Perfusion catheter

Details Perfusion catheter Perfusion catheter

1996-11-26

2001-02-27

Kennedy, Sharon (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S096010, C604S523000, C604S915000

Reexamination Certificate

active

06193685

ABSTRACT:

BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention is directed generally to catheter systems utilizing inflatable balloon dilatation devices for mechanical dilation of vascular stenoses and, more particularly, the invention addresses improvements in such systems related to the perfusion or bypassing of vessel fluid during such procedures to overcome limitations associated with the disruption of blood supply beyond the ditilation device that accompanies balloon expansion. Specifically, the invention deals with improvements in side opening flow passage arrangements including openings distal and proximal of the balloon in fluid communication with one another via a continuous lumen extending through and beyond the balloon.
II. Related Art
Percutaneous dilatation of arterial stenoses, particularly coronary artery stenoses, using a balloon dilatation catheter has become a recognized and common procedure that has proved to be effective in many instances. Inflation of the balloon to depress stenoses results in the obstruction of blood flow through the vascular passage of interest during the inflation. This, of course, is undesirable from the standpoint of loss of blood supply delivered to downstream tissues thus deprived. To prevent damage to these tissues, the inflation period of the balloon is limited to the time frame of about 2-3 minutes, after which the balloon must be deflated and flow allowed to pass to avoid tissue damage or even necrosis.
The dilatation time can be significantly lengthened, however, without increased risk of ischaemia by the provision of a bypass or perfusion system in which a passage is provided through the inflated balloon that enables vessel fluid flow to continue uninterrupted during the inflation or dilatation period.
Systems have been devised which include the provision of a perfusion path in dilatation catheters. One such system is illustrated and described in U.S. Pat. No. 5,201,723 to Quinn which incorporates a pattern of opposed elongated holes inclined and arranged to prevent kinking of the catheter. Another system is shown in U.S. Pat. No. 5,295,961 to Niederhauser et al that includes side openings connecting the vascular lumen with a common interior catheter lumen. The openings are arranged both distal and proximal of the balloon and the common catheter lumen extends through and beyond the balloon and are substantially perpendicular or normal to the longitudinal axis of the catheter in both the proximal and distal locations. The contents of U.S. Pat. No. 5,295,961 are deemed incorporated herein by reference for any purpose. While that system has accomplished perfusion and has met with a great deal of success, it would be more advantageous to provide a system that enjoys reduced pressure drop across the balloon system and reduces any tendency toward turbulent flow. In addition, severe directional changes and relatively sharp inlet and outlet opening edges may result in injury to blood cells as they negotiate the perfusion flow system. In this regard, it would be advantageous to provide an improved perfusion flow system in a dilatation catheter system which not only reduces pressure loss across the dilatation catheter and reduces the tendency toward turbulent flow, but which also provides a safer ingress and egress for the blood cells negotiating the system.
Accordingly, it is a primary object of the present invention to provide a perfusion flow system for a dilatation catheter which reduces the pressure drop across the balloon catheter and also reduces the tendency toward turbulent flow.
A further object of the present invention is to provide a perfusion flow arrangement for a dilatation catheter that reduces the tendency for blood cells negotiating the system to be damaged.
A still further object of the present invention is to provide a perfusion flow system for a dilatation catheter that maintains a blood flow of at least 40 cc/min. at about 80 mm Hg proximal perfusion pressure.
Other objects and advantages of the invention will occur to those skilled in the art upon familiarization with the description and accounts contained in the specification, together with the appended claims.
SUMMARY OF THE INVENTION
The present invention provides improvements in perfusion flow systems for vascular dilatation catheter devices which utilize an expanding member to provide mechanical dilation of coronary or other arterial stenoses in a procedure which temporarily blocks the vessel. The improvements of the invention modify the perfusion path and reduce the tendency toward turbulent flow and reduce pressure losses, but not the flow across the dilatation catheter. At the same time, the invention also provides a safer passage for blood cells navigating or flowing through the perfusion system. The system is designed for use with a typical balloon dilatation catheter system which utilizes a bilumen tubular member or shaft carrying an expandable balloon member and designed with two elongate, parallel lumens, one of which is in fluid communication with the balloon cavity and with an external source of inflation fluid for selectively inflating and deflating the expansible balloon member (nominally called herein the inflation lumen) and the other one of which traverses the expansible member or dilatation device and is nominally utilized for carrying a guidewire (called herein the guidewire lumen or the perfusion lumen), but which also provides the passage for the perfusion flow.
In accordance with one aspect of the invention, a pattern of perfusion openings or passages are provided in the bilumen tubular catheter member which provide inlet and outlet passages between and connecting the outside of the tubular member with the perfusion lumen proximal and distal the dilatation device which, with an intervening common segment of the lumen, provide a passage for blood or other fluid through the expansible dilatation member to supply points downstream in the normal direction of flow during balloon expansion.
In accordance with one aspect of the invention, the openings or passages proximal to the dilatation device are designed to breach the catheter wall at an acute angle with the normal axis or center line of the tubular catheter member (and thus with the vascular lumen) so as to reduce or minimize the deflection angle from the normal path between the local vascular blood flow and the by-pass or perfusion lumen. In addition to the angled posture of the openings, the outer edges that impinge entering blood cells are preferably flared to present a blunt edge to reduce cell injury and reduce tendencies toward turbulence in the flow pattern. The distal openings may also be designed to exit through the wall of the bilumen tubular member at an acute angle with the direction of flow if desired, however, the distal end of the guidewire lumen is typically open to accommodate a guidewire extending beyond the distal end thereof and this provides a main perfusion outlet channel parallel to the flow direction.
It has been found that it is preferable to locate the openings close to the dilatation device or balloon. The pattern of the openings may be linear, but any desired pattern can be used. The desired flow rate to be maintained in a coronary artery, for example, is approximately 40 cc/min at 80 mm Hg upstream or proximal perfusion pressure. For a lumen typically 0.031 in. (0.079 cm) to 0.036 in. (0.091 cm) I.D., the number of perfusion inlet openings required may range from about 25 openings having a nominal diameter of 0.14 in. (0.036 cm) to about 10 openings having a nominal diameter of 0.025 in. (0.064 cm). The distal guidewire opening in the guidewire perfusion lumen is about 0.018 in. (0.046 cm) for a guidewire having a diameter of 0.014 in. (0.036 cm). A lesser number of distal side openings are also provided, but, preferably, the flow area at the outlet is greater than that at the inlet and both inlet and outlet openings are designed so that the flow is limited only by the diameter (capacity) of the guidewire or perfusion lumen itself.
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