Surgery – Miscellaneous – Methods
Reexamination Certificate
2000-08-08
2002-02-05
McDermott, Corrine (Department: 3738)
Surgery
Miscellaneous
Methods
C623S003100, C623S003120, C606S016000
Reexamination Certificate
active
06343605
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to devices and methods for increasing the blood pumping efficiency of a heart muscle. More particularly, the present invention relates to devices and methods for treating a heart including one or more areas of non-contracting myocardial tissue that are causing low output ejection fraction.
BACKGROUND OF THE INVENTION
The blood pumping action of the heart muscle is critical to sustaining the life of a patient. One condition that is likely to reduce the blood pumping efficiency of the heart muscle is ventricular dilation. When ventricular dilation occurs a ventricle chamber (commonly the left ventricular chamber) becomes enlarged. As the chamber becomes enlarged, the internal surface area of the chamber increases rapidly. Blood flowing within the heart applies pressure to the internal surface of the heart chamber. Because the blood applies pressure inside the heart chamber across an increased surface area, the force which must be produced by the heart in order to pump blood also increases. In many cases, the cardiac disease which caused the ventricular dilation also limits the ability of the heart muscle to produce the increased force required to efficiently pump blood. In many cases, the dilation of the heart chamber becomes progressively worse, and the blood pumping efficiency of the heart muscle progressively declines. Ultimately, ventricular dilation may result in heart failure.
In order for the heart to function properly the tissues of the heart muscle must be continuously supplied and re-supplied with oxygen. To receive an adequate supply of oxygen, the heart muscle must be well perfused with blood. If the flow of blood to a portion of the heart muscle is interrupted or diminished, that portion of the heart muscle may stop contributing to the blood pumping action of the heart muscle.
In a healthy heart, blood perfusion is accomplished with a system of blood vessels and capillaries. However, it is common for the blood vessels to become occluded (blocked) or stenotic (narrowed). A stenosis may be formed by an atheroma that is typically a harder, calcified substance that forms on the walls of a blood vessel.
Historically, individual stenotic lesions have been treated with a number of medical procedures including coronary bypass surgery, angioplasty, and atherectomy. Coronary bypass surgery typically involves utilizing vascular tissue from another part of the patient's body to construct a shunt around the obstructed vessel. Angioplasty techniques such as percutaneous transluminal angioplasty (PTA) and percutaneous transluminal coronary angioplasty (PTCA) are relatively non-invasive methods of treating a stenotic lesion. These angioplasty techniques typically involve the use of a guidewire and a balloon catheter. In these procedures, a balloon catheter is advanced over a guidewire such that the balloon is positioned proximate a restriction in a diseased vessel. The balloon is then inflated and the restriction in the vessel is opened. A third technique that may be used to treat a stenotic lesion is atherectomy. During an atherectomy procedure, the stenotic lesion is mechanically cut or abraded away from the blood vessel wall.
Coronary by-pass, angioplasty, and atherectomy procedures have all been found effective in treating individual stenotic lesions in relatively large blood vessels. However, the heart muscle is perfused with blood through a network of small vessels and capillaries. In some cases, a large number of stenotic lesions may occur in a large number of locations throughout this network of small blood vessels and capillaries. The torturous path and small diameter of these blood vessels limit access to the stenotic lesions. The sheer number and small size of these stenotic lesions make techniques such as cardiovascular by-pass surgery, angioplasty, and atherectomy impractical.
When techniques that treat individual lesions are not practical other techniques of improving the oxygenation of myocardial tissue may be utilized. One technique of improving the oxygenation of myocardial tissue is known as percutaneous myocardial revascularization (PMR). A PMR procedure generally involves the creation of holes, craters or channels directly into the myocardium of the heart. PMR was inspired in part by observations that reptilian heart muscles are supplied with oxygen primarily by blood perfusing directly from within heart chambers to the heart muscle. This contrasts with the human heart, which is supplied by coronary vessels receiving blood from the aorta. Positive clinical results have been demonstrated in human patients receiving PMR treatments. These results are believed to be caused in part by blood flowing within a heart chamber through channels in myocardial tissue formed by PMR. Increased blood flow to the myocardium is also believed to be caused in part by the healing response to wound formation. Specifically, the formation of new blood vessels is believed to occur in response to the newly created wound. This response is sometimes referred to as angiogenisis. In addition to promoting increased blood flow, it is also believed that PMR improves a patient's condition through denervation. Denervation is the elimination of nerves. The creation of wounds during a PMR procedure results in the elimination of nerve endings which were previously sending pain signals to the brain as a result of hibernating tissue.
SUMMARY OF THE INVENTION
The present invention relates generally to devices and methods for increasing the volume of blood pumped by a heart muscle. More particularly, the present invention relates to devices and methods for treating a heart including one or more areas of non-contracting myocardial tissue that are causing low output ejection fraction. A therapeutic catheter in accordance with the present invention includes a distal end, a proximal end, and an elongate shaft defining a lumen. A hub is disposed about the elongate shaft proximate its proximal end and a cutter is fixed to the elongate shaft proximate its distal end. The cutter includes a distal edge and a cutter lumen.
The therapeutic catheter also includes a mooring member disposed at a distal end of a mooring shaft. In a preferred embodiment, the mooring shaft is slidingly disposed within the lumen of the elongate shaft and cutter lumen of the cutter. A knob is fixed to a proximal end of the mooring shaft. In a preferred embodiment, the knob is adapted to be rotated by the fingers of a physician. In this preferred embodiment, the rotary motion of the knob is transferred to the mooring member via the mooring shaft.
A trocar in accordance with the present invention includes a body defining a trocar lumen. The body of the trocar includes a flange, a penetrating portion, a distal end, and a proximal end. A proximal aperture of the trocar is in fluid communication with the trocar lumen. In a preferred embodiment, the trocar lumen of the trocar is adapted to receive the therapeutic catheter. In a preferred method in accordance with the present invention, the distal end of the therapeutic catheter is inserted into the trocar lumen through the proximal aperture.
A guide catheter in accordance with the present invention includes an elongate tubular member defining a central lumen. A plurality of moorings are disposed proximate a distal end of the guide catheter. In one method in accordance with the present invention, the moorings may be utilized to retain the distal end of the guide catheter proximate a donee site. In a preferred embodiment, each mooring comprises a vacuum orifice. In this preferred embodiment, each vacuum orifice is in fluid communication with a vacuum lumen defined by the elongate tubular member of the guide catheter.
Other embodiments of the moorings are possible without deviating from the spirit or scope of the present invention. For example, each mooring may be comprised of an elongate wire with a helix disposed proximate its distal end. The helical end of the elongate wire may be “threaded” into the tissue proximate the d
Chattopadhyay Urmi
Crompton Seager & Tufte LLC
McDermott Corrine
Scimed Life Systems Inc.
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