Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-05-16
2001-02-06
Weiss, John G. (Department: 3761)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S207000
Reexamination Certificate
active
06183444
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to surgical and interventional drug delivery devices, with or without auxiliary or enhanced visualization, capable of accessing the heart or other internal organ that includes drug delivery regulation mechanism incorporated in a hand-held assembly. In particular, the preferred devices are modular, comprising a drug delivery module with drug metering capability, optionally using an articulating or non-articulating rigid endoscope or a flexible catheter, and used in either open surgical procedures, minimally invasive surgical and percutaneous, catheter-based procedures.
2. Background of the Invention
The human heart is a muscular dual pump that beats continuously throughout life sending blood to the lungs and the rest of the body. The interior of the heart consists of four distinct chambers. The septum, a thick central muscular wall, divides the cavity into right and left halves. On the right side, the upper half is known as the right atrium. Deoxygenated blood from the rest of the body arrives in the right atrium via the vena cava, the blood is pumped across a one-way valve known as the tricuspid valve into the lower portion known as the right ventricle. From there the blood circulates to the lungs through the pulmonary valve via the pulmonary artery where it is oxygenated by circulation through the alveoli of the lungs (not shown). The blood returns via the pulmonary veins to the left atrium and flows through a second valve, the mitral valve into the left ventricle where it is pumped via the aorta to the rest of the body.
Much of the heart consists of a special type of muscle called myocardium. The myocardium requires a constant supply of oxygen and nutrients to allow it to contract and pump, blood throughout the vasculature. The inner surfaces of the chambers of the heart are lined with a smooth membrane, the endocardium, and the entire heart is enclosed in a tough, membranous bag known is the pericardial sac.
The pumping action of the heart has three main phases for each heart beat. Diastole is the resting phase during which the heart fills with blood: while deoxygenated blood is entering, the right atrium, oxygenated blood is returned from the lungs to the left atrium. During atrial systole, the two atria contract simultaneously, squeezing the blood into the lower ventricles. Finally, during ventricular systole the ventricles contract to pump the deoxygenated blood into the pulmonary arteries and the oxygenated blood into the main aorta. When the heart is empty, diastole begins again. The electrical impulses which stimulate the heart to contract in this manner emanate from the heart's own pacemaker, the sinoatrial node. The heart rate is under the external control of the body's autonomic nervous system.
Though the heart supplies blood to all other parts of the body, the heart it self has relatively little communication with the oxygenated blood supply. Thus, the two coronary arteries, the left coronary artery and the right coronary artery, arise from the aorta and encircle the heart muscle on either side “like a crown” to supply the heart itself with blood.
Heart disorders are a common cause of death in developed countries. They also impair the quality of life of millions of people and restrict activity by causing pain, breathlessness, fatigue, fainting spells and anxiety. The major cause of heart disease in developed countries is impaired blood supply. The coronary arteries become narrowed due to atherosclerosis and part of the heart muscle is deprived of oxygen and other nutrients. The resulting ischemia or blockage can lead to angina pectoris, a pain in the chest, arms or jaw due to lack of oxygen to the heart's myocardium, infarction or tissue necrosis in myocardial tissue.
Techniques to supplement the flow of oxygenated blood directly from the left ventricle into the myocardial tissue have included needle acupuncture to create transmural channels (see below) and implantation of T-shaped tubes into the myocardium. Efforts to graft the omentum, parietal pericardium, or mediastinal fat to the surface of the heart had limited success. Others attempted to restore arterial flow by implanting the left internal mammary artery into the myocardium.
Modernly, coronary artery blockage can be relieved in a number of ways. Drug therapy, including nitrates, beta-blockers, and peripheral vasodilator drugs (to dilate the arteries) or thrombolytic drugs (to dissolve clots) can be very effective. If drug treatment fails, transluminal angioplasty is often indicated—the narrowed part of the artery, clogged with atherosclerotic plaque or other deposits, can be stretched apart by passing a balloon to the site and gently inflating it a certain degree. In the event drug therapy is ineffective or angioplasty is too risky (introduction of a balloon in an occluded artery can cause portions of the atherosclerotic material to become dislodged which may cause a total blockage at a point downstream of the subject occlusion, thereby requiring emergency procedures), the procedure known as coronary artery bypass grafting (CABG) is the most common and successful major heart operation performed, with over 500,000 procedures done annually in America alone. A length of vein is removed from another part of the body. The section of vein is first sewn to the aorta and then sewn onto a coronarn artery at a place such that oxygenated blood can flow directly into the heart. CABG typically is performed in an open chest surgical procedure, although recent advances suggest minimally invasive surgery (MIS) techniques may also be used.
Another method of improving myocardial blood supply is called transmyocardial revascularization (TMR), the creation of channels from the epicardial to the endocardial portions of the heart. Initially, the procedure used needles to perform “myocardial acupuncture,” and has been experimented with at least as early as the 1930s and used clinically since the 1960s, see Deckelbaum. L. I., Cardiovascular Applications of Laser Technology,
Lasers in Surgery and Medicine
15:315-341 (1994). The technique was thought to relieve ischemia by allowing blood to pass from the ventricle through the channels either directly into other vessels perforated by the channels or into myocardial sinusoids which connect to the myocardial microcirculation. This procedure has been likened to transforming the human heart into one resembling that of a reptile. In the reptile heart, perfusion occurs via communicating channels between the left ventricle and the coronary arteries. Frazier, O. H., Myocardial Resascularization with Laser—Preliminary Findings,
Circulation
, 1995; 92 [suppl II:II-58-II-65]. There is evidence of these communicating channels in the developing human embryo. In the human heart, myocardial microanatomy involves the presence of myocardial sinusoids. These sinusoidal communications vary in size and structure, but represent a network of direct arterial-luminal, arterial-arterial, arterial-venous, and venous-luminal connections. The needle technique was not continued because the channels did not remain open, replaced by the use of laser energy to accomplish TMR.
Drug therapies with angiogenic growth factors may expedite and/or augment collateral artery development. To accomplish these needs, drug transfer devices for delivering precise amounts of these drugs can enhance this healing process. Surgeons who deal with minimally invasive surgical techniques, and interventional cardiologists who deal with percutaneous approaches, need devices for drug delivery procedures. The drugs used in modern medical technology are often quite expensive, potentially mixing and/or handling sensitive, and it is a new challenge to make these drugs or other compounds readily available for precise, predetermined delivery during these advanced or other procedures.
A great deal of published scientific information is currently available on the internet. One company, Annual Reviews is located at http://www.annurev.org. A l
Brown Daniel S.
Glines Robert C.
Lundquist Lauren
Phipps Richard D.
Blyveis Deborah
Heinkel Gregory L.
Iota Pi Law Group
MicroHeart, Inc.
Shahani Ray K.
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