Designing the Heart

In the time it takes you to read this article, your heart will have pumped enough blood to fill half a tank of gas. For free. Dr. Prasad Dasi’s job is to make sure you don’t pay more than you have to to keep your heart in working order.

Dr. Dasi’s lab is filled with prototype valves and floor-to-ceiling machines that simulate the flow in a human heart, an organ the size of your fist. He is developing heart valves that can be used to replace defective ones in patients suffering from heart related issues.

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Dasi came to the United States to pursue a PhD because, as he says, the quality of research in the U.S. is top notch. He studied at Georgia Tech, one of the top engineering schools in the country.

“The biggest break was perhaps getting into the good schools in India,” Dasi said, who completed his undergraduate degree in civil engineering at the Indian Institute of Technology in Mumbai.

Designing Blood Flow

Dasi came to CSU in 2009 and started the Cardiovascular Biofluid Mechanics Lab, which is focused on applying engineering principles as it pertains to fluid mechanics on a variety of cardiovascular problems.

“Cardiac surgery is so much intertwined with how to shape the flow of blood in the heart,” Dasi said.

Dasi says that whenever placing something artificial inside the body, you run up against two problems — clot formation and durability.

“A heart valve works like a door that opens in one direction,” Dasi said. “Based on the pressure changes of blood in the ventricle, the valve can open and close.”

If the valve is defective in any way, this can disrupt the flow of blood through the heart, causing problems.

“If you have a valve with parts in it that make the blood squeeze through in a way that blood doesn’t usually experience … you could have blood cells rupture,” Dasi said.

Questions to be Answered

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Dr. Chris Orton, the department head of clinical sciences and a veterinary heart surgeon, will be conducting pre-clinical trials on these valves by surgically implanting them in research animals.

Orton, who has been collaborating with Dasi on various projects since Dasi arrived at CSU, explains there are currently two types of heart valve replacements being used in humans — a mechanical valve and a bioprosthetic valve — and there are problems with each.

According to Orton, the mechanical valve is made out of inorganic material and is very durable, but requires the patient to take blood thinners for the rest of their life.

“If you’re young or a female of childbearing age, it’s not ideal,” Orton said.

The bioprosthetic valve is made from a pig valve that is treated in a special way to keep it from being rejected by the body. It does not require blood thinners, but does not last long either.

“If you’re 70-80 years old, it’s not a problem, but if you’re 30, you’re looking at another surgery in 15 years,” Orton said. “The valve that Dr. Dasi is developing would be like both — it would not require blood thinners, but would be much more durable.”

Cheaper material, Global impact

Dr. Susan James, head of mechanical engineering and professor in biomedical engineering, designs the materials that Dasi’s valve is made from. They are made from a natural material, called hyaluronan (HA), intertwined into a type of plastic.

“The idea is to take the strength and durability of this synthetic plastic, and add to it this more natural (molecule), so when the body looks at this material, it looks more like a natural tissue to them,” James said.

The other advantage to this material, according to James, is that it’s easy and cheap to make. Dasi and colleagues are trying to extend their work to India, where low cost medical devices are particularly important.

James adds that traditionally, bioprosthetic valves are hand sewn by women in developing countries. The tissue is fixed in preservatives, and it’s not a healthy work environment. HA, on the other hand, is a much more friendly material.

“Your natural heart valve leaflets have hyluronin in them,” James said. “Smart people have figured out how to harvest HA from natural forms, and get bacteria to produce it, which means it is commercially available and well controlled.”

Dasi says that he and colleagues do have a valve with some preliminary blood studies, all which point to a high rate of success.

Local and International Collaboration

Dasi and colleagues also have a grant pending at the National Institute of Health and the Department of Biotechnology in India, who have teamed up in order to treat specific issues going on in India, and to make lower cost medical devices available.

James explains that more young people need heart valve replacements due to diseases like rheumatic fever, which is much more prevalent in countries like India.

“In the United States, it’s mostly lifestyle choices that cause people to need heart valve replacements. In India, many more young people need heart valve replacements,” James said.

Dasi explains there are other causes of heart valve disease, many of which we cannot avoid.

“We can think of genes as a program to build an organ, and if you have a bad program you end up with some defect,” Dasi said.

Dasi adds that the applications of this new technology is not just heart valves. They can be used in arteries that supply the heart and other parts of the body.

“Heart-lung machines, dialysis, anything with blood flow that could have clotting issues,” Dasi said. “Taking a step further back, this could be used in artificial hearts as well,” Dasi adds.

Dasi’s colleague Dr. Susan James explains that without the new bioengineering building, these collaborations would all be much harder, but without Dasi they would be impossible.

“Dr. Dasi is by far the leader of this project and this wouldn’t be happening if he hadn’t come here- I wouldn’t be doing this research if he wasn’t here,” James said.

James adds that this research is truly a collaborative project that involves educating a lot of students, and goes far beyond just the research.

With so many educational opportunities in the field of medicine, Dasi encourages students to find their place.

“Whatever route you choose, you can find something meaningful to you,” Dasi said.

Collegian Science Beat Reporter Remi Boudreau can be reached at news@collegian.com.