WO1999023955A1

WO1999023955A1 - Vascular shunt apparatus

Info

Publication number: WO1999023955A1
Application number: PCT/US1998/023456
Authority: WO
Inventors: Robert Lazzara
Original assignee: Robert Lazzara
Priority date: 1997-11-12
Filing date: 1998-11-04
Publication date: 1999-05-20
Also published as: AU1378899A

Abstract

The present invention is directed to new and useful methods and apparatus for preventing or lessening external bleeding or escape of other bodily fluids during surgical procedures involving incision of a blood vessel. Upon proper insertion into a blood vessel, an elongated shaft with a hollow internal channel provides a virtually normal course for the flow of blood or other fluid, and thus eliminates ischemia in organs and tissues distal from the surgical site. A valve is attached to the shaft of the apparatus via flexible tubing. The valve and tubing are in fluid communication with the hollow internal channel and allow selective delivery of fluids and drugs through the apparatus. Such a feature is utilized, for example, to infuse fluids or drugs, or to withdraw fluids for sampling during the surgery. The present invention also relates to a method for use of a vascular shunt apparatus. According to one aspect of the present invention, a surgeon selects an apparatus according to the present invention which is sized to accommodate the diameter of and flow rate through a particular vessel. The surgeon then inserts the apparatus through an incision in the vessel such that each end extends beyond the length of the incision. The surgeon may then infuse a fluid or drug into the apparatus, such as for momentarily stopping the heart in coronary bypass surgery during which time the surgeon sutures a bypass graft. The present invention may also be utilized as a stent to open the internal diameter of a vessel during a procedure.

Description

BACKGROUND OF THE INVENTION

VASCULAR SHUNT APPARATUS

The Field of the Invention

The present invention is directed generally to methods and apparatus for halting external bleeding or loss of other bodily fluids during surgical procedures involving incision of a blood vessel. More specifically the present invention is related to methods and apparatus for reducing the risk of ischemia in the tissue downstream from a surgical incision in a blood vessel.

The Relevant Technology

During surgical procedures, and particularly many delicate surgical procedures requiring a clear, unobscured view of an extremely small surgical field, visibility is of critical importance. Throughout many surgical procedures, blood leakage becomes a major visual obstruction to the surgeon, and in turn may impede the surgical process.

Traditionally, surgeons have averted blood leakage during delicate surgical procedures by using surgical devices that occlude the flow of blood both upstream and downstream from the surgical site. The conventional approach for preventing bleeding in such surgeries has involved the use of clamps or stents. For example, PCT International Publication No. WO 92/19161, the entire disclosure of which is hereby incorporated herein by reference, illustrates an occluding device in the form of a vascular probe. This type of device provides a dry surgical field by preventing the flow of blood to the site of a vessel graft or anastomosis. Although effective for preventing unwanted bleeding into the surgical site, this approach also deprives downstream bodily tissues of oxygen and other vital blood-born constituents. In many cases the tissue downstream from the site of an anastomosis or other procedure would suffer from ischemia, or sustained periods without oxygen or other blood constituents.

For example, coronary artery bypass surgery is commonly required when coronary arteries narrowed by cholesterol-rich fatty deposits or plaques are unable to supply the heart muscle with a sufficient amount of blood, and as a result, the heart becomes starved for oxygen. Left untreated, coronary artery disease ultimately leads to acute myocardial infarction, commonly referred to as a heart attack. In coronary artery bypass surgery, a surgeon grafts a section of a healthy vessel to bypass a stenotic or partially blocked portion of a coronary artery in order to ameliorate the oxygen access to the heart muscle. While using conventional occluding devices, a surgeon encounters additional time pressure to complete the delicate surgery in order to restore blood flow and subsequent oxygenation to the heart muscle before the heart sustains irreversible damage of the very type the bypass is meant to prevent.

Similarly, in patients suffering from peripheral vascular disease, arterial reconstructive surgery may be necessary to prevent loss of a limb. In this disease, blood vessels in the legs or arms narrow due to fatty plaques forming on the interior surface of the arteries. This restricts blood flow beyond the affected areas, may cause pain, and eventually may result in death of the tissue supplied by the vessels, or gangrene, in which case amputation of the limb becomes necessary. Further delay of blood supply to the starved tissues during surgical procedures utilizing a conventional stent device may actually exacerbate the condition and result in additional ischemic damage. SUMMARY AND OBJECTS OF THE INVENTION

It is therefore a primary object of the present invention to provide methods and apparatus to avert leakage of blood into a surgical site, and improve visibility, without further impeding the flow of oxygenated blood to the heart muscle during coronary artery by-pass surgery, or to other tissues during peripheral vascular surgery while providing for infusion of fluids, such as nutrient solutions, blood, cardioplegia, contrast dye for x-rays, or drugs to the heart or other bodily organs and tissues.

Another object of the present invention is to provide methods and apparatus for withdrawing or sampling fluids from the surgical site.

A further object of the present invention is to provide methods and apparatus for facilitating momentary cardiac arrest.

Yet another object of the present invention is to provide methods and apparatus for performing coronary artery by-pass on a beating heart. These and other objects and advantages of the invention will be better understood by reference to the detailed description, or will be appreciated by the practice of the invention.

To achieve the foregoing objects, and in accordance with the invention as embodied and broadly described herein, the present invention relates to a vascular shunt apparatus that comprises an elongated shaft with a hollow internal channel in fluid communication with and connected perpendicularly to flexible access tubing.

In the presently preferred embodiment of the present invention, a valve is attached to the flexible access tubing to allow selective delivery of blood at normal body pressures, fluids, and drugs through the vascular shunt apparatus.

Such a feature is utilized, for example, to infuse fluids or drugs to arrest the heart for brief periods, such as from three to five seconds, which allows the surgeon a small window of time for suturing a vessel absent pulsing cardiac pressure. The valve and tubing also allow withdrawal of fluids for sampling during the surgery. The present invention also relates to a method for use of a vascular shunt apparatus. According to one aspect of the present invention, a surgeon selects an apparatus according to the present invention which is sized to accommodate the diameter of and flow rate through a particular vessel. The surgeon then inserts the apparatus through an incision in the vessel by first sliding one end of the apparatus into the interior of the vessel and then inserting the other end. The shaft of the apparatus is positioned in the vessel such that each end extends beyond the length of the incision. The surgeon may then infuse a fluid or drug into the apparatus, such as for momentarily stopping the heart in coronary by-pass surgery, during which time the surgeon sutures the by-pass graft.

Alternatively, the surgeon may connect the valve to an arterial blood line from the patient. The resulting connection of arterial blood through the shaft of the apparatus allows for continuous perfusion at physiologic blood pressures to prevent downstream ischemia to organs at risk following completion of the surgical procedure.

Alternatively, contrast dye can be injected into the valve and through the shaft such that x-rays can be taken to document patency and function of the completed procedure.

These .and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS In order to more fully understand the manner in which the above-recited and other advantages and objects of the invention are obtained, a more particular description of the invention will be rendered by reference to a specific embodiment thereof which is illustrated in the appended drawings. Understanding that these drawings depict only a typical embodiment of the invention and are not therefore to be considered to be limiting of its scope, the invention in its presently understood best mode for making and using the same will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

Figure 1 is a perspective view of a presently preferred embodiment of the present invention.

Figure 2 is a perspective view of another embodiment of the vascular shunt of the present invention depicted as being inserted into a vessel.

Figure 3 is a perspective view of the vascular shunt of Figure 2 situated in a vessel. Figure 4 is a perspective view of the vascular shunt of Figure 2 situated in a vessel during a graft procedure.

Figure 5 is a perspective view of the vascular shunt of Figure 2 as it is removed from the surgical site just prior to completion of a graft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to methods and apparatus for preventing or lessening external bleeding during surgical procedures involving incision of a blood vessel while averting ischemic damage to downstream tissues. For purposes of brevity and simplicity, the following discussion is directed to methods and apparatus for use in connection with coronary artery bypass procedures, but it should be understood that such discussion is merely exemplary. The present invention is also applicable to peripheral vascular procedures, for example. The coronary arteries, which branch immediately off of the ascending aorta as it exits the left ventricle, supply oxygenated blood to the heart muscle itself. These arteries are especially prone to developing fatty deposits or plaques that narrow the available diameter for blood flow to the heart. In turn, this causes a reduction in the amount of oxygen reaching the heart muscle, and can become so severe that the vessel is actually occluded resulting in myocardial ischemia or myocardial infarction, which is commonly known as a heart attack.

It is possible to ameliorate this condition by attaching a vessel that circumvents or "bypasses" the blockage. In a procedure known as coronary artery bypass, a length of blood vessel, usually taken from the saphenous vein in the leg, is sutured to the aorta and to the coronary artery at a location beyond the site of the occlusion.

Surgeons have conventionally used clamps or stent devices in coronary artery by-pass procedures to block the flow of blood to the site of the bypass. A stent device basically comprises a solid shaft terminating on each end with a bulbous tip. In a typical procedure, a surgeon inserts the stent into an incision in a coronary artery. With appropriately sized bulbous tips, the stent occludes flow of blood from one end of the stent to the other, both upstream flow (normal) and downstream flow (retrograde).

Although the conventional device facilitates a dry surgical field, it also prevents blood flow to the downstream tissues and potentially fosters additional ischemia or tissue damage. Furthermore, the conventional device is limited for use in small diameter blood vessels. The occlusive nature prevents the conventional device from use in larger vessels due to the enhanced probability of tissue damage from increased oxygen deprivation. Furthermore, the conventional clamps or stents necessitate additional procedures and devices for infusing fluids or drugs into the heart or peripheral tissue, or withdrawing fluids therefrom.

By way of contrast, Figure 1 illustrates features of the present invention that solve the problems encountered with conventional devices. A vascular shunt apparatus in accordance with the present invention allows blood to circumvent the surgical field and to flow to the heart muscle or peripheral tissue downstream from the surgical site. Rather than forming a barrier to the blood, for example, the present invention provides a channel which maintains a virtually blood-free surgical field for the substantial duration of a procedure, without further depriving the heart muscle or peripheral tissue of much needed oxygen and other blood constituents. See, e.g., co-pending United States Patent Application Serial No. 08/720,427, the entire disclosure of which is herein incorporated by reference in its entirety, commonly owned by the assignee of the present invention.

The present invention additionally enables selective infusion of fluids to the heart muscle or other tissue. In coronary artery bypass for example, the heart may be stopped for a brief moment by infusing drugs through the apparatus; the drugs follow the natural flow of blood to the heart muscle. Fluid flowing from the left ventricle can also be withdrawn in a similar fashion.

In accordance with the present invention, Figure 1 is a visual representation of the vascular shunt apparatus 10. The vascular shunt apparatus 10 employs a shaft 12 which is elongated such that upon insertion into a vessel, the length of the shaft preferably exceeds the length of the incision in the vessel.

An appropriate shaft length will necessarily be determined by the length of the incision. Moreover, ease of insertion is directly proportional to the length of the shaft in comparison with the length of the incision. Therefore, in one embodiment of the present invention, a plurality of devices would be available, each with a different length, to allow the surgeon to select the appropriate size for insertion through an incision in a particular vessel.

The shaft 12 further comprises an external diameter which approaches the internal diameter of the vessel in question. A preferred external diameter of the shaft would necessarily be determined by the internal diameter of the vessel.

Because the ease of insertion into and removal from the incision is relative to the diameter of the shaft in comparison with the internal diameter of the vessel, a preferred diameter of the shaft would not be greater than that of the vessel.

Therefore, in one embodiment of the present invention, a plurality of devices would be available, each with a shaft of a different external diameter, to allow the surgeon to select the appropriate size with respect to the internal diameter of a particular vessel.

In one embodiment of the present invention, the shaft would fit snugly inside the internal diameter of the vessel. The external diameter of the shaft would so closely approximate the internal diameter of the vessel that the shaft would actually block the flow of blood to the surgical site, while still allowing blood to flow therethrough.

The shaft 12 preferentially terminates on either or both ends in the form of an enlarged tip 16. The tip 16 may be an extension of or addition to the shaft 12. The tip 16 should be of a size which facilitates insertion into and removal from a vessel without damaging the vascular tissue. In a preferred embodiment, the tip should include an external diameter which approaches the internal diameter of the vessel. An optimum external diameter of the tip would necessarily be determined by the internal diameter of the vessel. Furthermore, in order to prevent the flow of blood into the surgical field, the tip should form a secure fit within the internal diameter of the vessel. Any space remaining between the tip and the internal vessel wall could allow blood to seep into the surgical site. On the other hand, a tip which substantially exceeded the internal diameter of the vessel could cause impairment of insertion and removal of the apparatus, as well as traumatic vessel distension or tearing. Therefore, in a preferred embodiment of the present invention, a plurality of shunt devices would be available, each having tips with a different external diameter, to allow the surgeon to select the appropriate size with respect to the internal diameter of a particular vessel. As illustrated in Figure 1, the tip preferably has a rounded and tapered shape, although various embodiments of the tip are equally effective in carrying out the intended function thereof.

In one embodiment of the vascular shunt apparatus, the tip comprises a soft, flexible material and has rounded edges and surfaces to minimize potential damage to the vessel tissue layers. An example of a suitable material for the tip by way of example and not limitation, is silicone. The tip may additionally comprise radiopaque material such that it can be easily located if necessary. Furthermore, each tip opens into a hollow internal channel 14 running the length of shaft 12. The hollow internal channel 14 preferably accommodates the rate or amount of blood flow through a particular vessel; larger vessels necessarily require greater shunting capabilities through the hollow internal channel than smaller vessels. Therefore, in one embodiment of the present invention, a plurality of devices would be available, each with a hollow internal channel of a different diameter, to allow the surgeon to select the appropriate size for the rate and amount of blood flow through a particular vessel.

The hollow internal channel 14 extends into and through the tip 16. Each tip also opens into the interior of the vessel, allowing blood or other fluids to pass freely through the hollow internal channel from one tip through the shaft and out the other tip to the tissue downstream.

The hollow internal channel 14 is further in fluid communication with access tubing 18. Access tubing 18 is preferably connected to the shaft 12 such that access tubing and the shaft form one molded piece. Such a connection increases the strength of the device, and decreases the likelihood of weakening or tearing at the intersection 26 of access tubing with the shaft.

Access tubing 18 allows selective infusion or withdrawal of fluids from the surgical site. For example, in a coronary bypass procedure, infusion of selected drug solutions through access tubing can stop the heart for very brief periods such that the surgeon can perform sutures without the pressure of blood flowing through the vessel, yet also without further compromising the tissue of the heart as may occur in longer duration hear stop procedures. In addition, access tubing allows selective infusion of dyes, fluids, or any other material as per the discretion of the surgeon. Alternatively, a surgeon may wish to withdraw fluids through access tubing 18 for procedures such as, but not limited to, ascertaining cardiac output or blood gas analysis.

In a preferred embodiment of the present invention illustrated in Figure 1, access tubing 18 is connected to a valve 22, which further facilitates administration or withdrawal of selected fluids. For instance, in a coronary bypass procedure, a surgeon may wish to connect a source of drug solution to access tubing 18 through valve 22 by way of proximal opening 24. When the valve is in the closed position, the drug solution does not flow to the heart tissue. The surgeon can quickly and easily open the valve and deliver a small amount of drag solution to the heart such that the heart stops only momentarily. In turn, the valve offers the surgeon unique control over the heart and surgical site.

The intersection 26 of access tubing to the shaft 12 may also serve as a positioning mechanism which assists the surgeon in proper placement of the apparatus in a vessel. For example, in a preferred embodiment, the tubing connects to the shaft at or near the midpoint of the shaft. Upon attachment at or near the midpoint of the shaft, the tubing may aid the surgeon in determining relative distances with respect to the vessel and the apparatus therein. The tubing additionally may serve as a location marker to prevent loss of the apparatus in a vessel.

In an alternate embodiment illustrated in Figure 2, a tether 28 may be affixed to the shaft in the manner shown in copending application 08/720,427, incorporated herein by reference. Tether 28 additionally serves as a location marker to prevent loss of the apparatus in a vessel. In addition, tether 28 diverts the surgeon from pulling on the access tubing 18 attached around the shaft 12 which helps prevent separation at the shaft-tubing intersection 26. The method for use of the present invention is substantially similar to that disclosed in copending patent application Serial No. 08/720,427 incorporated herein by reference. Figures 2-5 illustrate a presently preferred embodiment of the method for using the vascular shunt apparatus. As previously noted, the present disclosure shall be directed to the use of a vascular shunt apparatus in connection with a coronary artery bypass procedure although it should be understood that other procedures also benefit from such an apparatus.

In Figure 2, the vascular shunt 10 is inserted through an incision 30 in a vessel 20 by sliding the downstream end 32 into the interior 21 of the vessel 20. The shaft 12 is then extended into the remote space of the vessel 20. After sliding the vascular shunt 10 downstream, the surgeon may insert the upstream end 33 when the length of the incision 30 so allows. The surgeon then may slide the vascular shunt 10 upstream until the attachment point of the tether 28 and intersection of the tubing 18 is visible at the incision 30. If there is an optimal fit of the apparatus in the vessel, the blood should flow through the hollow internal channel of the vascular shunt 10 without leaking into the surgical site.

Figures 3-4 illustrate the vascular shunt appropriately positioned in situ. Figure 4 illustrates a bypass graft at a moment just prior to completion wherein the surgeon leaves just enough room in the graft 36 to allow removal of the vascular shunt 10. In addition, upon proper positioning of the vascular shunt in situ, fluids can be selectively infused through or withdrawn from the apparatus through valve 22 and access tubing 18. Figure 5 demonstrates the removal of the vascular shunt 10 before the surgeon completes the final sutures. Through the slight gap in the bypass graft 36, the surgeon removes the vascular shunt 10 by sliding the downstream end 32 (not shown in Figure 5) distally from the site of the remaining sutures and the gap in the graft 36 until the upstream end 33 is proximal to the suture site. The surgeon can then remove the vascular shunt 10 by sliding the proximal upstream end 33 out through the slight gap in the graft 36 and then removing the remaining shaft 12 and downstream end 32. When the surgeon has removed the vascular shunt 10 from the site of the bypass graft, the surgeon can resume stitching the remaining sutures necessary to close and complete the graft.

The invention disclosed herein may alternatively be utilized by inserting only one end of the apparatus downstream from the blockage in the vessel. By closing off the upstream opening in the apparatus, blood or other fluids can then be selectively infused to heart. Such an alternative procedure is useful when a blockage is so occlusive that it will not accommodate the upstream end of the apparatus. In view of the foregoing it is apparent that the vascular shunt apparatus can be used in surgical sites to allow blood flow to tissues that would otherwise be deprived of oxygen and other vital blood constituents for the duration of coronary or peripheral bypass surgery. The additional advantages derived from this shunt mechanism allow a dry field for the surgeon, and also alleviate the time pressure inherent in any surgery wherein the flow of blood is occluded for substantial durations. Thus, it should be apparent that other types of procedures that preferably include or necessarily require a dry field without the occlusive effects of the prior art, will benefit from this invention.

The vascular shunt apparatus can also be utilized as a stent to open a vessel during a procedure. Alternatively, the apparatus can be utilized with x- ray contrast dye for taking x-rays after the completion of a procedure to document function and patency.

Furthermore, the apparatus of the present invention may alternatively be utilized to inject radiographic contrast dye into vessels for the performance of intra-operative angiography. Alternatively, the apparatus may act as a guide for access to coronary vessels for the performance of intra-operative angioplasty and other types of interventional intra-operative cardiologic procedures. The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

What is claimed and desired to be secured by United States Letters Patent is:

1. An apparatus for minimizing leakage of bodily fluid while maintaining fluid flow through a body vessel comprising: a. an elongated shaft for placement within a body vessel; b. an internal channel through said shaft in fluid communication with said body vessel; and c. access tubing intersecting said elongated shaft and in fluid communication with said internal channel.

2. An apparatus as recited in Claim 1, wherein at least one end of said elongated shaft terminates in an enlarged tip.

3. An apparatus as recited in Claim 2, wherein said tip is cylindrical.

4. An apparatus as recited in Claim 2, wherein said tip is rounded.

5. An apparatus as recited in Claim 2, wherein said tip is made of a flexible material.

6. An apparatus as recited in Claim 2, wherein said tip is sized to fit the internal diameter of said body vessel.

7. An apparatus as recited in Claim 1, wherein the diameter of said internal channel is less than the diameter of the body vessel.

8. An apparatus as recited in Claim 1, wherein said internal channel has a diameter sufficient to accommodate the flow rate of a fluid through said body vessel in which the apparatus is to be placed.

9. An apparatus as recited in Claim 8, wherein said body vessel is a coronary artery.

10. An apparatus as recited in Claim 8, wherein said body vessel is a peripheral artery.

11. An apparatus as recited in Claim 1, wherein the diameter of said elongated shaft approximates the diameter of said body vessel.

12. An apparatus as recited in Claim 1, wherein the diameter of said elongated shaft is less than the diameter of said body vessel.

13. An apparatus as recited in Claim 1, wherein said elongated shaft at least partially extends upstream beyond the length of an incision in said body vessel.

14. An apparatus as recited in Claim 1, wherein said elongated shaft at least partially extends downstream beyond the length of an incision in said body vessel.

15. An apparatus as recited in Claim 1, wherein said elongated shaft is made of a flexible material.

16. An apparatus as recited in Claim 1, wherein said access tubing terminates peripherally in a valve means for selective infusion or withdrawal of fluids into and from said access tubing.

17. An apparatus as recited in Claim 1, wherein said elongated shaft includes a tether.

18. An apparatus for minimizing leakage of bodily fluid while maintaining fluid flow through a body vessel comprising: a. an elongated shaft for placement within a body vessel wherein the diameter of said elongated shaft approximates the diameter of said body vessel and at least one end of said shaft terminates in a rounded tip made of flexible material and sized to fit the internal diameter of said body vessel; b. an internal channel through said shaft in fluid communication with said body vessel wherein the diameter of said internal channel is sufficient to accommodate the flow rate of bodily fluid through said body vessel in which the apparatus is to be placed; and c. access tubing intersecting said elongated shaft and in fluid communication with said internal channel, said access tubing terminating peripherally in a valve means for selective infusion or withdrawal of fluids into and from said access tubing.

19. A method for using the vascular shunt apparatus comprising the steps: a. obtaining a shunt apparatus having an elongated shaft, an internal channel through said shaft, and access tubing in fluid communication with said internal channel; and b. inserting a first end of said shaft through an incision along a body vessel and guiding it into the interior of a body vessel.

20. A method according to Claim 19, wherein said first end of said shaft is inserted downstream from the site of an incision along a body vessel.

21. A method according to Claim 19, wherein a second end of said shaft is inserted upstream from the site of an incision along a body vessel.

22. A method according to Claim 19, wherein said access tubing is used to infuse fluids into said body vessel.

23. A method according to Claim 19, wherein said access tubing is used to withdraw fluids from said body vessel.

24. A method according to Claim 19, wherein said access tubing terminates proximally in a valve.

25. A method according to Claim 19, wherein said shunt apparatus is utilized as a guide for access to coronary vessels for the performance of intra-operative cardiologic procedures.