Magnets and valves?

[Emma]

Hi all,
I feel a bit silly asking this as I know I probably should know the answer (and suspect I do) almost 6 years into this valve replacement world but...

Have been reading a thread on another site about pacemakers and the danger of using magnets near them and wondered if anyone has ever heard of them affecting mechanical valves too?? I mean, if Chloe was to be using magnets and school and put one near her chest, could it affect the heart/valve??

Sorry to be naive!
Love Emma
xxx

 

[Ross]

I think that is myth. Someone said that they could hang a magnet off their chest. I tried it with all sorts of magnets, they all fell to the floor. Thinking further, they were talking about the wires in the chest rather then the valve, but nonetheless, can't be proven by me. Now pacemakers, I can understand since they have current flow and their own magnets with them.

 

[Rich]

Most mechanical valves are made of carbon, not metal.
Some parts of a valve may be metal, I'm not sure about all the different valves out there these days.
But any metal including chest wires should be a non-magnetic metal.
This is why people with a mechanical valve are allowed to have an MRI if needed.
The only question I never got answered was in regard to some staples that are still in there. They showed up on an x-ray taken for something else.
Rich

 

[hensylee]

I rather expect we'd have had a discussion if this were so. If anyone knows differently, please stop in and tell us what you know. Pacers, come on in.

 

[lcwhitney]

Most valves are titanium and are not affected by magnets. An MRI is partly a giant magnet. I have 2 St. Jude valves and I have been able to have several MRIS done since my 1st valve surgery in 2001

Lettitia

 

[Emma]

Thanks all - pretty much what I'd thought but needed someone else to confirm it if you see what I mean?
Completely see why pacemakers would be affected and had never thought about magnets with valves, but it was only when someone asked me on this thread yesterday about it that I stopped to question it myself and knew exactly where to come for expert advice!

Thank you all again
Love Emma
xxx

 

[Turkey Hunter]

http://www.valvereplacement.com/forums/showthread.php?t=5928&highlight=Magnets+chest
Here's a post where we discussed magnets hanging from our chest.
I can still doit with a small fridge magnet.

For those of you technically inclined (copied from Azom.com):

Background

Magnetic permeability is the ability of a material to carry magnetism, indicated by the degree to which it is attracted to a magnet. All stainless steels, with the exception of the austenitic group, are strongly attracted to a magnet.

Austenitic Grades

All austenitic grades have very low magnetic permeabilities and hence show almost no response to a magnet when in the annealed condition; the situation is, however, far less clear when these steels have been cold worked by wire drawing, rolling or even centreless grinding, shot blasting or heavy polishing. After substantial cold working Grade 304 may exhibit quite strong response to a magnet, whereas Grades 310 and 316 will in most instances still be almost totally non-responsive.

The change in magnetic response is due to atomic lattice straining and formation of martensite. In general, the higher the nickel to chromium ratio the more stable is the austenitic structure and the less magnetic response that will be induced by cold work. Magnetic response can therefore be used as a method for sorting grades of stainless steel, but considerable caution needs to be exercised.

My guess is there are many varieties or grades of wire used. Some may be magnetic and others not. I would also guess if you asked your surgeon, he would have no clue what grade of wire he uses!

this is from:
http://www.valvereplacement.com/forums/showthread.php?t=17868&page=2&highlight=Magnets+chest
Even a piture in this one to demonstrate the magnet thing works.

 

[NascarfanMary]

When I first went to our Walmart after my replacement and new pacemaker, I was exiting the store and the alarms went off. It frightened me. I thought maybe we had left something in the cart. I was so nervous.

Then I realized it was me. So my husband grabbed my purse so I could show them my cards stating I have a pacemaker and a mechanical valve. It happened once again, months later at the store.

When I go into our Courthouse, they have a sign posted about pacemakers and to walk around the scanner. It did beep the first time I went thru. I didn't see the sign posted. So I was surprised. So I tell the Deputy right away went I enter the building.

I have been to many different places since and no beeping when passing thur store scanners. But Last Sunday, I was at the mall with my family. I went into Walden Book Store, looking for a Bible Study Book. I purchased it and started to leave, when BEEP BEEP BEEP stopped me. The cashier rechecked the book on the scanner and said that should be ok. Well, BEEP BEEP BEEP it went.
So she took the book and walked thru. No BEEP. I went again. BEEP BEEP.

I told her about my pacemaker,and show her my cards that I carry, so I gave her the book. And then I went thru again. BEEP BEEP So It was my little metal pieces setting off the alarm. We had a good laugh that afternoon.

 

[tobagotwo]

Mechanicals and Magnets

Mechanicals and Magnets

The magnet test on the chest was for the sternum wires. I can't get any magnets to stick, either. Seemed like it would have been a good party trick...

So, how can you know if magnets are safe for heart valves?

There's not much available that's more magnetic than a Magnetic Resonance Imaging device. An initial part of its activity is to expose you to a magnetic field strong enough to force the axes of all the hydrogen atoms in your body to align to magnetic poles at your head and feet. And hydrogen atoms are not all that magnetic. No one is allowed to wear metal in the MRI room, as metallic objects can become injurious darts when the field is on.

An MRI test was done of different models of most of the major heart valve brands and models, including Sorin, St. Jude, ATS, even the Bjork-Shileys, as well as tissue valves like the Medtronics Hancock, other Medtronics tissue valves, a bovine tissue valve (not Edwards), and the Toronto SPV.

From the Journal of Magnetic Resonance Imaging12:363–369 (2000) http://www.imrser.org/PDF/Shellock.HeartValves.JMRI.pdf Prosthetic Heart Valves: Evaluation of Magnetic Field Interactions, Heating, and Artifacts at 1.5 T Maria-Benedicta Edwards, MPhil,1 Kenneth M. Taylor, FRCS,1 and Frank G. Shellock, PhD2

SUMMARY AND CONCLUSIONS
MRI safety was determined for 32 different heart valve prostheses using ex vivo test procedures in association with a 1.5-T MR system. All prosthetic heart valves were tested for magnetic field interactions, heating, and artifacts. The data revealed only minor magnetic field interactions with temperature changes that were substantially below that known to pose a hazard to human subjects. Artifacts were characterized as mild to severe in size. Based on this information, these heart valve prostheses should not present a hazard with respect to movement or dislodgement in MRI environments of 1.5 T or less. Additionally, RF energy-induced heating associated with a whole-body averaged SAR of 1.1 W/kg will not pose a risk to a patient with one of these heart valve prostheses. Accordingly, these heart valve prostheses should be considered “MR safe” according to the specific conditions used for testing.

(Note: "artifact" only means an item's image that shows up on the scan, nothing harmful. Remember also, this refers only to valves, not pacemakers or other equipment.)

If an MRI unit won't do it, no magnet your child will ever come into contact with will do it. Including the ones fishermen use to pick up 500lb objects underwater, like submerged outboard motors.

Rest easy, and buy her those Magnetix building kits she wanted.

Best wishes,

 

[ALCapshaw2]

Emma -

Did you receive a registration card from On-X ?

The card I received from St. Jude has "MRI COMPATIBLE" printed in BOLD LETTERS in the middle of the card.

'AL Capshaw'

 

[twinmaker]

I have a pacemaker/defibrillator combination and the way it's tested is with a magnet. When a magnet is placed over the device, my heart starts to beat very fast. All this is done either in the doc's office or over the phone with me using a special machine hooked up to my phone. Anyway, I'm supposed to stay away from magnets. No MRI's for me. LINDA P.S. I did have an MRI when I had my mechanical valve only and had no problem.

 

[Jkm7]

I don't know if it is wires used or staples or what, but some of our refrigerator magnets stick to my chest.....three years since surgery.