Catheter with high speed moving working head

A flexible, small diameter catheter for effecting various surgical procedures, such as opening a restriction formed of an undesirable material, e.g., atherosclerotic plaque, in a lumen, e.g., an artery, of a living being. The catheter includes a working head having at least one, non-sharp impacting surface arranged to be moved, e.g., rotated, at a high rate of speed by an associated drive means within the catheter. The catheter with the moving working head is brought into engagement to effect the opening of the restriction by dilating the artery and/or removing undesirable material therefrom. The removal of undesirable material results from the impacting surface impacting the material of the restriction repeatedly. A fluid is provided through the catheter to the working head and a portion is thrown radially outward. The fluid at the working head also flows in a vortex to cause any particles broken off from the restriction back to the moving working head where they are impacted again and again to further reduce their size. Such action creates particles of sufficiently small size that they may be enabled to flow distally without significant deleterious effects to distally located tissue.

BACKGROUND OF THE INVENTION 
This invention relates generally to medical devices and more particularly 
to flexible, power-driven catheters for intravascular surgery and other 
surgical procedures. 
Heretofore, the only interventional methods for treating atherosclerotic 
disease involves surgery for bypassing or remolding obstructive 
atherosclerotic material. Lasers have been suggested and are under 
investigation for transluminal revascularization. However, such devices 
have not been found common acceptance in medical practice because of 
various technical difficulties, the most serious of which being their 
tendency to perforate arterial tissue. 
In U.S. Pat. No. 4,445,509 (Auth) there is disclosed a recanalization 
catheter designed specifically for cutting away hard, abnormal deposits, 
such as atherosclerotic plaque, from the inside of an artery, and while 
supposedly preserving the soft arterial tissue. That recanalization 
catheter includes a sharp edged, multi-fluted, rotary cutting tip mounted 
at the distal end of the catheter and arranged to be rotated by a flexible 
drive shaft extending down the center of the catheter. The rotation of the 
cutting head is stated as producing a "differential cutting" effect 
whereupon relatively hard deposits are cut away from relatively soft 
tissue. Suction ports are provided in the cutting tips to pull the hard 
particles produced by the cutting action into the catheter for removal at 
the proximal end thereof so that such particles do not flow distally of 
the catheter where they could have an adverse effect on the patient's 
body. 
It has been determined that the use of sharp rotary cutting blades in a 
revascularization catheter can have various adverse effects on the 
arterial tissue, e.g., snagging, cutting or otherwise damaging the tissue 
of the artery wall. 
OBJECTS OF THE INVENTION 
Accordingly, it is the general object of the instant invention to provide 
catheters which overcome the disadvantages of the prior art. 
It is a further object of the instant invention to provide a catheter 
having a working head which is arranged for high speed movement to effect 
a surgical or medical procedure within the body of a being and without 
significant damage to adjacent tissue. 
It is a still further object of the instant invention to provide a catheter 
having a working head which is arranged for high speed movement to effect 
the opening of a restriction in a lumen and without damaging the lumen 
itself. 
It is still a further object of the instant invention to provide a catheter 
for intralumenal use which effects the dilation of the lumen without 
damaging the tissue thereof. 
It is still a further object of the instant invention to provide a catheter 
for use in opening restrictions formed of an undesirable material in a 
portion of a lumen by dilating the lumen and/or removing some of said 
undesirable material, allowing it to flow distally, all without resulting 
in injury to the patient. 
SUMMARY OF THE INVENTION 
These and other objects of the invention are achieved by providing a 
catheter for introduction into a lumen in a living being to open a 
restriction formed of an undesirable material in a portion of the lumen. 
The catheter comprises an elongated flexible member having a longitudinal 
axis, a working head located adjacent the distal end thereof and drive 
means therefor. The working head comprises at least one, non-sharp, 
impacting surface. The drive means is arranged for effecting the high 
speed movement of the working head to impact the undesirable material and 
thereby open said restriction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now in greater detail to the various figures of the drawing 
wherein like reference characters refer to like parts, there is shown in 
FIG. 1 the distal end of a catheter 20 for intravascular or other surgical 
applications, e.g., fallopian tube dilation. The catheter 20 is an 
elongated member including a flexible drive assembly 22 (only a portion of 
which can be seen in FIG. 2) located therein. The drive assembly is 
preferably constructed in accordance with the teachings of our copending 
U.S patent application Ser. No. 746,220, filed on June 19, 1985, entitled 
Spiral Wire Bearing for Rotating Wire Drive Catheter, now U.S. Pat. No. 
4,686,982 assigned to the same assignee as this application and whose 
disclosure is incorporated by reference herein. That drive assembly is 
particularly suited for in-body surgical applications, but can be used for 
other applications requiring the transmission of power at high speed and 
low torque, through a very narrow path, including bends of small, e.g., 
0.75 inches (1.9 cm) radius of curvature. Located at the distal end 
portion of the catheter 20 is a working head or tool 24. The working head 
is arranged to be moved at a high speed with respect to the catheter by 
the drive means to effect the surgical procedure to be carried out by the 
catheter. The proximal end of the drive means of the catheter and which is 
located outside the patient's body is adapted to be connected to a source 
of rotary power, e.g., an electric motor (not shown). In the preferred 
embodiment disclosed herein, the drive means 22 effects the rotary 
movement of the working head 24 under the power provided from the remote 
power source (motor). 
When the catheter 20 is used for treating occlusive atherosclerotic 
disease, such as opening a restriction in an artery formed by 
atherosclerotic plaque, the catheter is introduced into the vascular 
system of the patient such as through an opening in the femoral artery at 
a point in the groin. The catheter is then guided through the vascular 
system of the patient to the site of the vascular occlusion or blockage 
that has been determined to exist so that its working head 24 is located 
immediately adjacent the restriction. In the illustration in FIG. 1, the 
working head 24 is shown in position in a coronary artery 26 immediately 
adjacent a restriction 28, e.g., partial occlusion or full occlusion which 
is to be opened to the freer flow of blood therethrough. 
As will be recognized by those skilled in the art, such arterial 
restrictions are formed by the deposit of atherosclerotic plaque or some 
other material(s), such as wax and/or calcified athoroma, thickened and/or 
ulcerated intima, etc. Once in position, the catheter 20 is arranged to 
transluminally recatherize the diseased artery by dilating the stenotic or 
occluded area (which may or may not be covered by fibrous plaque) and/or 
selectively removing calcified thrombotic, or fatty tissue unprotected by 
fibrous plaque while alowing the artery wall to remain intact. 
The details of the construction and operation of the catheter will be 
described later. Suffice now to state that the working head 24 includes a 
pair of non-sharp impacting surfaces 24A and 24B for impacting the 
material forming th restriction. The impacting surfaces 24A and 24B are 
formed by rounded or radiused edges of a respective pair of cam surfaces 
24C and 24D. The cam surfaces are clearly shown in FIGS. 2, 4 and 6 and 
are formed by those convex outer surface portions of the working head 
located between a pair of relieved, e.g., flat, surfaces 24E and 24F. The 
working head 24 is arranged to be rotated about the longitudinal axis 25 
(FIG. 2) of the catheter at a high rate of speed, e.g., from 10,000 rpm to 
200,000 rpm. At the same time, fluid 27 (FIG. 5) is passed through the 
catheter and out of the base of the working head at the distal end of the 
catheter adjacent the central longitudinal axis thereof as shown in FIG. 
5. The opening of the restriction to allow freer flow of blood is effected 
by the dilation and/or selective emulsification properties of the 
catheter's working head. In this connection, during the operation of the 
catheter 20 (to be described in considerable detail later), the fluid jets 
exiting the distal end of the catheter at the rotating working head are 
immediately accelerated laterally by the relieved, e.g., flatted, 
surfaces. The fluid stream is thus broken up into small segments, bullets 
or slugs 29 (FIG. 5) that develop considerable momentum as they are flung 
radially outward toward the wall of the artery. These liquid slugs 
transfer their momentum to the artery wall, helping to force the artery 
wall outward laterally in all directions, thereby dilating it. The liquid 
also serves as a lubricant for the working head-tissue interface, a 
coolant to maintain the tissue temperature within acceptable limits, and a 
carrier for radiopaque media and/or other medications. The rotating 
working head with its non-sharp impacting surfaces 24A and 24B also serves 
to differentiate atherosclerotic tissue from normal tissue through the 
inherent differences in the tissue's physical properties and 
organizational patterns. Therefore, when the catheter is passed 
transluminally through a diseased artery, the device's working head serves 
to emulsify occlusive lesions not covered with fibrous plaque by 
repeatedly impacting the material forming the restriction as the working 
head is rotated and with minimal risk of puncture or perforation of the 
contiguous arterial wall. 
The non-sharp impacting surfaces 24A and 24B of the rapidly rotating 
working head removes atherosclerotic tissue by emulsification and 
differentiates the diseased tissue from the relatively undiseased tissue 
by using two properties found in normal tissue that is not found in most, 
if not all, atherosclerotic tissue. In this connection, when an artery 
wall is in contact with the high rotary speed working head, its most 
important protective property is its viscoelasticity. Simply stated, the 
artery wall tissue yields repeatedly under stress of the cam surfaces of 
rotating working head and returns to its original shape only after some 
delay, (i.e., the relieved surface following the cam surface pass the 
tissue so that the stress is removed, whereupon the tissue is enabled to 
recover as a function of viscoelastic memory). That stress is applied to 
the artery wall by the rounded edge of each cammed surface of the rotating 
working head with each revolution. As will be appreciated from the 
discussion to follow, the degree of deformation of the artery wall is 
affected by the height and profile of the cam surfaces and contiguous 
radiused impacting surfaces, and the axial load applied thereto by the 
operator. The degree of deformation and the frequency at which it takes 
place in turn define the energy the arterial tissue absorbs and, hence, 
the damage created. Damage to the artery wall can thus be reduced several 
ways, namely, keeping the height of the tissue engaging surfaces 
relatively small, making the cam profile a gentle rise, utilizing a high 
speed (frequency) revolution (tissue will essentially remain in its 
deformed state, touching only the outermost rounded edges of the working 
head adjacent each cam surface), and by keeping the axial load low to 
limit the stress on the artery wall. By appropriate selection of these 
parameters, the working head will do little or no damage to non-diseased 
tissue and will not puncture or otherwise perforate the artery wall except 
under excessive force or where the artery wall is totally diseased (e.g., 
non-viscoelastic as occurs in the case of a Monckeberg's sclerosis). 
Fibrous plaque, unlike most diseased tissue, is viscoelastic and is 
undamaged when the rotating working head with its cam surfaces pass over 
it. The rounded edged cam surfaces have great difficulty in penetrating 
the fibrous plaque. Therefore, in a stenotic or occlusive lesion where 
fibrous plaque lines the obstructive lesion, dilation rather than 
selective emulsification plays the major role in reestablishing blood 
flow. 
In contrast, atherosclerotic tissue is not viscoelastic. If calcific, 
fatty, thrombotic or a combination of all three exist and are not 
protected by fibrous plaque, such material will not yield under the stress 
induced by the rotating working head. Instead, such material absorbs the 
high frequency energy transmitted by the work head's impacting surfaces 
and the material is emulsified. The emulsification process is accomplished 
by the repeated impaction of the non-sharp impacting surfaces on the 
restriction forming material. Such action causes the material to be broken 
away in small particles. The catheter of the subject invention produces a 
powerful vortex flow illustrated diagrammatically and identified by the 
reference numeral 31 in FIG. 9. This vortex works in conjunction with the 
rotating working head so that the particles produced by the impacting 
action are repeatedly impacted over and over, so that upon each impaction 
their size is reduced further until the resulting particle size is 
sufficiently small that the particles can be permitted to flow downstream 
tissue without causing any significant deleterious effects to the patient. 
In this connection, it has been determined that in a typical operation 95% 
of the particles created during the impacting or emulsification process 
have a surface area smaller than that of a red blood cell. 
A second important protective property inherent in nondiseased artery walls 
is its highly organized fibrous structure. Thus, as can be seen in FIG. 1, 
the fibers 33 of an artery wall 26 run circumferential to the lumen of the 
artery and generally perpendicular to the impacting surfaces 24A and 24B 
of the working head where they meet. This perpendicular line between those 
impacting surfaces and the arterial wall fibers is protective. Thus, the 
rotating working head does not separate the fibers. Instead, they remain 
organized in parallel, resisting separation and penetration. The energy 
absorped from the rotating working head is distributed through the many 
fibers, thereby reducing the destructive force applied per fiber. 
Accordingly, individual fibers are undamaged and the artery wall remains 
intact. 
Like most pathologic tissue, atherosclerotic tissue is distinctively 
different from non-diseased tissue in one major respect, lack of unified 
organization. Thus, when such tissue is engaged by the rotating working 
head, minute portions of the atherosclerotic tissue must absorb the 
impacting surfaces' energy alone. Accordingly, a particle of the material 
breaks off from the adjacent tissue. As mentioned earlier and as will be 
described in detail later, the operation of the rotary working head 
creates a vortex flow 31 adjacent the working head which causes the 
particles broken away by the action of the working head to be repeatedly 
impacted by the non-sharp, impacting surfaces 24A and 24B, thereby 
breaking those particles into smaller and smaller particles until they 
become part of what is effectively a highly emulsified solution. 
The exact physiological reaction of the artery to the action of the working 
head is not known at this time. What is known is that the walls of the 
artery itself become dilated and remain dilated even after the catheter 
and its working head is withdrawn. In particular, it has been determined 
by angiogram and other testing procedures that after one has passed the 
working head of a catheter past the restriction that the walls of the 
artery have become stretched or dilated and remain such. More 
particularly, it has been found that the adventicia and media portions of 
the artery are stretched, while the intima (lining portion, which is most 
commonly the diseased portion) is fractured and fissured. Such action 
ensures that the restriction is thus "opened" to freer blood flow 
therethrough. Based on experience with balloon angioplasty the fracturing 
or fissuring of the intima enables renewed blood flow and naturally bodily 
processes to remodel and shrink the lesion in many cases. 
Among the factors which may play a part in the restriction opening process 
is the changing or rearrangement of the vessel structure, e.g., vessel 
fibers, etc., due to any one or more of the following: Mechanical 
stretching of the lumen structure resulting from the size of the working 
head (a static effect) and/or the dynamic effect of cyclical high speed 
mechanical movement, e.g., rotation of the working head; increase in 
temperature of the lumen structure resulting from the mechanical cycling 
of the viscoelastic properties of the lumen tissue, bombardment with 
liquid propelled at the lumen wall by the rapid movement, e.g., rotation, 
of the working head, whereupon the head pressure of the liquid impacting 
the walls exceeds the normal local blood pressure; forcing or wedging of 
liquid into the lumen walls by mechanically induced film pressure as the 
working head's cammed and impacting surfaces slide over the lumen surface, 
whereupon the tissue fibers are forced apart; and forcing of liquid into 
the lumen walls by the local dynamic or hydrostatic pressure induced by 
the injected liquid and/or the moving working head. Other, as yet 
undetermined, factors may also play a part in the dilation process. 
Referring to FIG. 2, the details of the distal end of a preferred 
embodiment of the catheter 20 will now be described. As can be seen the 
catheter 20 basically comprises an elongated, flexible tubular member or 
jacket 30 which is formed of a suitable material, e.g., plastic, and which 
has a small outside diameter. In a preferred embodiment shown herein the 
outside diameter is approximately 1.7 mm (5 French) or less. This size 
catheter is merely exemplary. Thus, in accordance with this invention, the 
catheter can be constructed as small as 2 French (0.67 mm). 
At the distal end of the catheter 20 there is secured a sleeve-like bushing 
32. The bushing includes a flanged end face 34 arranged to abut the end of 
the catheter's jacket 30 and a tubular portion 36. The outside diameter of 
portion 36 is approximately that of the inside diameter of the catheter's 
jacket 30 so that it is snugly fit therein. The bushing is held firmly in 
place by a retaining band 38 which tightly encircles the periphery of the 
catheter jacket 30 so that plural gripping teeth 40 located about the 
periphery of the tubular portion 36 dig into the interior surface of the 
catheter jacket 30 and hold the bushing tightly in place therein. The 
bushing 32 also includes a through bore 42 (FIGS. 2 and 3) extending 
theretnrough and aligned with the longitudinal central a is 25 of the 
catheter. The working head 24 includes a mounting shank or axle 44 
projecting proximally and passing through the bore 42 in the bushing 32. A 
multistrand drive cable 48 constructed in accordance with the teachings of 
our aforementioned copending U.S. patent application Ser. No. 746,220 
extends down the catheter's jacket 30 coaxial with axis 25 and terminates 
and is disposed within a longitudinal extending bore 50 in the shank 44 of 
the working head 24. The end of the drive cable 48 is secured in place in 
the bore 50 via a laser weld joint 52. The shape of the working head 24 
will be described later. Suffice now to state that it includes a generally 
planar rear surface 54 which engages the front surface 56 of the bushing 
flange 34. The working head 24 is prevented from axial movement within the 
bushing 32 by virtue of a retaining ring 58 mounted on the proximal end of 
the working head axle 44 contiguous with the proximal end of the bushing. 
The retaining ring 58 is secured to the proximal end of the working head 
axle 44 via another laser weld 52. 
The drive cable 48 is supported in the central position along axis 25 by 
means of a spiral bearing (not shown) also constructed in accordance with 
the teachings of our aforenoted copending patent application Ser. No. 
746,220. That bearing member thus comprises a helical or spiral 
cylindrical coil of wire surrounding the multistrand drive cable 48. The 
spiral bearing extends substantially the entire length of the catheter 
from a proximately located point adjacent the drive motor (not shown) to 
the distal end of the catheter. The outer diameter of the helical bearing 
coil is sufficiently great so that its loops just clear the interior 
surface of the catheter's jacket 30 to hold the bearing securely in place 
therein. The inside diameter of the central passageway extending down the 
length of the helical bearing is just slightly greater than the outside 
diameter of the drive cable 48 so that the drive cable can freely rotate 
therein. 
It should be pointed out at this juncture that the drive cable 48 can, if 
desired, be drawn or swaged so that its outer periphery of the cable has a 
greater contact surface area with the spiral bearing than if the cable 
were unswaged. This feature is shown and claimed in our copending U.S. 
patent application Ser. No. 938,698, filed on Dec. 5, 1986, and entitled 
Catheter With Means To Prevent Wear Debris From Exiting. Also disclosed 
and claimed in that application is a spiral bearing wire whose inner 
surface, that is, the surface defining the central passageway 
therethrough, is substantially planar in order to further increase the 
engaging surface areas. A bearing constructed in accordance with that 
feature can, if desired, be used to support the drive cable 48 herein. 
With such a construction, the drive cable 48 can be rotated at a high rate 
of speed, e.g., from 10,000 to 200,000 rpm, while the catheter is bent 
through a small radius of curvature, e.g., 0.75 inches (1.9 cm), and 
without the creation of any standing waves which could result in unwanted 
vibration to the catheter. 
The spacing between the convolution of the spiral bearing, the inner 
surface of the catheter tube 30 and the outer surface of the drive cable 
48 form a passageway (not shown) throuqh which a fluid (liquid) can flow 
from the proximal end of the catheter to the distal end. This liquid can 
be utilized to cool or lubricate the bearing system. Moreover, as will be 
described in detail later, and as mentioned earlier, this liquid is 
expelled at the rotating working head to aid in the dilation of the 
arterial tissue at the working head. Moreover, the liquid which is passed 
down the catheter can, if desired, be oxygenated to eliminate distal 
ischemia during the restriction opening procedure by the catheter. Also, 
if desired, nitrates, contrast media or other drugs can be added to the 
liquid as needed during the procedure. 
The means for enabling the liquid to exit the catheter at the distal end 
will now be described with reference to FIGS. 2, 4 and 5. 
Thus, as can be seen therein, extending down the central bore 42 of the 
bearing 32 are four, equidistantly spaced, grooves 60. The distal end of 
each groove 60 terminates at a fluid exit port 61 located at the distal 
end flange 34 of the bushing, while the proximal end of each groove 60 
terminates in a respective, generally radially extending, relief groove 
62. The fluid (liquid) 27 passing down the interior of catheter tube 30 
flows under pressure (denoted by the character P in FIG. 5) into the 
relief grooves 62, through the associated longitudinal grooves 60 and out 
through the ports 61 at the end face of the catheter closely adjacent to 
the longitudinal axis 25. 
The details of the working head 24 will now be discussed. As can be seen in 
FIGS. 2, 4, 6, 7 and 8, the working head 24 basically comprises a convex 
shaped tip of a generally hemispherical shape and having a pair of 
generally planar diametrically disposed side faces heretofore referred to 
as relieved surfaces 24E and 24F. Thus, the cam surfaces formed 
therebetween are sections of the surface of a sphere. The interface of the 
cam surfaces 24C and 24D with the relieved surfaces 24E and 24F are 
rounded (radiussed) so that each interface surface is not sharp (although 
in the scale of the drawings herein it may appear to be a sharp line). As 
can be seen in FIG. 8, the relieved surfaces 24E and 24F taper toward each 
other in the direction toward the distal end of the working head, with the 
maximum spacing between the relieved surfaces being approximately the 
diameter of the working head shaft 44. Thus, the flatted or relieved 
surfaces are at a negative rake angle to the cam surfaces. Further details 
of the working head will be described later. 
As can be seen in FIG. 4, by virtue of the shape of the working head as 
described above the fluid exit ports 61 at the distal end of two 
diametrically disposed grooves 40 are uncovered or exposed by the relieved 
surfaces 24E and 24F to enable fluid 27 passing through those grooves to 
exit the ports 61. As will be appreciated by those skilled in the art, 
since the working head rotates, the relieved surfaces of the working head 
sequentially cover and uncover diametrically opposed ports 61 at the 
distal ends of the grooves. This action breaks up the fluid streams 27 
exiting from those ports into the previously mentioned segments or slugs 
29. 
The fluid velocity is determined by the pressure at the point P in FIG. 5. 
For catheters of an 8 F (French) size, and whose working head is of 0.05 
inches radius a pressure of approximately 30 pounds per square inch is 
deemed sufficient to ensure that some liquid streams flow axially along 
axis 25 so that the exiting liquid is distributed in a generally 
hemispherical pattern about the working head. For catheters of 5 F 
(French), a pressure of 100 PSI is sufficient. Accordingly, with sufficent 
fluid pressure applied some of the liquid streams reach the end of the tip 
contiguous with the longitudinal central axis 25 while other streams are 
cut off and accelerated at an acute angle thereto and still further 
streams are cut off and accelerated almost radially. Accordingly, with a 
working head and catheter constructed as described, the fluid exiting from 
the ports is distributed almost hemispherically around the tip without the 
need for a central hole therein. 
In order to prevent heat induced injury to the artery, sufficient luquid 
should be expelled into the restriction at the working head. It has been 
found that 30 ccs per minute is suitable for an 8 F (French) instrument 
while 20 ccs per minute is suitable for a 5 F instrument. 
As will be appreciated by those skilled in the art, many of the liquid 
slugs 29 have some radial component and develop tremendous momentum as 
they are flung outwards toward the artery wall. The momentum of the slugs 
is transferred to the artery wall, thereby forcing the wall laterally 
outward in all radial directions to dilate it, as described earlier. 
Tests have shown that the radial pressure developed by the rotating working 
head is substantial and can raise local static pressure immediately 
adjacent the working head by approximately 100 to 200 millimeters of Hg. 
This increased pressure on the artery wall contiguous with the rotating 
working head is not due solely to the impact of the fluid slugs thereon, 
but is also due to the recirculation of the fluid surrounding the working 
head. In this connection, as noted earlier, the rotation of the working 
head about axis 25 produces a powerful, toroidal shaped vortex 31 
contiguous with the working head as shown in FIG. 9. The vortex 31 in 
addition to augmenting the application of increased pressure to the artery 
wall contiguous with the working head, also has the effect of 
recirculating any particles that may have been broken off from the 
restriction by the impact of the rotating working head with the material 
forming the restriction. Thus, if the material forming the restriction is 
such that particles are broken away they are circulated by the vortex and 
carried back into the rotating working head where they are progressively 
reduced in size. This progressive size reduction action has the result of 
producing particles which, as noted earlier, are safe to flow distally. 
The impacting surfaces 24A and 24B, i.e., the interfacial areas at which 
the spherical section cam surfaces 24C and 24D meet the relieved surfaces 
24E and 24F, are of sufficiently large radius to ensure that no damage to 
the healthy tissue of the artery occurs when those surfaces impact 
arterial tissue. In this regard, the viscoelastic nature of healthy tissue 
as well as diseased soft tissue is such that such soft materials can be 
stretched and negotiated by the rotating working head if its impacting 
surfaces are of sufficiently large radius that they allow the arterial 
tissue (in the form of a wave of tissue) to flow smoothly thereunder. At 
typical operating speeds the viscoelastic tissue wave is on the order of 
several thousands of an inch high. As long as the radius of the impacting 
surfaces 24A and 24B is of the order or greater than the tissue wave 
height, the tissue will not rupture during stretching. It has been found 
that for a working head like that shown herein and having two cam surfaces 
and running between 10,000 and 100,000 rpm a radius of 0.0015 for the 
impacting surfaces 24A and 24B is sufficient, providing the surgeon using 
the instrument is relatively skilled. A working head having an impacting 
surface whose radius is from 0.002 to 0.003 would be better to ensure that 
no damage results from the catheter's use by less skilled surgeons. 
Moreover the cam surface passing frequency, that is, the velocity of the 
cam surface coupled with the length of the cam surface should be large 
enough that the tissue cannot recover substantially before the next 
impacting surface arrives. This allows quite aggressive instrument feed 
rates without puncture. In this connection, it is suggested that the 
velocity of the impacting surfaces 24A and 24B at their maximum distance 
from axis 25 be in the range from 100 to 2,000 centimeters per second. 
This speed range ensures that at the low end the impacting surfaces of the 
rotating working head always describe a fine helix in the artery even at 
high feed rates of the order of ten centimeters per second. This makes use 
of the protective nature of the tip travel along the axis of the 
circumferential arterial wall fibers. The radius of the impacting surfaces 
24A and 24B should also not be too large. In this connection, as noted 
earlier, the rotating working head creates a powerful vortex for carrying 
any particles broken off from the material forming the restriction to be 
multiply impacted and subsequently reduced in size. Thus, in order not to 
compromise this action, it is necessary that the working head impacting 
surface radius not be too large to compromise such particle reduction 
action. For tips having an impacting surface radius of 0.002-0.003 inches 
the progressive particle reduction action operates at tip rotational 
speeds of 30,000 to 90,000 rpm. 
As just discussed, injury to soft tissue is controlled by the impacting 
surface radius and its passing velocity and to a lesser degree by its and 
the contiguous cam surface's clearance. However, hard tissue seems to be 
dramatically affected by clearance, with the smaller clearance, the less 
chance of injuring or perforating the arterial tissue. Directional 
protection control can also be achieved by varying the clearance of the 
working head's impacting surface radius. Hence, as can be seen in FIGS. 6, 
7 and 8, the portion of the working tip cam surfaces 24C and 24D 
contiguous with the rotational 25 is 45 is relieved by the formation of 
two diametrically opposed planar sections 24G and 24H. Thus, the radiussed 
impacting surfaces at the interface of the cam surfaces and the planar 
relieved surfaces have approximately zero degree clearance while the 
radiussed impacting surfaces at the interface of cam surfaces and the 
relieved surfaces form a ten degree clearance. Accordingly, the working 
head 24 of the subject invention has zero clearance at large radial 
distances from the rotational axis 25 and ten degree clearance at small 
radial distances. This feature compensates for the lower velocity of the 
impacting surfaces at smaller radial distances. Accordingly, in accordance 
with the subject invention, working heads can be produced to provide very 
small clearance at portions of the working head moving at high speed with 
respect to the material to be removed while providing some larger 
clearance at portions of the tip moving at lower speeds with respect to 
that material. 
In order to produce an even more gentle action on the arterial tissue wave 
created by the rotating cammed working head, it can be constructed a shown 
in FIGS. 10 and 11 and denoted by the reference numeral 100. Thus, in the 
working head 100 embodiment shown in FIGS. 10 and 11, the convex cam 
surface is not of a constant radius of curvature. In this connection, as 
can be seen in FIGS. 10 and 11, the working head 100 includes two 
quadraspherical section cam surfaces 100A and 100B, each of which has the 
same radius of curvature. The centers of generation of the quadraspheres 
are denoted by the reference numeral 101 and are spaced (offset) from each 
other by a distance D (FIG. 11). Accordingly, the surfaces 100A and 100B 
are separated from each other by an intermediate surface 100C whose width 
is D. As can be seen in FIG. 11, the surface 100C is tangential to the 
ends of the opposed quadraspherical surfaces 100A and 100B and is linear 
between the ends of those surfaces when viewed in the direction of lines 
11--11 in FIG. 10 but circular and of the same radius as surfaces 100A and 
100B measured around an axis 102 (FIG. 10). The plane in which the axes 25 
and 102 lie includes the two centers of generation 101 and bisects the 
working head 100 into two halves. That plane will be hereinafter referred 
to as the working head bisecting plane. In the embodiment 100 shown 
herein, the flatted or relieved surfaces 100D and 100E are similar to 
relieved surfaces 24E and 24F of working head 24. However, as can be seen 
in FIG. 10, the relieved surfaces 100D and 100E are oriented at an angle 
.THETA. with respect to the working head bisecting plane. Thus, the 
working head 100 is bisected into two symmetric portions by the working 
head bisecting plane. This construction results in the creation of a long 
ramp cam surface 100AL between the leading radiused impacting surface 100G 
and the highest point 104. The ramp can be appreciated by viewing the 
difference between the path of maximum radius R generated by the rotation 
of head 24 and the surface 100AL while creating a short ramp surface 100AS 
between point 104 and the trailing radiused impacting surface 100H. By 
virtue of the relatively long ramp cam surface 100AL leading to the point 
of maximum cam surface radius a gentle cam action results when the surface 
100AL makes contact with the material forming the restriction to result in 
lower acceleration (less aggression) applied to the particles produced by 
that impact. In alternative embodiments of the working head 100 the head 
bisecting plane can be oriented so that the angle .THETA. is between zero 
degrees and any maximum angle. If the head bisecting plane is parallel to 
the relieved surfaces 100E and 100F so that the angle .THETA. is zero 
degrees then the leading and trailing cam surfaces 100AL and 100AS will be 
the sam length. 
As should thus be appreciated by adjusting the orientation of the head 
bisecting angle, and hence the orientation of cam surfaces one can adjust 
the degree of aggression of the working head to a desired extent. 
It should be pointed out at this juncture other shaped working heads in 
lieu of those disclosed herein can be constructed in accordance with this 
invention. Thus, the cam surfaces need not be portions of a spherical 
surface, but can be ovoidal, conical or any other suitable shape. 
Moreover, the relieved surfaces need not be planar, but can be arcuate, 
multiplanar (portions in different planes), etc. Furtherstill, the 
impacting surfaces need not be of a constant radius so long as they are 
sufficiently rounded or arcuate to be substantially equal to or larger 
than the tissue wave to be created by the rotation of the working head. 
The vortex created by the rotation of the working head is effective in 
stopping large particles from passing downstream (distally). In this 
regard, it provides a very effective and important mechanism against 
macroembolization and distal infarction. Any particle that may break off 
distally or proximally to the rotating working head is immediately pulled 
into the vortex and its potential threat to a distal organ is terminated 
by its being reduced in size (repeatedly impacted to the point of 
emulsification). 
The mechanical and fluid forces applied by the working head allow the 
catheter to track the point of least resistance in total occlusions. In 
this regard, the working head finds the area of least resistance by 
dissecting the tissue with fluid pressure as it moves forward. From 
observation, the point of least resistance is always in the lumen of the 
previously patent artery. It is therefore relatively easy and safe to open 
totally obstructed tortuous arteries with the subject catheter. In this 
connection, the working head finds the area of least resistance and serves 
to guide the catheter and not vice versa. 
As will be appreciated by those skilled in the art, the catheter with its 
working head as disclosed and claimed herein has many properties useful in 
treating occulsive atherosclerotic disease. Moreover, the techniques for 
using the subject invention are simple and can be mastered easily and are 
moreover widely applicable to many organ systems relatively inexpensively 
and should be associated with low morbidity. 
It should also be appreciated by those skilled in the art, that the 
catheter of the subject invention as well as its method of use enable 
coronary as well as peripheral, e.g., leg, revascularization of patients 
either intraoperatively or percutaneously, thereby providing methods of 
treatment which are less invasive, less expensive and less time consuming 
than prior art techniques. Moreover, the catheters of the subject 
invention enable revascularization of smaller arteries and longer lesions 
than otherwise possible. Thus, with the subject invention one can 
prophylactically treat coronary artery disease, perhaps one of the most 
widespread diseases affecting Americans. It will also be appreciated by 
those skilled in the art that the subject catheters can be readily 
utilized to remove a thrombosis in a manner similar to the restriction 
opening process. 
The subject catheters are also of significant utility for effecting tube or 
duct, such as eustachian tube, fallopian tube, etc., dilation. With regard 
to the latter, a substantial number of women in the United States are 
infertile due to fallopian tube malfunction or stricture. At present, 
there is no device or simple procedure to dilate or open the fallopian 
tube. In this connection, while microsurgical procedures to attempt to 
alleviate the occlusion or stenosis, the results nave been poor, the 
technique difficult and expensive and of limited availability. By 
utilizing the catheters of this invention one can pass such catheters via 
the cervical os to the fallopian tube to effect the dilation of the 
stenosis or occlusion in the same manner as described with reference to 
revascularization of arteries. 
It has also been found that a catheter like those of this application can 
be utilized to stop spasm, i.e., uncontrolled constriction, in an artery 
or other lumen and for preventing it from going back into spasm. To that 
end, the catheter is inserted into the artery in spasm and operated, as 
described heretofore, whereupon the spasm immediately ceases and remains 
stopped even after the catheter is removed. While this effect, that is the 
stoppage and prevention of spasm, results from the use of catheters of 
this invention, the exact mechanism and exact physiological reaction of 
the lumen to the action of the catheter is unknown at this time. For 
example, the operation of the working head may cause the same effects 
discussed with respect to lumen dilation to occur to stop and prevent 
spasm. More particularly, the action of the working head may cause 
permanent change, e.g., damage to the neuromuscular junctions or muscles 
surrounding the lumen to prevent it from contracting. This antispasm 
technique is not limited to arterial or vascular applications. Hence, the 
technique can be used in any application where spasm of a tubular body is 
a problem, e.g., bronchial tubes, the bowl, the esophagus, etc. To that 
end, the subject catheters can be used with any tubular structure which 
may go into spasm. Moreover, the diameter of the tubular structure in 
spasm can be substantially larger, e.g., more than double the diameter, of 
the catheter with the antispasm procedure still being effective. 
As should now be appreciated the subject invention provides a catheter for 
use in a wide variety of non (or minimum) invasive surgical procedures. 
Those procedures specifically mentioned and discussed herein are by no 
means the only such procedures. Thus, other surgical procedures requiring 
access to an operative point or situs from a remote location may also be 
accomplished using the catheters of the subject invention, with such 
access being achieved either intraoperatively, percutaneously, or via a 
natural orifice. 
Without further elaboration, the foregoing will so fully illustrate our 
invention that others may, by applying current or future knowledge, 
readily adopt the same for use under various conditions of service.