Prosthesis for Banding of an Artery Capable of Dilation by a Balloon Dilator

This invention relates to a surgical device for banding an artery in order to constrict the flow through the artery, the device being subsequently expandable by use of a balloon dilator to reduce the constriction.

Pulmonary artery banding is frequently used to treat infants with congenital heart malformations in whom the malformation results in excessive pulmonary blood flow. In current clinical practice, radiopaque umbilical tape, coated with medical adhesive silicon rubber, is widely used to band and constrict the pulmonary artery to reduce the blood flow. Such a fixed band, however, is not dilatable and therefore does not allow for the increased pulmonary blood flow necessary as the infant grows. As a result, further surgery is often necessary to either enlarge the constricting band or create an aorticopulmonary shunt around the constriction site. It will be appreciated that this additional surgery places a great deal of stress on the infant and correction of the initial defect is often made more difficult.

The present invention is a banding prosthesis to constrict an artery for an extended period of time and subsequently allow for dilation of the prosthesis while in place about the artery by an intraluminal balloon dilator thereby avoiding further operations.

Accordingly, the present invention is a banding prosthesis comprising an expandable helical member encased within an elongatable outer covering, the ends of said outer covering being sealed and incorporating attachment means for joining the two ends of the banding prosthesis to form a band about a diameter of a tubular organ such as a blood vessel so as to encircle and constrict said organ whereupon an intraluminal balloon dilator inserted within said organ in the region of said band and inflated can be used to dilate said banding prosthesis.

The present invention provides a safe and reliable banding prosthesis which can be dilated in stages while in place in a patient's body.

A preferred embodiment of the present invention is shown in the accompanying drawings in which:

FIG. 1 shows the banding prosthesis of the present invention;

FIG. 2 shows the banding prosthesis in place about an artery of a dog.

FIG. 3 shows the banding prosthesis of FIG. 2 after dilation by a balloon dilator.

Referring to FIG. 1, there is shown a banding prosthesis 10 according to a preferred embodiment of the present invention. An expandable, helical member 12 is encased within a tubular, flexible and elongatable outer covering 14. In a preferred embodiment, helical member 12 is constructed using a stainless steel pacemaker electrode from a Medtronic (trademark) model 6957 pacemaker stretched to three times its original length. Outer covering 14 is made from silicon rubber tubing such as Silastic (trademark) medical-grade tubing.

Helical member 12 is inserted within the hollow inner core of covering 14 and the ends of the covering are sealed at 16 by silicone type A medical adhesive. Incorporated into the sealed ends 16 of covering 14 are attachment means 17 for joining the two ends of the prosthesis comprising double 3-0 silk sutures.

In use, the banding prosthesis of the present invention is placed about an artery 20 as shown in FIG. 2. Sutures 17 are tied together to form a constricting band to reduce the cross-sectional area of the artery available for blood flow. In a series of animal experiments on dogs, it was found that the prosthesis of the present invention could constrict an artery for a prolonged period, up to 129 days, without stretching and subsequently be capable of dilation by an intraluminal balloon dilator.

FIG. 3 shows the banding prosthesis after dilation by a balloon dilator. A conventional balloon dilator comprising an inflatable balloon portion and an inflation tube is inserted into the artery 20. The balloon dilator is manoeuvered through the artery in an uninflated state into constricted region 25 defined by the banding prosthesis 10. The progress of the balloon dilator in the artery can be observed using an image intensifier so that direct access to the operation site is not necessary. Upon inflation of the balloon portion of the balloon dilator, the outward expansion of the balloon acts against the banding prosthesis to permanently uncoil helix member 12 and stretch elongatable outer covering 14 so as to increase diameter of the constricted region 25 as shown in FIG. 3. In the animal experiments conducted, inflation of the balloon to six atmospheres pressure was necessary to expand the banding prosthesis. Outer covering 14 prevented tissue ingrowth into helical member 12 which would tend to prevent uncoiling of the helical member.

The banding prosthesis of the present invention can be expanded in stages using different sized balloon dilators. Each expansion procedure acts to partially uncoil helix member 12 and stretch elongatable outer covering 14. Once expanded to a larger size, helix member 12 maintains the new dilation. It is possible to accurately expand the applied prosthesis to a given diameter by using a balloon dilator having a known maximum dilatable diameter.

The present invention thus provides a safe and reliable banding prosthesis capable of constricting an artery and being subsequently dilated in stages by an intraluminal balloon dilator.