Abstract:
An intravenous surgical instrument comprises an inner shaft or post and an outer sheath. At a distal end of the inner post a spring-tail or whip-like electrode is disposed substantially in a sagittal plane, or one perpendicular to a longitudinal axis of the shaft. Following an insertion into a human vein or other circulatory vessel the distal end of the shaft is protruded from the sheath; thereafter sheath, post and electrode are simultaneously withdrawn from the vein, with a relative rotatory motion being imparted to the electrode. A current flow is preferably simultaneously imposed across the electrode into an inner surface of the surrounding vessel, facilitating a damaging of the vessel inner surface and a collapse of the vessel. This description applies primarily to veins, which may be drained of blood prior to a start of a collapsing procedure; for use in arteries a modified embodiment is disclosed employing a compound construction electrode tip which facilitates a limiting of current flow to a region of direct electrode contact with a circulatory vessel wall, and a reduction of stray currents conduction into the blood.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a method for treating a varicose vein. More particularly, this invention relates to a method for eliminating a varicose vein. This invention also relates to an associated device for use in the method. 
     In varicose veins, the valves arc malfunctioning or destroyed so that the veins balloon at the lower ends. This condition can be particularly pronounced in certain leg veins. In a conventional surgical procedure for the treatment of varicose veins, two incisions are made in a vein, one at the ankle and one at the groin. An elongate stripper instrument is then inserted through the ankle incision and passed through the vein to the groin. At the groin, a cup is attached to the distal end of the stripper. Subsequently, the stripper is pulled down the leg so that the cup rips out the vein. 
     In this procedure, other veins connecting to the varicose vein are torn. The leg subsequently turns ugly shades of black and blue. Of course, the patient experiences substantial pain and suffering from the procedure. 
     Various means have been proposed to eliminate or close varicose veins with less surgical trauma, including damaging an inner endothelial surface of a vein with laser, electric or radio-frequency energy. Motivation for such damage is the known tendency of internally damaged circulatory vessels to collapse and remain collapsed through adhesion of damaged or mutilated surfaces; essentially a beneficial application of otherwise undesirable or post-surgical adhesion. Known means to achieve endothelial damage however generally suffer from a drawback that the intensity of energy imparted to the endothelial surface is uneven, particularly so when the vein is irregular in cross-section, and the diameter varies over a treated length. 
     OBJECTS OF THE INVENTION 
     An object of the present invention is to provide a method for treating varicose veins. 
     Another object of the present invention is to provide such a method which results in less pain to the patient than the conventional technique. 
     An additional object of the present invention is to provide such a method which generates less hematoma than the conventional technique. 
     A further object of the present invention is to provide such a method wherein injury to the nerves is reduced. 
     Yet a further object of the invention is to provide a method and device for delivering a similar treatment to arteries. 
     These and other objects of the present invention will be apparent from the drawings and \ed descriptions herein. 
     SUMMARY OF THE INVENTION 
     A medical method for collapsing circulatory vessels in vivo in accordance with the present invention utilizes an elongate element having an at least partially flexible appendage attached to a tip of the element. The method comprises inserting said elongate element and said appendage in a circulatory vessel of a patient and then simultaneously rotating and withdrawing the elongate element from the blood vessel, causing the appendage to describe an essentially helical contact path with an inner surface of the vessel, to thereby damage the inner surface and facilitate a permanent collapse of the vessel. 
     In accordance with a particular embodiment of the present invention, the appendage takes the form of a whip-like surgical steel spring or spring-tail wire component of an intravenous surgical instrument and is disposed inside the vein or other elongate circulatory vessel in a sagittal plane thereof. The wire or spring-tail is attached at a first end to a central post or shaft of an elongate tool inserted in the vein, and coils outward in the sagittal plane, substantially perpendicular to a longitudinal axis of the elongate vessel. A second end of the spring-tail is free, and tangentially and pressingly disposed along an inner surface or endothelium of the vein. During a withdrawal of the instrument the shaft is simultaneously rotated and pulled from the vessel, and the second end of the spring-tail is drawn over the endothelium in a helical or spiral pattern in which the endothelium is scored or damaged. By a proper choice of size and relaxed shape of the spring-tail, the spring-tail remains in continuous contact with the endothelium during the withdrawal with approximately constant contact area. Therefore a relatively uniform amount of damage is done to the inner vessel walls during the withdrawal operation. 
     In the context of this disclosure, a “spring-tail” may be taken explicitly to mean a short wire-element, thin enough in cross-section, and of sufficient stiffness, to withstand a significant bending strain without plastic deformation. In other words, a spring-tail is an object having the mechanical properties of a section of a coil spring having an arcuate form elastically deformable between a straight configuration on one hand and approximately a full turn of coil on the other hand. 
     In a second particular embodiment of the present invention, the shaft is disposed within an first insulated sheath, electrically isolating the shaft from an inner surface or wall of the vessel. The spring-tail in this embodiment serves as a first electrode, a second electrode being disposed outside of a patient, possibly in a form of a grounding strip. A current path then exists along the central post or shaft, passing through the spring-tail or first electrode, through a contact point between the first electrode and an inner wall or endothelium of the circulatory vessel, and thence diffusely to an outer surface of the patient. The contact point between the first electrode and the endothelium thereby forms a most restricted, and therefore highest resistance, portion of the current path passing through fleshy part of the patient. Consequently, a highest concentration or intensity of cellular damage attributable to current flow is realized at the contact point with the endothelium. 
     While a degree or concentration of damage in cells of the endothelium is enhanced by the passage of current, over purely mechanical means, a drawback of this embodiment inheres in the conductivity of human blood, which comprises a saline solution, and a resultant dilution of a contact current density by a blood borne current. This limitation is overcome or compensated in a third embodiment of the present invention. In this embodiment, a modified, composite, first electrode includes a second sheath surrounding the spring-tail. The sheath is fabricated of a high-resistance alloy, such as would be suitable for thin film heater elements, and is insulated from the tail when in a relaxed or non-deformed configuration by either an air-gap, or a filling of a non-conductive gel, such as a petroleum jelly. When pressed against an inner surface or wall of a vessel, the sheath of the composite electrode deforms by design with marginally less stiffness than the tail, and as a result the sheath and tail are brought into an internal contact in an area of contact of the second sheath with the inner wall, as more fully described hereinafter with reference to the drawings. 
     It will be appreciated that in a thin film of high-resistance alloy conduction is more facile across a thickness of the film than along a surface direction. Accordingly, following a deformation of the composite electrode when pressed against a vessel wall, a substantial portion of the current will pass perpendicularly across the film and into the vessel wall, and a minor portion of the current will flow along a surface direction, and leak into surrounding blood. A degree of resistive heating will also be realized in the area of contact of sheath with the inner wall, and accordingly an enhanced degree of local cellular damage. 
     In case it is possible to empty a blood or circulatory vessel to be collapsed, as for example in the case of veins, the second embodiment will be seen to function optimally, without the appearance of leakage currents in the blood. In case the vessel cannot be drained, as is likely in the case of arteries, it will be seen that a utilization of the more complex third embodiment is indicated. 
     In yet another embodiment of a vascular surgical tool in accordance with the present invention, a modified form of the second embodiment, an electrode predisposed in a hollow version of the central post or shaft is compressively coiled inside the shaft. Upon being advanced toward a distal end of the shaft, a tip of the electrode emerges therefrom and partially uncoils, forming a spring-tail configuration lying in the sagittal plane of the circulatory vessel. Following a endothelium debriding operation, the partially uncoiled electrode tip may be snipped from the tool, preparatory to exposing a fresh surface in a subsequent operation. This method of feeding a spring or wire from a central shaft has application to both a purely mechanical and an electrically facilitated abrasion of the endothelium. A different mode of deployment is contemplated in the embodiment including a conducting sheath surrounding the spring-tail, or electrode tip. In this embodiment, the electrode tip and surrounding sheath are inserted into a vein or other vessel constrained by a first sheath to lie in generally a longitudinal axis of the vessel. Prior to commencement of a abrasion operation, a relative movement of a central post or shaft and the surrounding first sheath expels the electrode tip and sheath, which components are biased towards and then assume an arcuate conformation, lying generally at right angles to the central shaft, and in the sagittal plane. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic perspective of an intravenous surgical instrument in accordance with the present invention. 
     FIG. 2 is a schematic cross section of a human vein or artery, showing an insertion and a mode of employment of the surgical instrument of FIG.  1 . 
     FIG. 3 is a cross-sectional view of a modification of the instrument of FIG.  1 . 
     FIG. 4 is a cross-sectional view of an alternative modification of the instrument of FIG.  1 . 
     FIG. 5 is a schematic perspective, showing a mode of employment of the modified surgical instrument of FIG. 4 against an endothelial wall or inner surface of a human vein or artery. 
     FIG. 6 is yet another schematic perspective, showing an active tip of the modified surgical instrument of FIGS. 4 and 5, partially in cut-away view, in contact with a wall or inner surface of a vein or artery. 
     FIG. 7 is a schematic cross section of a human vein containing the instrument of FIG.  1 . 
     FIG. 8 is a geometric diagram illustrating characteristics of a helix. 
     FIG. 9 is partially a perspective view, partially a circuit diagram and partially a cross-section of an deployed intravenous electrical surgical instrument in accordance with the present invention. 
     FIG. 10 is a cross-section of a co-axial electrical cable. 
     FIG. 11A is a projection of an axis of a distal tip of the instrument of FIG. 4 in a plane containing a major longitudinal axis of the instrument. 
     FIG. 11B is a projection of an axis of a distal tip of the instrument of FIG. 4 in a plane perpendicular to a major longitudinal axis of the instrument. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As illustrated in FIG. 1, a surgical instrument  50  for use in effectuating the permanent collapse of tubular organs such as blood vessels comprises an outer tube or sheath  52  which substantially encloses an inner shaft or rod  54 . A tail or end-section  56  of rod  54  may be alternately protruded and withdrawn through a distal mouth  58  of the sheath, the protrusion or withdrawal being controllable from a proximal end of the surgical instrument. A flexible appendage in the form of a whip-like spring or spring-tail wire lead  60  is mounted on a tip  62  of rod  54 . The term “spring tail,” defined in detail above, refers to a wire segment with the mechanical properties of a short segment of a coil spring, although, possibly straight in a relaxed conformation. The term “whip-like” may be construed identically in this context, with an implied reference to so-called whip antennas. 
     Lead or spring-tail  60  has an arcuate form, as shown in FIG. 1, and, in a pre-loaded configuration (not shown) is withdrawn inside mouth  58 , in a coiled configuration, along with the rod tail  56 . An intended mode of use of instrument  50  is indicated by arrows AA and BB, signifying a rotation and simultaneous withdrawal of rod  54  relative to a human vein  68  in which the surgical device has been inserted (FIG.  2 ). As shown in FIG. 2, sheath  52  is simultaneously withdrawn from vein  68  along with rod  54  while the rod is being rotated. Rod  54  rotates relative to sheath  52  and with respect to an inner surface or endothelial layer  70  of the vein. In a relaxed or stationary extended configuration in vein  68 , spring-tail  60  is disposed in a generally circumferential configuration, as shown in FIG.  7 . Upon withdrawal and rotation of rod  54 , a locus or path of contact of spring-tail  60  with the inner surface or endothelial layer  70  of vein  68  will have a generally helical conformation, as shown in FIG.  2 . 
     Helix  72  has a pitch p (FIG. 8) determined both by a both a linear rate of withdrawal of rod  54  and a rate of angular rotation. Where rod  54  translates along a vein at a velocity v and with r rotations per unit time, the pitch p is equal to v/r, irrespective of an intravascular diameter d (FIGS.  7  and  8 ). Similarly, depending on intravascular diameter d and on instrument dimensions, control may be simultaneously effectuated over the dwell (the amount of time the wire lead is in contact with the endothelium while riding along the path or helix  72 ), spacing or pitch p, and in an embodiment where electric current is also employed, as discussed below, an electric current j. Thereby a degree of damage to the endothelium may be accurately controlled and a complete vein closure and collapse without wall breakthrough facilitated. 
     A second, alternative, embodiment of an intravenous surgical instrument is shown in FIG.  3 . Attached to rod  54  is an appendage in the form of extended spring or mechanical lead  74  predisposed in a distal end  76  of sheath  52 . In a deployment of the lead, following an insertion of the instrument into a circulatory vessel (not shown), rod  54  is advanced a predetermined distance dd, similar to an operation of the embodiment of FIG. 1, to expose a length of wire or spring-tail  78  at mouth  58  of the sheath. Contrary to a mode of operation of the embodiment of FIG. 1, however, only a portion of the lead or spring is exposed at mouth  58 , a remaining portion staying inside the sheath following the deployment. Relative longitudinal or axial positions of rod  54  and sheath  52  are then locked at a proximal end of the instrument by any means (not shown) which will be apparent to those skilled in the relevant mechanical arts, in a manner which still allows relative rotation of the rod and the sheath. 
     At least two modes of employment of the embodiment of FIG. 3 are contemplated. In cases where a diameter of vein  68  changes significantly over a length of intended collapse, exposed wire  78  may be paid out or withdrawn over a course of an operation, in compensation for the varying diameter, thereby maintaining an approximately constant degree of intensity of damage to the endothelium. Separately, when a tip  80  of lead  74  becomes eroded or worn, a region (not designated) adjoining the tip may be trimmed, and a fresh length of wire  74  be exposed at mouth  58  for the execution of subsequent operations. A replacement cost of the tip or spring tail may hereby be reduced relative to the embodiment of FIG.  1 . 
     The detailed embodiments discussed above contemplate a purely mechanical mode of damaging intravascular endothelium. An efficiency of tissue destruction, and hence vein collapse, may be increased by a passage of electric current through a rotating wire appendage or electrode and over the endothelial interface simultaneously with a rotation and withdrawal of the electrode. A design of an intravenous surgical tool for collapsing veins is schematically depicted in FIG.  9 . 
     A D-C current source  82  is connected to a head or control unit  84  of an intravenous surgical instrument (not separately designated). Head  84  incorporates a mechanism for rotation, withdrawal, and relative movement of an outer sheath  86  and an inner post or flexible stalk  88 . Sheath  86  is inserted through a break in a patient&#39;s skin (not shown) into a vein  90 . At a distal end of the instrument, an electrode appendage  92  in a shape of a spring-tail or partially uncoiled spring section is provided. Electrode appendage  92  is disposed, in an inserted condition prior to commencement of tissue destruction, against an inner vessel surface or endothelium, similarly to the instrument deployment shown in FIG. 7. A return current path is provided from the patient either in a form of a connection  94  from tissue  95  to ground, possibly in a form of a grounding strap or electrode securely attached to wrist of ankle with an intervening layer of conductive paste, as known in the art, or in a direct current return to the power supply (not shown). 
     A trigger or other actuating mechanism (not shown) may be operatively connected to head or control unit  84  for simultaneously commencing a current supply, a rotation and a controlled withdrawal at pre-determined rates. The rates and various fine control steps, as necessary, for example, for the above described ejection of the electrode tip from the mouth of the sheath, may be set or controlled by appropriate individual controls (none shown). In accordance with standard laboratory techniques, a current source may either be set for constant current, or constant voltage, or some more complicated digitally controlled profile of either current or voltage, and a rotation and withdrawal may either be set for constant torque or force, respectively, or constant rotation and withdrawal rates, within a set range of torque or force. A pre-determined range of motion may also be set, allowing a automatic stop after a pre-selected length of vein collapse. These and other optional features will be evident to those skilled in the appropriate electrical and mechanical arts, and are disclosed to the public for completeness, without in any way being taken to limit the scope of the invention as delimited in the claims. It will also be appreciated by those skilled in the art that an A-C, or more complicated pulsed or digitally controlled power supply, may be substituted for a simple regulated D-C supply. 
     In an employment of the embodiment of FIG. 9, a length of vein (not designated) is clamped and drained of blood prior to commencement of an operation to collapse that vein. The primary motivation for this draining, in addition to a facilitation of a collapse and adhesion of a drained, pre-collapsed or air-filled vessel, is elimination of blood-borne conduction, which otherwise serves as a parasitic current tap for current desirably injected into a vessel wall, and makes an electrically assisted method of endothelial destruction inefficient or impractical. 
     In the case of drained vessels, the embodiments of FIG. 1,  2 ,  3  or  7  which include an un-insulated tail or tip of a central electrode disposed intravenously, are suitable for electrification. In the case of an artery, however, contained blood cannot be drained from a target length of vessel because of the superior arterial pressure, and an alternative embodiment must be employed. An embodiment suitable for intra-arterial endothelial destruction is shown in FIGS. 4,  5  and  6 . 
     A third embodiment of an intravascular surgical instrument, as shown in FIG. 4, is suitable for employment in an undrainable vessel, such as a blood-filled artery. A spring-tail inner electrode  96  is attached in-line to a distal tip  98  of a shaft  100 . Shaft  100  is enclosed in a first inner sheath  112  which is in turn enclosed in an outer sheath  113  functionally similar to sheath  52  of FIG.  1 . 
     Shaft  100  optionally takes a form of a co-axial cable or conductor  101  (FIG. 10) having a center conductor  102  conductively connected to electrode  96  and an outer conductor  104  conductively connected to ground at a proximal end thereof, but not otherwise actively functioning as a circuit element. Outer conductor  104  is generally of a braided construction while inner or center conductor  102  is solid. Inner and outer conductors  102  and  104  are separated by an insulating layer  106 , generally fabricated of nylon, while cable  101  is in toto sheathed in an elastomeric insulating jacket  108 . 
     In the alternative, thinner construction, shaft  100  is replaced by a shaft of solid fabrication (not shown), lacking first inner sheath  112 . Inn that event, a layer of insulating lubricant is utilized in concentric annular space  110  to limit blood entry and current conduction in an interior of sheath  113 . 
     Completing the embodiment of FIG. 4, a second sheath  114  forms a termination of shaft  100 . Sheath  114  and electrode  96  together form a short section of co-axial conductor or cable, with inner and outer conductors formed by the electrode and the sheath, respectively. Inner electrode  96  is terminated and centered at an insulating end-cap  119  of sheath  114 . An annular space  116  intervening between electrode  96  and sheath  114  may be maintained as an air-gap, or optionally filled with a non-conductive gel (not shown), such as petroleum jelly, or other fluidic insulator material known in the art. Outer electrode or sheath  114  is sealed to elastomeric insulating jacket  108 , when employed, or to a solid shaft, but is otherwise electrically isolated from remaining components of the intravenous surgical instrument. 
     Both sheath  114  and electrode  96  are of sufficient stiffness and thinness to undergo a significant degree of bending without plastic deformation. Sheath  114  and electrode  96  together form a tail-assembly or appendage  118  (FIG. 5) and have a relaxed or rest configuration (not designated) which may be characterized by a shape of a curvilinear central axis CC. Axis CC may be taken as coincident with electrode  96  and has a shape which may be comprehended from an inspection of FIGS. 5,  11 A, and  11 B. 
     In a deployed configuration shown in FIG. 5, tail assembly  118  first takes a bend DD (FIG. 11A) of approximately 45° to 90° with respect to a central longitudinal axis FF of outer sheath  113 . Subsequently, moving along axis CC from the mouth  117  of sheath  113 , a second bend EE of approximately 45° (a right angle is shown) or greater is taken in a plane approximately perpendicular to axis FF. A net effect or resulting conformation from bends DD and EE on tail-assembly  118  is shown in perspective in FIG.  5 . The conformation of tail assembly  118  allows a smooth rotation of the assembly about axis FF, as indicated by arrow GG, while in contact with an inner wall or endothelium  70  of a circulatory vessel. A contact region  121  is, in operation, drawn along a substantially helical path  123 . In a pre-deployment configuration of the tail-assembly or compound electrode  118 , shown in FIG. 4, the assembly is disposed in a strained or elastically deformed configuration inside mouth  117  of sheath  113 . Following an insertion of sheath  113  into an artery or other circulatory vessel, a distal movement of shaft  100  relative to the sheath ejects or protrudes tail assembly  118 , allowing the assembly to relax into the configuration of FIG.  5 . In this deployed configuration, tail assembly  118  is subject to deflection only by contact with inner wall or endothelium  70  of the circulatory vessel. This deflection is utilized to actuate and localize a current flow across the endothelium, as discussed below. A simplified version (not illustrated) of the third embodiment modifies tail assembly or “pig-tail”  118  to have a relaxed configuration substantially similar to a rest configuration of spring-tail  60  in FIG. 1, which pig-tail may in turn be either pre-disposed circumferentially in an outer sheath similar to sheath  52  for an insertion into an artery, or inserted without outer cover. These and other variations will occur to the practitioner skilled in the art, without departing from the spirit of the embodiment. 
     In another feature of embodiment of FIGS. 4 and 5, inner conductor or electrode  96  and outer conductor or sheath  114  are configured to maintain the annular space or gap  116  while in the relaxed or rest configuration shown in FIG.  5 . Upon deflection by an arterial wall or endothelium  70 , however, inner electrode  96  makes contact with an inner surface (not designated) of sheath  114  in a region of the deflection. Sheath  114  is fabricated of a conductive, but relatively resistive, material, such as a high-resistance heating alloy or a conductive polymer. Sheath  114  is moreover of relatively thin wall construction. A net effect of a high-relative resistance and a thin barrier of such material is to tend to localize current flow in a contact region  120 , across a thin layer of resistive material, and limit current flow along the thin layer. Hence, current flow directly across the sheath in region of endothelial contact  120  is favored, and current loss into surrounding blood in a blood-engorged artery, via conduction along a surface of sheath  114 , is minimized. In an alternative, optional, realization (not shown), sheath  114  may be of bi-material construction substantially of a non-conductive polymer, with a conductive strip embedded in a region of expected contact with a vessel wall, to allow current transfer. 
     It should be realized in the preceding discussion that “conductive” and “resistive” and “highly resistive” are relative terms. A “highly-resistive” metal, for example, is considerably more conductive than a semi-conductor, and in general falling in the class of “conductors.” 
     Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. As noted above, a rotatable flexible appendage on an intravascular surgical instrument pursuant to the present invention may be made of a material other than metal. In that case, there is no cauterization current passing through the endothelial wall. Instead, the mechanical cutting force of the whipping appendage damages the tissues sufficiently to effectuate permanent vascular collapse. 
     The flexibility of the appendage may be due to a telescoping capability rather than to a bendability. The key is that the appendage has a variable effective length which adapts to essentially match the distance between tip of the surgical instrument and the inner surface of the blood vessel (or other tubular member) in which the instrument is placed. 
     Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.