
160 F.Supp.2d 927 (2001)
Sakharam D. MAHURKAR, M.D. and Sherwood Medical Company d/b/a Kendall/Sherwood-Davis & Geck, Plaintiffs,
v.
ARROW INTERNATIONAL, INC., Defendant.
No. 98 C 4890, 99 C 5711.
United States District Court, N.D. Illinois, Eastern Division.
August 9, 2001.
*928 *929 Kenneth J. Jurek, Rosanne J. Faraci, McDermott, Will & Emery, Chicago, IL, for Plaintiffs.
Joseph P. Reagen, Gardner, Carton & Douglas, Chicago, IL, Albert E. Fey, Glenn A. Ousterhout, Jane A. Massaro, Frances M. Lynch, Fish & Neave, New York, NY, for Defendant.


*930 MEMORANDUM OPINION AND ORDER

MORTON DENLOW, United States Magistrate Judge.
Plaintiffs, Dr. Sakharam D. Mahurkar ("Dr.Mahurkar"), owner of United States Patent No. 4,583,968 and Patent No. 4,895,561 and patent licensee, Sherwood Medical Company d/b/a Kendall/Sherwood-Davis & Geck ("Kendall") (collectively "Plaintiffs"), bring this patent infringement claim against Defendant Arrow International, Inc. ("Arrow"). A Markman hearing was held July 12, 2001 to construe the disputed claims of the 4,583,968 patent and the 4,895,561 patent. A detailed analysis of the Court's construction of the claims is set forth below.

I. BACKGROUND

A. TECHNICAL BACKGROUND
The patents-in-suit and the accused Arrow products all involve double-lumen catheters for use in hemodialysis. The role of kidneys in the body is to remove toxins from blood. When kidneys fail to function properly due to disease or injury, blood must be cleaned externally. In hemodialysis, blood is removed from a patient, diverted to a blood treatment unit where it is cleansed, and then returned to the patient. Hemodialysis catheters are devices that are inserted into a patient's vein for removal and return of blood. A double lumen hemodialysis catheter has two separate lumens, or channels, one for removing and one for returning blood. In re Mahurkar, 831 F.Supp. 1354 (N.D.Ill. 1993) (Easterbrook, J. sitting by designation).
A typical hemodialysis blood treatment system includes a blood treatment unit for cleansing the blood, a catheter inserted into a patient's vein for removal of the uncleansed blood and return of cleansed blood, and various connectors and extension tubes that connect the catheter to the blood treatment unit. Patients with diseased or damaged kidneys generally return to a hospital or clinic for regular hemodialysis.
There are over 25,000 U.S. patents that contain the term "catheter" in their specifications and almost 5,000 U.S. patents with this term in their title. The patents-in-suit relate to a certain subset of catheters, double lumen catheters.

B. DR. MAHURKAR, THE INVENTOR
Dr. Mahurkar is a licensed nephrologist who has lived in Chicago for the past 29 years. Until his retirement in 1995, Dr. Mahurkar conducted research and taught nephrology and internal medicine at Cook County Hospital in Chicago. In addition, Dr. Mahurkar has been an inventor, receiving 28 U.S. patents, primarily dealing with catheters and syringes. He has also published a number of academic articles on hemodialysis.
In the 1970s, Dr. Mahurkar designed a catheter divided internally by a septum which created two equal "D" shaped or semi-circular lumens ("double D") and having a beveled tip. This catheter is the subject of Dr. Mahurkar's first patent, U.S. Patent No. 4,134,402 ("the '402 patent"), which expired in 1997 and is not asserted in this suit.
In the early 1980s, Dr. Mahurkar filed a series of patent applications covering variations to his original double D catheter design relating to the catheter tip, and the holes or ports on the catheter. These improvements resulted in two inventions: (1) smooth bore septum-type double lumen catheters; and (2) bent extension catheter assemblies. The patents protecting these two inventions, U.S. Patent No. 4,583,968 ("the '968 patent") and U.S. Patent No. 4,895,561 ("the '561 patent"), are the two patents involved in this litigation.


*931 C. THE '968 PATENTSMOOTH BORE SEPTUM TYPE DOUBLE LUMEN CATHETERS
The '968 patent,[1] entitled "Smooth Bore Double Lumen Catheter," was issued to Dr. Mahurkar on April 22, 1986. The '968 patent is a catheter which is made of a cylindrical tube divided into two separate lumens. One lumen is used for removing unclean blood, and the other for returning cleansed blood. The exterior of the cylindrical tube is a smooth bore, and the tip of the tube is conical, making the catheter easy to insert.

D. PRIOR LITIGATION BETWEEN THE PARTIES
The present suit is not the first litigation between Dr. Mahurkar and Arrow concerning the '968 patent. In 1991, Dr. Mahurkar sued Arrow for infringement of the '968 patent. On July 22, 1992, the parties entered into an agreed order which terminated the case. Pursuant to the order, Arrow agreed to stop selling catheters having double D designs.
In July 1998, Dr. Mahurkar filed a motion for contempt, in which Kendall intervened, alleging that Arrow's post-agreed order catheters violated the agreed order and infringed claim 19 of the '968 patent. Judge Andersen denied Dr. Mahurkar's motion holding that the issues raised should be the subject of a new lawsuit. This action follows that decision.

E. OTHER LITIGATION INVOLVING THE '968 PATENT
In 1990, Dr. Mahurkar and Quinton Instrument Company ("Quinton"), Dr. Mahurkar's then licensee, filed a lawsuit against IMPRA, Inc., a non-party to the pending litigation, alleging infringement of the '968 patent. The case went to trial against defendant IMPRA before Judge Easterbrook in the Northern District of Illinois. In re Mahurkar, 831 F.Supp. 1354 (N.D.Ill.1993), aff'd, 71 F.3d 1573 (Fed.Cir.1995).
Claims 1 and 19 of the '968 patent were at issue in the case. Judge Easterbrook found IMPRA infringed on Mahurkar's patent. Id. Judge Easterbrook's reasoning and conclusions are extremely useful for the Court in construing the claims presented in this case. The Court will address relevant portions of Judge Easterbrook's opinion.

F. THE '561 PATENTBENT EXTENSION CATHETER ASSEMBLIES
The '561 patent,[2] entitled "Dual-Lumen Catheter-Connecting System," was issued to Dr. Mahurkar on January 23, 1990. The '561 patent concerns the portion of the catheter assembly that connects the catheter tube to the blood treatment unit. This invention improves patient comfort for certain types of catheter placements, and reduces the likelihood the catheters will pull out of the vein during or between hemodialysis treatments.
The present litigation involves two separate patent infringement suits that have been consolidated for discovery. The first suit, 98 C 4890, alleges infringement of the '561 patent, and the second suit, 99 C 5711, alleges infringement of the '968 patent. The parties have consented to this Court conducting the Markman hearing.
The Court will first explain the rules of claim construction and will then apply those rules to the disputed claims in the '968 patent and the '561 patent.


*932 II. RULES OF CLAIM CONSTRUCTION
An infringement analysis involves two steps. The first step is determining the meaning and scope of the patent claims allegedly infringed, also known as claim construction or interpretation. Markman v. Westview Instruments, Inc., 52 F.3d 967, 976 (Fed.Cir.1995)(en banc) aff'd 517 U.S. 370, 116 S.Ct. 1384, 134 L.Ed.2d 577 (1996). Claim construction is a matter of law for decision by the courts. Id. at 970. The second step is comparing the properly construed claim to the instrument accused of infringing. Id. at 976. This proceeding is concerned with the first step, commonly known as a Markman hearing.

A. SOURCES AND HIERARCHY FOR CLAIM INTERPRETATION
In interpreting a claim, a court first looks to the language of the claim, which defines the breadth and depth and bounds of the claim. York Products, Inc. v. Central Tractor Farm & Family Ctr., 99 F.3d 1568, 1572 (Fed.Cir.1996). The general rule is that terms in the claim are to be given their ordinary and accustomed meaning. Johnson Worldwide Assoc., Inc. v. Zebco Corp., 175 F.3d 985, 989 (Fed.Cir. 1999). A court must presume that the terms of the claim mean what they say, and give full effect to the ordinary and accustomed meaning of the claim terms unless otherwise compelled. Id. There are two instances in which a court may be compelled to give the definition of a term a meaning outside of the ordinary and accustomed one. The first one arises when a patentee has chosen to be his own lexicographer, as long as the special definition of the term is clearly stated in the patent specification or file history. Id. at 990; Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed.Cir.1996). The second arises when the terms chosen by the patentee "so deprive the claim of clarity that there is no means by which the scope of the claim may be ascertained from the language used." Zebco, 175 F.3d at 990.
Second, the court looks to the patent specification, containing a written description of the invention which must be clear and complete enough to enable those of ordinary skill in the art to make and use it. Vitronics, 90 F.3d at 1582. It is here where, if the patentee chooses to be his own lexicographer, the special meanings of the claim terms are typically found. Id. The specification is "always highly relevant" and is usually dispositive; it is the "single best guide to the meaning" of a disputed term. Id. All claims must be read in view of the specification, which acts as a sort of dictionary to explain the invention and may define the terms used in the claim. Markman, 52 F.3d at 979.
Third, the court may also consider the prosecution history of the patent, which contains the complete record of the proceedings before the Patent and Trademark Office ("PTO"), including any express representations made by the patentee regarding the scope of the claims. Vitronics, 90 F.3d at 1582. The prosecution history is often significant when determining the scope of a claim. Id. The prosecution history can and should be used to understand the language used in the claim, however, it can not be used to enlarge, diminish or vary the terms in the claim. Markman, 52 F.3d at 980. Included within an analysis of the file history may be an examination of the prior art cited therein, as the prior art gives guidance as to what the patent does and does not cover. Vitronics, 90 F.3d at 1583.
Finally, extrinsic evidence consisting of expert and inventor testimony, dictionaries and learned treatises, may be considered only to assist in the court's understanding of the patent, not to vary or contradict the terms of the claims. Markman, *933 52 F.3d at 980-81. However, in most situations, an analysis of the intrinsic evidence alone resolves a disputed claim term and unambiguously describes the scope of the patented invention. Vitronics, 90 F.3d at 1583. Under these circumstances reliance on extrinsic evidence is improper. Id.
In terms of hierarchy, evidence that is objective, reliable, and publicly accessible, such as prior art documents, dictionaries and treatises are preferred over other types of extrinsic evidence. Id. at 1585. Although dictionaries and treatises fall within the category of extrinsic evidence, they are worthy of special consideration. Judges are free to consult such resources at any time to better understand the underlying technology, and may rely on dictionary definitions as the ordinary and accustomed meaning of a term, as long as the dictionary definition does not contradict any definition found in or ascertained by a reading of the patent. Id. at 1584 n. 6. Prior art, although also extrinsic evidence, may be included in an analysis of the prosecution history if cited therein. Id. at 1583. A court may rely on prior art proffered by one of the parties, even if not cited in the specifications and file history, to aid in the court's understanding and to demonstrate how a disputed term is used by those skilled in the art. Id. at 1584. Opinion testimony of experts and the inventor should be treated with "utmost caution" and may only be relied upon if the patent documents taken as a whole are insufficient to enable the court to construe disputed claim terms, which is rare, if ever. Id. at 1584-85.

B. PATENTS ARE GENERALLY UNAMBIGUOUS
In most situations, there is no "ambiguity" in the claim language. Markman, 52 F.3d at 986. Statutory language requirements are designed to avoid ambiguity in a patent. Id. The statute requires that the specification contain a written description in "full, clear, concise and exact terms." 35 U.S.C. § 112. Patent applications are reviewed by examiners at the PTO who are "trained in the law and presumed to have some expertise in interpreting the prior art references and to be familiar from their work with the level of skill in the art and whose duty it is to issue only valid patents." Markman, 52 F.3d at 986. Thus, "[i]f the patent's claims are sufficiently unambiguous for the PTO, there should exist no factual ambiguity when those same claims are later construed by a court of law in an infringement action." Id.
However, because "a judge is not usually a person conversant in the particular technical art involved and is not the hypothetical skilled in the art to whom a patent is addressed, extrinsic evidence may be necessary to inform the court about the language in which the patent is written. But this evidence is not for the purpose of clarifying ambiguity in claim terminology. It is not ambiguity in the document that creates the need for extrinsic evidence but rather unfamiliarity of the court with the terminology of the art to which the patent is addressed." Id.

C. LIMITATIONS NOT SET FORTH IN THE CLAIM MAY NOT BE READ INTO THE CLAIM
There are two familiar claim construction canons regarding limitations imposed on claims, setting forth the relationship between the claims and the written description: 1) one may not read a limitation into a claim from the written description, and 2) one may look to the written description to define a term already in a claim limitation, as a claim must be read in view of the specifications of which it is a part. Renishaw PLC v. *934 Marposs Societa' per Azioni, 158 F.3d 1243, 1248 (Fed.Cir.1998). Thus, a limitation must appear in the language of the claim before one looks to the written description to define that limitation. "This is so because the claims define the scope and the right to exclude, and the claim construction inquiry ... begins and ends in all cases with the actual words of the claim." Id.
Without a term in the claim that would direct us to the written description for clarification, there is no legitimate way to narrow the claim. Id. Similarly, if the written description provides us a definition of a term used in the claim, then reading in a further limiting definition would be improper. Mantech Environmental Corp. v. Hudson Environmental Serv. Inc., 152 F.3d 1368, 1374 (Fed.Cir. 1998). The Supreme Court explained this requirement, stating, "We know of no principle of law which would authorize us to read into a claim an element which is not present, for the purpose of making out a case of novelty of infringement. The difficulty is that if we once begin to include elements not mentioned in the claim in order to limit such claim...., we should never know where to stop." Renishaw, 158 F.3d at 1248 (quoting McCarty v. Lehigh Val R.R., 160 U.S. 110, 116, 16 S.Ct. 240, 40 L.Ed. 358 (1895)).
Words in a claim should be accorded their ordinary and accustomed meaning, not a narrower scope than what is ordinarily accorded it. Renishaw, 158 F.3d at 1249. Thus, when a claim term contains a general descriptive term, the term will not be limited to a numerical range that is included in the written description. Similarly, a general term cannot be reduced to a narrower scope or subset of that term by a modifier if the claim does not expressly contain the modifier. For example, if the claim term recites a general noun without limiting that noun with an adjective, the claim should be construed to cover all known types of that general noun supported by the patent disclosure. Id. at 1250. Likewise, if the words of the claim recite a general verb without limiting it with an adverb, the claim should be construed to cover the ordinary broader meaning of the verb. Id. (citing Virginia Panel Corp. v. MAC Panel Co., 133 F.3d 860 (Fed.Cir.1997) (holding that "reciprocating" is not limited to linearly reciprocating)). In looking at the written description to define the scope of a claim term, the varied use of a term demonstrates the breadth of the term, demanding a broad construction, rather than a narrow one. Zebco, 175 F.3d at 991.
However, a common meaning, such as one found in a dictionary, that is inapposite to the context of the patent disclosure is not one that the court should adopt. Id. Indiscriminate reliance on definitions found in dictionaries can produce absurd results if not read in light of, and in the context of, the patent specifications. Id.

D. THE SCOPE OF THE CLAIM IS NOT LIMITED TO THE PREFERRED EMBODIMENT
As a general rule, the claim is not limited by the language of the preferred embodiments or specific examples included in the specification. Karlin Technology Inc. v. Surgical Dynamics, Inc., 177 F.3d 968, 972 (Fed.Cir.1999). "It is well settled that device claims are not limited to devices which operate precisely as the embodiments described in detail in the patent." Id. (quoting Virginia Panel, 133 F.3d at 866). Similarly, mere inferences drawn from the description of an embodiment cannot serve to limit claim terms. Johnson, 175 F.3d at 992. "Although the specification may aid the court in interpreting the meaning of disputed claim language, *935 particular embodiments and examples in the specification will not generally be read into the claims." Comark Communications, Inc. v. Harris Corporation, 156 F.3d 1182, 1186 (Fed.Cir.1998). The law "does not require that an applicant describe in his specification every conceivable and possible future embodiment of his invention. The law ... requires only that the inventor describe the `best mode' known at the time to him in making the invention." SRI International v. Matsushita Electric Corp. of America, 775 F.2d 1107, 1121(Fed.Cir.1985).

E. THE LITERAL SCOPE OF A MEANS-PLUS-FUNCTION CLAIM IS THE RECITED FUNCTION PERFORMED BY THE CORRESPONDING DISCLOSED STRUCTURE OR ITS EQUIVALENT STRUCTURES
Pursuant to 35 U.S.C. § 112, ¶ 6, a claim element "may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof." The claim elements written in this format are construed to cover the corresponding structures described in the specification, and equivalents thereof. Id.
A court's task in construing a means-plus-function element involves two steps. First, the court identifies the function portion of the element and construes any disputed terms in the function language. Second, the court identifies the corresponding structure(s) disclosed in the specification linked or associated with that function. Chiuminatta Concrete Concepts, Inc. v. Cardinal Indus., Inc., 145 F.3d 1303, 1308 (Fed.Cir.1998); B. Braun Medical, Inc. v. Abbott Lab., 124 F.3d 1419, 1424 (Fed.Cir.1997)(corresponding structure must be linked or associated with recited function). To determine the claimed function, the court must construe the specific terms in the claim. Chiuminatta Concrete Concepts, 145 F.3d at 1308. A means-plus function claim is indefinite, and thus invalid, if the specification fails to disclose an adequate structure corresponding to the means limitation. Kemco Sales, Inc. v. Control Papers Co., 208 F.3d 1352, 1360-61 (Fed.Cir.2000).
Not all aspects of the structure disclosed in the specification should be included in the court's claim construction. Details of the disclosed structure that are "unrelated to the recited function" are not "corresponding structure," and do not limit the scope of the means clause. Chiuminatta Concrete, 145 F.3d at 1308.

F. DIFFERENT CLAIMS IN A PATENT ARE PRESUMED TO HAVE A DIFFERENT SCOPE
The doctrine of claim differentiation creates a presumption that different claims in a patent have a different scope. Comark Communications, Inc. v. Harris Corp., 156 F.3d 1182, 1187 (Fed.Cir.1998). The doctrine "is ultimately based on the common sense notion that different words or phrases used in separate claims have different meaning and scope." Karlin Technology, Inc., 177 F.3d at 971-72. For example, a limitation found in a dependent claim ordinarily should not be read into the independent claim from which it depends. Id. at 972; See also Whittaker Corp. v. UNR Indus., Inc., 911 F.2d 709, 712 (Fed.Cir.1990) ("it is inconsistent with the principle of claim differentiation that...an independent claim should be given the same meaning" as claims that depend from the independent claim).

III. CLAIM INTERPRETATION THE '968 PATENT
The elements of the '968 patent requiring construction by the Court are all *936 found in Claims 12, 13, 14, 17, 18, 19 and 21-24.[3]

A. CLAIM 12
Claim 12 reads as follows, with language to be construed in bold:
A double lumen catheter comprising an elongated cylindrical tube including a planar axial divider bisecting said cylindrical tube into first and second lumens, the proximal end of said cylindrical tube connecting two separate tubes communicating with the respective first and second lumens for the injection and removal of fluid, the first lumen extending from the proximal end of said cylindrical tube to a first opening at the distal end of said cylindrical tube, the second lumen extending from the proximal end of said cylindrical tube to a second opening in the side of the cylindrical surface of said cylindrical tube, said second lumen terminating at said second opening and a relative concentration of material extending axially from the second opening to the distal end of said cylindrical tube, the distal end of said cylindrical tube having a smooth conical tapered tip that smoothly merges with the cylindrical surface of said cylindrical tube, the cylindrical surface of said cylindrical tube having at least one side hole exposing said first lumen axially spaced between said second opening and said conical tapered tip and circumferentially disposed on the opposite side of said cylindrical tube as said second opening, and the cylindrical surface of said cylindrical tube having at least one side hole exposing said second lumen axially spaced between said second opening and the proximal end of said cylindrical tube and circumferentially disposed on the same side of said cylindrical tube as said second opening.

1. Language in Dispute: "A relative concentration of material."
[4]Does "a relative concentration of material" mean (1) the presence of some material relative to the hollow lumens or (2) sufficient material to stiffen the tip relative to the remainder of the catheter body?
Answer: "A relative concentration of material" means sufficient material to stiffen the tip relative to the remainder of the catheter body.

a). Claim Language
The Court must interpret the term "relative concentration of material." The term "relative" is a comparative term and requires a determination of what is being compared. The claim does not explain to what the relative concentration of material should be compared. Plaintiffs argue it should be compared to the hollow lumen. Arrow argues that when looking at the claim language in the patent, the meaning of "relative concentration of material" cannot be determined because it does not say to what it is relative. The Court agrees. Therefore, the Court must look to the specification and written descriptions for guidance.


*937 b). Written Description
The specification of the '968 patent supports Arrow's construction of the claim. The specification clearly demonstrates that the term "relative" relates to a comparison of the stiffness or rigidity between the catheter tube, the body, and the tip. Each time the words "relative concentration of material" appear in the specification, they appear as a relative concentration to stiffen the tip. This is true in the Abstract, the Summary of the Invention, and also in the Preferred Embodiment.
The abstract explains: "to provide improved dilator characteristics, preferably the tip includes a relative concentration of material for rigidity." (Abstract). Similarly, the summary of the invention describes the conical tapered tip: "[it] comprises a relative concentration of material to impart relative rigidity so that the tip functions as an effective dilator for soft tissue and veins." ('968 patent, col. 2, lines 38-41). In the preferred embodiment, the specification describes figure 7 as showing a conical tip formed with "a relative concentration of material 23 to stiffen the tip 20. This stiffening aids penetration of the tip 20 into the body cavity (not shown) and also aids the dilation of soft tissue such as veins." ('968 patent, col. 4, lines 16-21).

c). Prosecution History
The prosecution history is also consistent with Arrow's claim construction. Dr. Mahurkar described the purpose of the relative concentration of material in his prosecution of the '968 patent: "This relative concentration of material further prevents kinking of the catheter tip during insertion." (Def. Ex. 2 at NSHN 128717). Thus, it is the relative concentration of material that stiffens the tip relative to the catheter body, which prevents it from kinking.

d). Prior Litigation
Judge Easterbrook in his opinion In re Mahurkar, 831 F.Supp. 1354, 1359 (N.D.Ill.1993) discussed figure 7 of the '968 patent. He explained that figure 7 "shows that the intake lumen of the Mahurkar catheter is sealed off below the intake ports and replaced with a plug of plastic, which the claims of the patent call a `relative concentration of material.' (This both stiffens the tip and eliminates space in which blood may pool and clot.)" In re Mahurkar, 831 F.Supp. at 1359.

2. Language in Dispute: "Extending Axially."
Does material "extending axially from the second opening to the distal end of said cylindrical tube" mean (1) material present in the second lumen between the inlet opening and the tip or (2) material to run continuously from the inlet opening through the tip?
Answer: Material "extending axially from the second opening to the distal end of said cylindrical tube" means material to run continuously from the inlet opening through the tip.

a). Claim Language
The issue in construing this language is whether the material must run continuously from the inlet opening through the tip. Dr. Mahurkar argues the term "extends axially" means that the material extends, or reaches toward the base of the conical tip from the inlet opening, but does not have to be continuous.
Arrow argues the claim language requires the relative concentration of material extend continuously from the second opening to the distal end of the cylindrical tube which has a conical tip. Therefore, the distal end includes the tip and the language extending axially from the second opening to the distal end requires there to be continuous material throughout. *938 Thus, in order for the material to go from the opening through to the tip axially, in that direction, it must go continuously.
The Court holds the claim limitation requires the relative concentration of material to go continuously from the inlet opening to the tip. The use of the term "extends axially" describes both the direction and the fact that it is continuous in that direction. To extend means to straighten out or to stretch out to full length. (Webster's II New Riverside University Dictionary 456 (1994)).

b). Written Description
Figure 7 is the only illustration in the patent of the "relative concentration of material." Arrow argues this figure is consistent with its construction of claim 12 because it depicts a solid material which runs continuously from the opening of the inlet through the tip.
The specification regarding figure 7 says, "As shown in fig. 7, the inlet lumen 14 terminates at the inlet aperture 19 and in place of the inlet lumen the relative concentration of material extends axially from the aperture to the distal end of the tube at the truncated apex of the conical tip." ('968 patent, col. 4, lines 21-25). The parties agree the specification calls for the relative concentration of material to be continuous, however Dr. Mahurkar argues this is one embodiment, and is not a requirement. The Court holds the written description accurately describes the claim.

c). Prior Litigation
In the earlier litigation, Judge Easterbrook stated that "extending axially" means "a relative concentration `extending' from intake through outlet." In re Mahurkar, 831 F.Supp. at 1382. To demonstrate what the court meant by "extending axially," Judge Easterbrook provided the following example, "[O]ne would suppose that a highway `extending' from Chicago to Milwaukee goes all the way; just so a relative concentration `extending' from intake through outlet." Id. However, Judge Easterbrook noted in the opinion, "Because Mahurkar and Quinton would not be entitled to any relief under Claims 12 and 25 that they do not obtain under claims 1 and 19, it is unnecessary for me to decide who is right." In re Mahurkar, 831 F.Supp. at 1382. Thus, although Judge Easterbrook did not make a ruling, this Court finds his reasoning to be correct and adopts it.

3. Language in Dispute: "conical tapered tip" and "a truncated cone"[5]
Does "smooth conical tapered tip" mean (1) a shape with a circular base tapering to a point as in either a centered (right circular) cone or an off-center (oblique circular) cone or (2) a shape tapering evenly on all sides as in a right circular cone?
Does "cone" mean (1) a shape with a circular base tapering to a point as in either a centered (right circular) cone or an off-center (oblique circular) cone or (2) a shape tapering evenly on all sides as in a right circular cone?
Answer: Both "smooth conical tapered tip" and "cone" mean a shape with a circular base tapering to a point as in either a centered (right circular) cone or an off-center (oblique circular) cone.

a). Claim Language
The parties do not dispute that the limitation in this claim covers an ordinary *939 centered (right circular) cone. Where they do not agree is whether the claim limitations also cover an off-center (oblique circular) cone. A right circular cone, or a centered cone, is a cone in which the apex is aligned with the center of the circle (i.e., an ice cream cone shape). In an oblique circular cone, or an off-center cone, the apex is above the circle, but not directly above the center of the circle. The Court holds the term "cone" includes both a right circular cone and an oblique circular cone. The claim language is helpful because in claim 12, it refers only to a "smooth conical tapered tip," whereas in claim 13, it specifies a type of cone when it states "said conical tip is substantially aligned with the axis of said cylindrical tube." Under the doctrine of claim differentiation, these two claims must mean different things. Thus, under claim 12, the cone may be either a right circular cone or an oblique circular cone and claim 13 is limited to only a right circular cone.

b). Written Description
The specification also supports construction of this claim as not limited to right circular cones. The specification states that in accordance with the invention:
the distal end portion of the tube 11 has a conical tip generally designated 20 which smoothly merges with the cylindrical body of the tube11. Preferably the apex of the conical tip 20 is centered on the axis of the cylindrical body of the tube 11 thus serving as a guidance point to uniformly distribute the frictional resistance encountered by the conical tip when the tube is inserted into the body cavity ... Since the frictional resistance is uniformly distributed and the conical tip smoothly merges with the body of the tube 11, insertion trauma and kinking are minimized. ('968 patent, col. 3, lines 47-54; 62-64). (Emphasis added).
In order for the frictional resistance to be uniformly distributed, the conical tip must be a right circular cone and not an oblique circular cone. The use of the term "preferably" indicates that the centered cone is Dr. Mahurkar's preferred configuration, but that he also contemplates other types of cones. Because claim 12 does not explicitly recite that the apex of the conical tip is centered on the axis of the cylindrical tube, claim 12 is not limited to this preferred approach. Had Dr. Mahurkar intended to limit claim 12 to right circular cones, he would simply have included the "centered apex" language of claim 13 within claim 12. See Rodime PLC v. Seagate Technology, Inc., 174 F.3d 1294, 1305 (Fed.Cir.1999)("Had [the patentee] intended or desired to claim thermal compensation as a function of the positioning means in the asserted claims, it could have done it explicitly as in claim 11").
It is agreed that all of the figures in the '968 patent depict right circular cones, not oblique circular cones. Arrow claims that "conical" must be limited to the described preferred embodiment because "no other embodiment of a tip shape is shown or described in the '968 patent." (Def. Br., at p. 22). Arrow is wrong about the law. A claim term can be limited to the described preferred embodiment only when the specification clearly and unambiguously so limits that term. See e.g., Johnson Worldwide Associates, 175 F.3d at 991. And, "just as the preferred embodiment itself does not limit claim terms....., mere inferences drawn from the description of an embodiment of the invention cannot serve to limit claim terms." Id. at 992.[6]


*940 c). Prosecution History
Arrow also seeks to support its narrow construction with passages from the prosecution history contending that Dr. Mahurkar was forced to distinguish a prior art oblique circular cone by limiting his claims to a right circular cone. During prosecution of the '968 patent, Dr. Mahurkar distinguished the Edelman structure. Arrow incorrectly characterizes Edelman's tip as an oblique circular cone. It is not. First, the Edelman tip has a rounded blunt end, not an apex. Second, one entire side of the Edelman tip is flat, and the base, therefore, is not a circle. The Edelman tip structure is perhaps best described as a "beak" or a "nose," not as a circular cone. The prosecution history statements cited by Arrow, therefore, do not support Arrow's argument.
Perhaps more importantly, the actual grounds upon which Dr. Mahurkar distinguished Edelman was that Edelman lacked the claimed smooth conical tip, not just that it lacked a conical tip. Regarding Edelman, Dr. Mahurkar described why his invention differed from Edelman's structure:
The Edelman et al. patent 4,403,983 shows a septum-type dual-lumen catheter in which the septum is inserted as a separate piece; the outer wall of one of the two lumens formed by the insertion of the septum is tapered toward the septum, and the other is cut off "normal to both the septum and the tube axis" (column 2, lines 59-60), thereby forming a sharply stepped tip which would also seem to produce high insertion trauma .... None of these septum-type catheters has applicant's smooth conical tapered tip which smoothly merges with the surface of the cylindrical tube ....
(Def. Ex. 2 at NSHN XXXXXX-XX.) This passage clearly shows that Dr. Mahurkar's primary concern with the Edelman structure was the sharp step between the tube and the tip. Dr. Mahurkar's claims distinguished this structure by reciting a smooth conical tapered tip that smoothly merges with the tube.
Dr. Mahurkar's statements during the prosecution history, therefore, never limited the word "cone" to right circular cones, and do not constitute a clear and deliberate surrender of claim scope. See Northern Telecom Ltd. v. Samsung Electronics Co., Ltd., 215 F.3d 1281, 1294-95 (Fed.Cir. 2000)("We cannot conclude that [the defendant] has demonstrated that the patentees with reasonable clarity and deliberation [citation omitted]defined `plasma etching' as excluding ion bombardment.").

d). Dictionary Definition
Medical dictionaries also support Plaintiffs' contention that "conical" is not limited to a centered (right circular) cone. Cone is defined as "a solid figure or body with a circular base tapering to a point." (Dorland's Illustrated Medical Dictionary, Twenty-Sixth Edition). Cone is defined as "a solid figure or body having a circular base and tapering to a point, ..." (MillerKeane Encyclopedia & Dictionary of Medicine, Nursing & Allied Health (5th Ed.1992)). Cone is defined as "a figure or *941 anatomic structure tapering to a point from a circular base." (Melloni's Illustrated Medical Dictionary (2nd Ed.1985)).

4. Language in Dispute: "Same Side" and "Opposite Side."
Does "same side of said cylindrical tube" refer to (1) the position on the cylindrical tube relative to the axial divider (i.e., the holes are on the portions of the tube on the same side of the axial divider) or (2) to the position on the cylindrical tube relative to the circumference of the cylindrical tube (i.e., the holes are aligned on the portions of the tube along the length of the tube)?
Answer: "Same side of said cylindrical tube" refers to the position on the cylindrical tube relative to the axial divider.
Does "opposite side of said cylindrical tube" refer to (1) the position on the cylindrical tube relative to the axial divider (i.e., the holes are on the portions of the tube on different sides of the axial divider) or (2) the position on the cylindrical tube relative to the circumference of the cylindrical tube (i.e., the holes are aligned on the portions of the tube along the length of the tube)?
Answer: "Opposite side of said cylindrical tube" refers to the position on the cylindrical tube relative to the axial divider.

a). Claim Language
These claim limitations concern additional side holes exposing the two lumens of the catheter to the blood stream. The dispute involves the meaning of the phrases "opposite side" and "same side." The Court holds "opposite side" to mean on the other side of the axial divider of the cylindrical tube without reference to any particular point and "same side" to mean on the same side of the axial divider of the tube without reference to any particular point.
The Court's construction is based largely upon the common usage and meaning of the terms "opposite" and "same" as they relate to the term "side." For example, during a tennis match, one player is on one side of the court and his opponent is on the opposite side of the net which divides the court in half. The opponent need not be directly opposite the player to be on the opposite side, he must just be on the other side of the net. Similarly, in a doubles tennis match teammates are considered to play on the same side when they are on the same side of the court as divided by the net. They need not be in the same service box, but just on the same side of the court.

b). Written Description
The illustrations in figs. 1 and 2 of the '968 patent illustrate one embodiment of the claimed side holes. Opening 19, the primary inlet opening for the second lumen, is "said second opening." Multiple holes 21 constitute "at least one side hole circumferentially disposed on the opposite side" of the tube as opening 19, and multiple holes 22 make up "at least one side hole circumferentially disposed on the same side" of the tube as opening 19.
The specification supports Dr. Mahurkar's construction of this claim:
The return holes 21 and the inlet holes 22 are further disposed circumferentially on opposite sides of the divider 12. Thus, there is axial as well as circumferential separation of the inlets and outlets for fluid circulation. ('968 patent, col. 4, lines 10-14).
Holes 21 and 22 are not lined up 180 degrees from each other. In fact holes 22 are much further away from the tip than holes 21. Thus they are on opposite sides of the divider, but not directly across from one another. In this specification there is not a requirement for the outlet hole to be *942 180 degrees (halfway) from the second opening to be "opposite." There must be holes on the opposite sides of the divider and also some on the same side.

c). Dictionary Definition
The construction of the words "opposite side" and "same side" is simple. The ordinary and accustomed meaning of the words provide their construction. The parties agree the cylindrical tube is divided in half by the axial divider. Therefore, the "opposite side" is simply the opposite side of the divider, and "same side" means the same side of the divider. This does not mean the holes must be exactly 180 degrees apart to be on "opposite sides" nor does it mean the holes must be axially aligned to be on the "same side." Webster's Dictionary defines "side" as "a place, space, or direction with respect to a center or to a line of division (as of an aisle, river, or street)." (Webster's Collegiate Dictionary 1089 (10th ed.1996)).
Common usage of the words here, leads the Court to construct "opposite side" as on the opposite side of the tube as determined by a center line, which in this case is the axial divider. Similarly, "same side" is on the same side of the tube as determined again by the axial divider.

B. CLAIM 13
Claim 13 reads as follows, with language to be construed in bold:
The double lumen catheter as claimed in claim 12, wherein the apex of said conical tip is substantially aligned with the axis of said cylindrical tube.

1. Language in Dispute: "the apex of said conical tip is substantially aligned with the axis of said cylindrical tube."
Does Claim 13 mean that (1) the apex is substantially centered on the cylindrical tube, and therefore, the "conical tip" is a centered (right circular) cone or (2) the apex is substantially centered on the cylindrical tube, and therefore, the "conical tip" is centered on the cylindrical tube?
Answer: Claim 13 means that the apex is substantially centered on the cylindrical tube, and therefore, the "conical tip" is a centered (right circular) cone.
Claim 13 is a dependent claim. The basis for the Court's holding is found in the Court's discussion of claim 12 at III. A. 3 supra.

C. CLAIM 19
Claim 19 reads as follows, with language to be construed in bold:
A double lumen catheter comprising an elongated unitary tube including an integral septum extending axially along the entire length of the tube and dividing the interior of said tube into a first and a second lumen, the outer circumference of said tube converging smoothly at the distal end portion of said tube defining a truncated cone, the first lumen opening at the truncated apex of said cone, and the second lumen being shorter in axial length than the first lumen and opening upon the outer circumference of said tube, said tube having a uniform diameter from its distal end portion to proximally beyond the opening of the second lumen upon the outer circumference.

1. Language in Dispute: "A double lumen catheter comprising an elongated unitary tube including an integral septum..."
Does "unitary tube" mean (1) the tube and tip are a single unit or (2) a tube and tip are of single-piece construction (i.e. integrally formed)?
Answer: "Unitary tube" means the tube and tip are a single unit.


*943 a). Claim Language
The issue in this claim is whether the term "unitary" requires the tube and tip to be formed from one piece of material. The Court answers this question no.
The claim language says "elongated unitary tube including integral septum." Integral means one-piece formation, as opposed to bonded, which is a two-piece construction. The patent does not say integral tube including integral septum. If that were the case it would be clear that the claim only covers a tube formed from a single piece and a septum formed from one piece. However, that is not what we have in claim 19.
The words integral and unitary are two different terms which are presumed to have two different meanings. Comark Communications, Inc., 156 F.3d at 1182. The patent, the prosecution history and the common usage of the terms all suggest "integral" means being formed from one piece of material while "unitary" requires the object be a single unit. Therefore, the adjective "unitary" describing the tube, requires that the elongated tube including its tip and integrated septum, be a single unit in the completed catheter product.

b). Written Description
The specification in the patent supports the construction that the elongated tube must be one unit in the completed catheter, but may be manufactured either integrally or by bonding. The specification shows an example of a unitary tube in the figures and states the tube can be made from one piece of material or multiple pieces joined together to form one unit:
It is readily apparent to persons of ordinary skill in the art that the tip 20 as shown in FIG. 7 is easily formed from thermo-plastic material. The tip 20 including the relative concentration of material 23 is easily molded and bonded or is integrally formed from the cylindrical tube 11 by the use of internal and external mandrels and the application of heat by any number of conventional means such as RF forming, thermal forming, or infrared forming. ('968 patent, col. 4, lines 29-37). (Emphasis added).
Thus, the written description in the patent corroborates Dr. Mahurkar's construction.

c). Prosecution History
Arrow contends the word "unitary" requires that the entire tube, including the tip, be constructed from a single piece of material. In support of this construction, Arrow cites a passage from the prosecution history which includes a discussion of the "unitary" and "integral septum" limitations:
Claim 21[now claim 19] further recites a double lumen catheter comprising an elongated unitary tube including an integral divider. Edelman et al. does not disclose a unitary structure. The unitary structure prevents mis-matching of components, the clotting of blood and tips breaking off into the patient. (Def. Ex. 2 at NSHN 128717).
This passage cites the advantages of the unitary structure, but does not limit the construction of the unitary tube to integral formation from a single material. This passage was presented by Dr. Mahurkar to demonstrate that the Edelman catheter is not unitary and his is. He was not equating the word "unitary" with "integral" but rather was equating "unitary" with a single unit, and explaining that the Edelman catheter has multiple pieces (the septum and the cylinder) that are not sealed. (See Edelman et al. Patent No. 4,403,983, col. 2 lines 29-32 and 46-49).
In another section from the prosecution history it is equally apparent that the word "unitary" means a single unit. In this portion of the patent prosecution Dr. Mahurkar described the tube and tip as "unitary" *944 and then stated that the septum is "of one-piece construction with said tube." (Def. Ex. 2 at NSHN 128764). If as Arrow contends, the words "unitary" and "integral" are synonymous, Dr. Mahurkar would not have found it necessary to describe the tube and septum separately with different adjectives. The prosecution history reinforces that the ordinary meaning of "unitary" is a single unit.

d). Dictionary Definition
The word "unitary" is best construed by its ordinary usage and accustomed meaning. Webster's defines "unitary" as "having the character of a unit: whole." (Webster's II New Riverside University Dictionary 1262 (1994)). Therefore, the word "unitary" an adjective describing the elongated tube, provides that the tube, including the septum, be a single unit in the catheter.

e). Prior Litigation
As discussed supra, the '968 patent was also the subject of previous litigation. Judge Easterbrook analyzed claim 19 in terms of its best mode, but did not decide the issue before this Court. In re Mahurkar, 831 F.Supp. at 1378.

2. Language in Dispute: "An integral septum."
Does "septum" mean (1) a dividing wall or (2) a flat divider?
Answer: "Septum" means a dividing wall.

a). Claim Language
The issue is whether the septum is limited to being flat. The Court holds the septum extending along the tube and dividing the tube into first and second lumens is not limited to a flat divider. The claim language provides that there must be a septum which is integral with the tube which divides the interior of the tube into the "first lumen" and the "second lumen." The claim language does not specify the type of septum, only that it must be integral. Therefore, the Court will not read another adjective into the claim language but will instead construe "septum" in accordance with its ordinary usage and accustomed meaning. The ordinary meaning of "septum" is divider.

b). Written Description
The specification supports the construction that a "septum" is a divider:
The tube 11 is circular in cross section... And has an internal divider 12 defining a return lumen 13 and an inlet lumen 14 within the interior of the hollow tube. ('968 patent col. 3, lines 17-20).
This language does not specify what type of divider must divide the tube into two lumens. Furthermore, the specification does not limit the "septum" of claim 19 to a planar septum, it merely discloses one preferred embodiment.
That Dr. Mahurkar intended for claim 19 to cover cathaters with a non-planar septum is made particularly clear by comparing claim 19 to the other independent claims of the '968 patent: claims 1, 12, and 25. Claims 1 and 25, unlike claim 19, both explicitly recite a "planar septum," and claim 12 recites a "planar axial divider." The patentee's use of the limiting adjective "planar" in some claims, but not others, must be given meaning. See Karlin, 177 F.3d at 972 ("different words or phrases used in separate claims are presumed to indicate that the claims have different meanings and scope").

c). Dictionary Definition
The dictionary defines "septum" as "a dividing wall or membrane." (Webster's Collegiate Dictionary 1068 (10th ed.1996)). The dictionary definition supports Dr. Mahurkar's construction of "septum" as a divider *945 that separates the interior of the tube into two lumens. Additionally, a medical dictionary definition of "septum" also supports the Plaintiffs' proposed construction. In Stedman's Medical Dictionary, "septum" is defined as "A thin wall dividing two cavities or masses of softer tissue." (Stedman's Medical Dictionary 1599 (26th ed.1995)). For example, the septum of the nasal passage divides the nose into two cavities. (Id).

d). Prior Litigation
Arrow contends Judge Easterbrook's decision in In re Mahurkar judicially estops Plaintiffs from asserting claim 19 is not limited to a planar septum. This Court disagrees. In In re Mahurkar, Judge Easterbrook wrote, "the essential question concerning infringement came down to a disagreement about the meaning of language in the '968 patent concerning the septum." In re Mahurkar, 831 F.Supp. at 1358. However, Judge Easterbrook was never required to construe the meaning of septum in claim 19 because he found IMPRA infringed without having to do so. IMPRA argued its catheter did not infringe claims 1 and 19 because the septum in its device was not continuous through the tip. Id. at 1358. Judge Easterbrook noted that, "[a] `septum' is something dividing two lumens; because at the tip IMPRA's device has only one lumen, it has no septum there." Id. However, Judge Easterbrook determined that Dr. Mahurkar's invention also had its septum "moved out of the way at the tip." Id. Thus, "the invention claimed and described in the patent has exactly the deflection that IMPRA's device does ... IMPRA's device literally infringes." Id. Therefore, this Court's holding that the septum in claim 19 should be construed as a divider which is not limited to being flat is not inconsistent with Judge Easterbrook's decision in In re Mahurkar, because Judge Easterbrook never decided this issue.
Arrow argues Dr. Mahurkar limited all his claims to a flat septum in In re Mahurkar, in order to claim priority from a design application. This is simply not what happened. The priority issue turned on whether the claims of the '968 patent, including those requiring a planar septum, were supported by the drawings presented in the design application. Judge Easterbrook's decision was based on his finding that the drawings in the design application satisfied the written description requirement of § 112. Id. at 1362. Judge Easterbrook found the claims of the '968 patent were supported by the drawings in the design application. Id. He did not limit the patent to only that which was shown in the drawings.
Similarly, Arrow quotes a portion of the In re Mahurkar opinion relating to an inequitable conduct defense:
But only a dunderhead looking at figures 6 and 7 of the original design application would have supposed that the septum is discontinuous, or curved in places not depicted... The design drawings alone therefore imply a unitary, planar, full-length septum. In re Mahurkar, 831 F.Supp. at 1381-82. (Emphasis in original).
When Judge Easterbrook rejected the inequitable conduct defense, he was not limiting claim 19 to a flat septum as shown in the drawings. This passage does not discuss whether all the claims of the patent, including claim 19 are limited to a flat septum, only that the drawings in the embodiment illustrate a flat septum. Claim 19 is certainly not limited to the drawings in the specification. See Karlin Technology Inc., 177 F.3d at 972.
Arrow also cites passages from Judge Easterbrook's opinion and a Federal Circuit opinion that describe Dr. Mahurkar's commercial embodiment and his preferred design. These passages were introductory *946 to describe Dr. Mahurkar's advance over other catheters, and do not concern the specific claim presented in claim 19.
Finally, Arrow argues that a planar septum was crucial to the court's finding that the '968 patent was valid over the prior art regarding the Blake balloon catheter. Judge Easterbrook did hold that the '968 patent was valid over Blake's prior art, but not because of a planar septum. The reason Judge Easterbrook held the '968 patent was valid over the prior art was because he found Blake's catheter to be an "utterly different beast" from Dr. Mahurkar's. Id. at 1376. He also stated that in Blake, the "lumens are not of equal size, are not D-shaped, there is no axial separation to improve flow (Blake was uninterested in flow), no details to prevent clotting." Id. However, this passage was not a holding that claim 19 is limited to the double D configuration or a planar septum.

IV. CLAIM INTERPRETATION THE '561 PATENT
The elements of the '561 patent requiring construction by the Court are all found in Claims 1, 10, 21, 34, and 42.[7]

A. CLAIM 1
Claim 1 states as follows, with language to be construed in bold:
A dual-lumen catheter assembly comprising:
a dual-lumen catheter having a distal end and a proximal end, flow diversion means having one end fastened to the proximal end of said catheter, and a flexible extension of tubes each having one end fastened to the opposite end of said flow diversion means from said catheter, each of said extension tubes being bent back toward the distal end of said catheter to form a bend having a predetermined shape, each bend being adapted to flex and deform from said predetermined shape in response to removal of said external force.

1. Language in Dispute: "catheter"
Does "catheter" mean (1) the portion of the assembly inserted into the patient or (2) the structure distal to the flow diversion means or connecting means?
Answer: "Catheter" means the portion of the assembly intended to be inserted into the patient.

a). Claim Language
The Court must determine the meaning of "catheter." Claim 1 begins with the components of a dual-lumen catheter assembly: a catheter, flow diversion means, and a pair of flexible extension tubes. The claim language supports the construction proposed by the Plaintiffs because it says that a catheter assembly requires a catheter and other items. Therefore the term catheter must mean only that portion of the catheter assembly intended to be placed into the body and not the entire apparatus which contains other parts as described by the claim.
A syringe contains a needle and a dispensing tube. We commonly describe the "needle" as the portion of the syringe from the tip up to the dispensing tube. Although on each person the portion of the needle that goes into the flesh may vary, the needle is still considered to be the part *947 of the syringe that could possibly enter the skin. Similarly, the term "catheter" is that portion of the catheter assembly which is intended to be inserted into the patient.

b). Written Description
The specification is consistent with defining "catheter" as that portion of the catheter assembly which is intended to be inserted into the body. The background of the invention section supports construing the word "catheter" as the tube intended to be inserted into the patient. In this section it describes that "catheters" are "routinely allowed to remain in patients" for weeks or months. ('561 patent, col. 1, lines 32-34). Additionally, the background section explains the potential problems with catheters including the potential for them to become dislodged or cause pain or discomfort in patients because of continual movement within the vein. ('561 patent, col. 2, lines 1-5).
The summary of the invention also supports construing the word "catheter" as the tube intended to be placed into the patient's body. The summary provides that the primary object of the invention is "to provide an improved dual-lumen catheter-connecting system which permits the catheter to remain relatively stable during the entire time the catheter remains inserted in the patient." ('561 patent, col. 2, lines 34-38). (Emphasis added). Furthermore, throughout the summary of the invention, reference is made to a catheter which is inserted into the patient's vein. For example: "... improves the comfort level of the patient in whom the catheter is inserted" ('561 patent, col. 2, lines 42-43); "regardless of the particular vein into which the catheter is inserted" ('561 patent, col. 2, lines 54-55); and "the catheter is inserted in a jugular vein" ('561 patent, col. 3, lines 3-5).

c). Dictionary Definition
The dictionary definition of "catheter" lends even more support to constructing "catheter" to mean the portion of the assembly intended to be inserted into the patient. Webster's II New Riverside University Dictionary defines "catheter" as "a slender, flexible tube inserted into a bodily channel, as a vein..." (Webster's II New Riverside University Dictionary 238 (1994)).
In addition, a medical dictionary definition is also consistent with this construction. Stedman's Medical Dictionary defines "catheter" as "a tubular instrument to allow passage of fluid from or into a body cavity." (Stedman's Medical Dictionary 292 (26th ed.1995)). The "catheter" is the tube inserted into the patient which makes it possible to extract fluid from or pass fluid into body cavities.

2. Language in Dispute: "flow diversion means"
Does the "flow diversion means" function to (1) divert fluid flow from the "dual-lumen catheter" into the "pair of flexible extension tubes" or to (2) divert fluid flow from the "dual lumen catheter" so that the flow paths diverge?
Answer: The "flow diversion means" function to divert fluid flow from the "dual-lumen catheter" into the "pair of flexible extension tubes."

a). Claim Language
The claim language lists "flow diversion means" as one of the components of the catheter assembly. The claim says the catheter assembly includes "flow diversion means having one end fastened to the proximal end of said catheter." Claim 1 is written in means-plus-function format. In order to construe the function portion of the element, the Court applies the normal *948 claim construction rules. Chiuminatta Concrete, 145 F.3d at 1308. The function portion of the element is "flow diversion." The parties agree that the corresponding structure for "flow diversion means" is Y-shaped connectors and equivalents thereof. The parties disagree, however, about the construction of the function portion of the means-plus-function clause: "flow diversion."
The common and ordinary usage of the phrase "flow diversion" is, directing a stream or other moving liquid. In this case the diversion or directing of the flow is between the catheter and the two extension tubes. The plain meaning of the claim is clear; the flow diversion means (the Y-connector) diverts fluid flow from the two lumens in the "dual-lumen catheter" into the "pair of flexible extension tubes."

3. Language in Dispute: "being bent back toward the distal end of said catheter"
Do the tubes being "bent back toward the distal end of said catheter" mean that (1) the tubes must be bent toward (i.e., in the direction of) the distal end of the catheter or (2) the tubes be bent so that the proximal ends of the extension tubes are facing the distal end of the catheter?
Answer: The tubes being "bent back toward the distal end of said catheter" means that the tubes must be bent toward (i.e., in the direction of) the distal end of the catheter.

a). Claim Language
Claim 1 lists what components are necessary for a catheter assembly. Among those mentioned are a "pair of flexible extension tubes." The claim language says each of these tubes have three characteristics: (1) they are "bent back toward the distal end"; (2) they "form a bend having a predetermined shape"; and (3) each bend is "adapted to flex and deform from said predetermined shape in response to an external force and...to return to [the] predetermined shape in response to removal of said external force."
Both parties agree that the extension tubes should have a memorized bend and that the tubes are resilient so that their shape can be changed by force, but that once the force is removed, the tubes will return to the original shape. Thus, the only issue for the Court to decide is whether these flexible tubes must have a memorized bend of at least 180 degrees. The Court answers this question no.
The ordinary meaning of "bend" is to form a curve. For example, a wire can be bent from a straight line into a curve, or a gymnast can arch her back and place her hands on a mat to perform a "back bend" or a "back handspring." The word "bend" in claim 1 is followed by a directional modifier describing the manner in which the flexible tubes should be bent. The claim language says they should "bend back toward the distal end." The term "back" ordinarily means the rear or from where something just came and "toward" means in a specific direction (i.e., together the words "back toward" mean in the direction of the rear). Therefore, in this claim, the common meaning of the words is that the flexible tubes should curve in the direction of the rear, or the distal end. This does not mean they must curve to at least 180 degrees. Again consider a gymnast's body, this time as a flexible tube. When a gymnast performs a "back bend" reaching her arms back (toward the rear) over her head and toward the ground, her body becomes a curve, she may place her hands in a position such that her body is curved 180 degrees, or so that her body is curved 150 degrees. No matter what the exact placement of her hands she still has *949 bent back toward the rear and caused her body to become curved. That is exactly what we have in this claim. So long as the flexible tubes are bent back toward the distal end, toward the catheter, they are not required to be at least 180 degrees, or facing the distal end of the catheter.
Furthermore, the doctrine of claim differentiation requires Claim 1 to be read without a limitation of the bend being at least 180 degrees. The claim language in Claim 8 reads, "The catheter assembly of claim 1 wherein said extension tubes are generally U-shaped." If claim 1 were meant to require a bend of at least 180 degrees, then claim 8 would conflict with claim 1 and violate the doctrine of claim differentiation. This is because claim 8 limits the bend to a shape which is generally 180 degrees, therefore it contemplates claim 1 can have a bend of potentially less than 180 degrees. Thus, in order not to have claim 8 conflict with claim 1, the tubes in claim 1 cannot be limited to a bend of at least 180 degrees.

b). Written Description
It is clear in the specification that the extension tubes must bend back toward the catheter tip in order to accomplish their purpose of making the catheter assembly more comfortable for the patient. The extension tubes are bent back toward the distal end of the catheter so that the catheter "can be accommodated in a small area around the access site on the patient's body." ('561 patent, col. 5, lines 60-61). Furthermore, the bend in the tubes also enables patients to change clothing and move about without projections interfering. ('561 patent, col. 5, lines 65-68 and col. 6, lines 1-3). Each of these goals can be achieved without limiting the bend of the tubes to at least 180 degrees. A bend short of 180 degrees would still provide for a patient to be able to change clothing and allow the catheter to be contained to a small area.

B. CLAIM 21
Claim 21 reads as follows, with language to be construed in bold:
A method of preparing a patient for extracorporaeal blood treatment comprising the steps of inserting into a vein selected from the group consisting of the jugular, subclavian and femoral veins of the patient, the distal end portion of a dual-lumen catheter assembly having flow diversion means having one end fastened to the proximal end of said catheter, a pair of flexible extension tubes each having one end fastened to the opposite end of said flow diversion means from said catheter, each of said extension tubes being bent back toward the distal end of said catheter and extending alongside said flow diversion means to form a bend having a predetermined shape, each bend being adapted to flex and deform from said predetermined shape in response to an external force and being adapted to return to said predetermined shape in response to removal of said external force, flow control means for controlling by the flow of blood between said duallumen catheter and an extracorporeal blood treatment unit, and coupling means for coupling said extension tubes to said blood treatment unit, and taping said flow diversion means and extension tubes to the skin of the patient.

1. Language in Dispute: "extending alongside said flow diversion means"
Does extending "alongside" said flow diversion means mean (1) that the extension tubes can extend on either opposite sides or the same side of the Y-connector or (2) that each extension tube extends on the opposite side of the Y-connector?
*950 Answer: Extending "alongside said flow diversion means" means that the extension tubes can extend on either opposite sides or the same side of the Y-connector.

a). Claim Language
The claim language calls for the flexible extension tubes to extend "alongside" the "flow diversion means," the Y-connector, to form a bend. The Court having already determined the meaning of "flow diversion means," must now construe the word "alongside." The common and ordinary meaning of "alongside" is, next to a side or being positioned on a side. In other words, the claim language in claim 21 means the bent extension tubes must extend next to a side of the catheter, or be positioned on a side of the catheter. The word "alongside" does not specify which side; it can be the same side or the opposite side. Thus, the extension tubes can extend along opposite sides or on the same side and still fall within the ordinary and accustomed meaning of the term "alongside."
For example when sportscasters are announcing a horse race and they say "Point Given" and "AP Valentine" are coming around the turn right "alongside" "Congaree", it is possible that the two horses are both on the left side of "Congaree," that they are both on the right side of "Congaree," or that "AP Valentine" is on the left of "Congaree" and "Point Given" on the right and vice versa. Thus, the two horses may be alongside the predicted winner if they are on the same side or on opposite sides of "Congaree."

b). Written Description
The specification of the '561 patent supports construing the phrase "alongside said flow diversion means" as the extension tube can extend on either opposite sides or the same side of the Y-connector. The specification reads, "the extension tubes are bent back toward the distal end of the catheter, preferably extending along the sides of the catheter ..." ('561 patent, col. 5, lines 56-57). (Emphasis added). The term "preferably" conveys the message that a particular method is desirable or a first choice; it does not convey the idea that something is mandatory. Thus, Dr. Mahurkar prefers the tubes extend along the opposite sides of the catheter, but has contemplated embodiments where the two extension tubes can extend along the same side of the Y-connector.

c). Dictionary Definition
The dictionary definition also supports construing the claim language extension tubes "extending alongside said flow diversion means" as the extension tubes can extend on either opposite sides or the same side of the Y-connector. The dictionary definition of "alongside" is "along, near, at or to the side." (Webster's II New Riverside University Dictionary 95 (1994)). Again, there is no specification as to whether something must be on the same side or the opposite side. Thus, the extension tubes may extend along the same side or opposite sides of the said "flow diversion means."

C. CLAIM 34
Claim 34 reads as follows, with language to be construed in bold:
A dual-lumen catheter assembly comprising a dual-lumen catheter, and connecting means attached to the proximal end of said catheter and forming a pair of internal passageways which communicate at one end thereof with the dual lumens in said catheter, said passageways curving back toward the distal end of said catheter so that forces exerted on said connecting means at the other ends of said passageways will tend to move said catheter in a direction opposite that of said exerted forces.


*951 1. Language in Dispute: "connecting means"
Do the disclosed structures corresponding to the "connecting means" include (1) a Y-connector fastened to bent extension tubes and a unitary connecting member or (2) a unitary connecting member only, or, if the Court finds sufficiently disclosed additional corresponding structure, also a Y-connector fastened to extension tubes that do not straighten out in response to forces?
Answer: The disclosed structures corresponding to the "connecting means" include a Y-connector fastened to bent extension tubes and a unitary connecting member.

a). Claim Language
"Connecting means" is a means-plusfunction clause. The function is connecting to the proximal end of that portion of the assembly that is inserted into the patient's body and forming a pair of internal passageways which communicate at one end thereof with the dual lumens in the catheter.

b). Written Description
The specification discloses two different corresponding structures which are linked to the function. First, the specification discloses a Y-shaped connector or hub (element 30) connected to two extension tubes (elements 40 and 41) that curve back toward the distal end of the catheter. Second, the specification discloses using a "a unitary connecting member" instead of the hub and two extension tubes:
...the curved passageways provided by [the] extension tubes may instead be formed by a unitary connecting member fastened to the proximal end of the duallumen catheter. More specifically, the unitary connecting member may form two internal U-shaped passageways, each of which is in communication with one of the lumens of the catheter. ('561 patent, col. 8, lines 14-22).
Thus, the "connecting means" may be: (1) a Y-shaped connector connected to extension tubes that curve back toward the distal end of the catheter, and equivalents thereof; and (2) a unitary connecting member forming two internal U-shaped passageways, each of which is in communication with one of the lumens of the catheter, and equivalents thereof. Other details of the specific structures mentioned in the specification such as the size of the hub and the materials used to make the extension tubes, are details "unrelated to the recited function" and therefore do not limit the claim. Chiuminatta Concrete, 145 F.3d at 1308.

V. CONCLUSION
The Markman hearing has been concluded, the claims have been construed and the saga continues in conformity with this opinion. *952 *953 *954 *955 *956 *957 *958 *959 *960 *961 *962 *963 *964 *965 *966 *967 *968 *969 *970 *971 *972
NOTES
[1]  A copy of the '968 patent is attached as Exhibit A to this opinion.
[2]  A copy of the '561 patent is attached as Exhibit B to this opinion.
[3]  Some of the terms in the '968 patent requiring construction appear in multiple claims. Identical claim terms appearing in multiple claims of a patent, "must be construed consistently." Southwall Technologies, Inc. v. Cardinal IG Co., 54 F.3d 1570, 1574 (Fed.Cir. 1995). Therefore, the Court will only address each disputed term the first time it appears in the patent and the construction of the term will apply for each claim where the term is found.
[4]  For each issue to be decided by the Court, Plaintiffs' proposed claim interpretation is listed as (1) and Defendant's proposed claim interpretation is listed as (2).
[5]  The parties have agreed that the ruling on claim 12 will be the same as the ruling on claim 19's construction. Thus, the word "cone" is equivalent to the word "conical" for purposes of this Markman decision. The language in dispute in claim 19 is: "... the distal end portion of said tube defining a truncated cone..."
[6]  Arrow also suggests that the word "cone" is limited to the right circular cone shown in the figures because the '968 patent claims priority from a design application. This argument is contrary to well established law. In Vas-Cath, Inc. v. Mahurkar, 935 F.2d 1555, 1565 (Fed.Cir.1991), the Federal Circuit held that Dr. Mahurkar's claims in a utility patent may claim priority from a design application (which shows only figures) so long as the figures in the design application satisfy the written description and enablement requirements of 35 U.S.C. § 112, ¶ 1. It is black letter law that a specification (or drawing) need not describe every possible embodiment covered by the claim to satisfy the written description requirement. See, e.g., Johnson Worldwide Assoc., 175 F.3d at 993. See also Lampi Corp. v. Am. Power Prods., Inc., 228 F.3d 1365, 1378 (Fed.Cir.2000). Thus, whether the drawings in the design application showed off-center cones in addition to right circular cones is immaterial.
[7]  Some of the terms in the '561 patent requiring construction appear in multiple claims. Identical claim terms appearing in multiple claims of a patent, however, "must be construed consistently." Southwall Technologies, 54 F.3d at 1574. Therefore, the Court, as it did with the '968 patent, will only address each disputed term the first time it appears in the patent and the construction of the term will apply for each claim where the term is found.
