Surgery – Devices transferring fluids from within one area of body to... – With flow control means
Reexamination Certificate
2000-02-10
2003-02-04
Jacyna, J. Casimer (Department: 3351)
Surgery
Devices transferring fluids from within one area of body to...
With flow control means
C600S016000, C623S003100
Reexamination Certificate
active
06514226
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to the treatment of congestive heart failure (CHF). In particular, the invention relates to a method and apparatus to treat patients with congestive heart failure by normalization of kidney perfusion to restore to the patient the benefits of normal kidney functioning.
BACKGROUND OF THE INVENTION
A. Congestive Heart Failure (CHF)
Congestive heart failure (CHF) is a serious condition affecting an estimated 5 million Americans. Increasing prevalence, hospitalizations, and deaths have made CHF a major chronic health condition in the United States. There are an estimated 400,000 new cases of CHF each year. These cases are often first diagnosed as the end stage of cardiac disease. The average mortality rate of CHF is 10 percent after the 1st year and 50 percent after 5 years. Thus, half of the patients diagnosed with CHF will die within 5 years of their diagnosis.
The magnitude of the problem is expected to get much worse as more cardiac patients are able to survive and live longer. As patients live longer, the potential for developing CHF increases. In addition, because the incidence of heart failure rises substantially beyond age 65, the prevalence of this condition is likely to increase as the population ages.
The high prevalence of heart failure and the resulting high cost of caring for these patients places a significant economic burden on society. The American Heart Association statistics report that, including medications, an estimated $22.5 billion will be spent for the care of CHF patients in hospitals, physicians offices, home care, and nursing homes including medications in the year 2000. In light of the high costs and poor prognosis of CHF, there is a pressing need to prevent this condition and provide better clinical management to reduce morbidity and mortality.
Congestive heart failure (CHF) is a diseased condition in which the heart fails to function efficiently as a pump to provide sufficient blood flow and/or pressure to fulfill the normal circulatory needs of a patient. CHF is the primary reason for tens of thousands of deaths each year and is a contributing factor in an additional 200,000 more deaths. CHF results in sudden shortness of breath, fainting and irregular heart beats that require frequent emergency room treatments (acute CHF), and in its chronic form leads to repeated hospital stays, deteriorating quality of life and significant costs to the health care system. Congestive heart failure is characterized by: (1) signs and symptoms of intravascular and interstitial volume overload, including shortness of breath, fluid in the lungs, and edema, and (2) manifestations of inadequate tissue perfusion, such as fatigue or poor exercise tolerance. These signs and symptoms result when the heart is unable to generate a cardiac output sufficient to meet the body's demands.
A healthy heart pumps blood by increasing the kinetic energy (pressure and/or velocity) of the blood flowing through a person's circulatory system. The energy imparted by a heart to the blood flow is normally sufficient to cause the blood to circulate through the lungs, kidney and other organs of the body. A failing heart is generally unable to maintain normal blood pressure within the circulatory system of a person. The body responds to a failing heart by diverting much of the available blood flow to the brain and heart and reducing the blood flow to other body organs, including the kidneys. Thus, the body acts to save the brain (which cannot survive more than a few minutes of inadequate blood flow).
The heart ejects oxygen-enriched blood into the aorta, which is a huge blood vessel, from which branches all other arteries that lead to the different organs of the body. These organs use the oxygen from the arterial blood. Used blood deprived of oxygen and containing the metabolic byproduct carbon dioxide is collected from the organs via individual veins and is returned to the lungs via the pulmonary vein. Accordingly, the heart pumps the blood into the aorta and forces the blood to circulate through the arteries, organs, veins and lungs.
Arteries by expanding or contracting regulate the blood supply flowing to individual tissues and organs. Arterial walls are made of thin layers of muscle fibers that expand and contract. The expansion and contraction of the arteries controls the flow of blood through a patient's circulatory system in a manner similar to the way valves control the flow of water through the water pipes in a home. The arterial walls contract or relax responding to different stimuli decreasing or increasing the inner cross section of the vessel. The contraction of the arteries is called vasoconstriction and the relaxation is called vasodilation. In this manner, depending on the oxygen needs of an organ or tissue, arterial blood flow is controlled and the supply of oxygen rich blood is regulated. Only as much arterial blood as needed is supplied to organs depending on the functions they are performing at the time.
When the demand for oxygen delivery from the blood exceeds the available blood supply for a particular organ, the organ becomes ischemic (which is a condition in which minimized blood flow can lead to oxygen starvation of an organ). If allowed to persist, ischemia leads to severe tissue damage. The complex network of neurohormonal messengers indicates to the brain that the blood supplied by the heart and the blood vessels is not sufficient to support the current metabolic needs of that organ. The body reacts to ischemic by supplying more blood to the organ(s) needing more oxygen in order of priority. For example, the legs of a human runner get more blood during exercise because the leg muscles are working hard and need extra oxygen. Similarly, the runner's gut receives an increase of blood flow when food is digested. If the runner tries to eat and run at the same time, he may get cramps in the legs or stomach pain because of ischemia. The brain reacts by altering the autonomic nervous system activity and neurohormonal secretions to attempt to divert additional blood flow from other organs to augment the blood supply to the ischemic organs to meet their metabolic demands. Accordingly, in a healthy patient, the circulatory system is adjusted by the brain so that all organs receive adequate blood supply. However, the body cannot supply adequate blood flow to all organs when the heart begins to fail during CHF. The ultimate priority for the body is always to maintain sufficient blood pressure in the aorta at any cost to protect the brain.
Heart failure is not simply a disease of the heart, but rather is a complex disease process that involves interaction of many of the body's systems. It is believed that the body reaction to a signal of low blood pressure is based on the body's interpretation that it has suffered a severe injury that caused massive bleeding. In this situation, the body attempts to reduce the probability of death from low blood pressure by diverting blood flow away from the organs that can temporarily tolerate ischemia (e.g., the body extremities, liver and kidneys) to the vital organs (brain and heart) that cannot tolerate even momentary ischemia (such as the brain and heart). In the situation of bleeding, if the bleeding stops in a brief amount of time, the blood pressure will rise in the circulatory system. As blood pressure rises, the body will restore normal blood flow through the entire circulatory system and to all body organs. It appears that evolution has adapted the human body to react to severely reduced blood pressure by temporarily reducing blood flow to less vital organs such as limbs, gut or kidney. This reaction assumes that normal blood pressure will be quickly restored or the person will die from their injuries.
This same originally beneficial evolutionary reaction to reduced blood pressure appears to be deleterious in the setting of congestive heart failure. Congestive heart failure is not relieved by reducing blood flow to body organs and body exterminates. In f
Gelfand Mark
Levin Howard R.
CHF Solutions Inc.
Jacyna J. Casimer
LandOfFree
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