Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
2000-02-25
2002-08-20
Truong, Kevin T. (Department: 3731)
Surgery
Instruments
Internal pressure applicator
C606S190000
Reexamination Certificate
active
06436118
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to harvesting blood vessels for coronary artery bypass grafting (hereinafter “CABG”), and more particularly to a device for facilitating harvesting internal mammary arteries for anastomosis to coronary arteries using minimally invasive procedures. Minimally invasive procedures are employed to minimize trauma to the patient in order to promote rapid healing and reduce the amount of pain during recovery. This invention relates particularly to a blood vessel harvesting apparatus that can be used for forming a small anatomic working space alongside an elongate vessel, particularly a blood vessel, and more particularly a small blood vessel such as an internal mammary artery (hereinafter “IMA”). The invention relates specifically to an assembly having a cannula and an assembled balloon.
BACKGROUND OF THE INVENTION
Diseases of the cardiovascular system affect millions of people each year and are a leading cause of death in the United States and throughout the world. The cost to society from such diseases is enormous both in terms of lives lost and the cost of treating cardiac disease patients through surgery. A particularly prevalent form of cardiovascular disease is a reduction in the blood supply to the heart caused by atherosclerosis or other conditions that create a restriction in blood flow in the arteries supplying blood to the heart.
Numerous surgical procedures have been developed to restore blood flow to the heart. For example, blockages can be treated with atherectomy or angioplasty, often followed by stent placement. But, when these methods of treatment cannot be used or have failed to clear the blocked artery, coronary bypass surgery may be indicated.
In the CABG procedure, the surgeon removes a portion of an artery or vein from another part of the body to use as a graft and installs the graft to bypass the obstruction. Alternatively, the surgeon dissects a healthy artery adjacent to the diseased artery, detaches one end of the healthy artery and connects that end to the coronary artery past the obstruction while leaving the other end attached to the natural arterial supply. Either of these two methods can restore normal blood flow to the heart.
The CABG procedure thus requires that one or more connections be established that bypass blockage in a diseased artery to restore an adequate blood flow. Typically, one end of a graft is sewn to the aorta, while the other end of the graft is sewn to a coronary artery, such as the left anterior descending artery (LAD), which provides blood flow to the left side of the heart. This procedure is known as a “free bypass graft.” Alternatively, the IMA pedicle may be dissected free of the chest wall, while still attached to its natural arterial supply, and its distal end attached to the blocked artery distal of the obstruction. This procedure is known as an “in situ bypass graft.”
In an in situ bypass graft, the IMA must be dissected free until there is sufficient length and slack in the IMA to ensure that the graft is not under tension and that it does not kink after it is repositioned. The IMAs, left and right, extend from the subclavian arteries in the neck to the diaphragm and run along the backside of the rib cage adjacent the sternum. They also contain side branches that require ligation to ensure that blood flow through the graft supplies the coronary artery, rather than being shunted off to other regions via various open branches.
Traditional methods for harvesting elongate vessels such as the IMAs involve the use of blunt probes that are pushed through body tissue to accomplish the dissection. (See Chin, U.S. Pat. No. 5,797,946, incorporated herein by reference). But, the force exerted during use of mechanical probes may lead to blood vessel trauma and branch avulsion.
Everting balloons, on the other hand, are more gentle and may be used to dissect along a vessel. But, it is difficult for the everting balloons presently available to follow vessels such as the IMAs. This is caused by the greater fixation that exists between these vessels and the tissue that surrounds them and to the characteristics of existing everting balloon dissectors. For example, a traditional everting balloon placed adjacent the saphenous vein in the leg, may squirt off in either direction upon inflation rather than track along the vein. This is due to the anatomical structures and to the fixation between the saphenous vein and the tissues that surround the vein.
Another problem associated with balloon dissectors adjacent a blood vessel is that after an initial dissection, a second dissection is more difficult. After connective tissue separating two layers of tissue has been ruptured due to an initial dissection, the healing process that ensues may involve formation of scar tissue. The scar tissue replacing the normal connective tissue is more difficult to dissect. The everting balloons presently available have difficulty tracking along a blood vessel through such scar tissue.
A need exists for new devices with adequate directional control to dissect small elongated cavities in tissue planes, particularly along the course of blood vessels, and more particularly, along the course of smaller blood vessels such as IMAs. A need also exists for new devices to dissect elongated cavities in tissue planes that have been dissected previously.
SUMMARY OF THE INVENTION
The present invention provides a cannula assembly for dissecting an elongated cavity in tissue planes, particularly along the course of a vessel, and more particularly along the course of a smaller blood vessel such as an IMA. The assembly includes an elongate tubular member comprising a hollow tube having a wall, proximal and distal ends and a lumen extending therethrough. In one embodiment, the hollow tube has a flattened or oval shaped distal end that is bent to facilitate insertion in between the ribs. Alternatively, the hollow tube can have an ogee offset at its distal end.
The dissection device also has means for connecting the hollow tube to an inflation source in order to inflate an elongate tubular balloon in fluid communication with the hollow tube. The means for connecting the hollow tube to an inflation source include an opening in the proximal end of the hollow tube or an opening in the wall of the hollow tube. Fluid, gas, or a liquid such as water or saline, can therefore be delivered from a syringe, a hand bulb pump, a piston pump, or the like to the interior of the elongate tubular balloon.
An elongate tubular balloon having an open proximal end and a closed distal end is coupled to the hollow tube and may be inverted and stored inside the hollow tube. The open proximal end of the elongate tubular balloon is coupled in a fluid-tight manner to the hollow tube. In one embodiment, the proximal end of the elongate tubular balloon is sealed around the outer wall of the hollow tube at its distal end. However, the open proximal end of the elongate tubular balloon may also be sealed to the lumen of the hollow tube or around the outer wall of the hollow tube at its proximal end.
The distal portion of the deflated elongate tubular balloon can be inverted toward the proximal portion and stored inside the hollow tube or in a reservoir formed in the balloon itself. Thus, in its deflated state, the distal end of the elongate tubular balloon may be stored proximal of its proximal end. Additional inward folds may be used to further shorten the length of the deflated elongate tubular balloon.
During inflation, this inverted embodiment of the elongate tubular balloon everts and advances beyond the distal end of the hollow tube until it is completely inflated. The fully inflated elongate tubular balloon can be as long as or longer than the hollow tube.
The dissection device also comprises a means for deflating the elongate tubular balloon, such as a vent or a deflation valve on the hollow tube. The elongate tubular balloon may be inflated and deflated multiple times during a single use.
The dissection device may also include means for retracting and re-inverti
General Surgical Innovations Inc.
Truong Kevin T.
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