Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
2001-04-30
2003-01-21
Hale, Gloria M. (Department: 3765)
Surgery
Instruments
Internal pressure applicator
C606S198000
Reexamination Certificate
active
06508826
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to medical devices useful for cannulation of a vascular tissue, such as the aorta, and for protecting against distal embolization during cardiovascular procedures. More particularly, the devices minimize plaque dislodgement and damage to a vessel wall during delivery of blood to the vessel.
BACKGROUND OF THE INVENTION
Aortic cannulation is commonly employed during various conventional or minimally invasive surgeries, such as coronary artery bypass grafting, heart valve repair or replacement, septal defect repair, pulmonary thrombectomy, atherectomy, aneurysm repair, aortic dissection repair, and correction of congenital defects, to establish cardiopulmonary bypass. After circulatory isolation of the coronary blood flow from the peripheral vascular system is established, a cannula is usually inserted in the ascending aorta to deliver oxygenated blood from a bypass-oxygenator to maintain blood flow to the peripheral organs, e.g., the brain and kidneys. It is well recognized that one of the complications associated with cardiovascular procedures is the dislodgement of embolic materials generated during manipulation of the aorta or the heart, thereby causing occlusion of the vessels downstream from the aorta causing ischemia or infarct of the organs, e.g., stroke. To minimize embolic complication, an arterial filter is often temporarily deployed in the aorta distal to the aortic cannula to capture embolic debris.
However, when oxygenated blood is delivered to the aortic cannula through the bypass-oxygenator, blood exits the cannula with a very high velocity, similar to a jet-like profile. When this jet is directed toward the aortic wall, it may damage the aorta causing aortic dissection or aneurysm. Furthermore, the jet may dislodge plaque on the aortic wall, causing distal embolization and peripheral organ infarction. When oxygenated blood is allowed to flow into a filter, the jet may cause turbulent flow in the filter, thereby washing out the emboli caught in the filter. As a result of the swirling action by the jet, the emboli may escape around the edges of the filter to cause distal embolization and result in damage to peripheral organs, or may travel upstream to reach a coronary artery and cause myocardial infarction.
New devices and methods are thus needed in aortic cannulation to minimize embolic dislodgement and vascular wall damage due to delivery of oxygenated blood to the aorta during cardiovascular surgeries.
SUMMARY OF THE INVENTION
The invention provides devices and methods for reducing the jet-like profile of blood delivered through a cannula and the swirling of the blood within a filter. It will be understood that, although the present invention is most useful in aortic cannulation during cardiovascular surgeries, the devices and methods can be used in any surgeries where delivery of fluid or blood through a cannula can potentially damage the body tissue.
In a first embodiment, the cannula is an elongate tubular member having a proximal end, a distal end, and a lumen therebetween. A blast plate deployable from within the lumen of the elongate tubular member is provided. The blast plate is retractable into the lumen of the elongate tubular member after use. In certain cases, the cannula is angled at its distal end, generally at a 90° angle to the axis of the lumen at a proximal end. In other cases, the cannula will further include a filter deployable from the distal end of the cannula. The filter may be mounted on the distal end of the cannula, or the filter can be mounted on a separately insertable member, such as a guidewire. In other cases, the cannula has more than one lumen extending from its proximal to its distal end. In still other cases, the cannula further comprises an occlusion member such as a balloon occluder, deployable from the distal end of the cannula. As with the filter, the occluder can be mounted on the cannula, or provided on a separately insertable member, such as an occlusion catheter.
The blast plate typically comprises a generally flat or curved surface, and may comprise a membrane mounted on a flexible wire ring. The membrane generally comprises a semi-permeable material. In certain cases the member is a mesh material. In still other cases, the membrane is made of an impermeable material. While in certain cases the blast plate is formed in the shape of a planar surface defined by a wire ring, in other cases the blast plate is a cone-shaped sleeve. The sleeve can be made of an elastomeric material. The blast plate may also take the form of a substantially flat surface mounted at the distal end of a flexible or an inflexible elongate member. For example, the blast plate may be fixed to the end of a wire. The blast plate will be angled relative to the elongate member, and the angle may be selected from a 45° angle, a 50° angle, a 55° angle, a 60° angle, a 65° angle, a 70° angle, a 75° angle, an 80° angle, an 85° angle, or a 90° angle.
In use, the surgeon inserts the cannula into a body cavity, e.g., a blood vessel. It will be understood that the cannula may comprise a standard commercially available cannula, or any of the novel cannula described herein. The surgeon will then advance a blast plate or dispersion mechanism through the lumen of the cannula and beyond the distal end of the cannula. The surgeon then flows a stream of fluid, e.g., blood, through the lumen of the cannula. The blood flow hits the blast plate, and the blood stream is diffused and dispersed by the blast plate without jetting against the wall of the aorta. After the infusion procedure is complete, the surgeon retracts the blast plate into the lumen of the cannula.
It will be understood that the methods of use have particular application where the body cavity is a blood vessel, where the blood vessel is an artery, and where the artery is the aorta. It will further be understood that there are several advantages to using the diffusion-diversion devices and methods described herein. For example, by dispersing the stream of blood flow, the devices and methods (1) avoid “sand blasting” embolic debris from the lumen of the vessel, (2) avoid the swirling of blood that may carry embolic debris upstream during CABG to the coronary arteries, where myocardial ischemia can occur, (3) avoid turbulence that can force embolic debris around the periphery of a deployed filter to cause distal embolization which can results in stroke, renal failure, or other organ damage.
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Lilly Richard S
Murphy Richard O.
EMBOL-X, Inc.
Hale Gloria M.
O'Melveny & Myers LLP
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