0
Design Innovation

Design Improvements and In Vitro Testing of an Implantable Muscle Energy Converter for Powering Pulsatile Cardiac Assist Devices

[+] Author and Article Information
Dennis R. Trumble1

Gerald McGinnis Cardiovascular Institute, Allegheny General Hospital, 8th Floor, South Tower (Room 803), 320 East North Avenue, Pittsburgh, PA 15212-4772; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213trumble@wpahs.org

Marshall Norris

 Flexial Corporation, Cookeville, TN 38502

Alan Melvin

 Surgical Energetics, Inc., Cincinnati, OH 45201

1

Corresponding author.

J. Med. Devices 4(3), 035002 (Sep 08, 2010) (4 pages) doi:10.1115/1.4002235 History: Received January 22, 2010; Revised July 15, 2010; Published September 08, 2010; Online September 08, 2010

Harnessing skeletal muscle for circulatory support would improve on current blood pump technologies by eliminating infection-prone drivelines and cumbersome transcutaneous energy transmission systems. Toward that end, we have built and tested an implantable muscle energy converter (MEC) designed to transmit the contractile energy of the latissimus dorsi muscle in hydraulic form. The MEC weighs less than 300 g and comprises a metallic bellows formed from AM350 stainless steel actuated by a rotary cam (440C) attached to a titanium rocker arm (Ti–6Al–4V). The rocker arm is fixed to the humeral insertion of the muscle via a looped artificial tendon developed specifically for this purpose. The device housing (Ti–6Al–4V) is anchored to the ribcage using a perforated mounting ring and a wire suture. Lessons learned through seven previous design iterations have produced an eighth-generation pump with excellent durability, energy transfer efficiency, anatomic fit, and tissue interface characteristics. This report describes recent improvements in MEC design and summarizes results from in silico and in vitro testing. Long-term implant studies will be needed to confirm these findings prior to clinical testing.

FIGURES IN THIS ARTICLE
<>
Copyright © 2010 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 3

Axisymmetric meshed 3D model created for bellows finite element analysis

Grahic Jump Location
Figure 4

Bellows stress distribution as computed via finite element analysis

Grahic Jump Location
Figure 5

Top: exploded view of camshaft, seal, washer, and mounting screw. Bottom: cycle test apparatus with rotary motor, rocker arm, and MEC mounted on saline submersion plate.

Grahic Jump Location
Figure 6

Comparison of needle bearings with (top right) and without (bottom right) guide cages. Use of the cageless bearing configuration was found to reduce shaft wobble by 6.6%.

Grahic Jump Location
Figure 7

Latest MEC actuator arm design featuring a knob-and-loop arrangement with a non-load-bearing cap. The LD muscle attaches to the MEC using the looped tendon arrangement.

Grahic Jump Location
Figure 8

Top: outer and inner surfaces of the MEC8 upper housing (Ti–6Al–4V). The span of the actuator arm has been widened and the internal cavity has been expanded (staying within the original MEC footprint) to accommodate broader cam and bearing surfaces. Bottom: current cam and cam follower profiles featuring wider contact surfaces for improved durability.

Grahic Jump Location
Figure 1

Artist’s conception of the MEC attached to the latissimus dorsi muscle of a human patient with a looped tendon attachment

Grahic Jump Location
Figure 2

Cutaway view of the MEC8 shown with actuator arm on top and bellows pumping chamber on the bottom: both gray. Cam and cam follower: yellow. Camshaft: red. Lip seal: green. Upper housing: orange. Lower housing: magenta. Mounting ring: blue.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In