Remember that the normal conduction of the heart begins in the SA node. The wave of depolarization moves across the atria, through the AV node, into the Bundle of HIS, down the Bundle Branches, and finally through the Purkinje fibers which conduct the electrical impulses throughout the ventricles. The activity of the heart produces electrical potentials that can be measured on the surface of the skin. Using the galvanometer EKG machine , differences between electrical potentials at different sites of the body can be recorded.
See illustration below:. In picture A above, the negative electrode is on the right arm and the positive electrode is on the left arm.
This is lead I. Lead I records electrical difference between the left and right arm electrodes. In picture B above, the negative electrode is on the right arm and the positive electrode is on the left leg left lower chest.
This is lead II. Lead II records electrical differences between the left leg and right arm electrodes. In picture C, the negative electrode is on the left arm and the positive electrode is on the left leg left lower chest. Picture C depicts lead III. Lead III records electrical difference between the left leg and the left arm electrodes. The other three frontal plane limb leads are called the augmented Vector leads. The Galvanometer EKG machine records potential differences and, therefore, the technique is Bipolar potential site A minus potential site B.
However, if the potential of B is zero the recorder records only the potential site A. As mentioned earlier, unipolar leads measure the electric impulses at only one point, instead of across two points, as the first three leads.
With these V leads, the second site is so there is noneed to measure from two pointes, only one point is needed. The machine automatically makes the needed connection to measure the voltage from these areas. As the above illustrations point out, the six limb leads measure the electrical activity of the heart from the frontal plan. The frontal plane only manes that the patient is in anatomical position and facing you. You also have the option to opt-out of these cookies.
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But there are times, I am asked to do an ekg, while the patient is upright, or laying on either side, or shaking so hard, it is almost impossible to get a decent tracing. So what I usually do, is just get the best tracing I can and relate the change of position, to the reading doctor and make note on the ekg. It frustrates me to occasionally have a less than clear ekg. These are the times I find myself asking questions, but cannot really get any clear answers. So I will investigate your web site and see, if I can pass on what I learn to my supervisor.
Thanks again, for a great intro. Jack, you draw out a good point. Medicine can often be related to working in less than ideal conditions.
Experience does help with efficiency, though. Thanks for the input. I was at my physicians office upset due to misdiagnosis and lack of empathy and ability to listen to me, I bacame very upset and I spoke to Manager for about an hour then as I was going to leave I didnt feel well my chest was ice cold my left arm tprwards the back shoukder hurt I explain this to them as I first arrived to office blood pressure was high after the discussion of dr not listening it was extremley higher they offered oxygen and I said I had horrible headache and that most likely call an ambulance doctor came in a few seconds and poped a pill in my mouth I dont know what it was all I remember is it me e my mouth very dry and I hurt and was stiff all over.
Dr called ambulance and didnt tell them she had given me any pill then paramedics placed the leads incorrecly after correcting this only a few short minutes they were done. They said nothing to me and I was unable to drive I left my car at dr parking lot. Many hours later dr calls to tell me the hospital told her that it was inaccurate results because I was moving. I couldnt move and I was given oxygen while this test is being done.
They were the ones who continued to laugh joke around and keep talking. Hi there. I am cardiac RN that works with nuclear stress testing.
During the stress portion, the patient is connected to a 12 lead EKG monitoring system and an EKG is printed every minute of the 4 minute test. The result is dependent on the imaging from the Spect-CT camera read by the radiologists in our hospital and the cardiologists dictate the 4 minute injection portion we use regadenoson.
My question is, how critical is lead placement? Again, the patient is discharged and or diagnosed dependent on the imaging portion, not the EKG tracings. For example, the cardiologist may not even dictate for weeks after the patient is discharged. Thank you for taking the time to read this and answer, Its a long one. Hi Cindy. Good questions.
If you happen to place a lead over a rib vs the intercostal space, that can affect what you see. Hope that helps. Most people do put it on the rib directly between V2 and V4.
I would recommend putting V3 on the 5th intercostal centered between V2 and V4. That should more than sufficiently capture the anterior part of the heart. The other day I had to make an EKG to a patient in prone severe respiratory distress. How would you place the leads from V1 to V6?
Thank you. The answer is that it depends. I have been a pre hospital provider for 26 years 18 of them as a paramedic. I have also been a nurse for nine years in the ED, flight, and now as an educator.
Nearly everyone says that leads should be placed under the breast of females. For years in the prehospital world as well as all of my time in the hospital, we have taught an exception to that rule.
In the case of extremely large breasted females, if the 5th intercostal space can be clearly palpated above the breast then that is where the leads are to be placed. We know that breast tissue is not a superconductor of electricity however; we go back to the bones guiding us. If the 5th intercostal space can be clearly palpated above the breast then there should be no more tissue interfering with the electrical activity then there is on a male.
As an argument say that I can clearly feel the 5th intercostal space and I still choose to place the leads under the breast. How far out of place, do you think the leads are now? A 12 lead serves as a diagnostic test. A single electrode is positioned between this pair of electrodes on the fourth intercostal space. An eighth electrode is placed between the fifth and sixth ribs at the mid-clavicular line, the imaginary reference line that extends down from the middle of the clavicle. The ninth electrode is positioned in line horizontally with the eighth electrode but in the anterior axillary line or the imaginary reference line running southward from the point where the collarbone and arm meet.
A report will be sent to your referring doctor, usually within 24 hours. Your doctor will discuss your results at your next appointment.
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