Surgery – Instruments – Means for inserting or removing conduit within body
Reexamination Certificate
2001-06-18
2002-09-10
Philogene, Pedro (Department: 3732)
Surgery
Instruments
Means for inserting or removing conduit within body
C606S194000, C623S001110, C623S001220
Reexamination Certificate
active
06447522
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to delivery devices for implants placeable within tissue of the human body. Specifically, the invention relates to delivery of implants configured to aid in the restoration of blood flow to myocardial tissue of the heart. The invention includes a mechanism to monitor the position of the device and deliver drugs.
BACKGROUND OF THE INVENTION
Tissue becomes ischemic when it is deprived of adequate blood flow. Ischemia causes pain in the area of the affected tissue and, in the case of muscle tissue, can interrupt muscular function. Left untreated, ischemic tissue can become infarcted and permanently non-functioning. Ischemia can be caused by a blockage in the vascular system that prohibits oxygenated blood from reaching the affected tissue area. However, ischemic tissue can be revived to function normally despite the deprivation of oxygenated blood because ischemic tissue can remain in a hibernating state, preserving its viability for some time. Restoring blood flow to the ischemic region serves to revive the ischemic tissue.
Although ischemia can occur in various regions of the body, often tissue of the heart, the myocardium, is affected by ischemia due to coronary artery disease, occlusion of the coronary artery, which otherwise provides blood to the myocardium. Muscle tissue affected by ischemia can cause pain to the individual affected. Ischemia can be treated, if a tissue has remained viable despite the deprivation of oxygenated blood, by restoring blood flow to the affected tissue.
Treatment of myocardial ischemia has been addressed by several techniques designed to restore blood supply to the affected region. Coronary artery bypass grafting CABG involves grafting a venous segment between the aorta and the coronary artery to bypass the occluded portion of the artery. Once blood flow is redirected to the portion of the coronary artery beyond the occlusion, the supply of oxygenated blood is restored to the area of ischemic tissue.
Early researchers, more than thirty years ago, reported promising results for revascularizing the myocardium by piercing the muscle to create multiple channels for blood flow. Sen, P. K. et al., “Transmyocardial Acupuncture—A New Approach to Myocardial Revascularization”,
Journal of Thoracic and Cardiovascular Surgery
, Vol. 50, No. 2, August 1965, pp. 181-189. Although others have reported varying degrees of success with various methods of piercing the myocardium to restore blood flow to the muscle, many have faced common problems such as closure of the created channels. Various techniques of perforating the muscle tissue to avoid closure have been reported by researchers. These techniques include piercing with a solid sharp tip wire, hypodermic tube and physically stretching the channel after its formation. Reportedly, many of these methods still produced trauma and tearing of the tissue that ultimately led to closure of the channel.
An alternative method of creating channels that potentially avoids the problem of closure involves the use of laser technology. Researchers have reported success in maintaining patent channels in the myocardium by forming the channels with the heat energy of a laser. Mirhoseini, M. et al., “Revascularization of the Heart by Laser”,
Journal of Microsurgery, Vol.
2, No. 4, June 1981, pp. 253-260. The laser was said to form channels in the tissue that were clean and made without tearing and trauma, suggesting that scarring does not occur and the channels are less likely to experience the closure that results from healing. U.S. Pat. No. 5,769,843 (Abela et al.) discloses creating laser-made TMR channels utilizing a catheter based system. Abela also discloses a magnetic navigation system to guide the catheter to the desired position within the heart. Aita U.S. Pat. Nos. 5,380,316 and 5,389,096 disclose another approach to a catheter based system for TMR.
Although there has been some published recognition of the desirability of performing transmyocardial revascularization (TMR) in a non-laser catheterization procedure, there does not appear to be evidence that such procedures have been put into practice. For example, U.S. Pat. No. 5,429,144 Wilk discloses inserting an expandable implant within a preformed channel created within the myocardium for the purposes of creating blood flow into the tissue from the left ventricle.
Performing TMR by placing stents in the myocardium is also disclosed in U.S. Pat. No. 5,810,836 (Hussein et al.). The Hussein patent discloses several stent embodiments that are delivered through the epicardium of the heart, into the myocardium and positioned to be open to the left ventricle. The stents are intended to maintain an open channel in the myocardium through which blood enters from the ventricle and perfuses into the myocardium.
Angiogenesis, the growth of new blood vessels in tissue, has been the subject of increased study in recent years. Such blood vessel growth to provide new supplies of oxygenated blood to a region of tissue has the potential to remedy a variety of tissue and muscular ailments, particularly ischemia. Primarily, study has focused on perfecting angiogenic factors such as human growth factors produced from genetic engineering techniques. It has been reported that injection of such a growth factor into myocardial tissue initiates angiogenesis at that site, which is exhibited by a new dense capillary network within the tissue. Schumacher et al., “Induction of Neo-Angiogenesis in Ischemic Myocardium by Human Growth Factors”,
Circulation,
1998; 97:645-650. The authors noted that such treatment could be an approach to management of diffused coronary heart disease after alternative methods of administration have been developed.
SUMMARY OF THE INVENTION
The present invention provides a delivery system for placing implants within tissue in the human body. The implant delivery system of the present invention provides several novel features, which are useful in delivering implants into tissue.
In one aspect of the invention a delivery device is provided that is especially configured to carry multiple tubular shaped implants at its distal end, engaging the implants by their inside surfaces. The delivery devices are inserted percutaneously into a patient and navigated to the site where the implant is to be located. The delivery systems of the present invention are particularly well suited for delivering implants into the myocardium to perform transmyocardial revascularization (TMR). Implants such as stents may be placed by the delivery device into the myocardial tissue to a proper depth to encourage revascularization of ischemic tissue. In such a procedure, positioning the implants into the proper depth within the myocardium is important to the success of the procedure because it has been observed that areas of the myocardium closer to the endocardial surface and to the epicardial surface are more likely to be responsive to revascularization. Additionally, spacing of the implants relative to one another in an area of ischemic tissue is important to the success of the revascularization process and avoiding undesirable side effects of placing foreign objects in the muscle tissue of the myocardium. Additionally, it may be desirable to deliver a therapeutic substance to the implant location, before, after or during delivery of the implant to promote revascularization activity such as angiogenesis. The features of the present invention address these concerns as will be discussed in greater detail below.
Reaching the intended implant delivery location with the delivery devices of the present invention first requires placement of a guide catheter prior to navigation of a deliverable catheter into the left ventricle. A steerable catheter that is placeable within the left ventricle and positionable in multiple locations with one catheterization is disclosed in U.S. application Ser. No. 09/073,118 filed May 5, 1998, the entirety of which is herein incorporated by reference. The delivery devices as described herein are insertable through the lumen o
Ahern John E.
Gambale Richard A.
Parascandola Michael
C. R. Bard Inc.
Kirkpatrick & Lockhart LLP
Philogene Pedro
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