Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-04-24
2004-06-01
Mendez, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S096010
Reexamination Certificate
active
06743196
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to medical devices. More particularly, the invention relates to methods and devices for augmenting blood flow to a patient's vasculature. More particularly, the invention relates to apparatus and methods which provide partial obstruction (“coarctation”) to aortic blood flow to augment cerebral perfusion in patients with global or focal ischemia. The devices and methods also provide mechanisms for continuous constriction and variable blood flow through the aorta.
BACKGROUND OF THE INVENTION
Patients experiencing cerebral ischemia often suffer from disabilities ranging from transient neurological deficit to irreversible damage (stroke) or death. Cerebral ischemia, i.e., reduction or cessation of blood flow to the central nervous system, can be characterized as either global or focal. Global cerebral ischemia refers to reduction of blood flow within the cerebral vasculature resulting from systemic circulatory failure caused by, e.g., shock, cardiac failure, or cardiac arrest. Shock is the state in which failure of the circulatory system to maintain adequate cellular perfusion results in reduction of oxygen and nutrients to tissues. Within minutes of circulatory failure, tissues become ischemic, particularly in the heart and brain.
The two common forms of shock are cardiogenic shock, which results from severe depression of cardiac performance, and hemorrhagic shock, which results from trauma. The most frequent cause of cardiogenic shock is myocardial infarction with loss of substantial muscle mass. Pump failure can also result from acute myocarditis or from depression of myocardial contractility following cardiac arrest or prolonged cardiopulmonary bypass. Mechanical abnormalities, such as severe valvular stenosis, massive aortic or mitral regurgitation, acutely acquired ventricular septal defects, can also cause cardiogenic shock by reducing cardiac output. Additional causes of cardiogenic shock include cardiac arrhythmia, such as ventricular fibrillation. Hemorrhagic shock is typically the result of penetrating injuries caused by, for example, traffic accidents and gunshot wounds. In this case, cardiac function is unimpaired and the cause of shock is blood loss.
Treatment of global cerebral ischemia involves treating the source of the systemic circulatory failure and ensuring adequate perfusion to the central nervous system. For example, treatment of cardiogenic shock due to prolonged cardiopulmonary bypass consists of cardiovascular support with the combination of inotropic agents such as dopamine, dobutamine, and intra-aortic balloon counterpulsation. Treatment of hemorrhagic shock consists of volume replacement and hemostasis. When these measures fail, supracoeceliac aortic clamping is used. Vasoconstrictors, such as norepinephrine, are also administered systemically to maintain systolic blood pressure (ideally above 80 mmHg). Unfortunately, these agents produce a pressure at the expense of flow, particularly blood flow to small vessels such as the renal arteries. The use of the vasoconstrictors is, therefore, associated with significant side effects, such as acute renal failure, congestive heart failure, and cardiac arrhythmias.
Focal cerebral 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. Such occlusion typically results in stroke, a syndrome characterized by the acute onset of a neurological deficit that persists for at least 24 hours, reflecting focal involvement of the central nervous system and is the result of a disturbance of the cerebral circulation. Other causes of focal cerebral ischemia include vasospasm due to subarachnoid hemorrhage or iatrogenic intervention.
Traditionally, emergent management of acute ischemic stroke consists of mainly general supportive care, e.g. hydration, monitoring neurological status, blood pressure control, and/or anti-platelet or anti-coagulation therapy. Heparin has been administered to stroke patients with limited and inconsistent effectiveness. In some circumstances, the ischemia resolves itself over a period of time due to the fact that some thrombi get absorbed into the circulation, or fragment and travel distally over a period of a few days. In June 1996, the Food and Drug Administration approved the use of tissue plasminogen activator (t-PA) or Activase®, for treating acute stroke. However, treatment with systemic t-PA is associated with increased risk of intracerebral hemorrhage and other hemorrhagic complications. Vasospasm may be partially responsive to vasodilating agents. The newly developing field of neurovascular surgery, which involves placing minimally invasive devices within the carotid arteries to physically remove the offending lesion may provide a therapeutic option for these patients in the future, although this kind of manipulation may lead to vasospasm itself. latrogenic vasospasm and vasospasm caused by subarachnoid hemorrhage may respond to treatment with aortic constriction.
In both global and focal ischemia, patients develop neurologic deficits due to the reduction in cerebral blood flow. One treatment may include the use of devices to increase blood flow to the cerebral vasculature as the sole therapy. Alternatively, treatments include measures to increase blood flow to the cerebral vasculature to maintain viability of neural tissue, thereby increasing the length of time available for any adjunct interventional treatment and minimizing neurologic deficit while waiting for resolution of the ischemia. Augmenting blood flow to the cerebral vasculature is not only useful in treating occlusive or vasospastic cerebral ischemia, but may also be useful during interventional procedures, such as carotid angioplasty, stenting or endarterectomy, which might otherwise result in focal cerebral ischemia, and also cardiac procedures which may result in cerebral ischemia, such as cardiac catheterization, electrophysiologic studies, and angioplasty.
New devices and methods are thus needed for augmentation of cerebral blood flow in treating patients with either global or focal ischemia caused by reduced perfusion, thereby minimizing neurologic deficits.
SUMMARY OF THE INVENTION
In one embodiment, the invention provides vascular obstruction, occlusion, and/or constriction devices and methods for augmenting blood flow to a patient's cerebral vasculature, including the carotid and vertebral arteries. The terms obstruction, occlusion, and constriction are used interchangeably herein to refer to partial or complete blockage of a vessel, and to any of the devices that provide such blockage. The devices comprise an obstructing, occluding, or constricting mechanism distally mounted on a catheter for delivery to a vessel, such as the aorta. The obstructor, occluder, and/or constrictor is collapsed to facilitate insertion into and removal from the vessel, and expanded during use to at least partially obstruct blood flow.
In one embodiment, the devices comprise an elongate catheter having a proximal and a distal region. The catheter may also have a lumen extending between the proximal and distal regions. An expandable device, e.g., a balloon in certain cases, is carried at the distal region of the catheter. The catheter in certain embodiments may include a second expandable device carried at the distal region of the catheter, proximal the first expandable device. In certain embodiments, the catheter will also include blood pressure measuring capabilities distal and/or proximal the first and/or second (when present) expandable devices.
In use, the catheter having one expandable device is located in the descending aorta so that the expandable device is suprarenal or infrarenal. The expandable device is then expanded to partially or completely obstruct the descending aorta. Cerebral blood flow and cerebral blood pressure rises and is maintained at an increased level as desired. Cephalad blood pressure and/or cerebral blood flow
Barbut Denise R.
Berhow Steven W.
Keith Peter T.
St. Germain Jon P.
CoAxia, Inc.
Mendez Manuel
O'Melveny & Myers LLP
LandOfFree
Partial aortic occlusion devices and methods for cerebral... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Partial aortic occlusion devices and methods for cerebral..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Partial aortic occlusion devices and methods for cerebral... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3297046