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Research Papers

The Design of an Improved Force Focused Angioplasty Catheter

[+] Author and Article Information
Bruce P. Murphy

Trinity Centre for Bioengineering,
Trinity Biomedical Sciences Institute,
Department of Mechanical and
Manufacturing Engineering,
School of Engineering,
152-160 Pearse Street,
Trinity College Dublin,
Dublin 2, Ireland;
National Centre for Biomedical
Engineering Science,
National University of Ireland,
Galway, Ireland
e-mail: bruce.murphy@tcd.ie

Liam T. Breen

Trinity Centre for Bioengineering,
Trinity Biomedical Sciences Institute,
Department of Mechanical and
Manufacturing Engineering,
School of Engineering,
152-160 Pearse Street,
Trinity College Dublin,
Dublin 2, Ireland
e-mail: Liam.breen@tcd.ie

Note this data only relates to failed devices that have been reported to the FDA and represents a small proportion of the number of cutting balloons used in the U.S. This analysis does not mean that the cutting balloon is clinically unsafe, however some trends in the failure modes can be observed.

1Corresponding author.

Manuscript received July 16, 2013; final manuscript received October 14, 2013; published online December 6, 2013. Assoc. Editor: Hamid M. Lankarani.

J. Med. Devices 8(1), 011007 (Dec 06, 2013) (5 pages) Paper No: MED-13-1171; doi: 10.1115/1.4025852 History: Received July 16, 2013; Revised October 14, 2013

Atherosclerosis is a disease that causes obstructions to develop within the arterial system; these obstructions can result in an acute vascular event such as a heart attack or stroke, and potentially death. In the majority of cases a standard angioplasty balloon is sufficient to dilate the site of an obstruction; however difficult obstructions, such as heavily calcified lesions require specialist dilation solutions. One such example of a device is Boston Scientific's cutting balloon. An analysis of the Food and Drug Administration's (FDA) Manufacturer and User Facility Device Experience (MAUDE) database demonstrates that the original cutting balloon has a number of distinct adverse events associated with it. In this study we describe the design, manufacturing, and testing of a new force focused angioplasty balloon that has the potential to reduce or eliminate the adverse events associated with the Boston Scientific cutting balloon. This design incorporates two elastomeric materials to aid recoiling of the device namely: nitinol and a silicone elastomer. New methods of manufacturing are described in this study, that ensure that precision molding and assembly can occur. To determine the effectiveness of our device, we simulated concentric calcified lesions with a surrogate chalk model. These results demonstrate that our device has a significantly lower lesion burst pressure in comparison to a standard angioplasty balloon, 174 atm versus 12.48 atm. To determine if our device reduced potential snagging, and thus reduced the risk of withdrawal resistance being encountered, we performed a withdrawal resistance test. A noticeably lower withdrawal force is associated with our device, the high peaks on the Boston Scientific device indicate that there may be wings forming on the balloon and these are catching on the tip of the introducer sheath. Finally, we demonstrated in vivo efficacy of our device in a porcine model. By the use of elastomeric recoiling features in a new cutting balloon design we have been able to overcome the three main reported adverse events associated with the Boston Scientific cutting balloon. Subsequently we experimentally demonstrated this improved efficacy for one particular peripheral balloon size (e.g., 5 mm diameter).

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References

Figures

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Fig. 8

(a) Depicts microdamage associated with our device, while image (b) depicts microdamage associated with Boston Scientifics cutting balloon device. These histology images demonstrate that the mechanism of action with both devices is comparable. The microblade damage is highlighted as the area encompassed by the black circles.

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Fig. 7

Images of our device and Boston Scientific's cutting balloon (pre-inflation (row (i)), during inflation (row (ii)), and postdeflation (row (iii)). The positions A, B, and C are associated with the crossing profile measurements obtained.

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Fig. 6

A plot of the comparative withdrawal resistance for the Boston Scientific cutting balloon and our force focused angioplasty balloon. There is a noticeable jump in the withdrawal resistance the wings of the Boston device are pulled into the introducer catheter, this is associated with the initial steep rise in force on the Boston Scientific curves. The experiment was repeated four times.

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Fig. 5

(a) Results of the simulated concentric calcified lesion test. Average values are displayed above the bars, and our force focused angioplasty balloon has a statistically significant lower burst pressure in comparison to a standard angioplasty balloon (p < 0.05).

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Fig. 1

(a) An image of a 5.0 mm diameter Boston Scientific peripheral cutting balloon is shown in the inflated position. (b) In this schematic the structure of an inflated cutting balloon is highlighted. The microblades are embedded within a polymer base, and subsequently the polymer base is bonded onto the surface of an angioplasty balloon.

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Fig. 4

(a) The total length of the mesh/blade arrangement is depicted in this image, while in (b) a close-up of the method that the blades integrate with the NiTi mesh is depicted. The upper blade details how the blade interacts with the upper surface of the mesh, while the blade is continuous below the mesh and cannot pass through the mesh. The small posts on the blade can be plastically deformed around the NiTi mesh for stability. The image in (c) shows a cross section with all five blades present. Please note the balloon and the sheath have been removed from this illustration to ensure the reader can identify the interaction between the blade and mesh.

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Fig. 3

(a) The image above details our elastomeric sheath with concealed blades seated between two protuberances, on this device five blades are equally distributed about the circumference of the sheath. (b) In this image the sheath is illustrated in the expanded configuration, the internal lumen has been enlarged and subsequently the sheath stretches and the protuberances are reduced in height exposing the blades. Moreover, the sheath stores elastic energy in this expanded configuration.

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Fig. 2

The data presented in this bar chart relates to a search performed within the FDA MAUDE database, the brand name entered was “cutting balloon” and the time period ranged from Jan. 1, 2011 to Dec. 31, 2011. A total of 115 records were retrieved and analyzed. Twenty-four events were removed from the data, as the adverse event occurred outside the body. Please note that this data only represents devices that have an adverse event associated with them and has been reported to the FDA, this proportion of cases represented a small minority of cutting balloons used in the U.S. in 2011.

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