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

2010 ◽  
Vol 4 (3) ◽  
Author(s):  
Dennis R. Trumble ◽  
Marshall Norris ◽  
Alan Melvin
Keyword(s):  
Lessons Learned ◽  
Circulatory Support ◽  
In Vitro Testing ◽  
Energy Converter ◽  
Cardiac Assist ◽  
Cardiac Assist Devices ◽  
Transcutaneous Energy Transmission ◽  
Previous Design ◽  
Muscle Energy

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.

scholarly journals A Muscle Energy Converter for Powering Implantable Cardiac Assist Devices

2009 ◽  
Vol 3 (2) ◽  
Author(s):  
D. R. Trumble ◽  
M. Norris ◽  
G. Peters
Keyword(s):  
Lessons Learned ◽  
Cycle Life ◽  
Patient Comfort ◽  
Circulatory Support ◽  
Energy Converter ◽  
Load Bearing ◽  
Assist Devices ◽  
Cardiac Assist ◽  
Cardiac Assist Devices ◽  
Muscle Energy

Harnessing skeletal muscle for circulatory support would improve on current blood pump technologies by eliminating infection-prone drivelines and expensive transcutaneous transmission systems. Here we describe an implantable muscle energy converter (MEC) designed to transmit the contractile energy of the latissimus doris muscle in hydraulic form. The MEC weighs just 290 grams and comprises a metallic bellows actuated by a rotary arm fixed to the humeral insertion of the muscle via a looped artificial tendon. The housing is anchored to the ribcage using a perforated mounting ring (83 mm diameter). Lessons learned through six design iterations have produced a 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, in vitro, and in vivo testing. The components most subject to wear in this device are the stainless-steel bellows, spring-loaded lip seals, and load-bearing surfaces (bearings, cams and shafts). Roller bearings supporting the camshaft and cam follower were replaced with needle bearings for better stress distribution and longer cycle life. Camshaft bearings were improved still further by changing to a full-complement configuration to lower stress concentration and reduce lateral (off-axis) shaft movement that could reduce lipseal life. Bellows cycle life was estimated using ANSYS V11 finite element analysis (FEA) software with a mesh size of 0.002”. In this simulation a pressure of 22 psi was applied to the internal surface of the bellows and compression length was set to the longest possible stroke (0.177”). All load-bearing surfaces were analyzed for fatigue stress and cycle life under these same loading conditions following closed form equations. Results show that the overall durability of the MEC device can be expected to exceed 450 million cycles, resulting in a minimum working life of 14.5 years given a 1 Hz cycle rate. Lipseal durability was tested empirically in a 37°C saline bath using a cycling apparatus designed specifically for that purpose. After 55 days (12.3 million cycles) the test was stopped and the unit disassembled and inspected. The shaft and seals showed evidence of contamination buildup in front of the lip seal but not behind it, indicating that the seal had functioned properly throughout the test period. Importantly, implant studies in 30–35 Kg dogs (n=7) confirm excellent anatomic fit, patient comfort, and device functionality to one month. These results suggest that muscle-powered cardiac assist devices are feasible and that efforts to further develop this technology are warranted.

scholarly journals Cardiac Assist Devices: Early Concepts, Current Technologies, and Future Innovations

2019 ◽  
Vol 6 (1) ◽  
pp. 18 ◽  
Author(s):  
Jooli Han ◽  
Dennis Trumble
Keyword(s):  
Mechanical Circulatory Support ◽  
Circulatory Support ◽  
Assist Device ◽  
Short Supply ◽  
Power Sources ◽  
Cardiac Assist ◽  
Cardiac Assist Device ◽  
Cardiac Assist Devices ◽  
Blood Pumps

Congestive heart failure (CHF) is a debilitating condition that afflicts tens of millions of people worldwide and is responsible for more deaths each year than all cancers combined. Because donor hearts for transplantation are in short supply, a safe and durable means of mechanical circulatory support could extend the lives and reduce the suffering of millions. But while the profusion of blood pumps available to clinicians in 2019 tend to work extremely well in the short term (hours to weeks/months), every long-term cardiac assist device on the market today is limited by the same two problems: infections caused by percutaneous drivelines and thrombotic events associated with the use of blood-contacting surfaces. A fundamental change in device design is needed to address both these problems and ultimately make a device that can support the heart indefinitely. Toward that end, several groups are currently developing devices without blood-contacting surfaces and/or extracorporeal power sources with the aim of providing a safe, tether-free means to support the failing heart over extended periods of time.

scholarly journals In Vitro Evaluation of Ventricular Cannulation for Rotodynamic Cardiac Assist Devices

2011 ◽  
Vol 2 (3) ◽  
pp. 203-211 ◽  
Author(s):  
Timothy N. Bachman ◽  
Jay K. Bhama ◽  
Josiah Verkaik ◽  
Stijn Vandenberghe ◽  
Robert L. Kormos ◽  
...  
Keyword(s):  
In Vitro Evaluation ◽  
Assist Devices ◽  
Cardiac Assist ◽  
Cardiac Assist Devices

scholarly journals Ghost Cells for Mechanical Circulatory Support In Vitro Testing: A Novel Large Volume Production

2020 ◽  
Vol 15 (4) ◽  
pp. 1900239
Author(s):  
Malte Schöps ◽  
Johanna C. Clauser ◽  
Matthias F. Menne ◽  
Dennis Faßbänder ◽  
Thomas Schmitz‐Rode ◽  
...  
Keyword(s):  
Large Volume ◽  
Mechanical Circulatory Support ◽  
Circulatory Support ◽  
In Vitro Testing ◽  
Ghost Cells ◽  
Volume Production

MECHANICAL CIRCULATORY SUPPORT (MCS) USING IMPLANTABLE CARDIAC ASSIST DEVICES FOR MORE THAN 200 DAYS

ASAIO Journal ◽  
1996 ◽  
Vol 42 (2) ◽  
pp. 33
Author(s):  
V. Theodoridis ◽  
J. M??ller ◽  
Y-G. Weng ◽  
M. Loebe ◽  
S. Spiegelsberger ◽  
...  
Keyword(s):  
Mechanical Circulatory Support ◽  
Circulatory Support ◽  
Assist Devices ◽  
Cardiac Assist ◽  
Cardiac Assist Devices

Method for measuring long-term function of muscle-powered implants via radiotelemetry

2001 ◽  
Vol 90 (5) ◽  
pp. 1977-1985 ◽  
Author(s):  
Dennis R. Trumble ◽  
James A. Magovern
Keyword(s):  
In Vitro Tests ◽  
Pressure Data ◽  
Hydraulic Pump ◽  
Energy Converter ◽  
Access Port ◽  
Animal Trials ◽  
Telemetry Unit ◽  
Muscle Energy

Long-term remote monitoring of muscle-powered implants has been made possible with development of an adjustable workload that can be remotely monitored to assess device function. This technique obviates the need for percutaneous access lines and allows test animals to remain untethered, eliminating deleterious effects caused by infection, sedation, or animal stress. Hardware components include a latex bladder fixed within a hermetically sealed canister, multichannel implantable telemetry unit, and subcutaneous access port (for pressure charge adjustment). To validate this method, in vitro tests were performed by using a third-generation muscle energy converter designed to function as an implantable hydraulic pump. Two channels of telemetered pressure data were collected and used to calculate six indexes of device function. Calculated parameters were then compared with measured values to determine accuracy. Correlation between measured and calculated parameters was high in all instances, with most estimates yielding errors of <3%. These results demonstrate the utility of this approach and support its use as a means to monitor muscle-powered devices during long-term animal trials.

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