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Heart Machine Expedites Research and Development of New Surgical Tools, Techniques

A new machine developed at North Carolina State University makes an animal heart pump much like a live heart after it has been removed from the animal’s body, allowing researchers to expedite the development of new tools and techniques for heart surgery. The machine saves researchers time and money by allowing them to test and refine their technologies in a realistic surgical environment, without the cost and time associated with animal or clinical trials.

Currently, most medical device prototypes designed for use in heart surgery are tested on live pigs, which have heart valves that are anatomically similar to human heart valves. However, these tests are both expensive and time-consuming, and involve a lengthy permission process to ensure that the use of live animals is necessary. So, researchers at NC State have developed a “dynamic heart system” – a machine that pumps fluid through a pig heart so that it functions in a very realistic way. “Researchers can obtain pig hearts from a pork processing facility and use the system to test their prototypes or practice new surgical procedures,” says Andrew Richards, a Ph. D. student in mechanical engineering at NC State who designed the heart machine.

The computer-controlled machine, which operates using pressurized saline solution, also allows researchers to film the interior workings of the pumping heart – enabling them to ascertain exactly which surgical technologies and techniques perform best for repairing heart valves.

By using the machine, researchers can determine if concepts for new surgical tools are viable before evaluating them on live animals. They can also identify and address any functional problems with new technological tools. “There will still be a need for testing in live animal models,” says Dr. Greg Buckner, who directed the project, “but this system creates an intermediate stage of testing that did not exist before. It allows researchers to do ‘proof of concept’ evaluations, and refine the designs, before operating on live animals.” Buckner is an associate professor of mechanical and aerospace engineering at NC State.

Using the system could also save researchers a great deal of money. Once the machine is purchased and set up, the cost of running experiments is orders of magnitude less expensive than using live animals. “It costs approximately $25 to run an experiment on the machine,” says Richards, “whereas a similar experiment using a live animal costs approximately $2,500.”

The National Heart, Lung, and Blood Institute of the National Institutes of Health funded the development of the heart machine system.

The Annals of Biomedical Engineering published the research, “A Dynamic Heart System to Facilitate the Development of Mitral Valve Repair Techniques,” in late April. Richards is the lead author. Co-authors are Buckner, and surgeons Richard Cook of the University of British Columbia and Gil Bolotin of the Rambam Medical Center in Israel.

– shipman –

Note to editors: The study abstract follows.

“A Dynamic Heart System to Facilitate the Development of Mitral Valve Repair Techniques”

Authors: Andrew L. Richards, Gregory D. Buckner, North Carolina State University; Richard C. Cook, University of British Columbia; Gil Bolotin, Rambam Medical Center.

Published: April 2009, Annals of Biomedical Engineering

Abstract: Objective: The development of a novel surgical tool or technique for mitral valve repair can be hampered by cost, complexity, and time associated with performing animal trials. A dynamically pressurized model was developed to control pressure and flowrate profiles in intact porcine hearts in order to quantify mitral regurgitation and evaluate the quality of mitral valve repair. Methods: A pulse duplication system was designed to replicate physiological conditions in explanted hearts. To test the capabilities of this system in measuring varying degrees of mitral regurgitation, the output of eight porcine hearts was measured for two different pressure waveforms before and after induced mitral valve failure. Four hearts were further repaired and tested. Measurements were compared with echocardiographic images. Results: For all trials, cardiac output decreased as left ventricular pressure was increased. After induction of mitral valve insufficiencies, cardiac output decreased, with a peak regurgitant fraction of 71.8%. Echocardiography clearly showed increases in regurgitant severity from post-valve failure and with increased pressure. Conclusions: The dynamic heart model consistently and reliably quantifies mitral regurgitation across a range of severities. Advantages include low experimental cost and time associated with each trial, while still allowing for surgical evaluations in an intact heart.