Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-04-02
2002-05-07
Jastrzab, Jeffrey R. (Department: 3762)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S006130, C604S006140, C604S043000, C604S113000, C604S096010, C128S898000
Reexamination Certificate
active
06383172
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to devices and methods useful in maintaining cerebral perfusion during global or focal cerebral ischemia. More specifically, the devices and methods provide effective retrograde perfusion to the cerebral circulation through the superior vena cava or the internal jugular veins. Retrograde venous perfusion may be used with hypothermia to provide isolated cerebral cooling. The devices and methods are also useful in improving perfusion to other peripheral organs besides the brain.
BACKGROUND OF THE INVENTION
Cerebral ischemia refers to cessation or reduction of blood flow to the cerebral tissues. Cerebral ischmia can be characterized as either global or hemispherical. Hemispherical or focal ischemia refers to cessation or reduction of blood flow within the cerebral vasculature resulting from a partial or complete occlusion in the intracranial or extracranial cerebral arteries. Global ischemia refers to cessation or reduction of blood flow within the cerebral vasculature resulting from systemic circulatory failure from various causes, including aortic surgery, cardiac arrest, shock, and trauma. Circulatory arrest is often required in performing surgeries on the aorta, e.g., aneurysm repair, aortic dissection, endarterectomy of aortic atheroma, and aortic stenting. Blood flow through the aorta is often interrupted due to opening of the aorta for these surgical procedures. Cessation of systemic circulation therefore places a patient at great risk, particularly in the cerebral vasculature where ischemia can rapidly lead to irreversible neurologic damage.
Various techniques have been proposed to improve cerebral perfusion in a patient suffering from either global or focal ischemia. For example, conventional cardiopulmonary bypass is used during cardiovascular surgeries to maintain perfusion to peripheral organs during cardiac arrest. However, cardiopulmonary bypass is generally not useful when the aorta fails to remain intact during aortic surgeries. Retrograde aortic perfusion (RAP) has been proposed to improve cerebral perfusion by clamping the ascending aorta and perfusing the aorta in a retrograde direction through a peripheral arterial access, typically the femoral artery. Disadvantages associated with retrograde aortic perfusion include significant cerebral embolization from dislodgment of atheromatous material in the descending aorta and the aortic arch. Moreover, RAP is not useful for aortic procedures distal or proximal to a limited surgical region of the aorta.
Another technique for protecting the brain during global or focal ischemia is provided by hypothermic circulatory arrest (HCA). HCA is achieved by inducing marked systemic hypothermia prior to cessation or reduction of systemic circulation. There are several disadvantages associated the HCA. For example, during cardiac arrest from cardiac arrhythmia or aortic surgeries, the systemic circulation remains stopped, thereby placing the patient at significant risk of ischemia despite utilizing hypothermia. Moreover, HCA has been associated with systemic coagulopathy, typically disseminated intravascular coagulopathy. Therefore, aortic surgery performed with HCA is associated with relatively high mortality (approximately 20 percent).
Another proposed technique for cerebral perfusion is referred to as selective antegrade cerebral perfusion (SCP). SCP is achieved by introducing a catheter through the aorta into a carotid artery to perfuse the cerebral vasculature. However, cerebral embolization can occur from introduction of the catheter which can dislodge atheromatous material, often present at the take-off from the aorta. Cerebral embolization can also occur from dislodgment of atheromatous material by clamping or snaring of the carotid artery. Air embolization can also occur from insertion of the catheter in the aorta or the carotid artery.
Another technique for improving cerebral perfusion is provided by retrograde cerebral venous perfusion (RCP), which is achieved by clamping the inferior vena cava and introducing oxygenated blood through a catheter inserted in the superior vena cava. Flow is established in a retrograde direction up the vena cava into the brachial and jugular veins. However, there are several disadvantages associated with using the RCP. For example, a majority (approximately 80%) of the oxygenated blood will run off into the arms and/or the heart and lungs, with as little as 20% of the blood entering the brain. Secondly, valves in the jugular veins may obstruct blood flow into the intracranial venous system. The blood can flow outwardly through the extensive collateral circulation without perfusing the brain. The amount of blood returned to the aorta from the carotid arteries represents no more than approximately 5% of the blood initially introduced to the superior vena cava. Thirdly, such retrograde perfusion often results in an increase in cerebral pressure which further inhibits blood inflow. Arterial efflux to the cerebral vasculature is found by the inventor to disappear after 20 minutes. Therefore, during RCP, the venous flow rates and pressures required to achieve and maintain significant arterial efflux are highly variable.
For these reasons, it would be desirable to provide improved devices and methods for protecting the brain and cerebral vasculature of patients suffering from global or focal ischemia, without the risk of cerebral embolization or systemic side effects.
SUMMARY OF THE INVENTION
The present invention provides devices and methods for improving cerebral perfusion in patients suffering from focal or global ischemia. More specifically, the devices and methods provide oxygenated blood flow to the brain using retrograde venous perfusion, which can be used in conjunction with hypothermia. In one embodiment, the medical device comprises a catheter which includes an elongate tubular member having a proximal end, a distal end, and first and second lumens. The first lumen communicates with the proximal end and an infusion port at the distal end of the catheter. The second lumen communicates with the proximal end of the catheter and a drainage port proximal to the infusion port. In certain embodiments, the second lumen communicates with a plurality of drainage ports. An expandable occluder, which may be an elastomeric balloon in certain embodiments, is mounted on a distal region of the catheter between the infusion port and the drainage port. A manometer is mounted on the catheter distal to the occluder for measuring blood pressure distal to the occluder. The proximal end of the catheter is adapted for attachment to an oxygenator machine and/or a pump.
In another embodiment, the device comprises first and second catheters. Each of the two catheters has a lumen communicating with a proximal end and an infusion port at a distal end. An expandable occluder is mounted on a distal region of each of the catheters proximal to the infusion port. A manometer is mounted distal to each occluder. The first catheter and the second catheter are joined for a substantial length and are separated at their distal ends. In certain embodiments, the catheters are separated at their proximal ends. The proximal ends of the catheters are adapted for attachment to an oxygenator machine and/or a pump.
In still another embodiment, the device having two catheters described above may include a third lumen communicating with the proximal end of the catheter and a drainage port at its distal end. The drainage port is located proximal to the occluders. In certain embodiments, the third lumen communicates with 2, 3, 4, 5, 6, 7, or any other number of drainage ports. The proximal end of the catheter is adapted for attachment to a pump and/or an oxygenator.
In a first method of using the devices, the distal end of the catheter is inserted through a peripheral vein, e.g., the femoral vein, into the vena cava. The distal region of the catheter and the occluder are positioned in the superior vena cava (SVC), and the occluder is expanded to isolate blood flow in the SV
Bianco Patricia
CoAxia, Inc.
Jastrzab Jeffrey R.
Lyon & Lyon LLP
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