Tubular restraint release approaches for electrolytic implant delivery system

Abstract

Medical devices and methods for delivery or implantation of prostheses within hollow body organs and vessels or other luminal anatomy are disclosed. The subject technologies may be used in the treatment of atherosclerosis in stenting procedures or be used in variety of other procedures. The systems may employ a self expanding stent restrained by one or more members released by an electrolytically erodable latch. Such release means do not connect directly to the implant, though one or more portions may contact it.

Description

BACKGROUND

[0001] Implants such as stents and occlusive coils have been used in patients for a wide variety of reasons. One of the most common “stenting” procedures is carried out in connection with the treatment of atherosclerosis, a disease which results in a narrowing and stenosis of body lumens, such as the coronary arteries. At the site of the narrowing (i.e., the site of a lesion) a balloon is typically dilatated in an angioplasty procedure to open the vessel. A stent is set in apposition to the interior surface of the lumen in order to help maintain an open passageway. This result may be effected by means of a scaffolding support alone or by virtue of the presence of one or more drugs carried by the stent to aide in the prevention of restenosis.

[0002] Various stent designs have been developed and used clinically, but self-expandable and balloon-expandable stent systems and their related deployment techniques are now predominant. Examples of self-expandable stents currently i...

Examples

example 1

[0209] The impact of AC voltage on actual erosion / corrosion rates during bench tests of tensioned 0.002″ stainless steel wire was conducted. Setups were provided in which an insulated wire was equally tensioned and exposed along a 0.020 inch long section. The wires were placed in 38° porcine blood and power was applied. When applying 2V DC, it took 3-4 minutes to break the wire. When applying 2V DC and 10 Vpp AC, time to separation ranged from 20-30 seconds. The setups tested under DC-only conditions were observed to generate roughly 0.040 inch balls of electrocoagulation on the ends of the wire opposite the eroded section. In marked contrast, the AC / DC power driven setups showed no visible electrocoagulation.

example 2

[0210] The same test piece setup described in Example 1 was used with a lower DC voltage. With only 1V DC the wire would not break even after 15 minutes of applied power. When a 10 Vpp AC signal was added to the 1V DC signal, the sample test section broke in roughly 1 minute.

example 3

[0211] Tests were conducted to determine the improvement offered over the power supply provided by Target Therapeutics for detatching GDC® coils. First a comparative model was developed. The electrolytic “joint” in a GDC system was determined to be about a 0.005 inch long, 0.003 inch diameter stainless steel wire. In 38° porcine blood, with the Target Therapeutics power supply set at a 1 mA currently delivery setting, voltage metered by the power supply initially showed at 3V, rose to 6.5V for the majority of the deployment time, and then rose to 8V. Over a deployment time measured at 40 seconds, the average voltage observed was about 6.5V. In addition, a ball of electrocoagulation having about a 1 / 32 inch diameter was observed.

[0212] A “test joint” model was developed to compare a number of samples in performance. It employed a roughly identically sized exposed wire extension as described above, but no occlusive coil attached thereto. In eroding the wire extension with the Target ...

BACKGROUND

[0001] Implants such as stents and occlusive coils have been used in patients for a wide variety of reasons. One of the most common “stenting” procedures is carried out in connection with the treatment of atherosclerosis, a disease which results in a narrowing and stenosis of body lumens, such as the coronary arteries. At the site of the narrowing (i.e., the site of a lesion) a balloon is typically dilatated in an angioplasty procedure to open the vessel. A stent is set in apposition to the interior surface of the lumen in order to help maintain an open passageway. This result may be effected by means of a scaffolding support alone or by virtue of the presence of one or more drugs carried by the stent to aide in the prevention of restenosis.

[0002] Various stent designs have been developed and used clinically, but self-expandable and balloon-expandable stent systems and their related deployment techniques are now predominant. Examples of self-expandable stents currently i...

Examples

example 1

[0209] The impact of AC voltage on actual erosion / corrosion rates during bench tests of tensioned 0.002″ stainless steel wire was conducted. Setups were provided in which an insulated wire was equally tensioned and exposed along a 0.020 inch long section. The wires were placed in 38° porcine blood and power was applied. When applying 2V DC, it took 3-4 minutes to break the wire. When applying 2V DC and 10 Vpp AC, time to separation ranged from 20-30 seconds. The setups tested under DC-only conditions were observed to generate roughly 0.040 inch balls of electrocoagulation on the ends of the wire opposite the eroded section. In marked contrast, the AC / DC power driven setups showed no visible electrocoagulation.

example 2

[0210] The same test piece setup described in Example 1 was used with a lower DC voltage. With only 1V DC the wire would not break even after 15 minutes of applied power. When a 10 Vpp AC signal was added to the 1V DC signal, the sample test section broke in roughly 1 minute.

example 3

[0211] Tests were conducted to determine the improvement offered over the power supply provided by Target Therapeutics for detatching GDC® coils. First a comparative model was developed. The electrolytic “joint” in a GDC system was determined to be about a 0.005 inch long, 0.003 inch diameter stainless steel wire. In 38° porcine blood, with the Target Therapeutics power supply set at a 1 mA currently delivery setting, voltage metered by the power supply initially showed at 3V, rose to 6.5V for the majority of the deployment time, and then rose to 8V. Over a deployment time measured at 40 seconds, the average voltage observed was about 6.5V. In addition, a ball of electrocoagulation having about a 1 / 32 inch diameter was observed.

[0212] A “test joint” model was developed to compare a number of samples in performance. It employed a roughly identically sized exposed wire extension as described above, but no occlusive coil attached thereto. In eroding the wire extension with the Target ...

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