Surgery – Instruments – Sutureless closure
Reexamination Certificate
1999-05-07
2001-03-27
Truong, Kevin (Department: 3731)
Surgery
Instruments
Sutureless closure
Reexamination Certificate
active
06206907
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION(S)
None.
BACKGROUND OF THE INVENTION
This invention relates to an occlusion device for the closure of physical anomalies like vascular or septal apertures, such as patent ductus arteriosus, patent foramen ovale, atrial septal defects, or ventricular septal defects. The invention comprises a center section extending in an axial direction, upper and lower stranded wire elastic shape memory fixation devices emanating from the center section, with first and second sheets of polyvinyl alcohol foam attached to the fixation devices. The stranded wire elastic shape memory fixation devices are formed from multiple wire strands. This formation greatly increases the resistance to fatigue of the fixation devices and significantly extends the life of the devices after implantation in a patient.
Normally, permanently repairing certain cardiac defects in adults and children requires open heart surgery. Open heart surgery is risky and painful. To avoid it, modern occlusion devices have been developed are that small, implantable devices capable of being delivered through a catheter. Rather than surgery, an occlusion device is deployed by a catheter inserted into a major blood vessel, a procedure that is performed in a cardiac cathlab and avoids the risks and pain associated with open heart surgery. These modem occlusion devices can repair patent ductus arteriosis, patent foramen ovale, atrial septal defects, ventricular septal defects, and other cardiac and non-cardiac apertures.
One such device, disclosed in PCT application PCT/US98/15961, entitled
Occlusion Device for the Closure of a Physical Anomaly Such as a Vascular Aperture or an Aperture in a Septum
, filed on Jul. 31, 1998 by Bernhard Schneidt, discloses a non-thrombogenic occlusion device that is insertable into an anomaly via a catheter. In addition, a similar device filed as German Appln. 297 14 242.9 on Aug. 8, 1997, discloses an occlusion device which can be inserted via a catheter.
The new occlusion devices that are inserted via a catheter include button devices, collapsible umbrella-like structures, and plug-like devices. One major draw back is that the intent of some of these occlusion devices is to fill the ductus and stimulate thrombosus, or a blood clot. Once the blood has clotted around the device, tissue begins to grow thus ensuring that the ductus is permanently closed. Blood clots, however, are potentially dangerous in that they may dislodge, get carried to the brain and cause a stroke.
Occlusion devices with umbrella-like structures use a system of small metal wires to hold the occlusion device in place. Due to the severe environment the human heart presents, including a continuous cycling of up to 5 billion pulses over the lifetime of a human, the wires may develop fatigue failure problems. With each pulse, the wires are strained and eventually may fracture or break, giving rise to potential complications and patient anxiety. In addition to the stress caused by the beating of the heart, metal wires may also be strained when a device is inserted into an irregularly shaped opening. For instance, one side of the opening may only be a few millimeters thick, but another side may be many more millimeters thick. Thus, one side of the occluding device may be bent open ether than the other side, putting more stress on the wires used on that side. This stress from being deformed and bent may also lead to fatigue failures.
Efforts to alleviate the fatigue failures described above include varying the shape and diameter of the wires used in occlusion devices. However, increasing the diameter of the wire can actually result in the wires becoming more brittle and more susceptible to fatigue failure and fracturing. Another effort to prevent failure of the wire is to use coils or hinges. The coils and hinges attempt to distribute the forces acting upon the wires, and prevent the problems with fatigue failures. However, the coils and hinges do not significantly decrease fractures or failures in the wires. So far, nothing has dealt satisfactorily with the fatigue failures in the wires.
Thus, there is a need in the art for an occlusion device that is collapsible enough to fold into a small catheter and constructed of materials that will not cause blood clots. In addition, there is a need for an occlusion device that is durable enough to withstand the heart's pulsing without experiencing fatigue failure.
BRIEF SUMMARY OF THE INVENTION
The present invention is an occlusion device for closure of a physical anomaly. The occlusion device is more durable and will not suffer from fatigue failures caused by the continuous pulsing of the human heart. This is because the fixation devices, which hold the device in place, are constructed of stranded wire. The stranded wire configuration greatly increases the strength and cycle life of the fixation devices without increasing the size of the device. Attached to the fixation devices are sheets (e.g. polyvinyl foam sheets) which serve to occlude the anomaly. The occlusion device is collapsible and capable of being inserted into an anomaly by means of a catheter.
The occlusion device is comprised of a center section to which the stranded wire elastic shape memory fixation devices are attached. The fixation devices hold the occlusion device in place once it is inserted into an aperture. In addition, the sheets attached to the fixation devices act to occlude the aperture. To prevent any damage to surrounding tissue, the fixation devices are fitted with atraumatic tips.
Each of the fixation devices are made of multiple wire strands or cables. Using multiple wire strands or a cable serves to greatly extend the cycle life of the fixation devices and prevent any fatigue failure caused by the severe environment the human heart presents for an occlusion device. Once attached to the center section, the fixation devices are collapsible so that the entire occlusion device can be moved through a catheter. The fixation devices have a shape memory, which allows the fixation devices to return to their original shape, or “remember” their shape even after being bent or deformed for passage through a catheter. In setting the shape, the deformation caused by passage through a catheter is taken into account.
A material suitable for the sheets is a polyvinyl alcohol foam, such as IVALON®. A first sheet is attached to the upper fixation devices and a second sheet is attached to the lower fixation device. The shape of the foam sheets can either be a square or a circle or any other such suitable shape. The sheet on the upper fixation device may be originated asymmetrically from the sheet on the lower fixation device. This is advantageous in that a wider variety of anomalies can be closed using such an arrangement, including anomalies of different sizes and shapes.
A method of inserting an occlusion device begins by using a guide catheter introduced through the femoral vein and lower vena cava and placed in the right ventricle of the heart. After passing through the defect in the atrial septum, the distal portion of the device is forced out of the catheter and unfolded in the left atrium, much like unfolding an umbrella. The unfolded portion is drawn back against the septum due to the pre-tensioning of the fixation devices. Then, the proximal parts of the implant are likewise pushed out of the catheter and independently unfolded in the right atrium. The insertion forceps used to guide the occlusion device through the catheter are then separated from the center piece.
REFERENCES:
patent: 4917089 (1990-04-01), Sideris
patent: 5108420 (1992-04-01), Marks
patent: 5171259 (1992-12-01), Inoue
patent: 5284488 (1994-02-01), Sideris
patent: 5425744 (1995-06-01), Fagan et al.
patent: 5433727 (1995-07-01), Sideris
patent: 5451235 (1995-09-01), Lock et al.
patent: 5634936 (1997-06-01), Linden et al.
patent: 5702421 (1997-12-01), Schneidt
patent: 5709707 (1998-01-01), Lock et al.
patent: 5725552 (1998-03-01), Kotula et al.
patent: 5741297 (1998-04-01), Simon
patent: 5944738 (1999-08-01), Amplat
Buonomo Peter M.
Corcoran Michael P.
Marino Joseph A.
Cardia Inc.
Kinney & Lange , P.A.
Truong Kevin
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