Posts tagged with "Brown School of Engineering"

Damaged Hearts rewired

Thin, flexible fibers made of carbon nanotubes  have now proven able to bridge damaged heart tissues and deliver the electrical signals needed to keep those hearts beating.

At Texas Heart Institute (THI) report they have used biocompatible fibers invented at Rice University in studies that showed sewing them directly into damaged tissue can restore electrical function to hearts.

“Instead of shocking and defibrillating, we are actually correcting diseased conduction of the largest major pumping chamber of the heart by creating a bridge to bypass and conduct over a scarred area of a damaged heart,” said Dr. Mehdi Razavi, a cardiologist and director of Electrophysiology Clinical Research and Innovations at THI, who co-led the study with Rice chemical and biomolecular engineer Matteo Pasquali.

“Today there is no technology that treats the underlying cause of the No. 1 cause of sudden death, ventricular arrhythmias,” Razavi said. “These arrhythmias are caused by the disorganized firing of impulses from the heart’s lower chambers and are challenging to treat in patients after a heart attack or with scarred heart tissue due to such other conditions as congestive heart failure or dilated cardiomyopathy.”

Results of the studies on preclinical models appear as an open-access Editor’s Pick in the American Heart Association’s Circulation: Arrhythmia and Electrophysiology. The association helped fund the research with a 2015 grant. The research springs from the pioneering 2013 invention by Pasquali’s lab of a method to make conductive fibers out of carbon nanotubes. The lab’s first threadlike fibers were a quarter of the width of a human hair, but contained tens of millions of microscopic nanotubes. The fibers are also being studied for electrical interfaces with the brain, for use in cochlear implants, as flexible antennas and for automotive and aerospace applications.

The experiments showed the nontoxic, polymer-coated fibers, with their ends stripped to serve as electrodes, were effective in restoring function during monthlong tests in large preclinical models as well as rodents, whether the initial conduction was slowed, severed or blocked, according to the researchers. The fibers served their purpose with or without the presence of a pacemaker, they found.

In the rodents, they wrote, conduction disappeared when the fibers were removed. “The reestablishment of cardiac conduction with carbon nanotube fibers has the potential to revolutionize therapy for cardiac electrical disturbances, one of the most common causes of death in the United States,” said co-lead author Mark McCauley, who carried out many of the experiments as a postdoctoral fellow at THI. He is now an assistant professor of clinical medicine at the University of Illinois College of Medicine.

“Our experiments provided the first scientific support for using a synthetic material-based treatment rather than a drug to treat the leading cause of sudden death in the U.S. and many developing countries around the world,” Razavi added. Many questions remain before the procedure can move toward human testing, Pasquali said. The researchers must establish a way to sew the fibers in place using a minimally invasive catheter, and make sure the fibers are strong and flexible enough to serve a constantly beating heart over the long term. He said they must also determine how long and wide fibers should be, precisely how much electricity they need to carry and how they would perform in the growing hearts of young patients.

“Flexibility is important because the heart is continuously pulsating and moving, so anything that’s attached to the heart’s surface is going to be deformed and flexed,” said Pasquali, who has appointments at Rice’s Brown School of Engineering and Wiess School of Natural Sciences.

“Good interfacial contact is also critical to pick up and deliver the electrical signal,” he said. “In the past, multiple materials had to be combined to attain both electrical conductivity and effective contacts. These fibers have both properties built in by design, which greatly simplifies device construction and lowers risks of long-term failure due to delamination of multiple layers or coatings.” Razavi noted that while there are many effective antiarrhythmic drugs available, they are often contraindicated in patients after a heart attack. “What is really needed therapeutically is to increase conduction,” he said. “Carbon nanotube fibers have the conductive properties of metal but are flexible enough to allow us to navigate and deliver energy to a very specific area of a delicate, damaged heart.” Rice alumna Flavia Vitale, now an assistant professor of neurology and of physical medicine and rehabilitation at the University of Pennsylvania, and Stephen Yan, a graduate student at Rice, are co-lead authors of the paper.

Co-authors are Colin Young and Julia Coco of Rice; Brian Greet of THI and Baylor St. Luke’s Medical Center; Marco Orecchioni and Lucia Delogu of the Città della Speranza Pediatric Research Institute, Padua, Italy; Abdelmotagaly Elgalad, Mathews John, Doris Taylor and Luiz Sampaio, all of THI; and Srikanth Perike of the University of Illinois at Chicago. Pasquali is the A.J. Hartsook Professor of Chemical and Biomolecular Engineering, a professor of materials science and nanoengineering and of chemistry.

The American Heart Association, the Welch Foundation, the Air Force. Office of Scientific Research, the National Institutes of Health and Louis Magne supported the research.

Credit James Philpot/Texas Heart Institute

Student Invention Gives Patients the Breath of Life

Natalie Dickman squeezed the bag again and again in an effort to revive a victim of cardiac arrest. After a mere 3 minutes, she could squeeze no more. 

“The patient had been down for 30 minutes and there wasn’t much hope, unfortunately,” said the Rice University student, a soon-to-be graduate of the Brown School of Engineering, who was covering a shift with Houston EMS as required by a Rice class in emergency medical techniques. “I was allowed to bag, but they make you switch in EMS settings because they know you won’t be as accurate once you hit that 2-to-3-minute mark. You get really tired.”

She thought about that often over the last year when she and her senior teammates worked at Rice’s Oshman Engineering Design Kitchen (OEDK) to perfect a cost-effective device that automates the compression of manual bag valve masks, which feed fresh air to the lungs of intubated patients. 

The senior capstone design team — bioengineering students Dickman, Carolina De Santiago, Karen Vasquez Ruiz and Aravind Sundaramraj, mechanical engineering and computational and applied mathematics student Tim Nonet and mechanical engineering student Madison Nasteff — is known as “Take a Breather.” 

The team has developed a system that compresses the bags for hours, rather than minutes, with settings to feed the right amount of air to adults, children and infants. The device seems simple — a box with paddles that rhythmically squeeze the bulb a programmed amount – but the engineering behind it is not.

The students used a $25, off-the-shelf motor and $5 microcontroller to power and program the rack-and-pinion device made primarily of plastic parts 3D-printed at the OEDK. They hope their use of inexpensive materials and the growing availability of 3D printers will make their machines easy to repair on-site.

They anticipate the device, which cost them $117 in parts to build, will be most useful in low-resource hospitals or during emergencies when there aren’t enough portable ventilators to meet the need. 

Dr. Rohith Malya, an assistant professor of emergency medicine at Baylor College of Medicine, brought the problem to the OEDK after witnessing family members at the Kwai River Christian Hospital in Thailand, where he is director of emergency medical services, squeezing intubation bags for hours on end to keep loved ones alive. 

“There is no reliable ventilation,” said Malya, who spends a month at the hospital every year. “Once we intubate somebody, the family has to bag the patient. But the family will get tired after a day and say, ‘They’re not getting better right now, just pull the tube and see what happens.’ And then the patient dies.”

Malya previously worked with Rice engineering students to develop a syringe regulating pump, and did not hesitate to bring a new idea to the OEDK. 

“The bag mask is ubiquitous, like the syringe,” he said. “Nothing has challenged it for 80 years. It’s stood the test of time, it’s reliable and it’s simple. And now we’re adding a modification to the original device so families don’t have to make those decisions.

“This will broaden the access to mechanical ventilation to a tremendous part of the world that doesn’t have typical ventilators,” said Malya, who plans to take the proof-of-concept device to Thailand for field testing next spring. 

The device is much smaller than the sophisticated ventilators found in American hospitals and portable versions used in emergency situations. Critically, it has to be able to operate for long stretches. In its most recent test, the team ran the device for more than 11 hours without human intervention.  

The students expect another Rice team will build a more robust version next year, and hope it will eventually be manufactured for use in low-resource and emergency settings. They anticipate a better-sealed and filtered box will be more suitable for hot, dusty environments, and said future designs should include more sophisticated controls.

For its efforts this year, the team won two prizes at the school’s annual Engineering Design Showcase, the Willy Revolution Award for Outstanding Innovation and the best interdisciplinary engineering design award. But the real payoff would be seeing the device further developed and deployed around the world. 

“If they can get it working fully in that kind of environment, this will be saving lives,” Nasteff said.

Rice U. Device Would Help Fix Fractured Bones

Threading a needle is hard, but at least you can see it. Think about how challenging it must be to thread a screw through a rod inside a bone in someone’s leg.

Rice University seniors at the Brown School of Engineering set out to help doctors simplify the process of repairing fractured long bones in an arm or leg by inventing a mechanism that uses magnets to set things right.

The students who call themselves Drill Team Six chose the project pitched by Rice alumnus Dr. Ashvin Dewan, an orthopedic surgeon at Houston Methodist Hospital, to simplify a procedure by which titanium rods are placed inside broken bones to make them functional once more. For its efforts, the team won the top prize, the Excellence in Engineering Award, at the school’s annual

Engineering Design Showcase.  

The student team — bioengineering majors Babs Ogunbanwo, Takanori Iida, Byung-UK Kang and Hannah Jackson and mechanical engineering majors Will Yarinsky and Ian Frankel — learned from Dewan that surgeons require many X-rays to locate pre-drilled 5 millimeter holes in the rod. The holes allow them to secure the rod to the bone fragments and hold them together.

The surgery typically requires doctors to insert the long rod with a guide wire inside into the end of the bone, drilling through marrow to align the fractured fragments. With that done, they depend on X-rays, their experience and, if necessary, a bit of trial and error to drill long surgical screws through one side of the bone, thread it through the rod and secure it to the other side.

“We want to reduce the amount of X-rays, the surgeon’s time, the operating room time, the setup time, everything,” Yarinsky said.

The Rice team would make the wire adjacent to the holes magnetic, because neither skin nor bone hinder a magnetic field

“That way, the magnets hold their position and we can do the location process,” Frankel said. “Once we’ve found them and secured the rod, we remove the wire and the magnets with it.”

The exterior mechanism is a brace that can be securely attached to the arm or leg with Velcro. A mounted sensor can then be moved along the stiff, 3D-printed carbon-fiber rods or around the limb until it locates the magnet. Then, the angle of the sensor can be adjusted. As each of the three degrees of freedom come into alignment with the target, a “virtual LED” lights up on a graphic display wired to the sensor. Then, the sensor is removed and a drill keyed to the mechanism inserted.

“We do the angular part because the rod is not in the center of the leg, and the hole is not necessarily perpendicular to the surface,” Yarinsky said. “The rod is about 10 to 20 millimeters thick and has a hole on one side and a hole on the other. We don’t want to hit the first hole at an angle where we miss the second

and don’t go all the way through.”

Working at Rice’s Oshman Engineering Design Kitchen (OEDK), the team tested its device on a mannequin leg and what it called a “wooden leg,” a frame that allowed for mounting the rod with its magnetized wire and checking the accuracy of their system.

Before it can be used by clinicians, the team said the device will require Food and Drug Administration approval.

“I’m very impressed with what the team put together,” said Dewan, who earned a bioengineering degree at Rice in 2005. “Where we ended up is completely different from what we imagined, but kudos to these guys. They went through many different proposals and ideas and ended up running with the one that seemed most promising.”

Having been through the senior capstone process at Rice himself, Dewan was particularly impressed with how the program has grown.

“The OEDK got off the ground a few years after I graduated, and at that point, senior design projects were isolated to individual projects,” Dewan said. “I didn’t work with mechanical or other engineering disciplines.

“I love the way they have a multidisciplinary approach to tackling problems,” he said.  “I think it’s much more of a real-world experience for them.”

Sabia Abidi, a lecturer in bioengineering, served as the team’s adviser, and it was sponsored by Chuck and Sharon Fox. ­­