NEW DEVICE FOR REMOVING BLOOD CLOTS FAR SUPERIOR TO EXISTING FDA APPROVED METHODS

A new approach to stroke treatment initially developed by Dr. Jeffrey Saver’s group at the UCLA Stroke Center combines the ability to restore circulation and remove clots using only a single device … and it’s showing significant promise in trials. In a study comparing the Covidien Solitaire FR Revascularization Device with the FDA-approved Merci Retriever, the device successfully and safely treated roughly 60 percent of stroke patients, compared to roughly 30 percent when the Merci Retriever was used.

Such treatment is intended to minimize brain damage due to lack of oxygen and/or glucose in patients presenting with blockage of large intracranial blood vessels – particularly those for whom the use of clot-dissolving drugs is not advisable.

Roughly speaking, there are four main steps in the operation:

1. Poke a hole in the clot with a microcatheter (roughly 2.5 mm/0.1-inch in diameter).

2. Slide the Solitaire device through the microcatheter until it extends on either side of the clot.

3. Slide the microcatheter back so that the Solitaire device expands and traps the clot.

4. Pull the Solitaire device back to the end of the microcatheter, and use suction to remove the clot from the blood vessel.

Various stages in the revascularization and clot removal procedure are shown in the picture gallery.

The Solitaire With the Intention For Thrombectomy (SWIFT) study was designed to compare the results of using the Solitaire on acute stroke patients with the FDA-approved Merci Retriever. The Merci Retriever functions like a corkscrew that snares and removes a clot, but has a tendency to uncoil and lose the clot.

The SWIFT study was ended prematurely because of the remarkable effectiveness of the Solitaire device. One hundred and forty-four patients with acute ischemic stroke who either were not candidates for clot-busting drugs or in whom they had been ineffective were chosen for the study. Patients were a mixed lot, but both treatment groups were very similar. The patients were randomly assigned to be treated with the Solitaire or with the Merci devices.

The results:

• Reestablishment of blood flow occurred in 83% of the Solitaire treatments versus 48.1% of the Merci treatments
• Reestablishment of blood flow without symptoms due to intracranial hemorrhage occurred in 60.7% of the Solitaire treatments versus 24.1% of the Merci group

The Solitaire group had lower mortality at 3 months: 17.2% versus 38.2% for the Merci treated patients

• Good mental/motor functioning was restored within 90 days in 58.2% of Solitaire patients as compared to 33.3% of Merci patients

“Initial treatment with Solitaire rather than Merci is associated with more frequent reperfusion, less symptomatic intracranial hemorrhage, reduced mortality, and increased good neurologic outcomes,” says Dr. Saver. More simply put, the Solitaire device does its job more effectively and causes fewer problems while doing it.

The Solitaire is now approved for use in the Interventional Management of Stroke trial study. This is a stage III clinical trial, started in 2006, whose purpose is to examine if a combination of clot-busting drugs and intra-arterial therapy is more effective than clot-busting drugs alone. Among the intra-arterial therapies is the Merci Retriever. Even though over 675 of the 900 patients participating in the trial have already been studied, it has been expanded to include the Solitaire as an intra-arterial treatment for the remainder of the study.

Inclusion in the IMS clinical trial study reflects the enthusiastic response of the neurological medical community for the results of the SWIFT study. Hopefully the FDA will put Solitaire on the fast track as well.

Sources: UCLA, Covidien

Published by Henry Sapiecha

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MEDICAL IMPLANT INTO BLOOD STREAM WITH SELF POWERED WIRELESS GADGET

With the wait still on for a miniaturization ray to allow some Fantastic Voyage-style medical procedures by doctors in submarines, tiny electronic implants capable of traveling in the bloodstream show much more promise. While the miniaturization of electronic and mechanical components now makes such devices feasible, the lack of a comparable reduction in battery size has held things back. Now engineers at Stanford University have demonstrated a tiny, self-propelled medical device that would be wirelessly powered from outside the body, enabling devices small enough to move through the bloodstream.

While the benefits of medical implants have already been realized with devices such as artificial pacemakers and cochlear implants, which are stationary within the body, energy storage continues to limit such devices. With half of the volume of implants often consumed by the battery, the locations in which they can be placed are limited. Additionally, batteries also need to be periodically replaced, which generally requires a surgical procedure.

Developing implants capable of traveling through the bloodstream not only requires an energy source to power the device’s medical functions, but also its propulsion system – something that today’s batteries are unable to deliver in a form factor that is small enough to fit inside arteries.

The obvious approach would be to remove the battery from the device altogether and look to wireless electromagnetic power delivery. This is just what many scientists have been working on for fifty years. While such wireless power transmission technology has recently entered the mainstream through wireless chargers for consumer devices such as mobile phones, it wasn’t believed the technology could be made small enough to be compatible with tiny implantable devices.

The problem is that, according to mathematical models, high frequency waves that would require antennas small enough to be used in such devices were believed to dissipate quickly in human tissue, fading exponentially the deeper they go. At the same time, antennas to harness enough power from low-frequency signals, which are able to penetrate the human body well, would need to be a few centimeters in diameter, making them OK for larger devices, but too large to fit in all but the biggest arteries.

However, when electrical engineer Ada Poon looked at the models more closely she realized they were calculated assuming that human muscle, fat and bone were generally good conductors of electricity. Realizing that human tissue is actually a poor conductor of electricity but that radio waves could still move through it, Poon decided to redo the models with human tissue as a type of insulator called a dielectric. Her new calculations revealed that high-frequency waves travel much farther in human tissue than previously thought.

“When we extended things to higher frequencies using a simple model of tissue we realized that the optimal frequency for wireless powering is actually around one gigahertz,” said Poon, “about 100 times higher than previously thought.”

This meant that antennae inside the body could be 100 times smaller while delivering the same amount of power. This finding enabled Poon to create an antenna of coiled wire small enough to be placed inside the body and receive power from a radio transmitter outside the body. The transmitter and the antenna are magnetically coupled so that any change in current flow in the transmitter induces a voltage in the coiled wire.

Poon has created two types of wirelessly powered devices that are able to propel themselves through the bloodstream. One creates a directional force by driving an electrical current directly through the blood to push itself forward at a velocity of just over half a centimeter (0.2 inches) a second. The second type switches current back-and-forth in a wire loop to produce a swishing motion to propel the device forward.

Poon’s research could finally enable the development of medical implants capable of traveling through the bloodstream to deliver drugs to a specific area, perform analyses, and maybe even zap blood clots or remove plaque from arteries.

“There is considerable room for improvement and much work remains before these devices are ready for medical applications,” said Poon. “But for the first time in decades the possibility seems closer than ever.”

Poon recently demonstrated one of her tiny, wirelessly powered, self-propelled devices at the International Solid-State Circuits Conference (ISSCC). The animation below produced by Carlos Suarez at StrongBox3d shows how such a device might move through the bloodstream.

Source: Stanford University

Sourced & published by Henry Sapiecha

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Open-source project intends to advance robotic surgery

A couple of years ago, the Willow Garage robotics company gave ten of its PR2 robots away to deserving research groups. The idea behind the project was that these groups would use the PR2s for robotics research, then share their discoveries with each other, thus advancing the field farther than would be possible if they each had to build their own unique robots from scratch. Now, a similar but unrelated project is underway, and this time the robots are designed specifically to perform surgery.

Sourced & published by Henry Sapiecha

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IS CAESAREAN THE WAY TO GO FOR DELIVERING NEW BORNES?

FOR years, women have been labelled ”too posh to push” for choosing caesarean births without medical reasons, but a controversial new study suggests they may be picking a better path for themselves and their babies.

Dr Stephen Robson, an associate professor of obstetrics at Australian National University, is recruiting 1000 pregnant women to test the long-held view that vaginal deliveries are better than caesareans for healthy women with uncomplicated pregnancies.

The study, which requires 500 women choosing a caesarean and 500 planning a vaginal birth, will look at psychological and physical outcomes for the women and their babies, including depression and breastfeeding rates.

Dr Robson said that although an estimated 10,000 Australian women chose to have caesareans each year without medical reasons, no one had ever comprehensively studied their outcomes because research tended to focus on women with problems. ”From a medical point of view, it’s difficult to counsel people because no one can give a reasonable comparison of what the risks are for women who are otherwise healthy,” he said.

Dr Robson said a study published in The Lancet in 2000, which compared caesareans with vaginal deliveries for babies in the breech position unexpectedly found that women in the caesarean group did slightly better overall than women in the vaginal group. The results left doctors around the world wondering if surgical deliveries could be better for healthy women.

”It dawned on people, what if it turns out to be safer to have a caesarean birth if you’re a healthy mother? … What would that mean? How would that affect society? The topic led to great discussion at a meeting I was at recently where one cheeky guy said, ‘Maybe we could do away with labour wards forever and save hundreds of millions of dollars,’ ” he said.

”Depending on what we find, there is a profound sense that maybe this will lead to an unanticipated and staggering finding.”

Current research cited by the Royal Australian and New Zealand College of Obstetricians and Gynaecologists says caesareans in healthy women may reduce the chance of injuries that lead to incontinence and difficulty with sex while also reducing the risk of their baby dying or getting cerebral palsy.

On the other hand, the college says it may slightly increase the risk of death for mothers while also increasing their risk of placenta accreta in future pregnancies – a serious complication that can cause significant blood loss. The recovery time is also longer compared with a vaginal delivery.

President of the college, Dr Rupert Sherwood, encouraged women to take part in the study.

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Blood transfusions may one day come from blood produced from a patient’s skin

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