Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-12-07
2003-07-15
Casler, Brian L. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S101010
Reexamination Certificate
active
06592567
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to in-situ perfusion of an organ in a human or animal. In particular, the invention relates to a perfusion catheter for providing supplemental blood flow to a kidney.
BACKGROUND OF THE INVENTION
A long-felt need exists for a renal therapy device that perfuses kidney(s) with blood or another perfusion substance for extended periods, such as for days. Kidneys filter blood to remove body fluids, sodium and toxins, which are expelled from the body as urine. The filtration of blood is performed by a specialized network of capillaries in the kidneys. To properly pass through the kidneys, the blood pressure at the renal artery (the inlet to the kidneys) should be sufficient to force the blood through the network of capillaries.
Kidneys function best when the blood pressure is within a range of normal mean blood pressures, e.g., 60 to 120 mm Hg. When the blood pressure in the renal artery falls below this range of normal pressure, blood does not pass through the kidneys in sufficient volume to properly filter all of the blood in a circulatory system of a patient. Under low blood pressure conditions, the kidneys suffer from impaired renal perfusion which results in a decrease in urine output (and hence a corresponding build-up of fluids, sodium and toxins in the body), unfavorable change of neurohormonal stimulation and increased vasoconstriction (contraction of blood vessels). Prolonged impaired renal perfusion can lead to acute tubular necrosis, renal failure and ultimately dependency on artificial kidney for life.
Impaired renal perfusion may result from chronic heart failure. Chronic heart failure is a condition in which the heart typically deteriorates over an extended period of time, e.g., months or years. Heart failure is a clinical syndrome or condition characterized by (1) signs and symptoms of intravascular and interstitial volume overload, including shortness of breath, fluid in 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. Heart failure is a major public health problem. The National Heart, Lung, and Blood Institute has estimated that more than 5 million Americans have heart failure and that about 400,000 new cases of heart failure are diagnosed each year. Total treatment costs for heart failure-including physician visits, drugs, and nursing home stays—were more than $10 billion in 1990.
A failing heart may not be able to generate sufficient blood pressure to properly perfuse the kidneys. 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 a human body. A failing heart is generally unable to maintain normal blood pressure within the circulatory system of a person. Blood pressure tends to progressively decrease as the heart. progressively fails in a patient suffering from chronic heart failure. Accordingly, chronic heart failure can lead to chronic impaired renal perfusion. Chronic heart failure patients are frequently admitted to the hospital with an onset of acute heart failure, which is an abrupt worsening of their condition that requires intensive care. During these periods of acute hypotension (or low blood pressure) their kidneys are particularly at risk from hypotension and can be severely injured.
There is a long-felt (although unrecognized) need for devices that can treat chronic impaired renal perfusion and, specifically, treat this condition in connection with the acute and chronic heart failure. In this condition patients blood pressure falls below the minimum level required for kidney function. As a result patients are admitted to the hospital with fluid overload resulting from the retention of fluid and sodium by the kidneys. To treat fluid overload, a device is needed that increases the arterial blood pressure at the kidney for extended periods, such as for several days.
In clinical practice it is sometimes desirable to isolate and perfuse an organ, such as the kidney, brain or liver. An organ suffering from inadequate blood flow, e.g., low systemic arterial pressure, may result in ischemia, organ shutdown or stroke. Extracorporeal perfusion of an organ is the process of artificially providing supplemental blood to that organ from an external source, usually a blood pump. The supplemental blood flow to the organ enables the organ to continue function properly, to avoid distressing the organ and may protect or revive an organ suffering from inadequate blood flow.
During perfusion, the blood or blood substitute is supplied to the organ by extracorporeal circuits from an external source, or may be blood drawn from the body and pumped by back into the body at the organ. An extracorporeal circuit, such as a blood pump connected by tubes and catheters to the body, may provide the blood to the organ for perfusion. The blood pump increases the kinetic energy of the blood or the perfusate, increases the perfusion pressure gradient, and sometimes, an oxygenator to add oxygen to the blood stream.
A kidney perfusion catheter is a device that increases the blood pressure at the kidney, and specifically in the renal artery. A catheter is typically a long, thin tube inserted through a patient's skin and into an artery or a vein. The catheter is connected at one end (commonly referred to as its proximate end) to a blood or saline bag, a blood pump or other medical device external to the body. Many people have had short catheters inserted into a vein in their arm to draw blood for blood donations, dialysis, or to receive blood during hospitalization.
Longer catheters exist that are inserted through the skin at the groin into the femoral artery (or vein). These longer catheters are advanced by an interventional radiologist or cardiologist through the artery to a body organ, such as the heart or kidney. These longer catheters often include guide wires, lumens, balloons, and other devices that perform a variety of catheter functions within an artery or organ. For example, a guide wire typically assists the physician in maneuvering the tip of the catheter along the passages of an artery to the intended position in the artery or organ. Once the catheter is properly positioned within a blood vessel, an instrument can be advanced via an internal lumen of the catheter to perform a therapeutic clinical intervention such as an ablation or dilatation or a diagnostic intervention such as angiography. Lumens are typically tubular passages within the catheter for the guide wires, sensor wires, and to pass blood or other fluids through the catheter.
Catheters exist for short-term perfusion of organs during cardiac surgery and other operations. Surgeons also are known to temporarily perfuse selected organs with extracorporeal pumps when major blood vessels, such as the aorta, are being repaired during surgery, vascular intervention and medical treatment. In addition, kidney perfusion catheters have been disclosed that perfuse kidneys in a dead patient until the kidneys are harvested for transplant. These catheters are not suitable for use beyond a few minutes or hours, and would be injurious to the patient if used for several days.
Existing catheters for in-situ perfusion of isolated organs or parts of the body with blood or chemical include a catheter for pelvic perfusion that isolates a portion of a major artery with two occluding balloons. The balloons are attached to a catheter to form a dumb-bell shape in which the balloons are at opposite ends of a tubular catheter section. The balloons anchor the catheter in an artery, form dams blocking the artery and allow the catheter to increase the blood pressure in the arterial section between the balloons. Fluid is infused by the catheter int
Bernard Steve
Gelfand Mark
Levin Howard R.
Casler Brian L.
CHF Solutions Inc.
DeSanto Matthew
Nixon & Vanderhye P.C.
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