WO2015110049A1

WO2015110049A1 - Method and apparatus for creating negative pressure in cardiovascular bed

Info

Publication number: WO2015110049A1
Application number: PCT/CN2015/071370
Authority: WO
Inventors: Zhimin Du; Kwokfu FU; Chingsau CHU
Original assignee: Vincent Medical Technology Co., Ltd.
Priority date: 2014-01-23
Filing date: 2015-01-22
Publication date: 2015-07-30

Abstract

A method creates negative pressure in a cardiovascular bed according to the steps of inserting a catheter containing an inflatable balloon and an aspiration lumen into a coronary artery connected to a cardiovascular bed, inflating the balloon, and providing a vacuum in the aspiration lumen. The inflatable balloon is external to the aspiration lumen. The inflated balloon substantially forms a seal with the coronary artery. The vacuum is sufficient so as to create negative pressure in the cardiovascular bed. A catheter useful in such a method is also provided.

Description

METHOD AND APPARATUS FOR CREATING NEGATIVE PRESSURE IN A CARDIOVASCULAR BED

FIELD OF THE INVENTION

The present invention relates to medical methods and devices. Specifically， the present invention relates to medical methods and devices， especially useful for treating ischemic heart disease.

BACKGROUND

Heart disease caused by atherosclerosis is increasingly common around the world. Significant damage， including cell necrosis occurs when the coronary artery atherosclerotic plaque breaks， activating the blood platelets to become a thrombus and blocking the blood flow through the coronary artery. Accordingly， in the cases of acute myocardial infarctions， the main objective is often the restoring of blood flow to the coronary artery and therefore the reperfusion of the myocardium.

Percutaneous Coronary Intervention (PCI) is an important method to restore the blood flow of patients with acute myocardial infarction， this always involves addressing the thrombus in the coronary artery， and often a stent and/or a catheter is used. Current catheters， such as aspiration catheters are typically employed to remove， via for example， aspiration， a thrombus blocking such an artery， but there exists significant risk that portions of the thrombus will break up and travel deeper into the cardiovascular bed (i.e.， “downstream” ) ， being carried there by the restored blood flow. These escaping thrombus pieces， usually called micro-thrombuses， can cause slow reflow or no reflow of blood through the coronary artery after PCI， and seriously affect the prognosis of the patient. In some cases reflow of the blood in the myocardium may also dislodge such thrombus pieces into non-culprit coronary arteries， cause formation of new thrombus and/or myocardial infarction， potentially leading to further damage of heart and /or complications.

To address such a situation， the physician seeks to achieve 100％removal of the thrombus， and to prevent pieces from breaking off and heading downstream. Current catheters may employ balloons to block the artery and then seek to completely aspirate the thrombus. Existing catheters may also possess a variety of tip shapes (e.g.， blunt， angled， and/or shaped tips) ， multiple lumens in the same catheter (see， e.g.， Fig. 4) ， and/or stents to achieve this goal. However， it has been found that such catheters may still not be completely effective at achieving the goal of complete aspiration.

Thus， the need still exists for methods and apparatuses for more completely aspirating a thrombus， especially a cardiac thrombus. Furthermore， the need remains for an improved method for treating a myocardial infarction.

SUMMARY OF THE INVENTION

The present invention relates to a method for creating negative pressure in a cardiovascular bed according to the steps of inserting a catheter containing an inflatable balloon and an aspiration lumen into a coronary artery connected to a cardiovascular bed， inflating the balloon， and providing a vacuum in the aspiration lumen. The inflatable balloon is external to the aspiration lumen. The inflated balloon substantially forms a seal with the coronary artery. The vacuum is sufficient so as to create negative pressure in the cardiovascular bed.

The present invention also relates to a catheter containing an outer catheter and an inner catheter. The outer catheter contains a lumen and an inflatable balloon and the inner catheter is contained within the lumen.

Without intending to be limited by theory， it is believed that the present invention may be sufficient to more completely remove the thrombus， reduce the proliferation of microthrombuses， and/or help to induce collateral blood flow so as to better re-perfuse the myocardium affected by the blockage. This in turn may help to reduce or avoid cell necrosis caused by blood flow stoppage.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a cut-away view of a coronary artery including the way catheters have been used in the past；

Fig. 2 shows a cut-away view of a coronary artery including the use of a catheter according to the present invention； and

Fig. 3 shows a schematic diagram of an embodiment of a catheter useful in the present invention.

Fig. 4 shows a cut-away view of a multiple-lumen catheter with the multiple lumens arranged in a coaxial manner.

Fig. 5 shows a partially-cut away view of a coronary artery including the use of multiple-lumen catheter with a guide wire.

The figures herein are for illustrative purposes only and are not necessarily drawn to scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Unless otherwise specifically provided， all tests herein are conducted at standard conditions which include a room and testing temperature of 15 ℃， sea level (1 atm. ) pressure， and pH 7， and all measurements are made in metric units. Furthermore， all percentages， ratios， etc. herein are by weight， unless specifically indicated otherwise.

As used herein， a “balloon” refers to any structure intended to inflate with an inflating media and increase in size so as to form a seal with a blood vessel， vein， and/or artery， for example， a coronary artery. The balloon herein is therefore an inflatable balloon. Furthermore， balloons are known to be classified as full-compliance balloons， semi-compliance balloons， and non-compliance balloons. Full-compliance balloons are typically for sealing a blood vessel， semi-compliance balloons are typically for pre-dilation and stent deployment， and non-compliance balloons are for post-dilation of a stent after deployment.

As used herein， a “branch” refers to any coronary artery branch， upstream of the thrombus， which has a diameter that is larger than or equal to the diameter of the coronary artery where the thrombus is located (except in a patient with a coronary artery malformation such as coronary artery aneurysm) . The diameter indicates the natural diameter of the respective artery portion， without any distortions caused by， for example， a thrombus， a stent， etc.

As used herein， the term “radiopaque” indicates that something is opaque to radiation such as X-rays. Radiopaque materials are well-known in the art and include， for example， gold， platinum， etc.

As used herein， a “sub-branch” refers to any portion of the coronary artery， downstream of the thrombus， which has a diameter that is smaller than the diameter of the coronary artery where the thrombus is tocated (except in a patient with a coronary artery malformation such as coronary artery aneurysm) . The diameter indicates the natural diameter of the respective artery portion， without any distortions caused by， for example， a thrombus， a stent， etc.

As used herein， “distal” indicates away from the catheter end which is intended to stay outside of the patient's body -i.e.， distal means farther from the catheter operator.

As used herein， “proximal” indicates closer towards catheter end which is intended to stay outside of the patient's body -i.e.， proximal means closer to the catheter operator

Pressure conversions： In this application， it is assumed that 100 mmHg (15 ℃， 0％humidity) is equal to 13,509 Pascals (Pa) ， or 13.5kPa. One skilled in the art recognizes that any differences from this conversion are minimal， and negligible. All pressures are measured at 15 ℃， or similar temperatures， the difference of which is negligible.

Generally in this application， numbers may be rounded， for example， to one decimal point， so as to make them easier to read. However， one skilled in the art would understand that rounded numbers are not inaccurate or technically improper merely because they have been rounded.

It has now been found that by employing a catheter containing a balloon into a coronary artery containing a thrombus， inflating the balloon， and then aspirating， a negative pressure can be created sufficient to remove the thrombus from the culprit coronary artery， and help to induce collateral blood flow so as to better re-perfuse the myocardium affected by the blockage. This in turn nay help to reduce or avoid cell necrosis caused by blood flow stoppage.

Accordingly， the present invention relates to a method for creating negative pressure in a cardiovascular bed according to the steps of： inserting a catheter into a blood vessel in the heart or near the heart， typically a coronary blood vessel， and even more typically a coronary artery connected to a cardiovascular bed， the catheter containing an aspiration lumen and an inflatable balloon external to the aspiration lumen， inflating the balloon to substantially form a seal with the coronary artery， and providing a vacuum in thc aspiration lumen. The vacuum is sufficient to create negative pressure in the cardiovascular bed. Without intending to be limited by theory， it is believed that such a technique may induce collateral blood flow in， for example， the cardiovascular bed； or the myocardiovascular bed， by providing sufficient negative pressure to open up the valves in the blood vessels of collateral circulation. This in turn allows the collateral blood flow to significantly improve the reperfusion of ischemic heart muscle. The Applicant believes that the present invention may be more effective to remove the thrombus from coronary artery and may facilitate the formation of collateral circulation so that the ischemic heart muscle reperfuses more quickly and/or effectively， and/or may avoid or reduce the presence ofmicrothrombuses in other coronary artery branches.

Without intending to be limited by theory， it is believed that in some cases such a re-perfusion of the myocardiovascular bed may be permanent， thereby allowing nourishment of the myocardial muscles when the catheter is removed， even if the thrombus or microthrombus is not completely removed. This may be because of pressure differences between the left coronary branch and the right coronary branch caused by the remaining thrombus. In other cases， when the catheter is removed (and aspiration is thereby discontinued) ， it is believed that the re-perfusion of the myocardiovascular bed is terminated. In the case where the thrombus is successfully removed， then the re-perfusion is typically via the regular blood pathway and this when the aspiration is terminated and the catheter removed， the pressure is equalized， the collateral blood flow is also terminated and regular blood flow resumes.

Such a re-perfusion may be identified by providing a contrast media in the blood on the side of the heart which is not affected by the thrombus， and then performing the procedure herein， while looking for a migration of the contrast media to the affected portion and/or the myocardiovascular bed. This in turn would indicate that re-perfusion has occurred. For example， the blood flow through collateral circulation may come from the unblocked coronary artery on the opposite side of the heart， e.g. when the Left Anterior Descending Artery is blocked and need aspiration， the blood flow from Right Posterior Descending Artery may be induced， and visa-versa.

Without intending to be limited by theory， it is believed that a vacuum of about -100 mmHg (-13.5kPa) to about -740 mmHg (-100.0kPa) ； or from about -300 mmHg (-40.5 kPa) to about -735 mmHg (-99.2 kPa) ； or from about -600 mmHg (-81.0 kPa) to about -730 mmHg (-98.5 kPa) ； or from about -650 mmHg (-87.8 kPa) to about -725 mmHg (-97.9 kPa) ； is typically sufficient to induce the collateral blood flow. Such a vacuum is typically measured by a standard pressure monitor which is operatively attached to aspiration lumen at， for example， the portion of the catheter external to the patient being treated. Without intending to be limited by theory， it is believed that such a negative pressure allows any thrombus pieces to be sucked into the aspiration lumen. It is also believed that the above represents the vacuum sweet spot which allows the present invention to achieve the goal ofinduce collateral blood flow. lf the vacuum is too low， then the valves in the blood vessel of collateral circulation will not open， and there will be no collateral blood flow to re-perfuse the ischemic heart muscle. In contrast， if the vacuum is too high， then other complications may occur， for example， blood vessels such as the artery， or other blood vessels may collapse， the vacuum may damage the coronary artery by， for example， sucking part of the artery wall into the aspiration lumen， etc. In an embodiment herein， the catheter further contains a relief valve which may prevent the vacuum from becoming too strong so as to avoid the above problems. In such a case， the relief valve will typically be calibrated to a specific threshold level. The valve remains closed until that threshold level is reached， upon which it opens so as to reduce the vacuum. The relief valve will then typically close again once the vacuum is reduced below the threshold level.

In an embodiment herein， the catheter comprises a vacuum mechanism which creates the vacuum. Such a vacuum mechanisn is typically located at the end of the catheter far from the aspiration tip， such as where the catheter is controlled by the physician. The vacuum mechanism may be， for example， a syringe， a pump， a disposable vacuum container， and a combination thereof； or a syringe， an electrical pump， a disposable vacuum flask， and a combination thereof； or a syringe， an automatic electrical pump with a pressure monitor， and a combination thereof. In an embodiment herein a syringe is employed to provide such a vacuum by， for example， operatively attaching it to the aspiration lumen， withdrawing the syringe pump to a desired volume， and then locking the syringe so that the (withdrawn) volume remains constant， In an embodiment herein， the syringe is selected form the group consisting of a 10 mL syringe， a 12 mL syringe， a 20 mL syringe， a 30 mL syringe， a 35 mL syringe， a 60 mL syringe， or a 140 mL syringe； or a 20 mL syringe， a 30 mL syringe， a 35 mL syringe， a 60 mL syringe， or a 140 mL syringe； or a 30 mL syringe， a 35 mL syringe， a 60 mL syringe， or a 140 mL syringe. The syringe useful herein may contain a lock therein， so as to constantly provide the desired vacuum， such as the Merit Endotek

negative pressure syringe series available from Merit Medical Systems， South Jordan， Utah， USA (www. merit. com/endotek) .

In an embodiment herein， the vacuum mechanisn may further be designed to maintain a constant pressure (e.g.， by using an automatic electrical pump) ， or be designed to provide a variable pressure. In an embodiment herein the vacuum mechanism provides a pulsing vacuum. Such a pulsing vacuum may be produced by， for example， adding to an automated electrical pump a relief valve which has a delayed action， by using an automatic electrical pump programmed to and/or able to pulse the vacuum， etc. In an embodiment herein， the pulsing vacuum is provided by a rotating valve which alternatively allows pressure to build and then release.

Turing to the Figures， Fig. 1 shows a cut-away view of a coronary artery， 20， including a branch， 22， and a sub-branch， 24. A thrombus， 26， is shown blocking the coronary artery， 20， between the branch， 22， and the sub-branch， 24. Fig. 1 shows a catheter， 28， containing a lumen， 30， terminating in an aspiration tip， 32. A balloon， 34， is shown inflated and forming a seal， 36， with the coronary artery， 20. As such a catheter， 28， has typically been used in the past， theballoon， 34， is inflated a certain distance away from the thrombus， 26， and then the lumen， 30， is aspirated so as to attempt to suck the thrombus， 26， into the lumen， 30. Sometimes， a guide wire (see Fig. 5 at 52) is provided， the tip of which may penetrate the thrombus. The guide wire may guide a special tip (not shown) to the thrombus to try to break up the thrombus into smaller pieces so as to allow it to be sucked into the catheter.

In some cases， the aspiration tip will actually be maneuvered so as to touch the thrombus， for example， prior to aspiration.

However， in such a case， it can be seen that blood will also be sucked into the aspirator tip， 32， from the branch， 22， and thus the power of the vacuum is not concentrated at the thrombus， 26， where it is needed.

In most cases where the aspiration catheter does not include a balloon， the aspiration catheter typically aspirates a significant amount of proximal blood from upstream of the thrombus. In such a case， again， the Applicant has found that the vacuum is not concentrated in the location of the thrombus so as to achieve the greatest effectiveness. The positioning of the catheter， 28， relatively far from the thrombus， 26， is typically due to the size of the catheter， 28， and the balloon， 34， as they are typically too largeto get close to a smaller thrombus， 26. Accordingly， blood flowing from the branch， 22， may also allow sufficient blood into the area so that microthrombuses (not shown) may flow downstream to the sub-branch， 24， or even down the branch， 22.

Fig. 2 shows a cut-away view of a coronary artery， 20， including the use of a catheter， 28， according to the method of the present invention. In the method herein， the balloon， 34， is located on the thrombus-side of the branch， 22， quite close to the thrombus， 26， so that the blood flow from the branch would not enter the aspiration tip， 32. The balloon， 34， forms a seal， 36， with the coronary artery， 20. As the vacuum applied via the lumen， 30， is therefore focused on the area where the thrombus， 26， is located， the chance of thrombus pieces escaping downstream is minimized.

Thus， in an embodiment herein， the balloon is inflated at a location where it is close to the thrombus so as to minimize the chances of blood flowing into the aspirator tip from a position which is not downstream of the thrombus. In an embodiment herein， the balloon is inflated at a location such that it is between the thrombus and any branches of the coronary artery. The diameter of a catheter herein may be either constant or may change along its length. In an embodiment herein a catheter portion distal from the balloon has an outer diameter of less than about 1.7 mm； or from about 0.3 mm to about 1.6 mm； or from about 0.5 nm to about 1.6 mm； or from about 0.55 mm to about 1.3 mm； or from about 0.6 mm to about 1.25 mm. The inner diameter of thc catheter (i.e.， the lumen diameter) is smaller than the outer diameter and may be less than about 1.69 mm； or from about 0.1 mm to about 1.69 mm； or from about 0.2 mm to about 1.59 mm； or from about 0.3 mm to about 1.29 mm； or from about 0.35 mm to about 1.24 mm.

As can be seen in Fig. 2， the thrombus， 26， is between the aspiration tip， 32， and the sub-branches， 24， so that any blood flowing into the aspiration tip， 32， does not come from the branch， 22. Without intending to be limited by theory， it is believed that such a position ensures optimal application of vacuum by the aspiration tip so as to increase the chances that the thrombus will be substantially evacuated via the aspiration tip. Therefore in an embodiment of the present invention， all sub-branches are located opposite the thrombus from the aspiration tip.

Fig. 3 shows a schematic diagram of an embodiment of a catheter， 28， useful in the present invention. The catheter， 28， has a plurality of humens， 30， herein parallel lumens， 30. In an embodiment herein the catheter contains a plurality of lumens； or at least about 1 lumen； or from about 1 to about 10 lumens； or from about 2 to about 7 lumens， or from about 3 to about 6 lumens. If multiple lumens are employed herein， they may be arranged in any way as long as they maintain their function. The lumens hereinare typically substantially parallel to each other. may be， for example， coaxial lumens. In an embodiment herein the lumens are not coaxially-arranged. In an embodiment herein， the lumens are substantially parallel and are not coaxial. In an embodiment herein， the lumens are stacked upon one-another， as seen in Fig. 3.

In Fig. 3， the catheter， 28， contains an aspiration lumen， 38， terminating at an aspiration tip， 32， through which the vacuum is applied to the coronary artery (see Fig. 2 at 22) . The catheter， 28， also includes an inflation lumen， 40， for inflating the balloon， 34. In order to do so， the inflation lumen， 40， is in connected relation to the balloon， 34， and in this case the inflation lumen， 40， is at least partially external to the aspiration lumen， 38. The inflation lumen， 40， further contains aninflation hole， 44， which connects to the balloon， 34. An inflating material， typically contrast media， flows through the inflation lumen， 40， and through the inflation hole， 44， and into the balloon， 34， to inflate it when it has reached the proper position

In Fig. 3， the inflation lumen 40 issealed at the location 42 and prevents the inflating material from escaping into the coronary atery and the patient's bloodstream. The inflating material is typically a liquid such as a contrast media. Without intending to be limited by theory， it is believed that a contrast media is typically the most effective inflating material， as it allows the operator to more easily visualize the location of the catheter and/or balloon， to more easily determine if it has properly inflated， in the proper location， etc.

The catheter， 28， in Fig. 3， also contains an injection lumen， 46， which is parallel to the aspiration lumen， 38 and the inflation lumen， 40. Th. e injection lumen， 46 terminates in an injection tip， 48， which allows the physician to inject， for example， a contrast media， saline， a drug， and/or other materialinto the coronary artery as desired.

In an embodiment herein， a contrast media is employed to help visualize the cardiovascular blood system， and indicate whether or not the collateral blood flow has occurred. In an embodiment herein， the contrast media， saline， drug and/or other material may be provided in the coronary artery in-between the thrombus and the catheter， in the coronary artery on the opposite side of the thrombus from the catheter， or on both sides of the thrombus. In an embodiment herein， a contrast media， saline， a drug， and/or other material； or a contrast media； is provided in the coronary artery on the opposite side of the thrombus from the catheter. Thus， an embodiment of the method herein includes the step of employing a contrast media to visualize the collateral blood flow. Such a contrast media may be delivered to various parts of the body by， for example， the injection lumen of the catheter inserted to the proper location， or by other methods known in the art such as injection. Without intending to be limited by theory， it is believed that especially by providing a contrast media on the side of the thrombus， the physician is able to visualize whether or not the collateral blood flow has successfully been induced in the patient.

The injection lumen may further be employed for other purposes as well. In an embodiment herein， the injection lumen is employed to deliver saline， for example to a location near the thrombus， so as to help reduce the total blood loss when vacuum is applied to the aspiration tip. In an embodiment herein， the injection lumen is employed to deliver a drug to a predetermined location in the body.

In an embodiment herein， the balloon is employed to deliver a drug. For example， the balloon may be coated with a drug which is delivered when the balloon inflates. Such a drug may be provided in the outer surface of the balloon， may be provided in another area of the catheter and is expelled when the balloon inflates， etc. Without intending to be limited by theory， it is believed that such a delivery method is highly effective as it is targeted to the location where it is needed， and also is more concentrated at tie site where it is needed. Such a method also allows a smaller dosage to be applied to the patient as compared to typical intravenous delivery， thereby potentially minimizing side-effects. Preferred drugs to be delivered in such a manner include， for example， anti-coagulants， anti-proliferative drugs， immunosuppressant drugs， and a combination thereof； or anti-coagulants， immunosuppressant drugs， and a combination thereof； or heparin， paclitaxel， rapamycin and a combination thereof. Known equivalents， pro-drugs， precursors， etc. of the above drugs may also be used herein.

The catheter， 28， also contains a locator， 50， which in Fig. 3 is located at the tip of the injection lumen， 46. The locator， 50， signals to the physician the physical location of the catheter， 28， and in this case， specifically the injection lumen tip， 48， of the catheter， 28. Thus， the physician is able to determine the exact location of the catheter's tip in real-time during an operation to make sure it is positioned correctly with respect to the coronary artery， the thrombus， etc. Typically， the locator will be a radioactive locator， a radio-frequency locator， a fluorescent locator， a marker band， and a combination thereof； or a radioactive locator； a radio-frequency locator， a metal marker band and a combination thereof； or a radioactive locator， a metal marker band and a combination thereof， In an emhodiment herein， the locator is a marker hand， typically a ring formed of a metal； or a radiopaque marker band； or a metal opaque to X-rays； or a marker band formed of platinum， gold and/or iridium， which is either embedded into the catheter and/or placed in one or more locations around the catheter and then crimped so as to be substantially flush with the catheter surface. The actual position of fhe locator may be in various places， such as at the aspiration tip， at either edge of the balloon， the injection lumen tip， etc. as desired by the user. In an embodiment herein， the catheter contains a plurality of locators. In an embodiment herein a locator is placed at each end of the balloon so as to clearly indicate to the physician the location of the balloon.

In Fig. 3， a locator， 50， is a metal marker band， 50' ， located at each end of the balloon so as to indicate the location of the balloon during use. In the embodirnent of Fig. 3， the edge of the locator， 50， is substantially flush with， or embedded into the side of the catheter， so as to prevent the marker band， 50' ， from being dislodged， catching on something during insertion/withdrawal， etc.

In an embodiment herein， the locator and the contrast media are coordinated such that they are both visual sable by the same method. For example， both may contain radioactive elements and therefore both be visualizable via radioactive detection methods. In an alternative embodiment herein， both the contrast media and the locator are visualizable via X-rays and/or a CT-scan. . Without intending to be limited by theory， it is believed that such a common visualization method is especially convenient and helpful for the physician， allowing the physician to see all relevant， real-time images on a single screen. In an embodiment herein， the locator and the contrast media are visualized in the patient via a real-time CT (computed tomography) scan， CAT (computed axial tomography) scan， and/or x-ray CT (x-ray computed tomography) scan， PET (positron emission tomography) scan， SPECT (single-photon emission computed tomography) scanand a combination thereof； or a real-time CT scan， CAT scan， and/or x-ray CT scan and a combination thereof.

During insertion of the catheter， 28， the balloon， 34， is typically deflated， and the inflation catheter， 40， may even be under vacuum； or a slight vacuum； so as to prevent the balloon， 34， from catching on something while the catheter， 28， is winding its way through the body.

Fig. 4 shows a cut-away view of a catheter， 28 herein. The catheter， 28， is a multiple-lumen catheter with the multiple lumens are arranged in a coaxial manner. In this case， one can see that the inflation lumen， 40， surrounds the aspiration lumen， 38. At the tip (not shown) ， the coaxial catheter， 28， the inflation lumen， 40， is typically sealed， so that only the aspiration lumen， 38， is able to contact the blood， thrombus， etc. In the embodiment of Fig. 4， there is no injection lumen， and thus， if needed， the aspiration lumen may be used for drug delivery， injection of contrast media， etc.

Fig. 5 shows a partially-cut-away view of a coronary artery， 20， containing a thrombus， 26， and a catheter， 28. The catheter is a coaxial multiple-lumen catheter. The catheter， 28， (in this case an outer catheter) contains a lumen， 30， which is typically but not necessarily an aspiration lumen， In Fig. 5， the guide wire， 52， penetrates through the thrombus， 26. The catheter， 28， contains； preferably slidably-contains； an inner catheter， 54 therein. The inner catheter contains a lumen， 30’ ， which may also be an aspiration lumen， but may be used for other purposes instead， or as well. The inner catheter's lumen， 30' ， may also contain the guide wire. In Fig. 5， the inner catheter， 54， contains； preferably slidably-contains； the guide wire， 52， but this is optional as the guide wire may be located elsewhere as well. Thus， in this embodiment， the catheter is an outer catheter； or the catheter having a lumen is an outer catheter； or the catheter having an aspiration lumen is an outer catheter. Thus， the outer catheter may contain an aspiration lumen， the inner catheter may contain an aspiration lumen， or both the inner catheter and the outer catheter may contain an aspiration lumen.

In the embodiment of Fig. 5， the outer catheter and the inner catheter are coaxial. In the embodiment of Fig. 5， theouter catheter， the inner catheter and the guide wire are coaxial.

The inner diameter of the catheter， 28， (e.g.， the lumen， 30) is larger than the outer diameter of the inner catheter， 54. Both the catheter， 28， and the inner catheter， 54 contain a marker band， 50' at their respective ends. The guide wire， 52， is typically itself a locater， 50， usually a radiopaque marker. The guide wire useful herein may be either completely radiopaque， or partially radiopaque， as preferred. The balloon， 34， is typically attached to the catheter， 28， as described above and may beinflated with an inflating material at a location in between a branch， 22 and the thrombus， 26.

In the process seen in Fig. 5， the doctor will typically insert the guide wire， 52， into the desired location so as to be close to， touch， or penetrate the thrombus， 26. The inner catheter， 55， and catheter， 28， are typically delivered to the thrombus， 26， together. During the procedure， the inner catheter， 54， and the catheter， 28， are typically loaded on the guidewire， 52， then inserted into a guiding catheter (not shown) . A physician usually then pushes the guide wire， 52， inner catheter， 54， and catheter， 28， through the guiding catheter quickly until the guidewire， 52， exits the guiding catheter near the entry to coronary artery. Then the physician advances the guidewire， 52， carefully through the coronary artery to the thrombus， 26. The inner catheter， 54， and catheter， 28， then follow the guide wire， 52， to reach the thrombus， 26. The guide wire， 52， and possibly the inner catheter， 54， are removed by sliding them out of the catheter， 28.

The balloon， 34， here a full-compliance balloon， is then inflated so as to form a seal， 36， with the coronary artery， 20. This seal， 36， blocks the proximal blood flow. The vacuum is applied to the catheter (i.e.， it this case the outer catheter) ， 28， which is now used as the aspiration lumen， so as to remove the thrombus， 26. In most cases， the balloon， 34， may be inflated before the guide wire， 52， and/or the inner catheter， 54， are removed.

The inner diameter of the catheter should be larger than the outer diameter of the inner catheter. In an embodiment herein， the inner catheter may have an outer diameter of less than about 1.68 mm， or from about 0.1 mm to about 1.68 mm； or from about 0.2 mm to about 1.58 mm， or from about 0.3 mm to about 1.28 mm； or from about 0.35 m to about 1.23 mm. The inner catheter may have an inner diameter (e.g.， the lumen diameter) of less than about 1.67 mm； or from about 0.05 mm to about 1.67 nm； or from about 0.07 mm to about 1.57 mm； or from about 0.1 mm to about 1.27 mm； or from about 0.15 mm to about 1.22 mm.

In an embodiment herein， the guide wire has a diameter of from about 0.05 mm to about 1 mm； or from about 0.07 mm to about 0.9 mm； or from about 0.1 mm to about 0.75 mm.

The use of the catheter shown in Fig. 5 may also be used in the method described herein to create negative pressure in the cardiovascular bed， preferably so as to induce collateral blood flow. This in turn may help to re-perfuse the myocardium affected by the blockage (e.g.， a thrombus) and reduce and/or avoid， for example， cell necrosis， etc.

In an embodiment herein， the inner catheter contains a lumen which may be used to aspire the thrombus. In an embodiment herein， the lumen of the outer catheter is used to aspire the thrombus. In an embodiment herein， both the inner catheter and the outer catheter contain separate lumens which may both be used for aspirating either simultaneously， or at different times.

In an embodiment herein， the outer catheter contains an aspiration lumen and the inner catheter contains an aspiration lumen. The outer catheter's aspiration lumen is typically used to aspire material from one side of the thrombus， while the inner catheter's aspiration lumen is used to aspire any microthrombuses which may break off of the original thrombus. The inner catheter's aspiration lumen may especially be effective to catch microthrombuses which may flow downstream of the original thrombus. Without intending to be limited by theory， it is believed that such a device and method helps to reduce the proliferation of microthrombuses (thrombus pieces which break off and/or escape downstream of the original thrombus) . In such an embodiment， the inner catheter's aspiration lumen may be connected to a vacuum mechanism， while the outer catheter's aspiration lumen is connected to the same or a different vacuum mechanism.

In an embodiment herein， the lumen of the inner catheter is used fora purpose other than aspiration， such as deploying a contrast media， deploying a drug， etc. In an embodiment herein， the lumen of the outer catheter is used for multiple purposes. In an embodiment herein， the lumen of the inner catheter is used for multiple purposes.

In an embodiment herein， the outer catheter's aspiration lumen is independently connected to the same or a different vacuum mechanism as the inner catheter's aspiration lumen such that each of the aspiration lumens may be operated independently.

In an embodiment herein， the inner catheter contains； or slidably-contains， a lumen for the guide wire， and the guide wire slides through this lumen.

The catheter， outer catheter， and/or inner catheterherein is typically known to be made at least partially of plastic， especially plastics which are flexible and which may be sterilized. The inner catheter may be constructed of the same materials， may be partially-constructed of the same materials， or may be completely made of different materials as the catheter. In an embodiment herein， the catheter contains

a polyether block amide by Arkema， Columbia， or a similar material. The catheter may be braided or un-braided. If the catheter is braided， then it may be fully-braided or partially-braided as desired. In an embodiment herein， the catheter tube is braided， while the catheter tip is not braided.

In an embodiment herein the balloon is formed from a flexible plastic material； or polyurethane， or

In an embodiment herein， the balloon is a full-compliance balloon. In an embodiment herein， the balloon is a semi-compliance balloon. The present invention may also include catheters such as described herein， which are capable of creating negative pressure in the myocardial bed， and/or inducing collateral blood flow.

In an embodiment of the invention， the catheter is substantially as depicted in the attached figures， and specifically as depicted in Fig. 5.

It should be understood that the description and figures hereinonly illustrate and describe examples whereby the present invention may be carried out， and that modifications and/or alterations may be made thereto without departing from the scope and spirit of the invention.

It should also be understood that certain features of the invention， which are， for clarity， described in the context of separate embodiments， may also be provided in combination in a single embodiment. Conversely， various features of the invention which are， for brevity， described in the context of a single embodiment， may also be provided separately or in any suitable subcombination.

Claims

A method for creating negative pressure in a cardiovascular bed according to the steps of：

A. inserting a catheter into a coronary artery connected to a cardiovascular bed， the catheter comprising an aspiration lumen and a balloon external to the aspiration lumen；

B. inflating the balloon， wherein the inflated balloon substantially forms a seal with the coronary artery； and

C. providing a vacuum in the aspiration lumen， the vacuum sufficient so as to create negative pressure in the cardiovascular bed.
The method according to Claim 1， wherein the vacuum induces collateral blood flow.
The method according to Claim 1， wherein the vacuum is from about -100 mmHg (-13.5kPa) to about -740 mmHg (-100.0kPa) .
The method according to Claim 1， wherein the catheter comprises a vacuum mechanism.
The method according to Claim 1， wherein the catheter comprises a pressure monitor.
The method according to Claim 1， wherein the catheter comprises a locator.
The method according to Claim 1， wherein the balloon is inflated at a location such that it is between the thrombus and any branches of the coronary artery
The method according to Claim 1， wherein the catheter comprising the aspiration lumen is an outer catheter， and wherein the outer catheter further comprises an inner catheter contained within the aspiration lumen.
The method according to Claim 2， further comprising the step of：

D. employing a contrast media to visualize the collateral blood flow.
The method according to Claim 4， wherein the vacuum mechanism is selected from the group consisting of a syringe， a pump， a disposable vacuum container， and a combination thereof.
The method according to Claim 4， wherein the vacuum mechanism comprises a relief valve.
The method of Claim 11， further comprising the step of：

D. employing a contrast media to visualize the collateral blood flow，

and wherein the contrast media is radioactive and the locator is a radiopaque locator.
A catheter comprising：

A. an outer catheter comprising：

i. a lumen and，

ii. an inflatable balloon； and

B. an inner catheter contained within the lumen.
The catheter according to Claim 13， wherein the catheter further comprises a guide wire.
The catheter according to Claim 13， wherein the catheter further comprises a locator.
The catheter according to Claim 13， wherein the inner catheter further comprises a lumen.
The catheter according to Claim 13， wherein the outer catheter and the inner catheter are coaxial.
The catheter according to Claim 14， wherein the guide wire is slidably-contained within the lumen.
The catheter according to Claim 14， wherein tihe guide whre is inside of the inner catheter.
Use of the catheter according to Claim 13 to create negative pressure in the cardiovascular bed.