Archive for the ‘Defibrillator’ Category

Backscatter Scanners and Pacemakers

November 16, 2010

As you may remember, I almost flew to Atlanta for the recent Heart Walk, but changed my mind when my parents decided to attend, too. While getting my gear organized for the trip I thought about the new “Backscatter” full body X-ray scanners being installed in airports: how do those things interact with pacemakers? The Transportation Security Administration (TSA) recommends that those of us with Pacer Power avoid the metal detectors, and since I got my pacer I’m not cool around large magnets. After all, the doctors use a magnet to set my pacemaker; it stands to reason that another magnet could scramble it! So I pull out my plastic card and tell the TSA agents that I have a pacemaker and request a hand patdown, and just avoid all that.

But what about the new scanners? Friend or foe? Not knowing, I called my pacer lab. The short answer: We don’t know.

The longer answer: There hasn’t been any testing done on pacemakers yet. It’s not really safe to get a human volunteer to test the scanner (“We don’t think anything well happen, Fred, but just in case… sign this release form.”) so the next best plan is a series of tests, usually involving calibrating a pacemaker, taping it to a mannequin, and sending him through a scanner – simulating what would happen to a traveler who happens to have a pacemaker.

If the pacer checks out, you run the test again, and again, and again, to see if going through the scanner multiple times will affect the pacer. Then you run the test yet again – with longer scans and higher radiation levels, to see if that affects the pacemaker. And you keep repeating these tests to eliminate the possibility of a fluke reading.

Wow, that’s pretty involved. It would probably be better if we could borrow a scanner for a few weeks, but I doubt that is going to happen. TSA like to keep things close to the vest, and I bet that goes double for their newest secuity tool. So I figure that the best thing to do if you have a pacemaker is not to risk it – just keep asking for a hand search.

Thankfully, my home airport is so small that they only have three gates. It will be quite a while before they get a Backscatter scanner!

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When the light fades

August 4, 2010

With new life extending technology comes new ethical questions – often not can you take advantage of it, but should you? A recent report by the Heart Rhythm Society offered detailed guidelines concerning shutting down a pacemaker or Implantable Cardioverter Defibrillators (ICDs) near the end of life. The purpose of the document is to outline the rights and responsibilities that patients, family, and caregivers have. Fully 10% of doctors may feel that deactivation of a pacemaker – even at the request of the patient or their family – is wrong.  (The percentage that see ICD shutdown as wrong is 1%, as an ICD can be changed to “pacemaker only mode”.)

A recent Mayo Clinic study found that withdrawing a Left Ventricle Assistance Device (LVAD) was ethical, if the patient (or their surrogate) recognized the eventual outcome of such an act.  While a heart may be strong enough to continue beating for a while without a pacemaker, shutting down a LVAD is an extremely serious step. The LVAD is a pump, and the heart is a pump; the only reason to hook a pump to a pump is because the first pump can no longer do its job. Death could come fairly quickly after LVAD shutdown. The writers of the Mayo Clinic study contend that turning off a LVAD (or refusing it altogether) is not physician assisted suicide or euthanasia.

But why would someone want to deactivate a pacemaker or LVAD? There are many illnesses that steal the body while leaving the Circulatory System functional. A stroke or Alzheimer’s can leave you incapacitated while your heart beats on. Or perhaps you have reached the end of your life, and your heart just can’t go any further, so it shuts down…. only to be zapped back to life by an ICD. Blogger Dr. John M. notes that things change, life changes – and occasionally he has to tell a patient “Sir, an ICD will no longer help you.” And Dr. Wes is there as a gentleman plays the last few notes of his life’s song.

80% of all Americans will probably die of an incurable chronic illness. Most of those people want to die at home, with as much dignity as possible and as little pain as possible. I plan to fight for as long as I can stand – Rage, rage, against the dying of the light! But in the back of every CHDer’s mind is the knowledge that one day our hearts will give out… and it will probably happen slowly.

Our light will fade away rather than being snuffed out.

Are you Iron Man? Nope! Just a Funky Heart!

May 28, 2010

This originally came from Salon.com, but I found it on Dr. Wes’ blog:

Iron Man’s powers are generated from an implant designed to keep his weakened heart from failing. Of course, there are differences in our individual circumstances. Tony Stark, the man beneath the Iron Man armor, designed his own implant in an effort to save himself from a piece of shrapnel traveling to his heart. Not only that, he created the device using material provided by his unwitting captors (Asian Reds in the original “Tales of Suspense” comic; Middle Eastern terrorists in the movie). I am not nearly that clever; my device was built by Medtronic, a Minneapolis company that was started in a garage and is now the largest medical device company in the world. We have so much in common, and yet I have so many things to learn from him. Sure he’s a little smoother in social situations, and better connected, yet at our core we share something rare. We are both cyborgs.



New ICD moves leads, reduces chance of infection

May 2, 2010

Implantable Cardioverter Defibrillators (ICDs) are cool. For people who are prone to tachycardia, V-Fib, or other rhythm disorders, it could be a lifesaver. An ICD is like having your own medical team with you all the time. The moment there is trouble they get out the paddles, shout “CLEAR!” and give you a life saving jolt. And very few people have to know you even have one.

But in most cases, the patient population for new ICD are older citizens. This 2007 clinical trial specifically tested the efficiency of pacemakers in patients that were 75 years old or older. But what about us younger folks who need an ICD? They usually aren’t recommended for the youngsters.

One of the potential problems are the ICD leads. The wires that run from the ICD have to go into the heart and connect inside of the heart muscle to deliver the shock if one is needed. Leads have to be strong, but flexible. You can have one or the other, but usually not both. At the Broken Hearts of the Big Bend Regional Forum on Congenital Heart Defects I attended in February, electrophysiologist Dr. Randy Bryant  said that most children who have either a pacemaker or an ICD needed to have their leads replaced. One of the more common reasons for the replacement is the Belly Flop into the swimming pool. Leads seem to have difficulty dealing with that!

And every time you change a lead, you run the risk of giving an infection a chance to get inside the body. The odds are low, but toss the dice enough times, and you’ll finally roll snake eyes.

And leads can just, for lack of a better word, wear down. They have to be connected to a certain spot inside of a muscle that is constantly in motion, with an owner who could turn, twist, or bend in any conceivable direction. As Dr. Martin Burke, Director of the Heart Rhythm Center at the University of Chicago Medical Center puts it:

“It’s a 98.6 degree, dynamic environment that pumps like a piston 60 to 100 times a minute; it’s a miracle they last 15-20 years in my mind.”

Burke has been part of a team that has tried to rethink the Defibrillator, take a good idea and make it even better. It looks as if they may be onto something: An Implantable Cardioverter Defibrillator (ICD) with leads that are not in the heart, but rather just below the skin. Putting the leads just below the skin (they don’t even go beyond the breastbone) means that the ICD has to deliver a shock that is two and a half times more powerful that the average ICD. But the computer that controls the ICD has also been improved. It can better detect heart rhythms that are unusual but not dangerous, and deliver fewer shocks.

The new Defibrillator (which is known as the S-ICD) has just entered clinical trials, so you won’t be able to go to your doctor and demand one. But in the future, hopefully it will become a common tool for CHDers and other heart patients.