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Design Innovation

Design of a Catheter-Based Device for Performing Percutaneous Chordal-Cutting Procedures

[+] Author and Article Information
Alexander H. Slocum, William R. Bosworth, Anirban Mazumdar, Miguel A. Saez, Martin L. Culpepper

Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139

Robert A. Levine

Massachusetts General Hospital, Non-Invasive Cardiology, Boston, MA 02114

J. Med. Devices 3(2), 025001 (Jun 04, 2009) (8 pages) doi:10.1115/1.3139835 History: Received May 01, 2008; Revised March 08, 2009; Published June 04, 2009

This paper focuses on the design and implementation of a percutaneous catheter-based device to provide physicians with an externally controlled tool capable of manipulating and cutting specific chordae tendinae within the heart to alleviate problems associated with some forms of mitral valve (MV) regurgitation. In the United States alone, approximately 500,000 people develop ischemic or functional mitral regurgitation per year. Many of these patients do not possess the required level of health necessary to survive open-heart surgery, and the development of a chordal cutting procedure and device is needed to allow these patients to receive treatment. A deterministic design process was used to generate several design concepts and then evaluate and compare each concept based on a set of functional requirements. A final concept to be alpha prototyped was then chosen, further developed, and fabricated. Experiments showed that the design was capable of locating and grabbing a chord and that ultrasound imaging is a viable method for navigating the device inside of the human body. Once contact between the chord and radio-frequency (RF) ablation tip was confirmed, the chord was successfully ablated.

Copyright © 2009 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Cross section of normal (left), post-infarct (center), and post chord-cut heart (right) (Reference 6)

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Figure 2

Diagram of current percutaneous procedure (Image source: www.nlm.nih.gov/medlineplus/ency/imagepages/18143.htm)

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Figure 3

Forceps design concept

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Figure 4

Clamshell design concept

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Figure 5

Hook design concept

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Figure 6

360 deg hook design concept

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Figure 7

Cross section of hook body design. Note nonconcentric hole for existing RF-ablator (units in mm).

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Figure 8

Characteristic dimensions of the hook mechanism

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Figure 9

Microvasive polypectomy snare (Image source: http://cookmedical.com/esc/content/thumbnail/esc_as.jpg)

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Figure 10

Hook loading diagram

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Figure 11

(a) Model for loading condition 1. (b) Model for loading condition 2.

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Figure 12

Our HTM reference diagram

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Figure 13

Hook (left) and hook mount (right)

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Figure 14

Cross section of assembled chord gripper

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Figure 15

Finite element analysis of the hook

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Figure 16

Detailed view of mechanism

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Figure 17

The mechanism, including the microvasive polypectomy snare, and steer-able catheter

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Figure 18

Our experimental setup, with the simulated femoral artery and porcine heart, and the device inserted into the simulated vessel

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Figure 19

The device in position to grip the mitral valve chordae tendinae

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Figure 20

Device (with RF-ablator on board) gripping mitral valve strut chord

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Figure 21

Echo image of catheter device

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Figure 22

Basal chord cut using RF-ablation

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