FDA Patient Safety News: Show #5, June 2002

New Device for Bilateral Control of Parkinson Symptoms

FDA recently approved the expanded use of an implanted device used to control the symptoms of Parkinson's disease. The device, a deep brain stimulator, is called the Activa Parkinson's Control System, and it's manufactured by Medtronic, Inc., of Minneapolis. The device sends a constant stream of electrical impulses to the brain, and this can alleviate the symptoms of Parkinson's disease in some patients.

This product was previously approved for unilateral implantation in the thalamus. That meant that it could control tremors on one side of the body only. The new approval allows bilateral implantation, which will help control symptoms on both sides of the body. This device is used in patients with advanced, levodopa-responsive Parkinson's disease who have movement-related symptoms that are not adequately controlled with medications, or who experience intolerable side effects from medications.

The Activa System consists of two sets of four electrodes that are implanted bilaterally in the brain. They're connected by leads that run beneath the skin to pulse generators implanted on each side of the chest. Electrical pulses are sent by the pulse generator to the globus pallidus or subthalamic nucleus, where they block signals from the brain and thus may alleviate the symptoms of Parkinson's disease.

The patient can turn the Activa System on or off by holding a small magnet over the area where each pulse generator is implanted. The generators will need to be surgically replaced every few years depending on the stimulation needs of the patient. This can usually be done under local anesthesia. In clinical studies with this device before it was approved, some patients derived significant benefits, but individual results varied a great deal, and so the results for any individual patient can't be predicted in advance.

Almost all of the patients enrolled in the study experienced one or more serious adverse events, which ranged from bleeding into the brain and device related infection, to weakness and hemiplegia. The manufacturer is going to conduct a three-year study to evaluate long-term clinical results.

Additional Information:

FDA Talk Paper. January 14, 2002.
http://www.accessdata.fda.gov/cdrh_docs/pdf/p960009S7a.pdf


New Device for Bilateral Control of Parkinson Symptoms

FDA recently approved the expanded use of an implanted device used to control the symptoms of Parkinson's disease. The device, a deep brain stimulator, is called the Activa Parkinson's Control System, and it's manufactured by Medtronic, Inc., of Minneapolis. The device sends a constant stream of electrical impulses to the brain, and this can alleviate the symptoms of Parkinson's disease in some patients.

This product was previously approved for unilateral implantation in the thalamus. That meant that it could control tremors on one side of the body only. The new approval allows bilateral implantation, which will help control symptoms on both sides of the body. This device is used in patients with advanced, levodopa-responsive Parkinson's disease who have movement-related symptoms that are not adequately controlled with medications, or who experience intolerable side effects from medications.

The Activa System consists of two sets of four electrodes that are implanted bilaterally in the brain. They're connected by leads that run beneath the skin to pulse generators implanted on each side of the chest. Electrical pulses are sent by the pulse generator to the globus pallidus or subthalamic nucleus, where they block signals from the brain and thus may alleviate the symptoms of Parkinson's disease.

The patient can turn the Activa System on or off by holding a small magnet over the area where each pulse generator is implanted. The generators will need to be surgically replaced every few years depending on the stimulation needs of the patient. This can usually be done under local anesthesia. In clinical studies with this device before it was approved, some patients derived significant benefits, but individual results varied a great deal, and so the results for any individual patient can't be predicted in advance.

Almost all of the patients enrolled in the study experienced one or more serious adverse events, which ranged from bleeding into the brain and device related infection, to weakness and hemiplegia. The manufacturer is going to conduct a three-year study to evaluate long-term clinical results.

Additional Information:

Activa® Parkinson's Control System P960009/S7
http://www.fda.gov/cdrh/mda/docs/p960009s7.html


Two New Devices to Treat Congenital Heart Defects

Now we want to talk about two recently approved devices used to treat congenital heart defects. Both devices are occluders that close an abnormal opening between two chambers of the heart, and both are positioned using catheters. That means they can provide an alternative to open heart surgery. Although these devices are used mainly in young children, they have also benefited adult patients.

The first device is the Cardioseal Septal Occlusion System, made by NMT Medical, Inc., of Boston. It's intended to treat complex ventricular septal defects in patients who are at high risk for standard surgical closure because of anatomical conditions or their overall medical condition.

This device had already been approved for limited marketing under the FDA's humanitarian device exemption. This is a special clearance that makes devices available for patients with rare medical conditions. The new approval removes the limitation on the marketing of this device.

The CardioSEAL system has two parts: a delivery catheter and a permanent implant. The implant is actually an occluder that closes the defect and prevents blood from the two ventricles from mixing. It looks like two little umbrellas set edge to edge. Each umbrella has special spring coils. This allows the device to be collapsed and advanced into the catheter, which is then threaded through the blood vessels to the defect in the heart.

When the occluder is in the correct position, the two umbrellas are opened so that there's one on each side of the defect. The spring coil design creates a slight tension that helps hold the umbrellas in place around the defect. Over time, tissue grows into the fabric of the umbrellas and the implant becomes part of the heart.

The new approval was based on a clinical study that included mostly pediatric patients with a variety of hemodynamically significant defects. In suitable patients, 72% had improved clinical status at 6 month follow-up and 84% of the patients had a reduction in flow through the defect or a reduced defect size. Adverse events occurred frequently, but all serious or moderately serious events had resolved by six months after the procedure.

The other device is the Amplatzer Septal Occluder made by AGA Medical Corporation of Golden Valley, Minnesota. This device is used to repair atrial rather than ventricular defects.

The device consists of two discs of wire mesh, linked by a short connector with the same diameter as the defect in the heart. The device is filled with polyester fabric, which promotes the formation of clots and thus helps to close the defect.

Using a special delivery system, the device is fed through a small catheter inserted through a vein in the groin. When the device is passed through the defect, the distal disc is released, the device is pulled against the defect and then the proximal disc is released. This "sandwiches" the defect between the discs. After deployment, the device is released by unscrewing it from the delivery cable. Eventually, tissue grows over the device, closing the defect.

Although a variety of factors influence proper patient selection for these two devices, in general they should not be used in patients with thrombus formation near the implant site, or with certain active infections or coagulation disorders.

The FDA is requiring both companies to continue to study their products for 5 years to better assess long-term safety and effectiveness.

Additional Information:

JAMA Article: Congenital Heart Defect Devices. February 2002.
http://jama.ama-assn.org/cgi/content/extract/287/5/578-b?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Congenital+Heart+Defect+Devices&searchid=1&


Two New Devices to Treat Congenital Heart Defects

Now we want to talk about two recently approved devices used to treat congenital heart defects. Both devices are occluders that close an abnormal opening between two chambers of the heart, and both are positioned using catheters. That means they can provide an alternative to open heart surgery. Although these devices are used mainly in young children, they have also benefited adult patients.

The first device is the Cardioseal Septal Occlusion System, made by NMT Medical, Inc., of Boston. It's intended to treat complex ventricular septal defects in patients who are at high risk for standard surgical closure because of anatomical conditions or their overall medical condition.

This device had already been approved for limited marketing under the FDA's humanitarian device exemption. This is a special clearance that makes devices available for patients with rare medical conditions. The new approval removes the limitation on the marketing of this device.

The CardioSEAL system has two parts: a delivery catheter and a permanent implant. The implant is actually an occluder that closes the defect and prevents blood from the two ventricles from mixing. It looks like two little umbrellas set edge to edge. Each umbrella has special spring coils. This allows the device to be collapsed and advanced into the catheter, which is then threaded through the blood vessels to the defect in the heart.

When the occluder is in the correct position, the two umbrellas are opened so that there's one on each side of the defect. The spring coil design creates a slight tension that helps hold the umbrellas in place around the defect. Over time, tissue grows into the fabric of the umbrellas and the implant becomes part of the heart.

The new approval was based on a clinical study that included mostly pediatric patients with a variety of hemodynamically significant defects. In suitable patients, 72% had improved clinical status at 6 month follow-up and 84% of the patients had a reduction in flow through the defect or a reduced defect size. Adverse events occurred frequently, but all serious or moderately serious events had resolved by six months after the procedure.

The other device is the Amplatzer Septal Occluder made by AGA Medical Corporation of Golden Valley, Minnesota. This device is used to repair atrial rather than ventricular defects.

The device consists of two discs of wire mesh, linked by a short connector with the same diameter as the defect in the heart. The device is filled with polyester fabric, which promotes the formation of clots and thus helps to close the defect.

Using a special delivery system, the device is fed through a small catheter inserted through a vein in the groin. When the device is passed through the defect, the distal disc is released, the device is pulled against the defect and then the proximal disc is released. This "sandwiches" the defect between the discs. After deployment, the device is released by unscrewing it from the delivery cable. Eventually, tissue grows over the device, closing the defect.

Although a variety of factors influence proper patient selection for these two devices, in general they should not be used in patients with thrombus formation near the implant site, or with certain active infections or coagulation disorders.

The FDA is requiring both companies to continue to study their products for 5 years to better assess long-term safety and effectiveness.

Additional Information:

Consumer Information on Cardioseal Septal Occlusion System. December 5, 2001.
http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/DeviceApprovalsandClearances/Recently-ApprovedDevices/ucm083993.htm


Problems After Vacuum-Assisted Childbirth

Now let's talk about specific ways to protect patients. FDA has alerted health professionals to the possibility of serious adverse events after the use of vacuum extractors to assist in childbirth. A vacuum extractor applies suction to the fetal scalp during childbirth to facilitate delivery.

An FDA article in the January issue of Nursing 2002 notes that infants delivered with this device commonly develop fluid in the scalp or a limited subperiosteal hemorrhage, and that these typically resolve spontaneously. But the FDA has received reports of much more serious complications, including subgaleal hematoma and intracranial hemorrhage. And although these are rare, they can be fatal.

To protect patients from harm, two things are important. First, in order to minimize the chance of an adverse event happening, it's important that people using these devices do so properly. And second, in order to minimize the possibility of serious damage to the infant when an adverse event does occur, it's important that people caring for vacuum extracted newborns monitor them for warning signs.

First let's talk about safe use. FDA stresses that users should be trained properly, and that they follow the manufacturer's instructions regarding things like positioning the vacuum cup, how much vacuum strength to use, and how long to continue the treatment. Also, the recommended technique for these products is to apply steady traction in the line of the birth canal, and not to rock or twist the device, which can be dangerous.

And now let's talk about monitoring. Here, FDA recommends alerting an infant's caregivers that vacuum extraction was used and instructing them to watch the infant for several days for possible problems. One way to be sure that's done is to note the use of a vacuum extractor in the infant's chart. And remember, parents should be instructed to look for warning signs, too. These signs include swelling of the head and neck, hypotension and pallor, lethargy, irritability, convulsions, rapid breathing and tachycardia. For a more complete list and discussion, look under this story on our web site.

Additional Information:

FDA Public Health Advisory: Need for CAUTION When Using Vacuum Assisted Delivery Devices. May 21, 1998.
http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PublicHealthNotifications/UCM062295


Misconnection of Tubes and Ports

And now for the portion of the broadcast that we call "Journal Scan," where we talk about recent publications that are particularly relevant to patient safety.

This time we want to call your attention to an alert issued by the Institute of Safe Medication Practices in November 2001. This alert described a patient who died when his IV tubing was mistakenly connected to the inflation port on the cuff of his tracheostomy tube. It should have been connected to his central line IV catheter. When the IV infusion pump was turned on, the tracheostomy cuff filled with fluid. This caused the tracheostomy tube to become obstructed, and the patient suffocated.

The ISMP report discusses how such an unusual event could occur. In other words, how could someone mistake a tracheostomy inflation port for a triple lumen IV catheter? Among the factors they listed were the fact that the patient had just been transferred to a medical unit where tracheostomy tubes were rarely used, that the light in the room was dim to avoid waking the patient, and that the patient's triple lumen catheter was not secured, so the tubing hung down at the same level as the tracheostomy cuff tubing.

The report notes that this case belongs to a larger class of errors that can be called "Wrong tube, wrong hole, wrong connector." And it gives several recommendations to avoid these kinds of errors.

For example, when the patient has more than one kind of tubing that could be attached to a port of entry into the body, attach an identifying label to each tube, near the end that's inserted. Before administering drugs or other products, trace the tubing from the source to the connection port, to be sure the connections are correct. If you're administering high alert medications, or the patient is high-risk, double check all line attachments with another practitioner. And monitor patients so as to detect errors quickly and minimize their consequences.

Additional Information:

ISMP Medication Safety Alert "IV connection to tracheostomy cuff inflation port reflects larger problem". November 28, 2001.
http://www.ismp.org/msaarticles/connection.html


Electrical Muscle Stimulators

And now for a new segment in FDA Patient Safety News. It's called "Patients are Asking," and it gives information that you may want to pass along to patients about medical products they may be using at home or at work. Today we want to talk about electrical muscle stimulators-the kinds of devices that are sold over the counter to tone the muscles, particularly those in the abdomen.

Some of your patients may be asking about whether these products work, and whether they're safe. Because these muscle stimulators are considered to be medical devices, FDA is responsible for regulating them. Most of the ones FDA has reviewed are for use in physical therapy and rehabilitation, under the supervision of a health care professional. They're used for such things as muscle re-education, relaxation of muscle spasms, increasing range of motion, and preventing muscle atrophy.

If a company chooses to sell its device directly to consumers, it must show FDA that the device is safe and effective for its intended use. For up-to-date information on which of these over-the-counter products have been cleared by FDA, go to our web site.

Now let's get back to whether these kinds of products work. They've certainly generated a lot of advertisements and infomercials. Some of the ads claim that they tone, firm and strengthen abdominal muscles, and that they'll give you "rock hard" abs. Some of them also claim to provide weight loss and a smaller waist size. If a patient asks about these claims, you should advise them that although these devices may strengthen or tone muscles to some extent, they won't produce a major change in your appearance all by themselves. And none of these products have been cleared for weight loss or for reducing waist size.

Now, what about safety? Patients should be advised that there have been reports of shocks, burns, bruising, skin irritation and pain while the device was being used. There have also been several incidents where the muscle stimulator interfered with implanted devices, such as pacemakers and defibrillators. It's also possible that among the muscle stimulators not cleared by FDA, some might not comply with electrical safety standards, and of course that raises the possibility of shock or electrocution.

To learn more about electrical muscle stimulators or to report a problem associated with one of these devices, please visit our website.

Additional Information:

Consumer Information on Electrical Muscle Stimulators. April 10, 2002.
http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/HomeHealthandConsumer/ConsumerProducts/ucm142478.htm



FDA Patient Safety News is available at www.fda.gov/psn