ECG Tracing

Great questions and answers

Hi, Kaley:

I am glad to hear that you are fine. Me too. I do not really make pacemakers, my company makes pacemakers. I wish I had made Mrs. Weeg's, then I could have a good excuse to come up and visit. You asked, "How do you recharge the pacemaker?"

Mrs. Weeg's pacemaker cannot be recharged. It will have to be replaced in a few years with a newer model (she will be re-energized). The pacemakers that we used to make that were rechargeable had to be recharged using a special "vest" that was placed over the pacemaker that recharged it through the skin. Please write anytime,

Your Keypal
Mr. D

Dear Ashleigh:

Please tell everyone that I very much appreciate the concern for me whhile I had my cold. You all made me feel so much better that I got well in less than a week. You are all *magic* ;-)

I am glad you enjoyed watching, and hearing, Mrs. Weeg having her pacemaker checked. It was me on the other side checking the ECG tracing. You asked, "How do the nurses and doctors know how to check the heart beats and stuff?

Checking the heart beats is easy, it's the "stuff" you have to be careful of. Doctors and nurses may learn about pacemakers during their years of training. The information that they learn while they are in school is then reinforced, by practice with real patients and by training conducted by pacemaker companies and the hospitals where they work. Thank you for your question, write to me anytime,

Your Keypal
Mr. Delos

Dear Danielle:

Do they ever call you Dani? You asked some very good questions.

1. When we heard Mrs. 'Weeg's heart beat, what made that double beating sound?

I think you heard the double sound when she placed the magnet over the pacemaker. What you were hearing was the sound the pacemaker spikes make when two are close together. Mrs. Weeg only had two pacemaker spikes together when the magnet was over the pacemaker. You can see them on the tracing that I sent.

2. Why did it make that sound?

The transmitter is really a modem. It uses sound transmitted over the telephone line to create an ECG tracing (you know the one I mean). Each fluctuation of the sound tells the needle on the ECG machine to go up or down and draw the ECG tracing.

3. How come in the beginning of the heart rate paper the QRS had shorter points and near the end they got longer?

Good pickup. On my end of the machine I have a little knob that I can turn to make the waveforms bigger and smaller. I must have been playing with it trying to get a little better tracing.

4. How many times does a person get the pacemaker battery checked and how long is it between battery checks?

It depends on the doctor and his usual practice. Some people get their pacemakers checked every 3 months, others every 6 months. It really just depends. I know some patients who only go to the doctor when they are not feeling so well because they believe that battery checks are a waste of time and money (this can be a very dangerous practice). I hope I have answered your questions so that they make a little sense to you. Maybe one day it will make sense to me.

Until "D" next time,
Mr. D.

Dear Ashley:

I hope I don't get a "C" :-( First of all, Good Job on finding the heart rates. The heart rate of a child was a little off, however. When babies are born, their hearts may be beating at faster than 150 bpm. As children get older, the heart rates usually get slower and slower. The normal range for an adult is considered to be between 60 and 100 beats per minute. Can you believe 615 beats per minute for a hummingbird? That's over 10 heart beats per second. How about taking a guess on the elephants heart beat based on what you already know about hummingbirds, children, adults and horses. Your questions from this go 'round are very interesting.

1. Can you put a pacemaker in an animal?

Yes, we can. In fact, some people put in their wills to donate *their* pacemakers to veterinary clinics to implant in dogs, cats, horses, kangaroos, etc. The animals usually do very well with their new *used* devices.

2. If there is a QRS absent, could you open the animal up and put in a pacemaker?

Pacemakers are placed in animals in much the same way as they are placed in humans. It would take far to much time to describe the different approaches to different sized animals. The only big difference (besides the different anatomy) is that animals are always put to sleep temporarily during the procedure and people are almost always awake. It's easier to tell a person to "be still" than Fido.

3. Back in the old days, how did they hook up an animal to the machine?

Back in the old days they usually didn't. Your letters are just about the right length for my feeble brain to retain all the good information that you share with me. You do not 'bug' me with your questions.

Until next time,
Mr. D

Dear Kim:

You asked some very interesting questions, and I will try to answer them.

1. How do those rings determine if her battery is good or not?

The rings are only used so that we can see her ECG rhythm. If we see the pacemaker acting in a certain way on the ECG that may tell us if the pacemaker is working normally or if the battery is low. When the battery is low in a pacemaker, a special circuit tells the pacemaker to send us a signal if a magnet is applied over the pacemaker.

2. How does that magnet go through her skin to the pacemaker?

I know Mrs. Weeg has a tough skin because she is a school teacher, but her skin is not tough enough or deep enough to stop that magnet from going through. Pacemaker magnets are very 'strong.' Much stronger that the magnet you might by at a toy store. When the magnet is over the pacemaker it is only a few millimeters away from the pacemaker.

3. Does the phone have to be a certain phone to check her battery?

It has to be the phone she is using. No special phone is required, but she must remember to place the mouthpiece of the phone over the little hole in the middle of the transmitter. If she places the earpiece of the phone over the hole, the person on the other side of the line will not get anything to record.

4. How does the machine know to send the signals to your end of the phone?

The 'machine' is actually a special kind of modem. It works exactly the same way as a computer modem and the machine on my side of the telephone 'decodes' the signal and we see the ECG. I hope this answers your questions. Please forgive me for being so long in getting them done. Write anytime.

You Keypal
Mr. D.

Dear Heather:

I know I am late on my homework. Sorry, I guess that a B- will have to do. I'll try to do better next time. I hope I can answer your questions accurately.

1. How long does it take to make a pacemaker?

This is a very hard question to answer. Pacemakers are not stamped out on an assembly line like cars, where one rolls off every two minutes. The different parts of the pacemaker are assembled (header, can, circuit board, etc.) and then the assembled parts are put together. During the building process, people who are called Quality Assurance Personnel (QA, for short) inspect and reinspect and reinspect again each part of the process over and over. Once everything is satisfactory, groups of pacemakers are placed in a gas sterilization chamber and sterilized. Because the people who receive pacemakers usually need them to improve their quality (and sometimes, quantity) of life, a great deal of care is required to build a pacemaker.

2. Do you like making them?

I do not make them. I only help people to understand how they are supposed to work. Most of the time when I explain how the pacemaker works, people say, "Wow!" but sometimes they say "Huh?" ;-)

3. What is the "lead configuration?"

When an electrocardiogram (ECG) is performed, we refer to the different ways we can look at the electrical signals coming from the heart as "ECG Leads." When Mrs. Weeg sends a transmission over the telephone line using the "ring electrodes" on a finger from each hand, this is what is known as a "Lead I" configuration. If she were to place one ring electrode on the index finger of her right hand and one on her left big toe this would be known as a "Lead II (pronounced lead 2)" (although I might call it a "Lead Toe." ) ECG lead configurations can be very confusion and I am still hurting from the last "Huh?"

4. What did you say "P waves" were again.

P waves represent the electrical signal that is seen on the ECG when the top chambers of the heart (atria) contract.

5. Are you ever going to come see us and teach us in person.

Good question. I hope to, one day, but I cannot promise you a visit. How far is it from Coral Springs, FL to Delmar, MD?

Bye, back at ya'
Mr. D

Hello, Vi:

Maybe I should call this "To Vi, From D" - it kind of rhymes. If you think you miss Florida now, wait until February! You asked me if I had ever been to Disney World (yes), Universal Studios (yes), Cypress Gardens (no, but I have been by there), Sea World (yes), Busch Gardens (yes), Adventure Island (no), and Spendid China (no).

Hope you enjoy the winter in MD.
Mr. D
Delos Johnson

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