Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-02-22
2002-11-12
Lazarus, Ira S. (Department: 3749)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S540000, C604S272000, C604S065000
Reexamination Certificate
active
06478769
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for evacuating anatomical fluids while preventing the puncture of underlying tissue, and especially relates to an apparatus and method for performing pericardiocentesis in response to emergent cardiac tamponade or other emergency conditions where pericardiocentesis is indicated.
Percardiocentesis, or pericardial tap, is the removal of fluid from the pericardial sac through a needle lumen. The pericardium is a fibrous organ that surrounds and encapsulates the heart. Under normal conditions, the pericardium is filled to a moderate pressure with a clear anatomical fluid. The function of the pericardium is to prevent dilatation of the heart chambers, to lubricate the surface of the heart, and to maintain the heart in its normal fixed position. The pericardium also functions to prevent the spread of infection from adjacent tissue to the heart, and prevents the adhesion of other tissues to the heart. The epicardium is the visceral portion of the pericardium that lies closest to the heart surface.
Pericardiocentesis may be indicated for numerous reasons. Pericardiocentesis is useful, for example, to withdraw fluids from the pericardium for study and analysis to assist in the diagnosis of pericardial diseases. In some cases, the patient upon whom diagnostic pericardiocentesis will be performed will be administered medication to prevent vasovagal reflex resulting in bradycardia (a slowing of the heartbeat) or hypotension (low blood pressure). The needle is inserted just below the sternum with a local anesthetic applied. As the needle is pushed forward into the pericardial sac, the fluid is withdrawn using the syringe attached to the needle. In some cases, an indwelling pericardial catheter may be placed in the patient for continuous drawing of the pericardial fluid for periodic analysis.
Another application for pericardiocentesis is the infusion of therapeutic agents into the pericardium for the treatment of disease. Generally speaking, however, intrapericardial injection of drugs is limited to the treatment of abnormal pericardial conditions and diseases, such as malignant or loculated pericardial effusions and tumors. Drugs that have been injected into the pericardium through pericardiocentesis include antibiotics, antineoplastic drugs, and radioactive agents. It is believed that a relatively low percentage of all pericardiocentesis procedures performed today are undertaken for this purpose. Intrapericardial drug delivery has not been utilized to treat heart-specific conditions because the pericardial space is quite small and difficult to access without invasive surgery, and the risk of cardiac injury through traditional pericardiocentesis techniques is quite high.
A third application of pericardiocentesis is the withdrawal of pericardial fluid for the treatment of acute cardiac tamponade. Acute cardiac tamponade occurs when fluid builds up within the pericardium sac, which leads to compression of the heart. As effusion fluid builds up within the pericardium, the fluid may exert sufficient pressure on the heart muscle to prevent it from pumping blood, thereby leading to the death of the patient. Cardiac tamponade is suggested by the findings of hypotension, increased central venous pressure, pulsus paradoxus, loss of the apical impulse, and distant heart sounds. Cardiac tamponade may occur due to medical causes, or may be the result of surgical procedures, such as in the case of postoperative anticoagulation or postpericardiotomy syndrome. Since patients requiring pericardiocentesis to relieve acute cardiac tamponade are often treated under emergency conditions with the patient near death as the procedure is performed, immediate diagnosis and administration of effective treatment is imperative.
A significant risk associated with the use of pericardiocentesis is the puncture of the myocardium (heart wall), a coronary artery, or the walls of other nearby organs, such as the lung, liver, or stomach. Because the pericardial space is quite small, it is difficult for the physician performing pericardiocentesis to accurately determine when the fibrous pericardium wall has been breached by the needle, while simultaneously preventing contact between the distal end of the needle and the myocardium. In an adult patient, 5-10 mm may be sufficient penetration beneath the skin to reach the pericardial fluid, but this number is highly variable based on the patient's height, weight, and condition. The physician performing this procedure inserts the needle immediately to the left of the xiphisternum and towards the tip of the left scapula, slowly drawing backward on the plunger of the syringe to which the needle is attached. The physician stops the advance of the needle when pericardial fluid is seen to begin collecting in the syringe. If, however, the physician does contact or puncture the myocardium, the result may be myocardial infarction, need-induced arrhythmias, ventricular fibrillation, or even acute cardial tamponade, any of which can lead to the death of the patient. One study reports that, although exact figures concerning the incidence of acute cardial tamponade as a result of pericardiocentesis are not known, the majority of one group of prominent cardiologists and surgeons had personal knowledge of one or two such incidents. Linton H. Bishop, Jr., et al.,
The Electrocardiogram as a Safeguard in Pericardiocentesis
, 162 J.A.M.A. 264 (Sept. 22, 1956). Because of the high risk associated with emergency-room use of pericardiocentesis to relieve acute cardiac tamponade, the procedure is currently performed only when the life of the patient is perceived to be immediately at stake.
A number of methods have been suggested to reduce the risk of contacting or puncturing the myocardium during pericardiocentesis. One method is to combine two-dimensional echocardiography with the pericardiocentesis procedure. Shigefumi Suehiro, et al.,
Echocardioranphy-Guided Pericardiocentesis with a Needle Attached to a Probe
, 61 Ann. Thorac. Surg. 741 (1996) discloses an echocardiographic probe with an attached pericardiocentesis needle for this purpose. The tip of the pericardial needle is scratched with a scalpel to improve the echo-return intensity of the needle. When the needle is inserted to perform the pericardiocentesis procedure, the tip of the needle can be seen on the echocardiograph monitor. The operator may thereby visually determine the position of the needle tip relative to the heart. Although Suehiro discloses that the procedure may be performed with one operator, such an operator would be required to divert his or her attention from the insertion of the needle to observe the echocardiography monitor.
Another method to reduce the risk of puncturing the myocardium during a procedure to access the pericardial cavity is disclosed in U.S. Pat. No. 5,827,216 to Igo et al. Igo et al. discloses an apparatus and method for introducing a tube percutaneously to contact the exterior surface of the pericardium. A vacuum is introduced within a tube such that a bleb is formed on the pericardium surface. A needle within the tube is then advanced to puncture the pericardial bleb, while avoiding contact with the myocardium. A guide wire within the needle may then be advanced into the pericardial cavity, and may be used to guide an intrapericardial catheter for injection or infusion of therapeutic agents. Drugs may also be injected directly through the needle into the pericardial space.
Perhaps the most widely recognized method to reduce the risk of puncturing the myocardium during pericardiocentesis is to connect the patient and needle to an electrocardiograph, as described in Bishop, supra; James R. Neill, et al.,
A Pericardiocentesis Electrode
, 264 N. Engl. J. Med. 711 (Apr. 6, 1961); Richard E. Kerber, et al.,
Electrocardiographic Indications of Atrial Puncture during Pericardiocentesis
, 282 N. Engl. J. Med. 1142 (May 14, 1970); and Mervyn S. Gotsman & Velva Schrire,
A Pericardiocentesis Electrode Needle
, 28 Brit.
Dougherty J. Charles
Lazarus Ira S.
Nguyen Tu Cam
The Board of Trustees of the University of Arkansas
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