Matter of Mahurkar Double Lumen Litigation

• Decision Date: 18 August 1993
• Docket Number: No. MDL 853.,MDL 853.
• Citation: 831 F. Supp. 1354
• Parties: In the Matter of MAHURKAR DOUBLE LUMEN HEMODIALYSIS CATHETER PATENT LITIGATION.
• Court: U.S. District Court — Northern District of Illinois

831 F. Supp. 1354

In the Matter of MAHURKAR DOUBLE LUMEN HEMODIALYSIS CATHETER PATENT LITIGATION.

No. MDL 853.

United States District Court, N.D. Illinois, E.D.

August 18, 1993.

COPYRIGHT MATERIAL OMITTED

Joseph N. Hosteny, Raymond P. Niro, John C. Janka, Michael P. Mazza, Niro, Scavone, Haller & Niro, Chicago, IL, for Sakharam D. Mahurkar.

Marvin A. Glazer, Janelle F. Raupp, Cahill, Sutton & Thomas, Phoenix, AZ, for IMPRA, Inc.

Granger Cook, Jr., Mark J. Murphy, Cook, Egan, McFarron & Manzo, Ltd., Chicago, IL, for IMPRA, Inc. Local Counsel.

OPINION

EASTERBROOK, Circuit Judge.^*

Kidneys remove toxins from the blood. Kidney failure is fatal unless a way can be found to replace their function. Hemodialysis does this. Blood is removed from the body, toxins are removed from the blood, and the blood is then returned to the body. Sometimes a few days or weeks of hemodialysis is enough; in the interim the kidneys, having suffered an acute failure because of trauma or disease, return to normal functioning. Chronic kidney failure requires long-term hemodialysis, with the blood being cleansed several times a week. In either event, physicians need access to the blood stream without doing excessive damage to the circulatory system and the blood itself.

This patent litigation arises out of a duallumen catheter developed to provide that access. Earlier opinions describe the litigation. See Vas-Cath Inc. v. Mahurkar, 745 F.Supp. 517 (N.D.Ill.1990), reversed in part, 935 F.2d 1555 (Fed.Cir.1991); In re Mahurkar Double Lumen Hemodialysis Catheter Patent Litigation, 750 F.Supp. 330 (N.D.Ill. 1990), 781 F.Supp. 1295 (1991), 140 B.R. 969 (1992). After a bench trial in the last of these consolidated actions, the others having been resolved by settlement, I now make the required findings of fact and conclusions of law.

Sakharam D. Mahurkar, a nephrologist, developed his first dual-lumen catheter in his kitchen in 1980, finishing the assembly on January 1, 1981. He has obtained a series of patents for that catheter and several variations, but the litigation has come to focus on No. 4,583,968, which issued on April 22, 1986. At the conclusion of the first phase of the bench trial, I informed the parties that in my view independent claims 1 and 19 of the '968 patent are valid and infringed by the devices IMPRA, Inc., has sold, and that dependent claims 2, 3, 6, 7, 8, 11, 20, 21, 22, and 23 also are valid and infringed by those catheters. Only one other patent, No. 4,692,141, issued on September 8, 1987, figures in Mahurkar's claims against IMPRA, and I concluded that I did not need to resolve certain issues concerning this patent in order either to decide liability or calculate damages. IMPRA informed me that it had taken its infringing dual-lumen catheters out of production, so I did not issue an injunction at the time. We proceeded to a trial on damages. This opinion elaborates on the oral decision on liability, addresses a few subjects that were not covered at trial, and reaches a conclusion on damages.

This litigation has been complex and extended, with disputes on hundreds of questions, central and tangential. In order to simplify this opinion, I confine my findings and conclusions to the issues that ultimately shape the decisions on the merits and relief. I assume familiarity with the earlier published opinions and do not recapitulate the nature of the devices and the background of the dispute. If the parties believe that some important factual or legal dispute still requires resolution, they should draw that issue to my attention promptly after receiving this opinion.

I

Mahurkar charges IMPRA with infringing his patents. On this question Mahurkar bears the burden of persuasion, In re Hayes Microcomputer Products, Inc., Patent Litigation, 982 F.2d 1527, 1541 (Fed.Cir. 1992), so I start here. The trial was structured in much the same fashion. See Howard T. Markey, On Simplifying Patent Trials, 116 F.R.D. 369 (1987); Rita Mankovich Irani, The New Skirmish in Patent Cases: Who Goes First at Trial and With What Evidence? 17 AIPLA Q.J. 364 (1989).

The '968 patent covers a smooth bore, dual-lumen catheter, and there is no doubt that IMPRA made such a catheter, all but identical to the one described in the '968 patent. Figures 1 and 2 (Figures 6 and 7 from the '968 patent) show the cross-section and tip of Mahurkar's device, and Figure 3 shows IMPRA's.

Changes were made to IMPRA's catheter through the years, but none of these changes is material to IMPRA's liability. For example, IMPRA added a bevel to the D-plug sealing off the intake lumen; this change made it more like the '968 design.

After the extended pretrial proceedings, and the admissions of the parties, resolved many disputes, the essential question concerning infringement came down to a disagreement about the meaning of language in the '968 patent concerning the septum. The septum is the divider between the lumens (that is, the tubes) of the catheter.

Claim 1 of the '968 patent describes a device including a "longitudinal planar septum ... said first lumen and the internal wall thereof formed by said septum extending continuously through said conical tapered tip". Claim 19 uses this variation: "integral septum extending axially along the entire length of the tube". IMPRA contends that its catheter does not have such a septum, for reasons related to the manner of its construction.

IMPRA made its catheters by extruding plastic tubing in a double-D configuration and inserting one end of the tube into a heated die. The die was shaped like an inverted cone, so that the catheter acquired a taper, and the die had a protrusion called a mandrel. The mandrel kept a circular hole open in the return lumen of the tube so that the catheter could be inserted into the patient's circulatory system over a guidewire (the Seldinger technique) and so that blood would pass through this opening while the catheter was in use. Using a die with mandrel to form the conic, tapered tip meant that the dividing wall between the double-D tubing was melted and pushed to the outer wall. This simultaneously closed off the intake lumen and produced a thickening of one side of the wall of the tip.

The parties have had some dispute about the precise construction and shape of IMPRA's device. To tie up loose ends, I find that Figure 3 (MMDL 327) is an accurate rendering of IMPRA's device. It is taken from a diagram attached to the narrative statement of Gary Smith, one of IMPRA's experts. Figure 3 shows two deflections of the septum: one drawn by IMPRA's inhouse staff, and another closer to the tip penciled in by Smith. Glen Harding, IMPRA's current engineering supervisor, confirmed that the Smith alterations to this drawing are accurate. Tr. 736-37. I find that Smith's correction depicts the tip. The hand-drawn nature of this drawing makes it hard to say exactly where the deflection begins, but it is less than 0.188 inch, the location of the deflection in the drawing before Smith made his correction. A photograph in the record (MMDL 441) shows the deflection at the very tip. Variations attributable to differing methods of construction do not affect my conclusions, so I do not include other figures.

The upshot: for the last fraction of an inch of the IMPRA catheter there is only one lumen, the material constituting the divider having been deflected to the sidewall by the mandrel. According to IMPRA, its catheter does not infringe claims 1 and 19 because the septum in its device is not continuous through the tip. A "septum" is something dividing two lumens; because at the tip IMPRA's device has only one lumen, it has no septum there. Moreover, the material from the wall between the D-shaped lumens acquires a curve at the very end. The mandrel that melts and deflects it has a circular cross-section, so the material from the dividing wall acquires a curve that at the tip approaches a semi-circle. Yet claim 1 speaks of a "planar" septum, which to IMPRA means an uncurved septum. Thus IMPRA's argument: its catheter does not have a "continuous" septum (claim 1) extending "along the entire length of the tube" (claim 19), but even if it does it still wins because the septum is not "planar".

Although IMPRA's arguments have some semantic attraction, they are ultimately inconsistent with the terms of the patent. Both the full text of claims 1 and 19, and the diagrams illustrating the invention, call for a conversion to a conic section at the tip. The preferred embodiment of the invention has the apex of this cone on the axis of the tube, and the opening in the conic tip is in the shape of a circle rather than a D, in order to facilitate insertion by the Seldinger technique. The apex of the cone can be on the axis of the tube only if the septum is moved out of the way at the tip, and the transformation from D-shape to O-shape is possible only if at least some portion of the septum (or what used to be the septum) is curved. In other words, the invention claimed and described in the patent has exactly the deflection that IMPRA's device does. "Continuous" and "planar" thus describe the construction of the septum until the tip, but not at the tip. IMPRA's device literally infringes.

A second set of considerations supports the same conclusion. Figure 2 (Fig. 7 of the '968 patent) 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.) Below the intake ports in the '968 device there is only one "lumen" through which blood flows. Yet the claims speak without embarrassment of a septum extending through the tip. If there cannot be a "septum" without two lumens, then the septum in the catheter described by claims 1 and 19 of the '968 patent must end at the intake ports. That would...