MEDICAL DEVICE
The present invention relates to a device for providing blood to, or removing blood from, the lumen of a blood vessel.
Heart disease and, in particular, heart attacks can result in significant reduction in the quality of life of those afflicted, as well as, of course, loss of life itself.
Disruption of blood flow to the coronary artery can lead to decreased blood flow to the muscles of the heart thereby causing ischaemia and consequent decrease in heart functions and even permanent damage to the heart muscle. However, the blood flow through the coronary artery is often disrupted in the cases of heart attacks, for instance, by blood clots forming in, or being trapped in the coronary artery or the blood vessels extending therefrom.
Furthermore, said disruption can also be caused during Beating Heart Surgery or during a failed angioplasty, for instance, when the balloon placed inside the coronary artery bursts.
During a failed angioplasty, the patient has to be rushed to theatre where a vein graft from the patient's leg of chest is required to be grafted from the Aorta to the coronary artery, beyond the ruptured portion thereof, in order to maintain blood flow to the rest of the heart muscle.
However, such a procedure takes at least 25 minutes, whereas ischaemia generally sets in at least 15 minutes, or even less. Thus, there is a crucial 10 minute period or thereabouts, wherein local ischaemia occurs, leading to heart damage and impaired heart function.
A number of devices known as intracoronary shunts are known in the art for use in coronary artery bypass operations, particularly in Beating Heart Surgery. However, the use of such shunts generally results in local coronary artery occlusion and a brief period of myocardial ischaemia.
The FloCoil shunt from the Guidant Corporation is an inter-arterial shunting device, a so-called "double-limb" shunt, which maintains myocardial perfusion during minimally invasive bypass surgery. It is inserted into the coronary artery and allows blood to flow from a distal point to a proximal point in the coronary artery, thereby bypassing the site of an anastomosis. When the anastomosis is ready to be closed, is easily retrieved by tugging on a radiopaque tab or ring connected to the shunt by means of a short wire.
However, as mentioned above, use of such an intracoronary shunt results in local coronary occlusion and, therefore, a period of myocardial ischaemia, as the blood flow through the blood vessel relies on the integrity of the damaged vessel itself and the seal between the shunt and the vessel.
Accordingly, there is a need in the art for a device which minimises the risk of myocardial ischaemia and increases perfusion, thereby helping to provide a minimallyinterrupted blood and oxygen supply to the heart muscle.
Thus, in a first aspect, the present invention provides a substantially T-shaped tubing device suitable to conduct blood to or from the lumen of a blood vessel, comprising a first cross-piece tube and a second tube at an angle to the cross-piece tube, the two tubes being in fluid connectivity, wherein:
the cross-piece tube is adapted to locate in and along the lumen of the blood vessel, at least a portion the cross-piece tube being adaptable or adapted to occlude blood flow rather than through the cross-piece.
The device is particularly useful in anastomosis procedures on the coronary artery, thereby reducing the effects of myocardial ischaemia.
Preferably, the angle between the first cross-piece tube and the second tube is substantially normal. Preferably, the cross-piece is securably fixable in the lumen, for instance by an occlusion means, preferably a balloon, such as that found in a catheter.
It is also preferred that the device is resiliently deformable, so that it may be deformed to avoid blocking the line of sight of the surgeon or to avoid organs or other vessels, for instance. In particular, it is preferred that the cross-piece tube is resiliently deformable so as to allow it to be removed from the lumen for instance at the last moment during an anastomosis procedure.
The cross-piece tube, preferably an intraluminal tube, is preferably for insertion into the lumen of the blood vessel through an incision or hole in the wall of the blood vessel, the cross-piece tube comprising at least one occlusion means for contacting the outer surface of the tube and the inner surface of the blood vessel and thereby substantially occluding the blood vessel from its inner surface to the outer surface of the tube.
Preferably, the second tube, preferably a delivery tube, is in fluid connectivity with the cross-piece tube so that blood may be provided to, or removed from, the crosspiece tube through the second tube; the cross-piece tube and second tube being arranged such that in use, the cross-piece tube may be positioned in the lumen of the blood vessel with the second tube being extendible out of the vessel through the hole or incision in the wall of the vessel.
Preferably, the device is for providing blood to the lumen of a blood vessel. Preferably, the blood is delivered through the second tube into the cross-piece tube, after insertion into the lumen of the blood vessel. In this instance, it is preferred that the blood flows out of each end of the cross-piece tube in a bi-directional manner, such that the blood is forced in both directions from the point of insertion of the device into the blood vessel. This is particularly preferred as it helps to prevent ischaemia in tissues that were previously "upstream" of the point in the blood vessel where the device is inserted.
Preferably, a third tube is in fluid connectivity with the second tube. Preferably said third tube is in fluid connectivity with the second tube at a point sufficiently distal from the cross-piece tube so that it does not hamper the user by getting in the way.
It is preferred that said third tube is suitable for de-airing the device and, in particular, the second and cross-piece tubes. Alternatively, it is also preferred that said third tube is suitable for connecting to an external blood pump. Thus, it is also preferred that said third tube is provided with a means for occluding the third tube, thus making it substantially air or fluid tight. Preferably, such a means is a clip, such as those that can be operated by the fingers of one hand, as are commonly known in the art. It is also preferred that said third tube is provided with a connecting means at the end of said tube distal from the portion where it contacts the second tube.
It is also preferred that said third tube is suitable for administration of drugs or solutions which the user, such as the heart surgeon, are minded to introduce to the coronary artery. The third tube may, therefore, comprise a number of junctions to which other tubes are connected or a number of connecting means for connecting vials or syringes to the third tube for administration of said drugs or solutions as required. A preferred example of such a drug or solution is a cardioplegia solution.
Thus, in a preferred embodiment, the present invention can be used for administration of a cardioplegia solution directly into the coronary arteries. A cardiplegia solution is used when the heart is connected, for instance, to a bypass machine in order to stop the heart and reduce the oxygen demand. However, a cardioplegic perfusate is effective only if it is well distributed. Antegrade maldistribution occurs in hypertrophied ventricles where subendocardial flow limitations occur. Therefore the present device helps to overcome this by ensuring a rapid distribution of such a solution to the heart muscle.
Figure 1 shows an embodiment of the present invention, comprising an crosspiece tube (1), a second tube (2), a connecting means (3), occlusion means (4), a means (5) for inflating, deflating or controlling the size of the occlusion means (4), a one-way valve (6) and a third tube (7).
Although reference is made to the coronary artery, this is, although a particularly preferred embodiment, only for the purposes of exemplification of the present invention. The skilled person will, of course, understand that the present device can be used on a whole range of blood vessels and for a whole range of purposes. Preferably, the blood vessel is a vein. More preferably, the blood vessel is an artery and, as mentioned above, it is particularly preferred that the blood vessel is the coronary artery.
Preferably, the second tube is provided with a means for connecting to a means for collecting blood when the present invention is used for the purposes of removing blood from the lumen of a blood vessel, such as when taking a blood sample, for instance, for the purposes of assessing the level of oxygenation or the presence of toxins present in the blood vessel at that time.
However, it is particularly preferred that the present invention is for the provision of blood to the lumen of a blood vessel. In a particularly preferred embodiment, the blood vessel is the coronary artery and blood is provided to the lumen of the coronary artery by means of the present invention, preferably during a disruption to the normal blood flow through the coronary artery, such as in the case of heart surgery, a failed angioplasty or accidental damage to the coronary graft during further or redo surgery, for instance.
It is, therefore, preferred that the second tube comprises means for connecting to a pump capable of providing or removing the blood under a suitable pressure. Alternatively, it is also preferred, in the instance where the present invention is used on a still-beating heart, that the second tube comprises a means for delivering blood from the aorta of the same patient.
Thus, it is preferred that the second tube comprises a means, preferably at a distal end of the second tube from the connection between the second tube and the cross-piece tube, for establishing fluid connectivity with the patient's aorta. Such a means is well known in the art, but is preferably a catheter, for instance a 16G (16 gauge) catheter, which may be introduced, for instance, into the ascending aorta. In this particularly preferred embodiment, oxygenated blood pumped from the beating heart of the patient is introduced in a controlled manner into the lumen of the coronary artery, for instance, thus providing the coronary artery with an oxygenated blood supply and thereby reducing the chances of m ȯcardial ischaemia occurring.
Preferably, the device according to the present invention comprises a means for controlling the flow of blood to or from the lumen of the blood vessel in which it is inserted. In particular, if the device is used to remove blood from the aorta and provide it to the lumen of a blood vessel, such as the coronary artery for instance, then it will be appreciated that the rate of flow or pressure of the blood taken from the aorta, which is under relatively high pressure, will need to be suitably controlled, so as not to damage the blood vessel into which the device is inserted. Preferably, the present invention comprises a means for controlling the volume or pressure of the blood provided to the lumen of the blood vessel.Preferably, the means is a clamp or gauge that may be configured so as to ameliorate the volume or pressure of the blood provided into the blood vessel into which the present device is inserted.
Alternatively, it will be appreciated that the width of the tubes used in the present device can be adapted to perform this task. For instance, the selection of narrow diameter tubes will help to reduce the flow of blood through the tubes. Although this may result in an increase in pressure, the skilled person will be able to select the appropriate diameter of tube and would know that increased frictional forces resulting from tubes of a narrow diameter will help to ameliorate this effect.
The diameter and length of the tubes, with the exception of the cross-piece tube, is not critical. The skilled person would understand that the diameter of cross-piece tube can be adapted depending on the nature of the blood vessel to which it is to be used. For instance, larger arteries will require larger tubes in order to prevent significantly reduced blood flow.
Preferably, the present device is for use in anastomosis.
In particular, it is preferred that the cross-piece tube is sufficiently short and sufficiently flexible so that the device is removable through the hole or incision, for instance an arteriotomy, in the vessel wall, preferably without the need to increase the size of the incision or hole in order to remove the present device. Thus, it is particularly preferred that the cross-piece tube is sufficiently short and flexible so that the device can be removed through the hole or incision when said hole or incision is narrower in diameter than the length of the cross-piece tube.
In other words, it is envisaged that the cross-piece tube will be able to bend sufficiently so as to be able to be extracted, for instance during the final stages of an anastomosis. In particular, it is preferred that the present device can be used at the site of an anastomosis where the artery or vein that has been grafted or sewn onto the damaged vessel, so that when it comes to the end of the anastomosis, such that the final or penultimate stitch or suture, for instance, is in place, the present device may be quickly and easily removed just before the anastomosis is completed. The advantage of this is that the supply of blood to the lumen of the blood vessel, in the embodiment where blood is provided to the blood vessel, can be maintained up until the very last minute.
The device comprises at least one occlusion means. The function of this occlusion means is, inter alia, to aid in securing the device in the lumen of the blood vessel and, in particular, to prevent leakage of blood or other fluid from the lumen of the blood vessel, for instance, through the incision or hole through which the present device is inserted, in a substantially water-tight manner.
Preferably, the cross-piece tube comprises at least two occlusion means.
It is preferred that there is at least one occlusion means at either end of the crosspiece tube or preferably that there is at least one occlusion means on either side of the junction between the second tube and the cross-piece tube to prevent blood or fluid passing external to the cross-piece, for instance between the inner surface of the lumen and the outer surface of the cross-piece.
In one embodiment, the occlusion means is a frusto-conically-shaped tip to the cross-piece, arranged so that the end of the cross-piece is more easily inserted in to the lumen and, at its widest point, occludes the lumen.
In a particularly preferred embodiment, the occlusion means are small balloons, preferably of the type used in standard catheters. In this embodiment, it is preferred that the device further comprises an inflation tube, preferably passing within the cross-piece and second tubes and preferably of a narrow diameter compared to the cross-piece and second tubes, suitable for inflating the one or more occlusion means.
It is envisaged that there may be two or more such inflation tubes. However, it is preferred that there is only one inflation tube and that the inflation tube is suitably branched in order to connect with each one.
Alternatively, it is also preferred that each occlusion means has an independent inflation tube running therefrom, thus allowing the user a greater degree of flexibility as to when the occlusion means are inflated and/or deflated.
Whilst the inflation tube is, of course, suitable for inflation of the occlusion means, it will also be appreciated that in order for the device to be suitably removed from the lumen of the blood vessel, the occlusion means will also, preferably, have to be deflated. Thus, it is preferred that the inflation tubes are also suitable for this purpose.
Preferably, the inflation tubes run inside the cross-piece and also, preferably, inside the second tube. It is preferred that the inflation tube or tubes pass out of the second tube, preferably at a suitable distal point from the cross-piece tube, so as not to get in the way of the user. Preferably, the inflation tube or tubes are provided with suitable connecting means for attachment to a means for inflating and/or deflating the occlusion means. Such systems will be well known to the skilled person.
Preferably, the second tube is an enclosed duct. It will be appreciated that that the cross-section of the cross-piece and, in particular, the enclosed duct, can be varied. Although substantially circular is preferred, particularly for the cross-piece to reduce abrasion, the second tube or enclosed duct may be square in cross-section, for instance.
Preferably, the cross-piece tube and the second tube are arranged in a substantially T-shaped configuration, wherein the cross-piece tube and the second tube are normal to each other. By this it is meant that the tubes are preferably substantially perpendicular to each other. It will be appreciated that it is not necessary for the functioning of the present invention that the angle between the tubes is strictly adhered to, provided that the device functions in the manner described in the present application and, in particular, that substantially bi-directional flow is permitted in the cross-piece tube and that the cross-piece tube fits into the lumen of the blood vessel.
The T-shaped configuration is preferred so as to allow substantially equal bydirectional blood flow of blood through the cross-piece tube in particular, so that blood may flow out of the second tube, preferably equally into either arm of the cross-piece tube, although this may be controlled by adapting the angle between the tubes and the diameter thereof or providing additional means for doing so, such as a valve.
The T-shaped configuration is also preferred to provide greater strength to the device, so that, for instance, the junction between the second tube and the cross-piece tube is not unduly stressed during removal of the device from the blood vessel. Thus, it is envisaged that some deviation from a 90 degree angle between the tubes is permitted, provided the functional requirements above are retained.
Preferably, the patient is a mammal and most preferably, a human.
The present invention also provides a kit comprising the device. Preferably the kit comprises suitable connecting means and pumps as discussed above.
In an alternative aspect, the present invention also provides a piece of T-tubing that fits in a blood vessel, the upright being attachable in a water-tight fashion in vivo, and wherein the outer circumference of the cross-piece is the same as or greater than the inner circumference of the vessel.
In a further aspect, the present invention also provides a method of providing blood to or removing blood from the lumen of a blood vessel comprising the use of the present device. Preferably, the method is for providing blood to the blood vessel, preferably to the coronary artery. It is preferred that the blood is provided from the ascending aorta.
In particular, it is preferred that the method comprises inserting the present device into an artery, such as the coronary artery, and connecting the second tube to the ascending aorta, thus providing a flow of oxygenated blood from the aorta to the coronary artery. This is particularly preferred during an anastomosis, wherein it is preferred that the device is removed substantially contemporaneously with the completion of the anastomosis, but just before the anastomosis is sealed.
Preferably, the second tube comprises a valve, preferably a one-way valve, for preventing blood flowing in the opposite direction to that required. In addition, it is also preferred that the second tube and/or the third tube are fitted with suitable connecting means for attachment to other medical devices, such as pumps or degassing means or syringes, for instance.