangerous, and expensive operations, requiring highly trained practitioners and specialized equipment. They are, moreover, procedures which themselves create major trauma to the patient, cause significant suffering, and are generally followed by long and difficult convalescence.  
           [0013]    Consequently, there is a widely recognized need for, and it would be highly advantageous to have, a minimally invasive technique for creation of lesions capable of blocking pathological electrical conduction in atrial tissue, thereby permitting treatment of atrial fibrillation and of other forms of cardiac arrhythmias, yet which does not require subjecting a patient to the trauma of open chest and open heart surgeries.  
           [0014]    Techniques for creating the required lesions while avoiding open-heart surgery have been evolved. These include small intercostal percutaneous penetration into the body cavity, endovascular trans-catheter approaches, and others. One popular technique is the use of what is known as a “purse string” procedure to enable a surgeon to practice an opening in an atrial wall, insert a surgical tool, and cut, burn, or freeze tissues therein, while yet allowing continued functioning of the heart.  
           [0015]    “Beating heart” surgeries, however, carry with them an intrinsic difficulty. Even for the best of surgeons, it is extremely difficult to position a therapeutic probe in the correct spot for a treatment, and to keep the probe in place during the duration required for a treatment procedure, when that spot is a constantly moving target, a selected tissue on or within a beating heart.  
           [0016]    Consequently, there is a widely recognized need for, and it would be highly advantageous to have, a therapeutic device and method enabling to place a therapeutic probe in or on a selected portion of a beating heart, and to maintain that probe accurately in place for a required duration of treatment, without resorting to heart immobilization.  
           [0017]    In recent practice, loci in the pulmonary veins are accepted by expert cardiologists as a target for treatment of cardiac arrhythmias. Left atrial muscle fibers are known to penetrate the pulmonary veins, especially the superior pulmonary vein. Pace-maker type cells have been found within these structures, supporting the hypothesis that such structures are a source of ectopic activity and a substrate for multiple re-entry circuits leading to the formation of atrial tachycardia. It is known that persistent atrial tachycardia will cause atrial electrical remodeling, and initiate atrial fibrillation.  
           [0018]    Consequently, the pulmonary vein entrance to the atrium has become a locus of a variety of treatment methodologies. However, current techniques using radio frequency energy and high-intensity focused ultrasound to ablate the pulmonary veins orifices are difficult to use successfully, due to inaccurate ablation of tissues in a constantly beating heart, and to inadequate achievement of transmurality.  
           [0019]    Thus, there is a widely felt need for, and it would be highly advantageous to have, techniques for creating a circumferential conduction block in a pulmonary vein ostium, which techniques are minimally invasive, minimally traumatic, and which produce lesions sufficiently wide and deep to create a conductive block, yet which do not substantially disturb nor destroy the structural integrity of the atria.  
           [0020]    Cryogenic techniques have been used in the field of arrhythmia treatment primarily to effect atrial mapping. Atrial mapping is a procedure utilizing cooling and freezing of tissues to create a temporary blockage of electrical conduction therein. According to atrial mapping procedure, a tissue is selected for inspection and is cooled to a temperature sufficient to temporarily block electrical conductivity, and then the effect of this blockage on the patient&#39;s heart rhythms is observed. In this manner, it is possible to map regions responsible for aberrant electrical pulses and non-synchronized contractions, since when such a region is thus cooled, arrhythmia is reduced or abolished.  
           [0021]    Atrial mapping, however, is a long and slow procedure. Moreover, currently accepted therapeutic techniques utilize cryogenic mapping to map areas responsible for pathological conduction, and then utilize a separate technique, such as ablation by laser, by radio frequency energy, or by high-intensity focused ultrasound, to ablate the pathological tissues.  
           [0022]    Thus, there is a widely felt need for, and it would be highly advantageous to have, a device and method for combining mapping of pathological areas and treatment of those pathological areas in a single coordinated technique. It would be yet further advantageous if such a coordinated technique guaranteed a high degree of reliability in ensuring that the problematic locations identified by mapping are indeed the locations subsequently subject to ablation.  
         SUMMARY OF THE INVENTION  
         [0023]    According to one aspect of the present invention there is provided a form-fitting cryoprobe having a treatment head sized and formed to fit a shape of a specific organic cryoablation target, said treatment head comprising a Joule-Thomson cooler operable to cool said treatment head, and optionally comprising a Joule-Thomson heater to heat said treatment head.  
           [0024]    According to another aspect of the present invention there is provided a shape-adaptable cryoprobe having a treatment head operable to conform to a shape of a cryoablation target, said treatment head comprising a Joule-Thomson cooler operable to cool said treatment head, and preferably a Joule-Thomson heater to heat said treatment head.  
           [0025]    According to yet another aspect of the present invention there is provided a cryoprobe for cryogenic treatment of cardiac arrhythmia, said cryoprobe comprising:  
           [0026]    a) a form-fitting treatment head sized and shaped to fit a pulmonary vein ostium;  
           [0027]    b) a Joule-Thomson cooler operable to cool said treatment head.  
           [0028]    According to further features in preferred embodiments of the invention described below, the cryoprobe further comprises a Joule-Thomson heater operable to heat said treatment head, a gas input lumen operable to supply compressed cooling gas to the treatment head; and a gas exhaust lumen operable to exhaust gas from the treatment head.  
           [0029]    According to still further features in the described preferred embodiments, the cryoprobe further comprises a plurality of gas input lumens and supply of gas to each of the plurality of gas input lumens is operable to be individually controlled.  
           [0030]    According to still further features in the described preferred embodiments, the treatment head further comprises a Joule-Thomson orifice, a heat exchanging configuration, and an active cooling module on a distal face of the treatment head. The active cooling module is operable to create a temporary conduction block in a pulmonary vein ostium, and to create a permanent conduction block in a pulmonary vein ostium.  
           [0031]    According to still further features in the described preferred embodiments, the active cooling module is further operable to heat tissues of a pulmonary vein ostium.  
           [0032]    According to still further features in the described preferred embodiments, the cryoprobe further comprises a plurality of active cooling modules on the distal face of the treatment head, which may be radially distributed or circumferentially distributed. Each of the plurality of active cooling modules is in fluid communication with an independently controlled source of cooling gas.  
           [0033]    According to still further features in the described preferred embodiments, supply of gas to each of a plurality of gas input lumens is operable to be individually controlled.  
           [0034]    According to still further features in the described preferred embodiments, the active cooling module comprises a heat-conductive surface operable to conduct heat between the cooling module and tissues of a body.  
           [0035]    According to still further features in the described preferred embodiments, the cryoprobe further comprises a flexible shaft attached to the treatment head, which may comprise flexibly attached rigid segments.  
           [0036]    According to still further features in the described preferred embodiments, the cryoprobe further comprises a sensor operable to transmit data to a control module external to the cryoprobe. The sensor may be operable to transmit data over a wire, or by wireless transmission.  
           [0037]    According to still further features in the described preferred embodiments, the sensor is a thermal sensor, or a pressure sensor.  
           [0038]    According to still further features in the described preferred embodiments, the cryoprobe further comprises a plurality of sensors operable to transmit data to a control module external to the cryoprobe, and at least one of the plurality of sensors is a thermal sensor and at least one of the plurality of sensors is a pressure sensor.  
           [0039]    According to another aspect of the present invention there is provided a shape-adaptable cryoprobe, having a treatment head operable to adaptively conform to a shape of an organic target, thereby enhancing transfer of heat between the treatment head and the organic target.  
           [0040]    According to further features in preferred embodiments of the invention described below, the treatment head is operable to adaptively conform to a shape of a pulmonary vein ostium.  
           [0041]    According to further features in preferred embodiments of the invention described below, the treatment head is inflatable, and operable to be cooled by Joule-Thomson cooling, and comprises a Joule-Thomson orifice.  
           [0042]    According to further features in preferred embodiments of the invention described below, the treatment head is operable to be heated by Joule-Thomson heating.  
           [0043]    According to further features in preferred embodiments of the invention described below, the treatment head comprises an expandable volume defined by a flexible inflatable external sleeve and is operable to be cooled by expanding cooling gas flowing into the expandable volume through a Joule-Thomson orifice.  
           [0044]    According to further features in preferred embodiments of the invention described below, the treatment head comprises a Joule-Thomson cooler, a gas input lumen for supplying a pressurized cooling gas, a Joule-Thomson orifice at a termination of the gas input lumen, a flexible inflatable external sleeve operable to be inflated by gas passed through the Joule-Thomson orifice, a gas exhaust lumen for exhausting gas from the treatment head, and a gas exhaust valve operable to control flow of gas through the gas exhaust lumen.  
           [0045]    According to further features in preferred embodiments of the invention described below, the cryoprobe further comprises an inner cooling module operable to be cooled by a Joule-Thomson cooler, and an exterior expansion volume defined within a flexible inflatable exterior sleeve, the exterior expansion volume being exterior to the inner cooling module. Preferably, the inner cooling module comprises a Joule-Thomson orifice, a fluid transfer lumen, a gas input lumen, and a gas exhaust lumen.  
           [0046]    Preferably, the expansion volume is in fluid communication with the fluid transfer lumen and is operable to expand when filled by a fluid supplied under pressure through the fluid transfer lumen.  
           [0047]    Preferably, the inner cooling module is operable to cool a fluid within the expansion volume.  
           [0048]    According to still another aspect of the present invention there is provided a linear cryoprobe operable to apply cryogenic cooling to body tissues in an elongated pattern, which comprises:  
           [0049]    a) a treatment head comprising a Joule-Thomson orifice and a heat-conducting surface so shaped that a ratio of length of the surface to width of the surface is greater than six to one;  
           [0050]    b) a gas input lumen; and  
           [0051]    c) a gas exhaust lumen;  
           [0052]    According to further features in preferred embodiments of the invention described below, the treatment head further comprises an insulating shroud.  
           [0053]    According to still another aspect of the present invention there is provided a system for treating cardiac arrhythmia, which comprises  
           [0054]    a) a control module operable to receive data from a sensor;  
           [0055]    b) a cryoprobe which comprises:  
           [0056]    i) a treatment head comprises a Joule-Thomson orifice; and  
           [0057]    ii) a gas input lumen operable to supply a pressurized gas to the Joule-Thomson orifice; and  
           [0058]    b) a gas supply module operable to supply compressed gas to the gas input lumen.  
           [0059]    According to further features in preferred embodiments of the invention described below, the cryoprobe further comprises a cryoprobe sensor operable to transmit data to the control module, preferably by wireless communication.  
           [0060]    According to further features in preferred embodiments of the invention described below, the cryoprobe further comprises a plurality of cryoprobe sensors operable to transmit data to the control module, including thermal sensors and pressure sensors.  
           [0061]    According to further features in preferred embodiments of the invention described below, the gas supply module comprises a plurality of sources of compressed gas.  
           [0062]    According to further features in preferred embodiments of the invention described below, the plurality of sources comprises a source of compressed cooling gas.  
           [0063]    According to further features in preferred embodiments of the invention described below, the plurality of sources comprises a source of compressed heating gas.  
           [0064]    According to further features in preferred embodiments of the invention described below, the plurality of sources comprises a source of mixed cooling gas and heating gas.  
           [0065]    According to further features in preferred embodiments of the invention described below, the plurality of sources comprises a plurality of sources of mixed cooling gas and heating gas.  
           [0066]    According to further features in preferred embodiments of the invention described below, the system further comprises a cooling gas input valve controlling flow of cooling gas from the gas supply module into the gas input lumen.  
           [0067]    According to further features in preferred embodiments of the invention described below, the cooling gas input valve is controllable by commands transmitted by the control module.  
           [0068]    According to further features in preferred embodiments of the invention described below, the system further comprises a heating gas input valve controlling flow of heating gas from the gas supply module into the gas input lumen.  
           [0069]    According to further features in preferred embodiments of the invention described below, the heating gas input valve is controllable by commands transmitted by the control module.  
           [0070]    According to further features in preferred embodiments of the invention described below, the gas supply module comprises a heat exchanging configuration.  
           [0071]    According to further features in preferred embodiments of the invention described below, the cryoprobe comprises a heat-exchanging configuration.  
           [0072]    According to further features in preferred embodiments of the invention described below, the cryoprobe comprises a treatment head sized and shaped to fit a pulmonary vein ostium.  
           [0073]    According to further features in preferred embodiments of the invention described below, the cryoprobe comprises a treatment head operable to adaptively conform to a shape of an organic target, thereby enhancing transfer of heat between the treatment head and the organic target.  
           [0074]    According to further features in preferred embodiments of the invention described below, the cryoprobe is operable to adaptively conform to a shape of a pulmonary vein ostium.  
           [0075]    According to further features in preferred embodiments of the invention described below, the treatment head is inflatable and comprises a Joule-Thomson orifice.  
           [0076]    According to further features in preferred embodiments of the invention described below, the cryoprobe is operable to apply cryogenic cooling to body tissues in an elongated pattern.  
           [0077]    According to further features in preferred embodiments of the invention described below, the cryoprobe comprises:  
           [0078]    a) a treatment head which comprises a Joule-Thomson orifice and a heat-conducting surface so shaped that a ratio of length of the surface to width of the surface is greater than six to one;  
           [0079]    b) a gas input lumen; and  
           [0080]    c) a gas exhaust lumen.  
           [0081]    According to still another aspect of the present invention there is provided a method for treating cardiac arrhythmia, which comprises:  
           [0082]    a) introducing a cryoprobe into an atrium of a heart;  
           [0083]    b) positioning the cryoprobe at an ostium of a pulmonary vein, in such a position that an active cooling module of the cryoprobe is in contact with tissues of the ostium;  
           [0084]    c) cooling the active cooling module to a first temperature, the first temperature being such as to cause the cryoprobe to adhere to tissues of the ostium, thereby causing the cryoprobe to adhere to the tissues of the ostium;  
           [0085]    d) testing the positioning of the cryoprobe by cooling the active cooling module to a second temperature, the second temperature being such as to create a temporary conduction block in the ostium if the cryoprobe is correctly positioned, thereby creating a temporary conduction block in the ostium if the cryoprobe is correctly positioned;  
           [0086]    e) evaluating the positioning of the cryoprobe by determining whether the temporary conduction block was created by step (d);  
           [0087]    f) if the temporary conductive block was created by step (d), cooling the active cooling module to a third temperature, the third temperature being such as to create a permanent conductive block in the ostium, thereby creating a permanent conductive block in the ostium, thereby treating the cardiac arrhythmia.  
           [0088]    According to further features in preferred embodiments of the invention described below, the method further comprises  
           [0089]    g) heating the cryoprobe to free the cryoprobe from the adhesion if a conductive block is not created by step (d); and  
           [0090]    h) repositioning the cryoprobe at the ostium, and preferably  
           [0091]    i) heating the cryoprobe after cooling the active cooling module to the third temperature, thereby releasing the cryoprobe from the adhesion after having created the conductive block.  
           [0092]    According to further features in preferred embodiments of the invention described below, the cryoprobe is sized and formed to conform to a shape of a pulmonary vein ostium.  
           [0093]    According to further features in preferred embodiments of the invention described below, the cryoprobe comprises an inflatable portion, and is operable to adaptively conform to a shape of a pulmonary vein ostium.  
           [0094]    According to further features in preferred embodiments of the invention described below, the method further comprises  
           [0095]    j) endoscopically introducing the cryoprobe into an atrium;  
           [0096]    k) introducing a distal portion of the cryoprobe into an opening of a pulmonary vein; and  
           [0097]    l) inflating the inflatable portion;  
           [0098]    thereby adaptively conforming the cryoprobe a shape of the pulmonary vein ostium.  
           [0099]    According to still another aspect of the present invention there is provided a method for treating cardiac arrhythmia, which comprises:  
           [0100]    a) positioning at an exterior wall of a atrium a cryoprobe having a treatment head which comprises an elongated cooling surface;  
           [0101]    b) cooling the cooling surface to a first temperature, the first temperature being such as to cause the cryoprobe to adhere to tissues of the atrium wall, thereby causing the cryoprobe to adhere to tissues of the atrium wall;  
           [0102]    c) testing the positioning of the cryoprobe by cooling the cooling surface to a second temperature, the second temperature being such as to create a temporary conduction block in the atrium wall if the cryoprobe is correctly positioned, thereby creating a temporary conduction block in the atrium wall if the cryoprobe is correctly positioned;  
           [0103]    d) evaluating the positioning of the cryoprobe by determining whether the temporary conduction block was created by step (d);  
           [0104]    e) if the temporary conduction block was created by step (d), cooling the active cooling module to a third temperature, the third temperature being such as to create a permanent a permanent conduction block in the atrium wall, thereby creating a permanent conduction block in the atrium wall,  
           [0105]    thereby treating the cardiac arrhythmia.  
           [0106]    The present invention successfully addresses the shortcomings of the presently known configurations by providing a minimally invasive technique for creation of lesions capable of blocking pathological electrical conduction in atrial tissue, which technique permits treatment of atrial fibrillation and of other forms of cardiac arrhythmias, yet which does not require subjecting a patient to the trauma of open chest and open heart surgeries.  
           [0107]    The present invention further successfully addresses the shortcomings of the presently known configurations by providing a therapeutic device and method enabling to place a therapeutic probe in or on a selected portion of a beating heart, and to maintain that probe accurately in place for a required duration of treatment, without resorting to heart immobilization.  
           [0108]    The present invention still further successfully addresses the shortcomings of the presently known configurations by providing techniques for creating a circumferential conduction block in a pulmonary vein ostium, which techniques are minimally invasive, minimally traumatic, and which produce lesions sufficiently wide and deep to create a conduction block, yet which do not substantially disturb nor destroy the structural integrity of the atria.  
           [0109]    The present invention still further successfully addresses the shortcomings of the presently known configurations by providing a device and method for mapping pathological areas responsible for arrhythmia, and for treating those pathological areas, in a single coordinated technique, while guaranteeing a high degree of reliability in ensuring that the problematic locations identified by mapping are indeed the locations subsequently subject to ablation.  
           [0110]    Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.  
           [0111]    Implementation of the method and system of the present invention involves performing or completing selected tasks or steps manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of preferred embodiments of the method and system of the present invention, several selected steps could be implemented by hardware or by software on any operating system of any firmware or a combination thereof. For example, as hardware, selected steps of the invention could be implemented as a chip or a circuit. As software, selected steps of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In any case, selected steps of the method and system of the invention could be described as being performed by a data processor, such as a computing platform for executing a plurality of instructions. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0112]    The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.  
         [0113]    In the drawings:  
         [0114]    [0114]FIG. 1 is a simplified schematic of a cryoprobe having a form-fitting treatment head adapted to conform to the shape of a pulmonary vein ostium, according to an embodiment of the present invention;  
         [0115]    [0115]FIG. 2 is a simplified schematic presenting details of a Joule-Thomson cooler operable to cool a cooling module of a cryoprobe, according to an embodiment of the present invention;  
         [0116]    [0116]FIG. 3 is a simplified schematic presenting currently preferred recommended dimensions for a treatment head of a cryoprobe, according to a preferred embodiment of the present invention;  
         [0117]    [0117]FIG. 4 is a simplified schematic illustrating an alternate construction of a cooling module of a cryoprobe, according to an embodiment of the present invention;  
         [0118]    [0118]FIG. 5 is a simplified schematic illustrating a further alternate construction of a cooling module of a cryoprobe, according to an embodiment of the present invention;  
         [0119]    [0119]FIG. 6 is a simplified schematic presenting a configuration of a shaft of a cryoprobe, according to an embodiment of the present invention;  
         [0120]    [0120]FIG. 7 is a simplified schematic presenting an alternate configuration of a shaft of a cryoprobe, according to an embodiment of the present invention;  
         [0121]    [0121]FIG. 8 is a simplified schematic illustrating a shape-adaptable cryoprobe configured for endovascular insertion, according to an embodiment of the present invention;  
         [0122]    [0122]FIG. 9 is a simplified schematic presenting a shape-adaptable cryoprobe configured for treating body tissues;  
         [0123]    [0123]FIG. 10 is a simplified schematic illustrating a double-layered shape-adaptable cryoprobe configured for endoscopic insertion, according to an embodiment of the present invention;  
         [0124]    [0124]FIG. 11 a simplified schematic illustrating a double-layered shape-adaptable cryoprobe configured for treatment of tissues, according to an embodiment of the present invention;  
         [0125]    [0125]FIG. 12 is a simplified schematic illustrating a cryoprobe having an elongated treatment head, according to an embodiment of the present invention;  
         [0126]    [0126]FIG. 13 is a simplified schematic of an elongated treatment head of a cryoprobe, according to an embodiment of the present invention;  
         [0127]    [0127]FIG. 14 is a simplified schematic of a system for cryosurgery comprising a cryoprobe having a form-fitting treatment head, according to an embodiment of the present invention;  
         [0128]    [0128]FIG. 15 is a simplified schematic of a system for cryosurgery comprising a shape-adaptable cryoprobe, according to an embodiment of the present invention;  
         [0129]    [0129]FIG. 16 is a simplified schematic of a system for cryosurgery comprising a double-layered shape-adaptable cryoprobe, according to an embodiment of the present invention; and  
         [0130]    [0130]FIG. 17 is a simplified schematic of a system for cryosurgery comprising a cryoprobe having an elongated head, according to an embodiment of the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0131]    The present invention is of devices, systems, and methods for cryosurgical treatment of cardiac arrhythmia. Specifically, the present invention can be used to create a conduction block in a pulmonary vein ostium and in an atrial wall, to treat cardiac arrhythmia.  
         [0132]    The principles and operation of cryoprobes specialized for treatment of atrial arrhythmia according to the present invention may be better understood with reference to the drawings and accompanying descriptions.  
         [0133]    Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.  
         [0134]    To enhance clarity of the following descriptions, the following terms and phrases will first be defined:  
         [0135]    The phrase “heat-exchanging configuration” is used herein to refer to component configurations traditionally known as “heat exchangers”, namely configurations of components situated in such a manner as to facilitate the passage of heat from one component to another. Examples of “heat-exchanging configurations” of components include a porous matrix used to facilitate heat exchange between components, a structure integrating a tunnel within a porous matrix, a structure including a coiled conduit within a porous matrix, a structure including a first conduit coiled around a second conduit, a structure including one conduit within another conduit, or any similar structure. It is to be noted that in the accompanying figures and in discussion of those figures hereinbelow, a particular exemplary configuration of a heat-exchanging configuration is shown in the figures, by way of illustration. It is to be understood that illustration of a particular configuration of heat-exchanging configuration in a figure is by way of example only, and is not intended to be limiting. The heat-exchanging configurations illustrated in the various figures may be any heat-exchanging configuration conforming to the definition of heat-exchanging configurations hereinabove.  
         [0136]    The phrase “Joule-Thomson heat exchanger” as used herein refers, in general, to any device used for cryogenic cooling or for heating, in which a gas is passed from a first region of the device, wherein it is held under higher pressure, to a second region of the device, wherein it is enabled to expand to lower pressure. A Joule-Thomson heat exchanger may be a simple conduit, or it may include an orifice through which gas passes from the first, higher pressure, region of the device to the second, lower pressure, region of the device. A Joule-Thomson heat exchanger may further include a heat-exchanging configuration, for example a heat-exchanging configuration used to cool gasses within a first region of the device, prior to their expansion into a second region of the device.  
         [0137]    The phrase “cooling gasses” is used herein to refer to gasses which have the property of becoming colder when passed through a Joule-Thomson heat exchanger. As is well known in the art, when gasses such as argon, nitrogen, air, krypton, CO 2 , CF 4 , xenon, and N 2 O, and various other gasses pass from a region of higher pressure to a region of lower pressure in a Joule-Thomson heat exchanger, these gasses cool and may to some extent liquefy, creating a cryogenic pool of liquefied gas. This process cools the Joule-Thomson heat exchanger itself, and also cools any thermally conductive materials in contact therewith. A gas having the property of becoming colder when passing through a Joule-Thomson heat exchanger is referred to as a “cooling gas” in the following.  
         [0138]    The phrase “heating gasses” is used herein to refer to gasses which have the property of becoming hotter when passed through a Joule-Thomson heat exchanger. Helium is an example of a gas having this property. When helium passes from a region of higher pressure to a region of lower pressure, it is heated as a result. Thus, passing helium through a Joule-Thomson heat exchanger has the effect of causing the helium to heat, thereby heating the Joule-Thomson heat exchanger itself and also heating any thermally conductive materials in contact therewith. Helium and other gasses having this property are referred to as “heating gasses” in the following.  
         [0139]    As used herein, a “Joule-Thomson cooler” is a Joule-Thomson heat exchanger used for cooling. As used herein, “Joule Thomson cooling” is cooling by Joule Thomson cooler. As used herein, a “Joule-Thomson heater” is a Joule Thomson heat exchanger used for heating, and “Joule-Thomson heating” is heating by Joule-Thomson heater.  
         [0140]    References hereinbelow to a pulmonary vein ostium are to be understood to refer to tissues within and immediately around a pulmonary vein ostium, that is, within and immediately around the point of entry of a pulmonary vein in an atrium of the heart. Thus, for example, reference to creation of a conduction block in a pulmonary vein ostium may be understood to include creation of a conduction block in epicardial tissue around and within a pulmonary vein ostium.  
         [0141]    In discussion of the various figures described hereinbelow, like numbers refer to like parts.  
         [0142]    Referring now to the drawings, FIG. 1 is a is a simplified schematic of a cryoprobe having a form-fitting treatment head sized and formed to match the shape of a pulmonary vein ostium, according to an embodiment of the present invention.  
         [0143]    [0143]FIG. 1 presents a cryoprobe  100  comprising a shaft  160  (shown here in abbreviated form) and a form-fitting treatment head  10  whose shape conforms to the shape of the ostium region  114  of a pulmonary vein  112 , approached from within the left atrium  116  of a heart. Cryoprobe  100  is designed and constructed to treat atrial arrhythmia by use cryogenic cooling to create a circumferential conduction block in a pulmonary vein  112 .  
         [0144]    Cryoprobe  100  may be inserted into atrium  116  through open-heart surgery, yet in a preferred mode of operation cryoprobe  100  is inserted into atrium  116  in a minimally invasive procedure, and most preferably endovascularly.  
         [0145]    Cryoprobe  100  comprises active cooling module  120 , which in a preferred embodiment is formed as a circumferential zone on a distal face of treatment head  110 , and is sized and formed to substantially conform to size and shape of ostium  114  of vein  112 .  
         [0146]    Cooling module  120  is operable to be cooled to cryoablation temperatures. Cooling module  120  preferably comprises a thermally conductive distal face  121 , shaped and configured to form close contact with heart tissue at ostium  114 , thereby enhancing heat transfer between cooling module  120  and tissues in and around ostium  114 . Thus, cooling module  120  is operable to create a lesion, to damage or to ablate tissues of ostium region  114 , and thereby to create a conduction block within region  114 , without substantially disturbing the structural integrity of the atria.  
         [0147]    Attention is now drawn to FIG. 2, which is a simplified schematic showing details of a Joule-Thomson cooler operable to cool cooling module  120 , according to an embodiment of the present invention.  
         [0148]    [0148]FIG. 2 presents a gas input lumen  130 , operable to supply pressurized cooling gas to a Joule-Thomson orifice  140  situated in or near cooling module  120 . Pressurized cooling gas from gas input lumen  130 , passing through orifice  140 , is enabled to expand. Expansion of pressurized cooling gas cools that gas, which consequently cools cooling module  120 , and in particular distal face  121  of cooling module  120 . If treatment head  110  of cryoprobe  100  is installed in close contact with tissues of ostium  114  and cooling module  120  is cooled by expansion of cooling gas from orifice  140 , then thermal contact between tissues of ostium  114  and distal face  121  of cooling module  120  leads to cooling of those ostium tissues.  
         [0149]    Expanded gasses are free to exit from cooling module  120  through one or more exits  123  in cooling module  120 . Total cross-sectional area of exits  123  is significantly larger than that of orifice  140 , thus substantially eliminating hydraulic resistance to gas outflow. Optional heat exchanging configuration  124  may be used to pre-cool cooling gas in gas input lumen  130 , by exchanging beat between input gas in gas input lumen  130  and cold exhaust gas in gas exhaust lumen  132 .  
         [0150]    In a preferred embodiment of the present invention, gas input lumen  130  is further operable to supply pressurized heating gas to orifice  140 . Expansion of pressurized heating gas heats that gas, which consequently heats cooling module  120 , and in particular distal face  121  of cooling module  120 . Optional heat exchanging configuration  124  can be used to pre-heat heating gas, by exchanging heat between hot expanded heating gas in gas exhaust lumen  132  and input heating gas in gas input lumen  130 .  
         [0151]    In a preferred mode of operation of cryoprobe  100 , cooling of tissues of ostium  114  is used to produce several useful effects.  
         [0152]    A first useful effect of cooling of tissues of ostium  114  by treatment head  110  is to cause treatment head  110  to adhere to those tissues. Such adherence is extremely useful, in that it creates a temporary bond between treatment head  110  and region  114 , providing consistent positioning of treatment head  110  with respect to pulmonary vein  112 , hence enabling a controlled and consistent process of further therapeutic cooling. This controlled and consistent process may be contrasted to processes of prior art arrhythmia therapies. Arrhythmia is preferably treated without stopping beating of the heart, yet the necessity of aiming a therapeutic probe at a moving target, and maintaining a contact with that target over an extended period of time while performing a therapeutic act, adds greatly to the difficulty of such therapeutic procedures. Adhesion, which occurs when cooling module  120  of treatment head  110  is cooled to a vicinity of −20° C., greatly simplifies continuation of a therapeutic procedure, because treatment head  110  maintains a consistent relationship to ostium  114 , even though the heart is beating.  
         [0153]    It is further noted that adhesion between treatment head  110  and tissues of ostium  114  is easily reversible. As described above, in a preferred embodiment gas input lumen  130  is operable to supply a heating gas to orifice  140 . Supplying compressed heating gas to orifice  140  has an effect of heating treatment head  110 , which liberates head  110  from adhesions caused by tissues freezing to head  110 . Thus, it is possible for an operator to position head  110  with respect to a therapeutic target, cool head  110  sufficiently to cause adhesion, and inspect that positioning to determine if it is satisfactory. If so, the therapeutic process can continue. If not, head  110  is heated, the adhesion is released, and the operator is enabled to reposition head  110 .  
         [0154]    In an additional preferred mode of operation of cryoprobe  100 , utilizing a second useful effect of cooling tissues of ostium  114 , treatment head  110  is cooled to a moderate degree of cooling, preferably between −10° C. and −30° C, and most preferably between −15° C. and −25° C. Such moderate cooling causes a temporary blockage of electrical transmission through the cooled tissues. This temporary blockage is in effect a simulation of the permanent blockage that would be produced by more intense cooling. At a moderate cooling level, conduction blocking is temporary and reversible. Thus, in a preferred mode of operation, an operator is enabled to position head  110  at a therapeutic target, cool head  110  sufficiently to cause adhesion, and cool head  110  sufficiently to cause temporary blockage of electrical conductivity (generally, temporary conduction blockage takes place at temperatures similar to those which cause adhesion). The operator may then evaluate the results. If atrial arrhythmia is reduced or prevented, correct positioning of heat  110  is confirmed. If, on the other hand, arrhythmia is not significantly corrected, then no permanent damage has been done to the cooled tissues, head  110  is heated to release adhesion, and head  10  may be repositioned.  
         [0155]    Positioning, adhering, testing, freeing, and repositioning may be repeated until a position is found which successfully reduces arrhythmia when tested by moderate cooling.  
         [0156]    In an additional preferred mode of operation of cryoprobe  100 , utilizing a third useful effect of cooling tissues of ostium  114 , once appropriate positioning of head  110  has been achieved and tested, ostial tissues  114  are further cooled, to effect permanent blockage of electrical conductivity.  
         [0157]    To permanently affect blockage of electrical conductivity in the treated tissues, cooling module  120  is preferably cooled to a temperature between −30° C. and −120° C., and more preferably between −40° C. and −80° C., to create permanent electrical conductivity blockage.  
         [0158]    Heating of head  110  may subsequently optionally be practiced, to secure release of adhesions between head  110  and tissues which adhered to head  110  when frozen.  
         [0159]    Attention is now drawn to FIG. 3, which is a simplified schematic presenting currently preferred dimensions for treatment head  110 , according to a preferred embodiment of the present invention. Diameter  170  is preferably between 5 mm and 25 mm, and most preferably between 10 mm and 20 mm. Diameter  171  is preferably between 10 mm and 35 mm, most preferably between 15 mm and 25 mm. Distance  172  is preferably between 5 mm and 30 mm, and most preferably between 10 mm and 20 mm. In a preferred mode of utilization, a surgeon would be supplied with a plurality of cryoprobes  100  of varying dimension, and would thus be enabled to choose an appropriate model, in view of the actual size of a patient&#39;s ostium, after access is made and the ostium observed.  
         [0160]    Attention is now drawn to FIG. 4, which is a simplified schematic illustrating an alternate construction of cooling module  120 , according to an embodiment of the present invention. FIG. 4 presents a treatment head  110  having a plurality of separately coolable cooling modules  120 , concentrically arranged. Exemplary modules are designated in FIG. 4 as  120 A and  120 B. Cooling module  120 A receives gas from a gas input lumen  130 A. Cooling module  120 B receives gas from gas input lumen  130 B. Flow of gas in each of gas input lumens  130 A and  130 B is individually controllable, consequently cooling of cooling modules  120 A and  120 B is individually controllable as well.  
         [0161]    Attention is now drawn to FIG. 5, which is a simplified schematic illustrating a further alternate construction of cooling module  120 , according to an embodiment of the present invention. FIG. 5 presents a treatment head  110  having a plurality of separately coolable cooling modules  120 , radially arranged. Exemplary modules are designated in FIG. 5 as  120 E,  120 F, and  120 G. Cooling module  120 F receives gas from a gas input lumen  130 F. Cooling module  120 G receives gas from gas input lumen  130 G. Other cooling modules  120  are similarly supplied with gas (additional gas input lumens not shown). Flow of gas in each gas input lumen (e.g.,  130 F and  130 G) is individually controllable, consequently cooling of each cooling module  120  is individually controllable as well.  
         [0162]    Attention is now drawn to FIG. 6, which is a simplified schematic presenting a configuration of shaft  160  of cryoprobe  100 , according to an embodiment of the present invention. Shaft  160  of probe  100  is a continuously flexible shaft  162 , preferably constructed of a flexible material, such as, for example, Biocompatible Tygon(R).  
         [0163]    Attention is now drawn to FIG. 7, which is a simplified schematic presenting an alternate configuration of shaft  160  of cryoprobe  100 , according to an embodiment of the present invention. In this alternative configuration, shaft  160  of probe  100  is a modularly flexible shaft  164 , comprising a plurality of rigid segments  166 , flexibly connected to each other.  
         [0164]    It is noted that flexible shaft  162 , illustrated in FIG. 6, and modularly flexible shaft  164 , illustrated in FIG. 7, are optional implementations of shaft  160  of cryoprobe  100 , described hereinabove with reference to FIGS.  1 - 5 . It is further noted that flexible shaft  162 , illustrated in FIG. 6, and modularly flexible shaft  164 , illustrated in FIG. 7, are optional implementations of shaft  160  of cryoprobe  200 , described hereinbelow with reference to FIGS.  8 - 9 , and of shaft  160  of cryoprobe  300 , described hereinbelow with reference to FIGS.  10 - 11 , and of cryoprobe  400 , described hereinbelow with reference to FIG. 12.  
         [0165]    Attention is now drawn to FIG. 8, which is a simplified schematic illustrating a shape-adaptable cryoprobe  200  configured for endovascular insertion, according to an embodiment of the present invention.  
         [0166]    Shape-adaptable cryoprobe  200  comprises an inflatable/deflatable head  210  having an expandable internal volume  218  hermetically contained within a flexible inflatable external sleeve  212 . When deflated, cryoprobe  200  is configured for endovascular insertion or for other uses requiring passage through narrow openings. When deflated, diameter of head  210  is preferably not substantially larger than diameter of shaft  160 .  
         [0167]    Attention is now drawn to FIG. 9, which is a simplified schematic presenting shape-adaptable cryoprobe  200  configured for treating ostial tissues  114 , or other tissues. In operation, cooling gas supplied through gas input lumen  130 , and passing through an optional heat-exchanging configuration  124 , expands though Joule-Thomson orifice  140  into internal volume  218 . Cooling gas passing through orifice  140  has a double role. First, expanded cooling gas is cold, and serves to cool flexible inflatable external sleeve  212  of inflatable/deflatable head  210 . Second, gas expanding into external sleeve  212  inflates sleeve  212 , expanding head  210  into a form which may bring it into close contact with tissues to be treated.  
         [0168]    In a recommended method of use, with head  210  deflated, distal portion  211  of inflatable/deflatable head  210  is first inserted into the opening of pulmonary vein  112 . Inflatable/deflatable head  210  is then both cooled and inflated by cooling gas or by a mixture of gasses, causing it to expand against ostial tissues  114  and neighboring tissues. Ostial tissues  114  and optionally other neighboring tissues  214  may then be treated with various degrees of cryogenic cooling, as described hereinabove.  
         [0169]    Internal volume  218  communicates with gas exhaust lumen  132 , whereby expanded gas is eliminated from cryoprobe  200 .  
         [0170]    According to a preferred embodiment, a desired pressure is maintained in volume  218  by appropriate use of a gas exhaust valve  220  controlling outflow of gas from gas output lumen  132 . Gas exhaust valve  220  is optionally implemented as a remotely-controlled valve responsive to commands received from a command module  450  (not shown in FIG. 9). In a preferred embodiment command module  450  is operable to receive pressure data from a pressure sensor  222 , which measures pressure in gas exhaust lumen  132  and communicates its measurements to command module  450 , either by wire or by wireless communication.  
         [0171]    In a preferred embodiment, gas input lumen  130  is operable to receive heating gas as well as cooling gas, and further operable to receive a mixture of heating and cooling gasses. Pressure can thus be introduced into volume  218  using an expanded gas which cools head  210 , or using an expanded gas which heats head  210 , or using an expanded gas which leaves temperature of head  210  substantially unchanged.  
         [0172]    In a recommended use, once head  210  has been positioned and inflated as described hereinabove, cryoprobe  200  is useable in the various ways, and with the various effects, as were described hereinabove with reference to uses of cooling and heating of cryoprobe  100 , particularly with reference to the discussion of FIG. 2.  
         [0173]    Attention is now drawn to FIG. 10, which is a simplified schematic illustrating a double-layered shape-adaptable cryoprobe  300  configured for endoscopic insertion, according to an embodiment of the present invention.  
         [0174]    Cryoprobe  300  shares many of the features, uses, and advantages of cryoprobe  200  illustrated by FIG. 8 and FIG. 9, yet cryoprobe  300  is differently constructed. Cryoprobe  300  comprises a shaft  160  and a shape-adaptable treatment head  330 .  
         [0175]    Shaft  160  comprises an input gas lumen  130 , a gas exhaust lumen  132 , and a fluid transfer lumen  312 .  
         [0176]    Treatment head  330  comprises a flexible inflatable exterior sleeve  320 , an inner cooler  310  (also called an inner cooling module  310 ), and an exterior expansion volume  314  defined within exterior sleeve  320  and exterior to inner cooler  310 . Exterior volume  314  is hermetically contained by sleeve  320 .  
         [0177]    Inner cooler  310  is formed within a cooler wall  326 , which defines and hermetically contains a cooler interior volume  324 . Inner cooler  310  further comprises a Joule-Thomson orifice  140  through which pressurized gas from gas input lumen  130  may expand into interior volume  324 . As explained hereinabove, cooling gas expanding through orifice  140  will cool inner cooler  310 , and heating gas expanding through orifice  140  will heat inner cooler  310 . Expanded gas exhausts from volume  324  through gas exhaust lumen  132 .  
         [0178]    When cryoprobe  300  is in a deflated configuration, as shown in FIG. 10, exterior expansion volume  314  is preferentially substantially empty of fluid.  
         [0179]    Exterior expansion volume  314  is in fluid communication with fluid transmission lumen  312  extending through shaft  160 . Fluid transmission lumen  312  is operable to transfer a fluid into and out of exterior volume  314 .  
         [0180]    To deflate treatment head  330 , fluid is drained or allowed to drain from exterior volume  314 , through fluid transmission lumen  312 , thereby emptying or partially emptying exterior volume  312  and deflating exterior sleeve  320 , thereby contracting head  330 . In a preferred embodiment, diameter of treatment head  330  when contracted is not substantially larger than diameter of shaft  160 , thereby facilitating insertion of cryoprobe  300  through narrow openings, and in particular facilitating endovascular introduction and deployment of probe  300 .  
         [0181]    Attention is now drawn to FIG. 11, which is a simplified schematic presenting cryoprobe  300  in inflated configuration.  
         [0182]    To inflate treatment head  330 , a fluid  316  is forced under pressure through fluid transmission lumen  312  into exterior expansion volume  314 , thereby inflating exterior sleeve  320  and expanding treatment head  330 , as illustrated by FIG. 11. In a preferred embodiment, fluid  316  is a liquid, yet fluid  316  may be a gas.  
         [0183]    When it is desired to cool treatment head  330 , cooling gas is supplied under pressure, through gas input lumen  130 , to Joule-Thomson orifice  140 , whence it expands into interior volume  324 , is cooled by expansion, and cools cooler wall  326 . Cooler wall  326  is preferably constructed of heat-transmissive material, such as a metal, to facilitate transfer of heat between inner cooler  310  and fluid  316 . Thus, cooling cooler wall  326  cools fluid  316 , which in turn cools exterior sleeve  320 . Thus, cooling inner cooler  310  cools exterior sleeve  320 .  
         [0184]    In use, exterior sleeve  320  is positioned in contact or near proximity with tissues of ostium region  114  which is desired to treat, and cooling inner cooler  310  when head  330  is positioned in contact with, or close to, tissues of ostium region  114  cools those tissues.  
         [0185]    Recommended uses of cryoprobe  300  include positioning and inflating cryoprobe  300  as described hereinabove, and then cooling and heating cryoprobe  300  to various temperatures, to affect ostial tissues  114 , as discussed hereinabove with respect to cryoprobe  100 , particularly with reference to the discussion of FIG. 2.  
         [0186]    As shown in FIGS. 10 and 11, cryoprobe  300  optionally comprises one or more heat exchanging configurations, similar to that described hereinabove with reference to cryoprobe  100 , for pre-cooling cooling gas and for pre-heating heating gas directed through gas input lumen  130  into cooler  310 .  
         [0187]    Attention is now drawn to FIG. 12, which is a simplified schematic illustrating a cryoprobe having an elongated head, according to an embodiment of the present invention.  
         [0188]    A well-known method of treatment of atrial arrhythmia comprises practicing long and narrow lesions in exterior portions of an atrial wall. FIG. 12 presents a cryoprobe  400  adapted to producing such lesions.  
         [0189]    Cryoprobe  400  comprises an elongated treatment head  410  and a shaft  160 .  
         [0190]    Shaft  160  comprises a gas input lumen  130 , a gas exhaust lumen  132 , and one or more optional heat exchanging configurations  124 .  
         [0191]    Treatment head  410  comprises at least one and preferably a plurality of Joule-Thomson orifices, through which compressed cooling gas and compressed heating gas from gas input lumen  132  passes into an expansion chamber  406 . Cooling gas, expanding into chamber  406  and cooled by expansion, cools expansion chamber  406 .  
         [0192]    Treatment head  410  has an elongated shape, that is, treatment head  410  is relatively longer than it is wide. A preferred ration of length to width is preferably greater than 6 to 1. For example, a recommended dimension for a preferred embodiment of treatment head  410  is of a length between 10 mm and 80 mm, and a width of between 1 mm and 10 mm. It is noted, however, that in a preferred mode of utilization, a surgeon would be supplied with a plurality of cryoprobes  400  of varying dimension, and would thus be enabled to choose an appropriate model, in view of the actual size of a treatment locus, once access is made and the locus observed.  
         [0193]    Attention is now drawn to FIG. 13, which is a simplified schematic of treatment head  410  of cryoprobe  400 , according to an embodiment of the present invention. FIG. 13 illustrates treatment head  410  as viewed from a narrow side. That is, FIG. 13 illustrates treatment head  410  as viewed from the side designated  412  in FIG. 12.  
         [0194]    In FIG. 13, arrows illustrate passage of a gas (e.g., a cooling gas) from gas input lumen  130 , expanding into expansion chamber  406 , from whence gas is exhausted through gas exhaust lumen  132 . Expansion of cooling gas into chamber  406  cools chamber  406 . An insulating shroud  402 , preferably of biomedical plastic material such as Teflon®, provides insulation on an exterior wall of proximal portion  403  of head  410 , and serves to protect tissues in contact with proximal portion  403  from being unduly cooled by contact with treatment head  410 . A thermally conductive surface  404 , for example a metal strip, is provided on distal portion  405  of head  110 , and serves to enhance thermal conductivity between head  410  and body tissues. Thus, when treatment head  410  is cooled, tissues touching conductive strip  404  or in close proximity to conductive strip  404  will be efficiently cooled by head  410 , whereas tissues touching or in close proximity to proximal portion  403  of head  410  will be protected by insulating shroud  402  and will be relatively uninfluenced by treatment head  410 .  
         [0195]    In a recommended usage, treatment head  410  of cryoprobe  400  is positioned against, and in contact with, an exterior surface of an atrial wall, where treatment head  410  is cooled to create a conduction block within atrial wall tissues. Recommended usages for cryoprobe  400  include those outlined above with respect to cryoprobe  100  and in particular with reference to FIG. 2.  
         [0196]    Attention is now drawn to FIG. 14, which is a simplified schematic of a system for cryosurgery comprising a cryoprobe having a form-fitting treatment head, according to a embodiment of the present invention.  
         [0197]    System  90 , illustrated by FIG. 14, is particularly recommended for treating of atrial arrhythmia, and in particular for forming a conduction block in a pulmonary vein ostium.  
         [0198]    System  90  comprises a cryoprobe  100 , as described hereinabove with particular reference to FIGS.  1 - 5 . System  90  further comprises a gas supply module  460  and a command module  450 .  
         [0199]    Gas supply module  460  is operable to supply compressed gas to gas input lumen  130  of cryoprobe  100 .  
         [0200]    Gas supply module  460  comprises a cooling gas source  420 , which is a source of compressed cooling gas, and a heating gas source  422 , which is a source of compressed heating gas. Flow of gas from cooling gas source  420  is controlled by cooling gas input valve  424 , which is preferably a remotely controllable valve. Flow of gas from heating gas source  422  is controlled by heating gas input valve  426 , which is preferably a remotely controllable valve. Gas supply module  450  further comprises one-way valves  428 .  
         [0201]    Gas supply module  460  optionally further comprises a mixed gas source  440 , which is a source of a mixture of cooling gas and heating gas in selected proportion. Flow of gas from mixed gas source  440  is controlled by mixed gas input valve  442 , which is preferably a remotely controllable valve.  
         [0202]    Gas supply module  460  further optionally comprises a heat-exchanging configuration  124 , operable to pre-cool cooling gas flowing towards gas input lumen  130  by transferring heat from cooling gas flowing towards gas input lumen  130  to cold cooling gas exhausting from gas exhaust lumen  132 .  
         [0203]    Heat exchanging configuration  124  is further operable to pre-heat heating gas by transferring heat from hot heating gas exhausting from gas exhaust lumen  132 , which has been heated by expansion, to compressed heating gas flowing towards gas input lumen  130 .  
         [0204]    Gas supply module  460  may further comprise other optional means for cooling of cooling gas flowing towards gas input lumen  130 , and for heating of heating gas flowing towards gas input lumen  130 .  
         [0205]    Command module  450  is operable to receive real-time data from one or more optional thermal sensors  430  and one or more optional pressure sensors  432 . Thermal sensor  430  may be a thermocouple, or other form of heat sensor.  
         [0206]    Thermal sensors  430  and pressure sensors  432  may be situated within treatment head  110  of cryoprobe  100 , as illustrated in FIG. 14, or alternatively maybe be situated in shaft  160  of cryoprobe  100 , or further alternatively may be situated at various points within gas supply module  450 .  
         [0207]    Thermal sensors  430  are operable to communicate temperature data to command module  450  in real time. Pressure sensors  432  are also operable to communicate temperature data to command module  450  in real time.  
         [0208]    Command module  450  is operable to receive data from thermal sensors  430  and from pressure sensors  432 . Command module  450  is further operable to receive instructions from an operator. Command module  450  preferably comprises a memory  452  and a display  454 . Command module  450  is preferably operable to display data received from sensors  430  and  432 , and to display instructions received from an operator. Command module  450  is operable to send commands to cooling gas input valve  424 , to heating gas input valve  426 , and to mixed gas input valve  442 , and is optionally further operable to send commands to other valves and controls of system  90 .  
         [0209]    Command module  450  is further preferably operable to algorithmically select or generate commands to be sent to gas input valve  424  and to heating gas input valve  426  and to mixed gas input valve  442 , such commands being based on algorithmic evaluations of data received from sensors  430  and  432 , and further based on instructions received from an operator. Algorithms thus used may be stored in memory  452 .  
         [0210]    Command module  450  is further operable to record in memory  452 , for later display and analysis, data received from sensors  430  and  432  and instructions received from an operator.  
         [0211]    In a preferred use, command module  450  is operable to respond to instructions from an operator by adjusting flow from a plurality of gas sources, to produce a mixture which, when expanded in a Joule-Thomson orifice, will produce a selected degree of cooling. As was noted hereinabove, selected steps in a therapeutic process of treatment of atrial arrhythmia may require selected degrees of cooling during different phases of a treatment process. Command module  450  is preferably operable to deliver to gas input lumen  130  a selected mixture of gas such as will produce a selected degree of cooling in treatment head  110 . In a preferred embodiment, command module  450  is operable to deliver this selected mixture of gas according to a pre-selected mixture of cooling gas and of heating gas. In a further preferred embodiment, command module  450  is operable to deliver this selected mixture of gas according to algorithmically selected commands to gas input valves  424 ,  426 , and  442 , in response to temperature and pressure data receive from sensors  430  and  432 .  
         [0212]    An alternate preferred embodiment of gas supply module  460  (not shown) presents a plurality of mixed gas sources  440 , (e.g.,  440 A,  440 B, etc.), each operable to supply a mixture of heating gas and cooling gas in a selected proportion. Preferably, each of mixed gas sources  440  presents a mixture operable to supply a desired degree of cooling for a particular phase of treatment of arrhythmia, as described hereinabove.  
         [0213]    In an optional embodiment of system  90 , wherein cryoprobe  100  comprises a plurality of gas input lumens, gas supply module  460  optionally comprises a plurality of cooling gas input valves  424  (e.g.,  424 A,  424 B,  424 C), a plurality of heating gas input valves  426  (e.g.,  426 A,  426 B,  426 C), and optionally a plurality of mixed gas input valves (e.g.,  442 A,  442 B,  442 C), (not shown in FIG. 14). In a preferred embodiment, command module  450  is operable to control each of said plurality of gas input values individually, thereby individually controlling cooling and heating of each of a plurality of active cooling modules  120  (e.g.,  120 A,  120 B,  120 E,  120 F,  120 G).  
         [0214]    Attention is now drawn to FIG. 15, which is a simplified schematic of a system for cryosurgery comprising a shape-adaptable cryoprobe, according to an embodiment of the present invention.  
         [0215]    System  91 , illustrated by FIG. 15, is particularly recommended for treating atrial arrhythmia, and in particular for forming a conduction block in a pulmonary vein ostium.  
         [0216]    System  91  comprises a shape-adaptable cryoprobe  200 , as described hereinabove with particular reference to FIG. 8 and FIG. 9. System  90  further comprises a gas supply module  460  and a command module  450 .  
         [0217]    Gas supply module  460  is operable to supply compressed gas to gas input lumen  130  of cryoprobe  200 .  
         [0218]    Gas supply module  460  comprises a cooling gas source  420 , which is a source of compressed cooling gas, and a heating gas source  422 , which is a source of compressed heating gas. Flow of gas from cooling gas source  420  is controlled by cooling gas input valve  424 , which is preferably a remotely controllable valve. Flow of gas from heating gas source  422  is controlled by heating gas input valve  426 , which is preferably a remotely controllable valve. Gas supply module  450  further comprises one-way valves  428 .  
         [0219]    Gas supply module  460  optionally further comprises a mixed gas source  440 , which is a source of a mixture of cooling gas and heating gas in selected proportion. Flow of gas from mixed gas source  440  is controlled by mixed gas input valve  442 , which is preferably a remotely controllable valve.  
         [0220]    Gas supply module  460  further optionally comprises a heat-exchanging configuration  124 , operable to pre-cool cooling gas flowing towards gas input lumen  130  by transferring heat from cooling gas flowing towards gas input lumen  130  to cold cooling gas exhausting from gas exhaust lumen  132 .  
         [0221]    Heat exchanging configuration  124  is further operable to pre-heat heating gas by transferring heat from hot heating gas exhausting from gas exhaust lumen  132 , which has been heated by expansion, to compressed heating gas flowing towards gas input lumen  130 .  
         [0222]    Gas supply module  460  may further comprise other optional means to cool cooling gas flowing towards gas input lumen  130 , and to heat heating gas flowing towards gas input lumen  130 .  
         [0223]    Command module  450  is operable to receive real-time data from one or more optional thermal sensors  430  and one or more optional pressure sensors  432 . Thermal sensor  430  may be a thermocouple, or other form of heat sensor.  
         [0224]    Thermal sensors  430  and pressure sensors  432  may be situated within treatment head  210  of cryoprobe  200 , as illustrated in FIG. 15, or alternatively maybe be situated in shaft  160  of cryoprobe  200 , or further alternatively may be situated at various points within gas supply module  450 .  
         [0225]    Thermal sensors  430  are operable to communicate temperature data to command module  450  in real time. Pressure sensors  432  are also operable to communicate temperature data to command module  450  in real time.  
         [0226]    Command module  450  is operable to receive data from thermal sensors  430  and from pressure sensors  432 . Command module  450  is further operable to receive instructions from an operator. Command module  450  preferably comprises a memory  452  and a display  454 . Command module  450  is preferably operable to display data received from sensors  430  and  432 , and to display instructions received from an operator. Command module  450  is operable to send commands to cooling gas input valve  424 , to heating gas input valve  426 , and to mixed gas input valve  442 , and is optionally further operable to send commands to other valves and controls of system  91 .  
         [0227]    Command module  450  is further preferably operable to algorithmically select or generate commands to be sent to gas input valve  424 , to heating gas input valve  426 , and to mixed gas input valve  442 , such commands being based on algorithmic evaluations of data received from sensors  430  and  432 , and further based on instructions received from an operator. Algorithms thus used may be stored in memory  452 .  
         [0228]    Command module  450  is further operable to record in memory  452 , for later display and analysis, data received from sensors  430  and  432  and instructions received from an operator.  
         [0229]    It is further noted that in system  91 , command module  450  is operable to send commands to gas exhaust valve  220 , and thus to control outflow of gas from gas output lumen  132 . Thus, by coordinating inflow of gas from gas supply module  460  into gas input lumen  130 , and outflow of gas from gas output lumen  132 , command module  450  is operable to control pressure within internal volume  218  of head  210  of cryoprobe  200 , and thereby to control inflation and deflation of inflatable/deflatable head  210  of cryoprobe  200 . Control module  450  preferably controls inflation and deflation of head  210  under algorithmic control, according to pre-set programmed instructions, or according to instructions received from an operator in real time.  
         [0230]    In a preferred use, command module  450  is operable to respond to instructions from an operator by adjusting flow from a plurality of gas sources, to produce a mixture which, when expanded in a Joule-Thomson orifice, will produce a selected degree of cooling. As was noted hereinabove, selected steps in a therapeutic process of treatment of atrial arrhythmia may require selected degrees of cooling during different phases of a treatment process. Command module  450  is preferably operable to deliver to gas input lumen  130  a selected mixture of gas such as will produce a selected degree of cooling in treatment head  210 . In a preferred embodiment, command module  450  is operable to deliver this selected mixture of gas according to a pre-selected mixture of cooling gas and of heating gas. In a further preferred embodiment, command module  450  is operable to deliver this selected mixture of gas according to algorithmically selected commands to gas input valves  424 ,  426 , and  442 , in response to temperature and pressure data receive from sensors  430  and  432 .  
         [0231]    An alternate preferred embodiment of gas supply module  460  (not shown) presents a plurality of mixed gas sources  440 , (e.g.,  440 A,  440 B, etc.), each operable to supply a mixture of heating gas and cooling gas in a selected proportion. Preferably, each of mixed gas sources  440  presents a mixture operable to supply a desired degree of cooling for a particular phase of treatment of arrhythmia, as described hereinabove.  
         [0232]    Attention is now drawn to FIG. 16, which is a simplified schematic of a system for cryosurgery comprising a double-layered shape-adaptable cryoprobe, according to a embodiment of the present invention.  
         [0233]    System  92 , illustrated by FIG. 16, is particularly recommended for treating atrial arrhythmia, and in particular for forming a conduction block in a pulmonary vein ostium.  
         [0234]    System  92  comprises a double-layered shape-adaptable cryoprobe  300 , as described hereinabove with particular reference to FIG. 10 and FIG. 11. System  92  further comprises a gas supply module  460 , a command module  450 , and a fluid pump  470 .  
         [0235]    Fluid pump  470  is operable to pump fluid into fluid transfer lumen  312  of cryoprobe  300 . Fluid pump  470  is preferable also operable to pump fluid out of fluid transfer lumen  312 , yet alternatively fluid pump  470  may be operable to allow fluid to drain from fluid transfer lumen  312 . Fluid pump  470  is preferably operable to respond to commands from command module  450 .  
         [0236]    Gas supply module  460  is operable to supply compressed gas to gas input lumen  130  of cryoprobe  300 .  
         [0237]    Gas supply module  460  comprises a cooling gas source  420 , which is a source of compressed cooling gas, and a heating gas source  422 , which is a source of compressed heating gas. Flow of gas from cooling gas source  420  is controlled by cooling gas input valve  424 , which is preferably a remotely controllable valve. Flow of gas from heating gas source  422  is controlled by heating gas input valve  426 , which is preferably a remotely controllable valve. Gas supply module  450  further comprises one-way valves  428 .  
         [0238]    Gas supply module  460  optionally further comprises a mixed gas source  440 , which is a source of a mixture of cooling gas and heating gas in selected proportion. Flow of gas from mixed gas source  440  is controlled by heating gas input valve  426 , which is preferably a remotely controllable valve.  
         [0239]    Gas supply module  460  further optionally comprises a heat-exchanging configuration  124 , operable to pre-cool cooling gas flowing towards gas input lumen  130  by transferring heat from cooling gas flowing towards gas input lumen  130  to cold cooling gas exhausting from gas exhaust lumen  132 .  
         [0240]    Heat exchanging configuration  124  is further operable to pre-heat heating gas by transferring heat from hot heating gas exhausting from gas exhaust lumen  132 , which has been heated by expansion, to compressed heating gas flowing towards gas input lumen  130 .  
         [0241]    Gas supply module  460  may further comprise other optional means to cool cooling gas flowing towards gas input lumen  130 , and to heat heating gas flowing towards gas input lumen  130 .  
         [0242]    Command module  450  is operable to receive real-time data from one or more optional thermal sensors  430  and one or more optional pressure sensors  432 . Thermal sensor  430  may be a thermocouple, or other form of heat sensor.  
         [0243]    Thermal sensors  430  and pressure sensors  432  may be situated within treatment head  330  of cryoprobe  300 , as illustrated in FIG. 16, or alternatively maybe be situated in shaft  160  of cryoprobe  300 , or further alternatively may be situated at various points within gas supply module  450 .  
         [0244]    Thermal sensors  430  are operable to communicate temperature data to command module  450  in real time. Pressure sensors  432  are also operable to communicate temperature data to command module  450  in real time.  
         [0245]    Command module  450  is operable to receive data from thermal sensors  430  and from pressure sensors  432 . Command module  450  is further operable to receive instructions from an operator. Command module  450  preferably comprises a memory  452  and a display  454 . Command module  450  is preferably operable to display data received from sensors  430  and  432 , and to display instructions received from an operator. Command module  450  is operable to send commands to cooling gas input valve  424  to heating gas input valve  426 , and to mixed gas input valve  442 , and is optionally further operable to send commands to other valves and controls of system  92 .  
         [0246]    Command module  450  is further preferably operable to algorithmically select or generate commands to be sent to gas input valve  424 , to heating gas input valve  426 , and to mixed gas input valve  442 , such commands being based on algorithmic evaluations of data received from sensors  430  and  432 , and further based on instructions received from an operator. Algorithms thus used may be stored in memory  452 .  
         [0247]    Command module  450  is further operable to record in memory  452 , for later display and analysis, data received from sensors  430  and  432  and instructions received from an operator.  
         [0248]    In system  92 , command module  450  is further operable to send commands to fluid pump  470 , and thus to control inflow and outflow of fluid to and from fluid transfer lumen  312 . Thus, by controlling flow of fluid into and out of fluid transfer lumen  312 , command module  450  is operable to control pressure within exterior volume  314  of cryoprobe  300 , and thereby to control inflation and deflation of shape-adaptable treatment head  330  of cryoprobe  300 . Control module  450  preferably controls inflation and deflation of head  330  under algorithmic control, according to pre-set programmed instructions, or according to instructions received from an operator in real time.  
         [0249]    In a preferred use, command module  450  is operable to respond to instructions from an operator by adjusting flow from a plurality of gas sources, to produce a mixture which, when expanded in a Joule-Thomson orifice, will produce a selected degree of cooling. As noted hereinabove, selected steps in a therapeutic process of treatment of atrial arrhythmia may require selected degrees of cooling during different phases of a treatment process. Command module  450  is preferably operable to deliver to gas input lumen  130  a selected mixture of gas such as will produce a selected degree of cooling in treatment head  330 . In a preferred embodiment, command module  450  is operable to deliver this selected mixture of gas according to a pre-selected mixture of cooling gas and of heating gas. In a further preferred embodiment, command module  450  is operable to deliver this selected mixture of gas according to algorithmically selected commands to gas input valves  424 ,  426 , and  442 , in response to temperature and pressure data receive from sensors  430  and  432 .  
         [0250]    An alternate preferred embodiment of gas supply module  460  (not shown) presents a plurality of mixed gas sources  440 , (e.g.,  440 A,  440 B, etc.), each operable to supply a mixture of heating gas and cooling gas in a selected proportion. Preferably, each of mixed gas sources  440  presents a mixture operable to supply a desired degree of cooling for a particular phase of treatment of arrhythmia, as described hereinabove.  
         [0251]    Attention is now drawn to FIG. 17, which is a simplified schematic of a system for cryosurgery comprising a cryoprobe having an elongated head, according to a embodiment of the present invention.  
         [0252]    System  93 , illustrated by FIG. 17, is particularly recommended for treating atrial arrhythmia, and in particular for forming a conduction block in a wall of an atrium of a heart.  
         [0253]    System  93  comprises a cryoprobe  400  having an elongated treatment head, as described hereinabove with particular reference to FIG. 12. System  93  further comprises a gas supply module  460  and a command module  450 .  
         [0254]    Gas supply module  460  is operable to supply compressed gas to gas input lumen  130  of cryoprobe  400 .  
         [0255]    Gas supply module  460  comprises a cooling gas source  420 , which is a source of compressed cooling gas, and a heating gas source  422 , which is a source of compressed heating gas. Flow of gas from cooling gas source  420  is controlled by cooling gas input valve  424 , which is preferably a remotely controllable valve. Flow of gas from heating gas source  422  is controlled by heating gas input valve  426 , which is preferably a remotely controllable valve. Gas supply module  450  further comprises one-way valves  428 .  
         [0256]    Gas supply module  460  optionally further comprises a mixed gas source  440 , which is a source of a mixture of cooling gas and heating gas in selected proportion. Flow of gas from mixed gas source  440  is controlled by fixed gas input valve  442 , which is preferably a remotely controllable valve.  
         [0257]    Gas supply module  460  further optionally comprises a heat-exchanging configuration  124 , operable to pre-cool cooling gas flowing towards gas input lumen  130  by transferring heat from cooling gas flowing towards gas input lumen  130  to cold cooling gas exhausting from gas exhaust lumen  132 .  
         [0258]    Heat exchanging configuration  124  is further operable to pre-heat heating gas, by transferring heat from hot heating gas exhausting from gas exhaust lumen  132 , which has been heated by expansion, to compressed heating gas flowing towards gas input lumen  130 .  
         [0259]    Gas supply module  460  may further comprise other optional means to cool cooling gas flowing towards gas input lumen  130 , and to heat heating gas flowing towards gas input lumen  130 .  
         [0260]    Command module  450  is operable to receive real-time data from one or more optional thermal sensors  430  and one or more optional pressure sensors  432 . Thermal sensor  430  may be a thermocouple, or other form of heat sensor.  
         [0261]    Thermal sensors  430  and pressure sensors  432  may be situated within treatment head  410  of cryoprobe  400 , as illustrated in FIG. 17, or alternatively maybe be situated in shaft  160  of cryoprobe  400 , or further alternatively may be situated at various points within gas supply module  450 .  
         [0262]    Thermal sensors  430  are operable to communicate temperature data to command module  450  in real time. Pressure sensors  432  are also operable to communicate temperature data to command module  450  in real time.  
         [0263]    Command module  450  is operable to receive data from thermal sensors  430  and from pressure sensors  432 . Command module  450  is further operable to receive instructions from an operator. Command module  450  preferably comprises a memory  452  and a display  454 . Command module  450  is preferably operable to display data received from sensors  430  and  432 , and to display instructions received from an operator. Command module  450  is operable to send commands to cooling gas input valve  424  to heating gas input valve  426 , and to mixed gas input valve  442 , and is optionally further operable to send commands to other valves and controls of system  93 .  
         [0264]    Command module  450  is further preferably operable to algorithmically select or generate commands to be sent to gas input valve  424 , to heating gas input valve  426 , and to mixed gas input valve  442 , such commands being based on algorithmic evaluations of data received from sensors  430  and  432 , and further based on instructions received from an operator. Algorithms thus used may be stored in memory  452 .  
         [0265]    Command module  450  is further operable to record in memory  452 , for later display and analysis, data received from sensors  430  and  432  and instructions received from an operator.  
         [0266]    In a preferred use, command module  450  is operable to respond to instructions from an operator by adjusting flow from a plurality of gas sources, to produce a mixture which, when expanded in a Joule-Thomson orifice, will produce a selected degree of cooling. As was noted hereinabove, selected steps in a therapeutic process of treatment of atrial arrhythmia may require selected degrees of cooling during different phases of a treatment process. Command module  450  is preferably operable to deliver to gas input lumen  130  a selected mixture of gas such as will produce a selected degree of cooling in treatment head  410 . In a preferred embodiment, command module  450  is operable to deliver this selected mixture of gas according to a pre-selected mixture of cooling gas and of heating gas. In a further preferred embodiment, command module  450  is operable to deliver this selected mixture of gas according to algorithmically selected commands to gas input valves  424 ,  426 , and  442 , in response to temperature and pressure data receive from sensors  430  and  432 .  
         [0267]    An alternate preferred embodiment of gas supply module  460  (not shown) presents a plurality of mixed gas sources  440 , (e.g.,  440 A,  440 B, etc.), each operable to supply a mixture of heating gas and cooling gas in a selected proportion. Preferably, each of mixed gas sources  440  presents a mixture operable to supply a desired degree of cooling for a particular phase of treatment of arrhythmia, as described hereinabove.  
         [0268]    It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.  
         [0269]    Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.