Perfusion filter catheter

Details Perfusion filter catheter Perfusion filter catheter

1998-09-22

2002-03-26

Reip, David O. (Department: 3731)

Surgery

Instruments

Internal pressure applicator

C606S151000, C606S194000

Reexamination Certificate

active

06361545

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to a catheter or cannula for infusion of oxygenated blood or other fluids into a patient for cardiopulmonary support and cerebral protection. More particularly, it relates to an arterial perfusion catheter with a deployable embolic filter for protecting a patient from adverse effects due to emboli that are dislodged during cardiopulmonary bypass.
BACKGROUND OF THE INVENTION
Over the past decades tremendous advances have been made in the area of heart surgery, including such life saving surgical procedures as coronary artery bypass grafting (CABG) and cardiac valve repair or replacement surgery. Cardiopulmonary bypass (CPB) is an important enabling technology that has helped to make these advances possible. Recently, however, there has been a growing awareness within the medical community and among the patient population of the potential sequelae or adverse affects of heart surgery and of cardiopulmonary bypass. Chief among these concerns is the potential for stroke or neurologic deficit associated with heart surgery and with cardiopulmonary bypass. One of the likely causes of stroke and of neurologic deficit is the release of emboli into the blood stream during heart surgery. Potential embolic materials include atherosclerotic plaques or calcific plaques from within the ascending aorta or cardiac valves and thrombus or clots from within the chambers of the heart. These potential emboli may be dislodged during surgical manipulation of the heart and the ascending aorta or due to high velocity jetting (sometimes called the “sandblasting effect”) from the aortic perfusion cannula. Air that enters the heart chambers or the blood stream during surgery through open incisions or through the aortic perfusion cannula is another source of potential emboli. Emboli that lodge in the brain may cause a stroke or other neurologic deficit. Clinical studies have shown a correlation between the number and size of emboli passing through the carotid arteries and the frequency and severity of neurologic damage. At least one study has found that frank strokes seem to be associated with macroemboli larger than approximately 100 micrometers in size, whereas more subtle neurologic deficits seem to be associated with multiple microemboli smaller than approximately 100 micrometers in size. In order to improve the outcome of cardiac surgery and to avoid adverse neurological effects it would be very beneficial to eliminate or reduce the potential of such cerebral embolic events.
Several medical journal articles have been published relating to cerebral embolization and adverse cerebral outcomes associated with cardiac surgery, e.g.: Determination or Size of Aortic Emboli and Embolic Load During Coronary Artery Bypass Grafting; Barbut et al.; Ann Thorac Surg 1997;63;1262-7; Aortic Atheromatosis and Risks of Cerebral Embolization; Barbut et al.; J Card & Vasc Anesth, Vol 10, No 1, 1996: pp 24; Aortic Atheroma is Related to Outcome but not Numbers of Emboli During Coronary Bypass; Barbut et al.; Ann Thorac Surg 1997;64;454-9; Adverse Cerebral Outcomes After Coronary Artery Bypass Surgery; Roach et al.; New England J of Med, Vol 335, No 25, 1996: pp 1857-1863; Signs of Brain Cell Injury During Open Heart Operations: Past and Present; Aberg; Ann Thorac Surg 1995;59;1312-5; The Role of CPB Management in Neurobehavioral Outcomes After Cardiac Surgery; Murkin; Ann Thorac Surg 1995;59;1308-11; Risk Factors for Cerebral Injury and Cardiac Surgery; Mills; Ann Thorac Surg 1995;59;1296-9; Brain Microemboli Associated with Cardiopulmonary Bypass: A Histologic and Magnetic Resonance Imaging Study; Moody et al.; Ann Thorac Surg 1995;59;1304-7; CNS Dysfunction After Cardiac Surgery: Defining the Problem; Murkin; Ann Thorac Surg 1995;59;1287+Statement of Consensus on Assessment of Neurobehavioral Outcomes After Cardiac Surgery; Murkin et al.; Ann Thorac Surg 1995;59;1289-95; Heart-Brain Interactions: Neurocardiology Comes of Age; Sherman et al.; Mayo Clin Proc 62:1158-1160, 1987; Cerebral Hemodynamics After Low-Flow Versus No-Flow Procedures; van der Linden; Ann Thorac Surg 1995;59;1321-5; Predictors of Cognitive Decline After Cardiac Operation; Newman et al.; Ann Thorac Surg 1995;59;1326-30; Cardiopulmonary Bypass: Perioperative Cerebral Blood Flow and Postoperative Cognitive Deficit; Venn et al.; Ann Thorac Surg 1995;59;1331-5; Long-Term Neurologic Outcome After Cardiac Operation; Sotaniemi; Ann Thorac Surg 1995;59;1336-9; and Macroemboli and Microemboli During Cardiopulmonary Bypass; Blauth; Ann Thorac Surg 1995;59;1300-3.
The patent literature includes several references relating to vascular filter devices for reducing or eliminating the potential of embolization. These and all other patents and patent applications referred to herein are hereby incorporated herein by reference in their entirety.
The following U.S. patents relate to vena cava filters: U.S. Pat. Nos. 5,549,626, 5,415,630, 5,152,777, 5,375,612, 4,793,348, 4,817,600, 4,969,891, 5,059,205, 5,324,304, 5,108,418, 4,494,531. Vena cava filters are devices that are implanted into a patient's inferior vena cava for capturing thromboemboli and preventing them from entering the right heart and migrating into the pulmonary arteries. These are generally designed for permanent implantation and are only intended to capture relatively large thrombi, typically those over a centimeter in diameter, that could cause a major pulmonary embolism. As such, these are unsuitable for temporary deployment within a patient's aorta or for capturing macroemboli or microemboli associated with adverse neurological outcomes. Vena cava filters are also not adapted for simultaneously providing arterial blood perfusion in connection with cardiopulmonary bypass.
The following U.S. patents relate to vascular filter devices: U.S. Pat. Nos. 5,496,277, 5,108,419, 4,723,549, 3,996,938. These filter devices are not of a size suitable for deployment within a patient's aorta, nor would they provide sufficient filter surface area to allow aortic blood flow at normal physiologic flow rates without an unacceptably high pressure drop across the filter. Furthermore, these filter devices are not adapted for simultaneously providing arterial blood perfusion in connection with cardiopulmonary bypass devices.
The following U.S. patents relate to aortic filters or aortic filters associated with atherectomy devices: U.S. Pat. Nos. 5,662,671, 5,769,816. The following international patent applications relate to aortic filters or aortic filters associated with atherectomy devices: WO 97/17100, WO 97/42879, WO 98/02084. The following international patent application relates to a carotid artery filter: WO 98/24377. This family of U.S. and international patents includes considerable discussion on the mathematical relationship between blood flow rate, pressure drop, filter pore size and filter area and concludes that, for use in the aorta, it is desirable for the filter mesh to have a surface area of 3-10 in
2
, more preferably 4-9 in
2
, 5-8 in
2
or 6-8 in
2
, and most preferably 7-8 in
2
. While these patents state that this characteristic is desirable, none of the filter structures disclosed in the drawings and description of these patents appears capable of providing a filter surface area within these stated ranges when deployed within an average-sized human aorta. Accordingly, it would be desirable to provide a filter structure or other means that solves this technical problem by increasing the effective surface area of the filter mesh to allow blood flow at normal physiologic flow rates without an unacceptably high pressure drop.
SUMMARY OF THE INVENTION
In keeping with the foregoing discussion, the present invention takes the form of a perfusion filter catheter or cannula having an embolic filter assembly mounted on an elongated tubular catheter shaft. The elongated tubular catheter shaft is adapted for introduction into a patient's ascending aorta either by a peripheral arterial approach or by a direct aortic puncture. A f

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