The present invention relates generally to medical devices for aspirating air or gas from a patient""s body cavity, such as a vessel or cardiac chamber. More particularly, the devices comprise a catheter having a chamber filled with gas of low density and mounted at a distal end of the catheter. The chamber provides buoyancy to the catheter tip which seeks out and aspirates air or gas in the body cavity.
Aspiration catheters are frequently used during surgical or interventional procedures for removing air, fluid, and/or blood from a patient""s body cavity. During cardiovascular procedures, such as coronary artery bypass grafting surgery, ventricular septal defect repair, heart valve repair or replacement, ventricular myomectomy (Bautista procedure), septal-myomectomy, aortic aneurysm repair, or aortic thrombectomy, removal of air from a cardiac chamber and/or the aorta is particularly important since distal embolization of air may result in ischemia or infarction of peripheral organs. Treatment of vascular stenosis using endovascular procedures, e.g., angioplasty, stent deployment, or atherectomy, is also associated with increased risk of air embolization resulting in cerebral ischemia or infarction.
Current aspiration catheters are designed to remove fluid in a body cavity. Removal of air, however, is difficult because the air bubbles tend to accumulate against the vessel wall at a position difficult to reach. Thus, air removal is often not complete and patients remain at risk for air embolization.
Thus, there is a need for devices and methods which effectively remove air within a patient""s body tissue or cavity during surgical or endovascular procedures.
The present invention provides a buoyant tip aspiration catheter adapted for insertion into a patient""s body cavity. The catheter is most useful in removing air from a cardiac chamber, e.g., the left atrium or left ventricle, and a vessel, including arteries and veins of various sizes. It will be understood that the catheter can also be used in removing air in any other body cavity, e.g., biliary tree.
In a first embodiment, the catheter comprises a flexible elongate tubular member which has a lumen communicating with a proximal and a distal end. The tubular member is made from a thin-walled material, e.g., thermal plastic, polyvinyl chloride, polyolefin, or PEBAX. The distal end includes an aspiration port which communicates with the lumen. A chamber which is filled with a gas, such as helium, hydrogen, or carbon dioxide, is mounted at the distal end. In certain embodiments, the chamber comprises a toroidal or annular balloon or an olive-shaped balloon which communicates with an inflation lumen. In other embodiments, the chamber can have the shape of a sphere or ellipse or any other suitable geometric shape.
In another embodiment, the catheter is insertable through an introducer, such as a cannula. The proximal end of the catheter is connected to a pump which applies negative pressure to the lumen. In certain embodiments, a small wire is helically wound within the catheter to prevent kinking.
In a first method of using the aspiration catheter disclosed herein for removing gas from fluid or blood within a body cavity, the distal end of the catheter is inserted through an incision in tissue, such as a vessel. The distal end is directed to and seeks out the location of gas within the body cavity by the buoyant chamber. The gas is then removed from the body cavity through the distal port and lumen under suction. During cardiovascular surgeries, such as heart valve repair or replacement, removal of gaseous material from the cardiac chambers and aorta reduces a patient""s risk of peri-operative complication, such as neurocognitive, e.g., stroke and delirium.
It will be understood that there are several advantages in using the aspiration catheters and methods disclosed herein for treating a vascular lesion. For example, the catheters (1) can be inserted in arteries or veins of various diameter, (2) provide near-total capture of embolic gaseous bubbles, thereby dramatically reducing the risk of distal embolization, and (3) are insertable through an introducer and can be used with other endovascular devices.