Talk:Electrocardiography

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This article was the subject of a Wiki Education Foundation-supported course assignment, between 3 September 2019 and 19 December 2019. Further details are available on the course page. Student editor(s): 10ebyu10e. Peer reviewers: DrScienceGuy, Travm808.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 20:22, 16 January 2022 (UTC)

Untitled

   Contrary to usual WP talk conventions, the respective discussions on this "talk" page of two distinct matters were once addressable at best by the title of this page, and later by Talk:Electrocardiography#Untitled (which never placed the older of the two discussions at the top of the browser's page-content portion). Now, the newer of those discussions can now be found at

Talk:Electrocardiography#"Untitled" re lengths of PQ features

and the older at

Talk:Electrocardiography#"Untitled" re suggested QTc ref

^{--Jerzy•t 08:04, 7 June 2013 (UTC)}

   The first section on this page to bear "Untitled" as its title included at least four contributions (by at least three editors), namely those

1. creating the talk page by suggesting a ref re QT_c (Jfdwolff, 11:15, 7 May 2004)
2. adding, ahead of that, at least one of the tan-box "WikiProject" and {{WP1.0}} templates in the (then, and now soon again to be, untitled) lead section (an edit or edits i'm not taking the trouble to track down)
3. starting a new topic re lengths of PQ features, above both of those contribs (131.220.35.12 (talk · contribs · WHOIS), 21:52, 28 January 2010)
4. (inter al.) putting the title "Untitled" on the lead section containing the preceding 3 items (User:SmackBot at 07:34, 10 September 2010)

As an aid to later editors studying the edit history, i am adding this documentation of the preceding hard-to-trace events, and saving, prior to an additional edit for the following purpose:

putting top-level sections into order of increasing date of the first body-text that belongs under those respective top-level sections -- in spite of duplicated or belated titling of topics, starting topics above pre-existing top-level sections, and the like.

--Jerzy•t 08:04, 7 June 2013 (UTC)

"Untitled" re suggested QT_c ref

Talking about QT_c, how about providing the references to Bazett's and Rautaharju's publications???
JFW | T@lk 11:15, 7 May 2004 (UTC)

question

I didn't understand what is the "lead". Does it have anything to do with the chemical element?--132.66.16.12 08:44, 26 Aug 2004 (UTC)

A lead (rhymes with speed) is a recording electrode which measures voltage at a particular point in the body. It's not related to the chemical element, lead (rhymes with Fred). In EKG and related techniques, usually between 5-12 leads are placed on the limbs and ankles, and are used to record a profile of the electrical activity of the heart. --Diberri | Talk 14:49, Aug 26, 2004 (UTC)

In (probably) simpler words, a lead is a PAIR of electrodes, & any electrical disturbance created by the activity of the heart has to "do work" against the potential difference existing between the 2 electrodes. It is not explained in the article, but the electrodes function as if acting from the points of attachment of the limb to the body. Even though potential difference is a scalar, the leads have a direction. For instance, in lead I, the the electrode attached to the left upper limb is it at a higher potential than the opposite arm, so a positive electrical disturbance (generated from the heart) will have to do positive work in travelling from the left to the right side. Hence, this will be registered as a positive deflection. KC Panchal 11:10, 5 February 2007 (UTC)

Why do vawes start with the letter "P"? Why it does not start with, for example, "A"? Why does zero degree of the axis in frontal projection place at "03.00"?Simonnanlohy 17:28, 30 July 2007 (UTC)

J. Willis Hurst, MD, "Naming of the Waves in the ECG, With a Brief Account of Their Genesis," Circulation 1998;98:1937-1942

A zero degree axis in the frontal plane correlates to 3 o'clock by convention. Since the normal axis runs in a right shoulder to left leg direction, the normal quadrant (or left inferior quadrant) is 0 - 90 degrees (although it can extend leftward to (-30) and still be a normal variant). There is no other reason that I am aware of. MoodyGroove 18:43, 30 July 2007 (UTC)MoodyGroove

Requested move

move to electrocardiography?

like electroencephalography - Omegatron 18:20, Apr 19, 2005 (UTC)

That sounds like the right thing to do. Jonas Olson 21:49, 22 Apr 2005 (UTC)

It IS the right thing to do. Then there could be a discussion of invasive electrocardiography, which is an important procedure these days. Lou Sander 15:29, 14 January 2007 (UTC)

It's okay with me. MoodyGroove 00:47, 16 January 2007 (UTC)MoodyGroove

This definitely should be moved "To be consistent with EEG, EMG, EOG, ERG and any others. --83.146.15.165" (from Wikipedia:Requested moves). Since the discussion has been open for 4 years with no opposition, it should be non-controversial. Therefore, involvement of Wikipedia:Requested moves is not really necessary, and I added {{db-move}} to electrocardiography. --Scott Alter 01:11, 13 March 2009 (UTC)

jargon

"through the interventricular septum. Very wide and deep Q waves do not have a septal origin, but indicate myocardial infarction."

all these medical words (all over the article) need either linking or explanatory text in the article itself, for us laymen. - Omegatron 18:30, Apr 19, 2005 (UTC)

The Q-wave normally indicates the phase during which the septum depolarises. However, a similar change (but much more pronounced) is seen in the hours after the onset of a heart attack. JFW | T@lk 10:24, 20 Apr 2005 (UTC)

EKG-ECG

I've heard that electrocardiogram (ECG) is pronounced EKG so it would be easier to differentiate from EEG in speech, it's also phonetic, not because cardio- starts with K in german Prometheus235 14:27, 14 Jun 2005 (UTC)

Agree. Bart 12:29, 9 October 2007 (UTC)

This practice of pronouncing ECG as "EKG" is an American idiosyncrasy, not used where British English is spoken. NRPanikker (talk) 00:47, 13 June 2008 (UTC)

The usage of EKG is not merely for pronunciation, as your comment would suggest, EKG is often written out as well. ECG seems to be primarily used in marketing, presumably due to its use in British English making marketing more widely applicable. _{216.196.204.110 (talk) 15:09, 22 April 2015 (UTC)}

Einthoven article

The article on Willem Einthoven (Nobel Prize winner for his EKG work) is currently quite stubby. Could someone with expertise in this area expand his article a bit? Sayeth 21:21, 6 February 2006 (UTC)

Figure

The figure [[2]] labels the PQ segment as a PR segment. —Preceding unsigned comment added by 194.171.252.100 (talk • contribs) 19 Sep 2006

My understanding: The QRS complex may have one of Q, R, or S, or a combination or even another R (r'), but the segment is always called "PR" by convention. A-giau 09:53, 29 September 2006 (UTC)

That is correct. PR is used by convention because not all QRS complexes have a Q wave. Granted, not all QRS complexes have an R wave, but such complexes are generally labeled QS complexes, and the PR interval is the PQ interval. MoodyGroove 22:34, 22 January 2007 (UTC)MoodyGroove

ECG as Security Device

I am reading Fundamental Accounting Principles (18 edition, Wild, Larson, Chiapetta, www.mhhe.com/wildFAP18e McGraw-Hill Irwin) and on page 314 it says "There's a new security device -- a person's ECG (electrocardiogram) reading -- that is as unique as a fingerprint and a lot harder to lose or steal than a PIN. ECGs can be read through fingertip touches. An ECG also shows that a living person is actually there, whereas fingerprint and facial recognition software can be fooled." It would be interesting to add this information to the article, and if anyone has any more information reguarding this. I'm not sure how to reference it or where to put it, so if someone else could do it, that would work.— Preceding unsigned comment added by 66.68.213.216 (talk) 19:21, 22 November 2006

Sounds like a bit of a tall story to me. --John24601 11:49, 23 November 2006 (UTC)

Anything intended to be used as a personal identity mark has to be unique (which your source claims the ECG to be, but is hard to digest), but more than that, it has to be REPRODUCIBLE, which ECG, most certainly, is not. That's because, the tracing keeps on changing not just from minute-to-minute, but even with something as simple as breathing in (heart rate increases) or breathing out. So, I totally agree with John. KC Panchal 11:17, 5 February 2007 (UTC)

It is true that an EKG is probably akin to a fingerprint in a given individual especially if they have an electrical birthmark (many folks do). Transthoracic computational analysis of a standard EKG reads perhaps less than 40% of subjects as normal. Straightforward presentations of recent, evolving or past Myocardial Infarction or Bundle Branch Block immediately identify a given individual. Variability in lead placement probably negates the admissability of this evidence in a court of law. Limb leads may narrow the agreed upon signature. Interventional electrophysiology allows selective changes in the EKG and thus seals the identity beyond question. Anyone who has had an EP study is probably easily later recognizable to the operator that performed the study. Retrieval of an EKG of any quality through the touch of fingertips sounds 50 years out. --lbeben 00:31, 27 March 2010 (UTC)

I have no knowledge or experience of ECG as security devices, but do know that apart from physiological changes affecting ECGs, biochemical disturbances, some medications and a number of disease processes affect ECG tracings (and at times dramatically) thus undermining their reproducibility, as KC Panchal suggests. Could Lbeben or John cite some peer-reviewed primary sources (i.e. experimental data) to support their claims? Kitb (talk) 02:53, 4 February 2010 (UTC)

So if you're post MI you couldn't access your bank account due to your lengthened QT interval? I really can't see this idea taking off. In cardiac electrophysiology patients are treated all of thetime via RF (or cryo) ablation with the very idea of changing their ECG. Look at pre ablation and post ablation ECGs and you wouldn't know it was the same person. 87.114.241.27 (talk) 20:56, 12 March 2010 (UTC)

History

Oxford DNB credits Alexander Muirhead with using an electrocardiogram as early as 1872. I've credited him with this 'first' though others exploited it. Ephebi 16:10, 27 November 2006 (UTC)

There have been many developments in instrumentation, and they are not covered here at all. Today's ECG machines often provide computerized interpretation, for example. Lou Sander 13:30, 26 March 2007 (UTC)

Yes they do. In fact, the GE-Marquette 12SL ECG interpretive algorithm is the industry standard. It has an excellent specificity for acute myocardial infarction. MoodyGroove 02:30, 14 April 2007 (UTC)MoodyGroove

The history section is very poorly written and misleading. For example even the date that Einthoven invented the string galvanometer is wrong. I believe the authors have simply reworked secondary publications and have not done the primary research of the dates and people involved in the early years of electrocardiography. I suggest having a look at my extensively researched account on http://www.ecglibrary.com/ecghist.html Dean.jenkins (talk) 21:14, 7 September 2009 (UTC)

Pictures

Could we please get an image of an electrocardiograph from after a hundred years ago? I don't want people thinking doctors still use EK graphs that look like they were commissioned to be built by the tsar. VolatileChemical 10:55, 3 January 2007 (UTC)

the lack of a penis on the picture is offensive and odd. I would serously consider changing it.
— Preceding unsigned comment added by 131.227.105.78 (talk) 17:57, 11 June 2010

Posterior Leads

Discussion of posterior leads needed.
— Preceding unsigned comment added by 147.188.80.202 (talk) 14:55, 14 February 2007

There is a discussion of posterior leads in the electrocardiogram section.MoodyGroove 15:12, 14 February 2007 (UTC)MoodyGroove

I'm sorry, I got this confused with the myocardial infarction article. There is a discussion of posterior leads under the electrocardiogram section of the myocardial infarction article. I'm not sure whether or not this article would benefit from a discussion of posterior leads, since it's a rather obscure tactic for detecting myocardial ischemia in the distribution of the circumflex artery. At it stands right now, I'm okay with it being in the myocardial infarction article. If we're going to go that far here, then there are a great many other things that need to be included, and it seems to me that this article should be a general overview of electrocariography. That's not to say I would fight someone if they wrote a section for non-conventional leads, I just don't know that it's necessary for this article. MoodyGroove 17:23, 14 February 2007 (UTC)MoodyGroove

(Exam vs. lab)

Gd afternoon sir,

---

What is the different between physical examination and clinical laboratory  ?

   < Physical examination : body temp.  , BP ,

   clinical laboratory : ECG , blood clotting  >

In physical examination , body temp. have to be used termometer , Blood pressure have to be used Sphygmomanometer .

Both of them are used equipment to approach. So i think that they should be grouped in the clinical laboratory such like ECG and blood clotting. But why they are grouped in Physical exam ?

thank you ,

protrude from sulcus limitans , k_pinyosamosorn@hotmail.com
— Preceding unsigned comment added by Protrude-from-Sulcus-limitans (talk • contribs) 10:31, 30 March 2007

Image:ECG Vector.svg

Hi, the above named image from this article needs to be changed as there is a slight mistake. The second arrow down is pointing the wrong way, so is identical to the diagram above it. The negative deflection on the ECG should be represented by current moving away from a positive electrode. Thanks. Djsilverspoon 16:01, 3 April 2007 (UTC)

Previous version of the image has been restored due to unintentional error in .svg image. MoodyGroove 02:26, 14 April 2007 (UTC)MoodyGroove

ST interval

I removed this section from the article:

The ST interval comprises the ST segment and the T wave. The fetal ST interval may be analyzed during labor (ST analysis) to identify fetuses at risk for asphyxia. Changes in the ST segment and increased T wave height (in relation to the QRS complex) are indications of fetuses at risk. (Neilson JP (2006). “Fetal electrocardiogram (ECG) for fetal monitoring during labour”. Cochrane Database. PMID 16855950)

In my opinion, this gives the concept of an 'ST interval' undue weight. It's an obscure, minority concept in electrocardiography, and not particularly notable. I've heard it referred to as the JT interval (J point to end of the T wave) which is a more precise description. The JT interval is used to estimate the QTc for patients with a baseline intraventricular conduction defect. But no one talks about an ST interval (or JT interval) in common practice. I'd like to see more references to prove this measurement is notable. MoodyGroove 20:31, 10 April 2007 (UTC)MoodyGroove

confusing

Moved this section to the bottom of talk page per talk page guidelines. MoodyGroove 02:42, 5 May 2007 (UTC)MoodyGroove

Actually, it says "The latest topic should be the one at the bottom of the page." But this one was not the latest on the 5th (when you moved it) but several weeks earlier. I could sympathize with the argument that it should stay at the bottom for a week or 2, on the presumption that it needs that long for those (most of us!) who follow the talk page "from the bottom", but any longer than that just adds to long term chaos. It's now overdue to move from May 5's position to April 11th, which i now effect.
--Jerzy•t 07:30, 8 June 2013 (UTC)

This whole page is confusing except for the history! And I'm a brand new med student too... —Preceding unsigned comment added by Flashpoint145 (talk • contribs) 23:19, 11 April 2007

I don't find it confusing at all. I'm removing the tag until you can give a more detailed explanation of what the problem is. Saying the "whole page except for the history" is confusing isn't helpful. It also isn't reasonable. In my opinion, useless tags do nothing but clutter up the Wikipedia. It's better to light one candle than curse the darkness. MoodyGroove 15:15, 13 April 2007 (UTC)MoodyGroove

Why don't YOU find it confusing? Because you thoroughly understand the topic? I've always thought of Wikipedia to be a great source of education. It is difficult to learn something if you do not understand what is being said. If the medical terms and jargon were to be dumbed down to a middle or high school level, the article would be much easier for the general public to comprehend. Imagine a middle school student having to do a science project on EKG's. Would that student find this article easy to read? Put yourself in the shoes of others. What I'm trying to say here is that the wording of the article is too technical and needs to be fixed in such a way that the article can be understood by people outside of the medical field. With that said, I'm re-tagging the article due to the vocabulary and terminology in these sections:

1) Precordial

2) Ground

3) Entire section on Waves & Intervals

4) Clinical Lead Groups

Flashpoint145 18:32, 4 May 2007 (UTC)

I do thoroughly understand the topic, Flashpoint145. But that's after 10 years of study, which included many different books, dozens of journal artilces, and hundreds of real life case studies. I don't think it's reasonable to expect that a middle school (or high school) student should be able to grasp a topic this technical from reading one encyclopedia article. Most textbooks on electrocardiography are hundreds of pages long, with dozens upon dozens (if not hundreds) of example ECGs. I actually think this article gives a decent overview, all things considered. It's just been rated B-class on the assessment scale, and it's well on its way to being a good article, in my opinion. It could be expanded a bit (axis will need to be a separate article), but certain topics are sufficiently technical that they will contain a certain amount of esoteric terminology (certainly many medical and computer articles will be this way). A review of your contributions suggests that you tag a lot of articles for being confusing.[3][4][5][6][7][8] I don't necessarily have a problem with that, if that's how you choose to contribute to the Wikipedia, but I think you yourself might benefit from putting yourself in the shoes of the editors who create content. I still don't think tagging the entire article is reasonable, but I will defer to the judgment of other editors in this matter. I'd actually prefer the "too technical for a general audience" tag to the "some readers may find this confusing" tag. You can't always help what some readers find confusing. MoodyGroove 02:32, 5 May 2007 (UTC)MoodyGroove

I do appreciate it. Confusing may have been the wrong word and technical may have been the correct one. Thank you.

72.40.44.83 11:02, 5 May 2007 (UTC)

You're welcome. I placed the history section up near the top per suggestion from article assessment and changed the "confusing" tag to the "technical" tag (starting at the graph paper section) pending further comments from other editors who may wish to comment. Best, MoodyGroove 17:12, 5 May 2007 (UTC)MoodyGroove

The section on "axis" is confusing.

69.140.164.142 05:24, 19 April 2007 (UTC)

I'll grant you that. It's a difficult topic, even for medical students. I started the hexaxial reference system article (very stubby) to help explain it, but it needs a lot of work. MoodyGroove 21:13, 19 April 2007 (UTC)MoodyGroove

My question is: What is the significance of the elevated and depressed ST segment? Apparently it refers to a myocardial infarction, and that seems to be a leading cause of cardiac related death - so should it not have its own sub-heading and discussion? Nitric Oxide 19:32, 14 August 2007 (UTC)

It may or may not refer to myocardial infarction, but the significance of ST segment elevation is explored fully in the electrocardiogram section of the myocardial infarction article. MoodyGroove 19:59, 14 August 2007 (UTC)MoodyGroove

Deploarisation wavefront and postivive electrode diagram

Should the middle image in this diagram not feature the depolarisation moving away from the positive electrode to cause a negatively deflected wave? richard —The preceding unsigned comment was added by 81.129.83.203 (talk) 09:35, 13 April 2007 (UTC).

Yes it should. The old version of the image is correct. MoodyGroove 15:07, 13 April 2007 (UTC)MoodyGroove

The old image has been restored until such time as the .svg image is corrected. MoodyGroove 02:27, 14 April 2007 (UTC)MoodyGroove

article assessment

I would like to suggest that this article be assessed by an expert for Good Article status. (Reason that I am not adding this directly to WP:GA/N is that I specifically request that the evaluation be done by an expert.) 69.140.164.142 04:48, 19 April 2007 (UTC)

ECG innovation and ETG

While working with the Electrotridoshagraphy technology [9], which is an Ayurvedic whole body scan and is also used for status quantification of the Ayurvedic basic principles, the inventer of the ETG technology Dr. Desh Bandhu Bajpai have innovated presently ECG machine, which is an advance level achievement of the Electrocardiography. Conventional ECG machine can diagnose whether the sick person is suffering from cardiac disorders or not. But this innovative machine [10]is able to diagnose, if the complaints are due to Thyroid, pulmonary circulation, Muscular or neurogical problems, epigastritis, Pancreatitis, renal problems etc. user:debbe,28 April 2007,11:19 PM IST. — Preceding undated comment added 17:42, :42, & :45, 28 April 2007

Unfortunately, you cannot reference your own blog for such extraordinary claims. As I noted on your talk page, it appears as though you have a direct conflict of interest concerning this device, and even if you didn't, your claims would need to be appropriately sourced because original research is not allowed on the Wikipedia. Good luck! MoodyGroove 17:56, 28 April 2007 (UTC)MoodyGroove

Who makes treatment decisions

I removed this comment from the article:

Due to the inherent subtleties in interpretation only paramedics and qualified physicians should make treatment decisions based on rhythm analysis.

This is inflammatory, and it simply isn't true.
--MoodyGroove 21:47, 2 May 2007 (UTC)MoodyGroove

Language is too technical

I was reading the chapter in Harrison's on electrocardiography and I wanted to review it in an article on the level of the general reader (which is what Wikipedia is supposed to be).

This entry has a lot of interesting background, particularly the history, but it's pretty difficult reading, for all the reasons people have already given.

I think of a prototypical reader of Wikipedia as a technical person who may not know much about medicine but who just had a diagnosis of heart disease and wanted to understand his EKG. Or it could be an intelligent high school student (or anybody) who's curious. Such a person couldn't understand this article.

For example, if I didn't know what a depolarization vector was, I couldn't figure it out from reading this article. The sections on the limb leads and precordial leads don't clearly explain what the purpose of those leads are (to identify the direction of the vector in the frontal and horizontal plane, respectively, as Harrison's explained it).

The curious thing about this article is that it starts off to explain something, and then goes off on a digression. The section on limb leads starts to explain what they are, and then goes off about Einthoven's buckets of salt water. I realize this is interesting to you (and to me), but an ordinary reader can't follow this if you keep interrupting with historical footnotes.

Richard Feynmann (and others) said that, if you can't explain something to a 12-year-old, you don't understand it yourself. An intelligent high school science student could get through the Harrison's chapter. And there's the idiot's guide to EKGs, Dale Durbin's "Rapid Interpretation of EKG's". It's not an inherently difficult subject. Nbauman (talk) 00:54, 20 January 2008 (UTC)

Introduction

   The following yellow boxes in this section demarcate a large edit (whose content includes 7 subsections of this section, & nearly all of its remaining subsection) made with attention that (in light of its inclusion of extracted content contributed on a different page by another editor) was inadequate to documenting the scope of the contributor's sigs. And later -- as if that were not enough! -- an IP inserted an unsigned contrib within the content of the large edit.

   (With overwhelming frequency, a single unsigned tag is used on a contribution that had included no sig. Even tho this single contrib -- corresponding to one click on "Save" that resulted in an entry on page's and the contributor's edit-histories -- already included several copies of the same sig, i have added add'l unsigs at points where absence of a sig compromised clarity and consistency.)
--Jerzy•t 01:28, 8 June 2013 (UTC)

(I'm moving this from my user page.)

Hi. With regard to your recent edits, the heart does not create electrical waves when it pumps. Rather, it pumps in response to the electrical waves it creates. It is electrodes that are connected to the skin. The electrocardiogram does not give information about the strength or weakness of cardiac muscle. The fascicles in the electrical conduction system are not nerves. I would not substitute the word 'salt' for 'electrolyte' and potassium is more important than calcium. As a stand alone comment, it is false that the ECG measures the pumping action of the heart. Overall, with regret, I would have to say that you did more harm than good to the article. I would prefer that you revert the changes, post your changes to the talk pages, and take comments. The lede simply isn't accurate anymore. It needs to be as simple as possible, but not more so. Best, MoodyGroove (talk) 03:35, 22 January 2008 (UTC)MoodyGroove

— Preceding unsigned comment added by Nbauman (talk) 17:23, 22 January 2008

OK, thanks for your comments. Let's work on this.

But first I'll remind you of what the Nobel laureate Francois Jacob said: "In describing genetic mechanisms, there is a choice between being inexact and incomprehensible." Or, as Sven Gard rephrased it, "as inexact as conscience permits." Nobel I'll also remind you of a review in Science of Al Gore's "An Inconvenient Truth." The reviewer said that (while it was basically accurate) "we scientists" wouldn't have oversimplified it like that, "we scientists" have been trying unsuccessfully to get the public's attention for 10 years, until Gore produced an award-winning movie that educated millions of people.

I want to break up your comments into separate headings, so we can discuss them one at a time. I've interviewed hundreds of doctors for publication, and we go through a negotiating process. The statements have to be accurate, but they also have to be comprehensible to a layman. (I enjoy this process, because it helps me understand things accurately.) It's not a reasonable objection to say, "That's true, but it doesn't give additional important facts."

There's a balance between accuracy and comprehensiveness, OTOH, and clarity and simplicity OTOH. Clarity and simplicity is most important in the introduction. You simplify in the introduction, and explain in more precise detail later.

One of the typical readers that I imagine is a sysadmin with a degree in computer science who just got back from the doctor after a heart attack and a copy of his ECG, and wants to figure it out. (Like Andrew Grove with his prostate cancer.)

It's certainly possible to describe an ECG to an intelligent, science-literate layman -- as in for example the Merck Manual, or Harrison's, or Dale Dubin's Rapid Interpretation of EKG's, or in Anaesthetist.com which is linked in the article. I've already quoted Richard Feynmann. It can be done.

So you can object if it's not accurate, but I can object if a layman can't understand it. These goals can almost always be resolved, at least for an introductory article in medicine.

Agreed?
Nbauman (talk) 17:23, 22 January 2008 (UTC)

Creating electrical waves

I wrote: The heart muscles create electrical waves when they pump.

You wrote:

the heart does not create electrical waves when it pumps. Rather, it pumps in response to the electrical waves it creates.

Harrison's 16th ed., p. 1311 says, "The electric currents that spread through the heart are produced by three components: cardiac pacemaker cells, specialized conduction tissue, and the heart muscle itself. The ECG, however, records only the depolarization (stimulation) and repolarization (recovery) potentials generated by the atrial and ventricular myocardium."

So in my reading, Harrison's says that "the heart muscle itself" (along with the pacemaker and conduction tissue) produces electrical waves. Correct?
Nbauman (talk) 17:23, 22 January 2008 (UTC)

Electrodes

I wrote: These waves pass through the body and can be measured by wires attached to the skin.

You wrote:

It is electrodes that are connected to the skin.

Electrodes are wires, right? We agree there, don't we?

(I used the simpler word "wires" rather than "electrodes" because a reader in talk didn't understand the meaning of the word "lead". I've been surprised at how even intelligent, educated people who have learned about their disease didn't understand what I would think are simple medical terms.)

— Preceding unsigned comment added by Nbauman (talk) 17:23, 22 January 2008

Information about cardiac muscles

I wrote: Wires [electrodes] on different sides of the heart measure the activity of different muscles.

OK?

I wrote: An ECG displays the voltage of these wires, and the muscle activity that they measure from different directions.

I wrote: This display indicates the overall rhythm of the heart,

OK?

I wrote: and weaknesses in different muscles.

You wrote:

The electrocardiogram does not give information about the strength or weakness of cardiac muscle.

I'm looking at figure 210-11 in Harrison's (to use a source that is easily accessable to both of us). It shows how the ST elevation is changed when a muscle is injured by ischemia. When a muscle is injured, it's weaker.

That's what I was referring to.

On the basis of that statement in Harrison's, isn't it accurate to say that the ECG gives information about the injury of muscles?

Is it therefore accurate to say that it gives information about the strength or weakness of muscle?
Nbauman (talk) 17:23, 22 January 2008 (UTC)

Conduction

 

The uns contrib in the following pink box was inserted within the previous discussion surrounding it; the {{uns}} call following it is supplied by me.--Jerzy•t 01:28, 8 June 2013 (UTC)

u r perfectly fine...could u explain me Fibras de Has de His...its stimulation in heart region...._? — Preceding unsigned comment added by 200.55.135.211 (talk) 18:05, 24 May 2010

 

I wrote: It is the best way to measure and diagnose abnormal rhythms of the heart[1],

OK?

I wrote: particularly abnormal rhythms caused by damage to the nerves that carry electrical signals

You wrote:

The fascicles in the electrical conduction system are not nerves.

You're right. My references keep referring to "conduction tissue," and I conceptualized them as nerves. But they never say "nerves."Thanks for the correction.

Nbauman (talk)

Electrolytes

I wrote: or abnormal rhythms caused by levels of salts, such as calcium, that are too high or low.[2]

You wrote:

I would not substitute the word 'salt' for 'electrolyte'

Why not? The rule in Wikipedia is that we're writing for ordinary people, not experts (although I personally don't mind writing more difficult material further down in the article). People who have trouble with the meaning of the word "lead" are going to have trouble with the word "electrolyte". I remember a BMJ essay in which a doctor described how a patient dropped a term that he hadn't used since medical school, and he had to stop and think about what it meant.

The people who edited the Merck Manual into the layman's edition did studies and found that laymen like to learn the technical terms, and so they gave the technical terms accompanied by definitions in layman's terms. But you can't do that in the introduction.

The more technical terms you put into an introduction, the the more people will find it incomprehensible. And it only takes one technical term in the introduction to make people give up on the whole article.

We could say, "salts (electrolytes)," but even that would impair readability, the way the climate scientists lost their audience when they tried to be more precise.

You wrote:

and potassium is more important than calcium.

OK. I was just using an example. We can substitute potassium if you like. But if we list every electrolyte in the introduction, we lose readability.
— Preceding unsigned comment added by Nbauman (talk) 17:23, 22 January 2008

Identify damaged muscles

I wrote: In myocardial infarction (MI), the ECG can often identify the heart muscles that are damaged, but it's not sensitive enough to rule out certain kinds of damage.[3]

OK?
— Preceding unsigned comment added by Nbauman (talk) 17:23, 22 January 2008

Measuring pumping

I wrote: The ECG can also measure the pumping ability of the heart, although ultrasound is more accurate.[4]

You wrote:

As a stand alone comment, it is false that the ECG measures the pumping action of the heart.

That was my rewrite from the earlier version of the article, which said:

The electrocardiogram does not directly assess the contractility of the heart. However, it can give a rough indication of increased or decreased contractility.[4]

[4], the Am J Med. 1989 [!] article, says:

CONCLUSION: Thus, an entirely normal result on a resting 12-lead electrocardiogram in patients with suspected coronary disease but no history of a previous myocardial infarction is a reliable (95%) predictor of normal left ventricular function.

I don't know enough about this to comment. I can't recall what I read about this in other sources. Could you clarify what it means by "contractility"? I was just trying to include as much of the original content as possible in my edit. Unless it's important, it doesn't belong in the introduction.

— Preceding unsigned comment added by Nbauman (talk) 17:23, 22 January 2008

Improving the lead

You wrote:

Overall, with regret, I would have to say that you did more harm than good to the article. I would prefer that you revert the changes, post your changes to the talk pages, and take comments. The lede simply isn't accurate anymore. It needs to be as simple as possible, but not more so. Best, MoodyGroove (talk) 03:35, 22 January 2008 (UTC)MoodyGroove

It is often traumatic for a writer to see his beloved words edited. But there is no point to writing about medicine if your target audience can't understand what you're writing. In Wikipedia, your target audience is the ordinary reader, not the specialist. For this article, there is clear documentation in Talk that Wikipedia readers can't understand what you're writing. For a writer, this is a problem.

It's even a problem to a doctor if a patient can't explain what he's saying. (I have a citation somewhere of a baby who died because its mother didn't understand the doctor's instructions to "push fluids". He used a technical term rather than an ordinary term that his patient would understand.)

I once met Stephen Petranek, the editor of Discover. He said that when he took the magazine over, it was unreadable (and losing money). He couldn't get through some of the stories himself. He had to make it readable -- what he called "super-readable".

This article is unreadable. I rewrote the original lede because it was unreadable. (Interestingly, there are studies which found that bulleted points are harder to understand than a well-written paragraph. I used a lot of bulleted points before I saw that, and that was in the days before PowerPoint.) An editor once kicked a story back at me and said, "Rewrite this. Don't touch it up. Rewrite it from the beginning."

And that, with regret, is what I would say about this lede, if you want to meet the Wikipedia standard of being understandable by the general reader. You can go through the original lede in Talk and rewrite it point by point, or you can go through my lede in Talk and rewrite it point by point, or you can do both. But that original lede needs a chain saw, not a scalpel.

T.S. Eliot got used to having his writing edited, and I'm sure you will too.
Nbauman (talk) 17:23, 22 January 2008 (UTC)

Another voice, I have enjoyed reading EKGs for many years. None of my four adult sons has the least bit of interest in this topic but all read Wiki on a regular basis. If I could "dumb this down" to their level they would still not read it. This area is incredibly technical and not easily broken down to easily written bites but the literary goal is noble. How can I help? —Preceding unsigned comment added by Lbeben (talk • contribs) 00:57, 25 May 2010 (UTC)

Abnormal rhythms

Toozdaygirl, instead of saying,

"It is the most painless, inexpensive and quick way to measure and diagnose abnormal rhythms of the heart."

isn't it simpler to say,

"It is the best way to measure and diagnose abnormal rhythms of the heart."

I think that's what the source, Braunwald, says.

Is there a better way to measure and diagnose abnormal rhythms? Is there a better way that is painful? Nbauman (talk) 15:58, 18 February 2008 (UTC)

Cardiac catheterisation isn't entirely painless but is done under local anisthetic and conscious sedation. This is a much more accurate way to diagnose problems as catheters can be placed inside the heart to record the intracardiac electrograms. This also allows ablation of the problem area with a catheter. Beyond this, the electrical system of the heart can also be mapped with catheters to build a geomemetry and visualise the electrograms moving across the myocardium. There are also a few surgical methods too. 87.114.241.27 (talk) 21:05, 12 March 2010 (UTC)

Color code of limb leads

Image from the article

It appears that the color coding of the electrodes for the limb leads is different in different countries. And this seems to be just the just the right place to find out more about it. I guess a small table is the easiest way to do so. Feel free to add or not to add a respective link as you see fit. --Dietzel65 (talk) 09:34, 7 May 2008 (UTC)

RA=white LA=Black LL=red RL=green

as described in the article.

Note: This appears to be the American Health Association (AHA) recommendation [11]

Used in which countries?

• USA (white on right, smoke over fire, clouds over grass). [12] Welch Allyn PIC50 defibrillator manual. Page 57, manual section 4.7. 19mb file, so use a fast connection.

JPINFV (talk) 20:59, 12 May 2008 (UTC)

• ?

RA=red LA=yellow LL=green RL=black

Called "traffic light code", at least in Germany.

Note: This appears to be the International Electrotechnical Commission (IEC) recommendation [13]

Used in:

• Germany [14] --Dietzel65 (talk) 09:34, 7 May 2008 (UTC)
• Belgium --Steven Fruitsmaak (Reply) 12:08, 9 May 2008 (UTC)
• Hungary + France Lennert B (talk) 20:48, 10 May 2008 (UTC)
• Austria --PatDin (talk) 19:32, 21 May 2008 (UTC)
• United Kingdom -- NRPanikker 17:07, 8 July 2008 (UTC)

RA=? LA=? LL=? RL=?

Are there additional color codes used anywhere? If so, please add them.— Preceding unsigned comment added by Dietzel65 (talk • contribs) 09:34, 7 May 2008
RA=Red, RL= Blue, LL=Green, LA=Yellow — Preceding unsigned comment added by 117.228.60.17 (talk) 16:07, 2 August 2011 (UTC)

Salt --> Electrolytes

I have replaced the word salt by electrolytes, because it was just plain wrong. A salt is a compound composed of two differently charged ions (e.g. Sodiumchloride or Potassiumbicarbonate), whereas an electrolyte is an electrically active dissolved ion. I read (and generally agree with) the reasoning above about using as simple as possible words in the introduction as to not discourage readers, but I believe this should not happen at the expense of correctness. Lennert B (talk) 12:06, 11 May 2008 (UTC)

I agree that the article should be correct, but it must also be understandable to the general reader. How would you propose that we do both? The general reader won't know the term "electrolytes." My Merck Manual Home Edition (1st edition, not the online edition) says that electrolytes are dissolved salts (in my summary). Is that right? Can we say "dissolved salts (electrolytes)"? Nbauman (talk)

It's better, but still not great. However, I believe the introduction of the article Electrolytes explains it pretty good. Why not just link there? That way those unfamiliar with the term can just look it up, but the use of incorrect terminology is avoided. Lennert B (talk) 15:45, 12 May 2008 (UTC)

I don't think a layman could understand the article Electrolytes. What's a free ion? (If you click on the link for ion, you get another difficult page. What's a valence?)

"Dissolved salts" is correct terminology, BTW. The Merck Manual, which has been extensively reviewed, uses it. It's just not the technical term. Nbauman (talk) 17:51, 12 May 2008 (UTC)

It's odd that a "layman" is expected to know what a "lede" is, but not a "lead," and not to understand words like "ion" or "valence." We are all infotainment professionals, it appears, but otherwise wholly ignorant. Is it really feasible to make sense of the ECG without having a little secondary school physics and chemistry first? Therein lies the problem of infotainment: to gain the pleasure of understanding something without the pain of studying it. NRPanikker (talk) 15:28, 13 June 2008 (UTC)

Many of the people who read WP are secondary school students who are first learning physics and chemistry, and I would commend them for learning about the practical applications of those subjects as they go along. You don't fault them for that, do you?

As to your question of whether it is feasible to make sense of the ECG without already having that background, the answer is clearly yes. Look at the Merck Manual home edition (which I linked to above) which does exactly that. Nbauman (talk) 17:46, 13 June 2008 (UTC)

As a common reader of EKGs for nearly thirty years, I find an encyclopedic compendium of this fascinating subject to be most meaningful because so many with a similar interest have contributed. Indeed I would estimate 90% is well written but a bit jumbled in a noble attempt to literally explain an exceedingly complex physiologic phenomena once recorded only on paper. There is a team at work here but they are running in different vectors. Recommend a common and agreeable fact check criteria be applied to the present and future article.--Lbeben (talk) 01:51, 18 September 2008 (UTC)

Wasn't Clément Ader the inventor of the string galvanometer instead of Einthoven.

According to Jaakko Malmivuo & Robert Plonsey: Bioelectromagnetism - Principles and Applications of Bioelectric and Biomagnetic Fields, Oxford University Press, New York, 1995. chapeter 15.1 Clément Ader was the inventor of the string galvanometer. They cite Ader C (1897): Sur un nouvel appareil enregistreur pour cables sousmarins. Compt. rend. Acad. Sci. (Paris) 124: 1440-2 as source for this statement. Which is older than all papers by Einthoven on this subject.

see: [15] —Preceding unsigned comment added by Frodo Muijzer (talk • contribs) 10:28, 20 October 2008 (UTC)

• According to this PubMed article [16], a less sensitive string galvanometer was indeed invented by Ader in 1897, however, Einthoven is said to have separately invented his version of the device, suitable for the heart. These claims are also supported by this MIT of the week article. I've adjusted the WP article text with this info.

--User:OnixWP — Preceding undated comment added 23:53, 29 October 2008

Readership of EKG Article

Reading of the above is acknowledged. This is a wonderful, important and (my opinion) confusing article to mostmuch of the Wiki readership out there. I have always enjoyed reading EKGs for many years but cannot for the life of me explain the concept to my (somewhat disinterested) adult sons. I'm I am not certain about the rules on articles, but could it the Electrocardiogram article be edited to an A level of understanding as well as a concurrent B level of understanding in effort to smooth ruffled feathers? The electrocardiogram is actually a very complex and evolving Einthoven opened a keyhole on transthoracic appreciation of organized electrical activity of the heart. Evolution of this concept as evidenced by the contributions is rapidly advancing under the discipline of invasive EP Invasive Electrophysiology. The readership of the article is probably heavily weighted to the B level of understanding. Perhaps we could better define the readership demographics and edit it the article into two channels.--lbeben 03:58, 20 December 2008 (UTC)— Preceding unsigned comment added by User:Lbeben (talk • contribs) 01:24 & :26, 19^th, & 03:58, 20^th December 2008

I rewrote some of the article to make it comply with WP:MTA [17] but people keep replacing the simple language in the lead with technical jargon. I don't feel like fighting them over it. If there is consensus for simplifying it, I can easily replace the simplified text. Nbauman (talk) 19:14, 20 December 2008 (UTC)

I am a 3rd year med student and I've have never before been so confused by an explanation of ECGs. I plan to do an overhaul of this entire article as I have time. There is too much extraneous information throughout the article, and the language regarding leads is confusing (lapsing into incorrect). I suggest condensing historical information into one section so as to keep the other sections free of clutter.Walking Softly (talk) 10:13, 11 May 2009 (UTC)

   As my grandfather said to the proctologist, what we do have is As to invasive electrophysiology, there are

1. a section at Cardiology diagnostic tests and procedures#Electrophysiology study and
2. an article Electrophysiology study;

the former makes it sound pretty invasive to me, tho the latter seems to emphasize "minimally invasive procedure".
--Jerzy•t 05:20, 8 June 2013 (UTC)

Edit of Limb Leads section

I did a major edit of a small section just now. I removed a lot of historical info that I didn't think belonged in a section that a lot of people were probably going to view as (a) confusing enough already and (b) the practical "how to" section of the article. See above discussion of readability if you have thoughts of adding technical jargon back into this section. Btw, ELECTRODES go on the body. LEADS are the signals. Walking Softly (talk) 10:13, 11 May 2009 (UTC), Card Zero (talk) 14:50, 8 March 2011, & Jerzy•t 06:39, 8 June 2013 (UTC)

References don't work on talk pages, and create an error at the foot of the page, so I have taken the liberty of moving your reference out of its <ref> tags.  Card Zero  (talk) 14:50, 8 March 2011 (UTC)

   Actually, they do work, bcz we have the technology for that; it's called {{Reflist-talk}} and it presents a list (of all refs since the last use of the template?), intended to typically display the refs in a talk-page section, or, i think, subsection; see the example at the end of this section, reflecting my restoration of WS's ref, and my addition of this one:
--Jerzy•t 06:39, 8 June 2013 (UTC)

References

Image of 12-lead ECG

The diagram is horrendous. The precordial leads aren't even properly placed. I am going to change the caption to make it misleading no longer, but the whole picture needs to go. Can we please have someone do a new diagram? If someone is artistic, please let me know, and I will point you to a proper diagram to "adapt."Walking Softly (talk) 10:13, 11 May 2009 (UTC)

I have just entered the Biomedical Engineering Technician field and was drawn to this article so that I could have some clarification on ECGs. After reading the article several times, I feel that the limb leads (and below) sections are very 12-leads centric, even though most ECG monitoring doesn't use 12-lead configurations.

Thanx, Ed

The.loquitur (talk) 03:30, 9 June 2009 (UTC)

The image with the augmented leads is still misleading as the augmented leads do not originate from the Wilson's central termínal, but from the "average" of other two leads. This is not the same ! 188.238.152.205 (talk) 07:36, 6 April 2019 (UTC)

Wilson's central terminal

I have added this sentence in brackets, as I did not understand the purpose of Wilson's central terminal was.

(recall that Wilson's central terminal is the average of the four limb leads. This will approximate ground)

I am only a lowly first year medical student, so if it is wrong, please correct it. M0rt (talk) 07:49, 13 May 2009 (UTC)

vectorcardiograms

ECG should also have info about vector cardiograms —Preceding unsigned comment added by Syeda Fizza Batool (talk • contribs) 11:05, 30 June 2009 (UTC)

"Untitled" re lengths of PQ features

I am not shure, how short the PQ segment can be, but it must not be longer than about 120ms, because the PQ intervall must not be longer than 200ms. —Preceding unsigned comment added by 131.220.35.12 (talk) 21:52, 28 January 2010 (UTC)

Cardio

heart is a massive problem —Preceding unsigned comment added by 174.114.236.189 (talk) 02:35, 12 February 2010 (UTC)

technical POV

I came looking for some info about EKG machines, but this page seems to be concerned mainly with biology/medicine of EKG. I'd expect at least a block scheme and short text commenting that & linking to respective electronics articles, eg. Instrumentation amplifier, Transient voltage suppressor etc... Would that belong here? VladimirSlavik (talk) 11:53, 18 November 2010 (UTC)

Same here, I want to know about the engineering and the coding that make an ecg work. I want to know about all that makes an ecg. —Preceding unsigned comment added by 68.19.159.27 (talk) 04:55, 13 May 2011 (UTC)

If you are capable, please include this information. Remember the reading of EKGs is most important so any physics/technical information regarding EKGs should be included at the bottom. I need to spend more time with PDEs before I feel comfortable summarizing information I have in a few biomechanics books and a mathematical physiology book I have regarding EKGs. If you want to know, in general, how they work, it's a pretty simple process of putting two electrodes at different parts of the body and recording voltage disturbances in body's surface potential generated by the heart's electric potentials as a function of time and direction. They're not complicated machines at all unless you get one of the fancy ones that makes you a 3d representation of the heart's potential vectors on a screen. Bloomingdedalus (talk) 17:42, 19 June 2011 (UTC)

I started a section on this...now almost 6 years later. Feel free to spruce it up and include a block diagram. There's a lot that could go into this section though. Cburnett (talk) 17:23, 24 April 2016 (UTC)

Electrocardiogram heterogeneity section

I just cleaned this up. I have not removed the "needs cleanup" template, because the long paragraph starting "the time intervals between consecutive heart beats" has a funny smell. It all seems like useful technical information - I wouldn't know - but it was all added at once, was duplicated in cardiac cycle (I have removed it from there), and spoke gushingly (I have removed the gushing) about this wonderful new process called CZF, then linked to a website which, as well as telling you all about it, will sell it to you. So I don't think it needs a stylistic cleanup any more, but it needs checking out by somebody who knows anything about electrocardiography (not me).  Card Zero  (talk) 14:47, 8 March 2011 (UTC)

Q wave and S wave

The section on waves explains both waves and segments but leaves out the Q wave and R wave. It would be helpful if someone could break down the reason for the QRS morphology.

AriaNo11 (talk) 16:49, 30 March 2011 (UTC)

The tangent function

Within the ekg coding, is the tangent function involved in anyway? —Preceding unsigned comment added by 68.19.159.27 (talk) 23:00, 12 May 2011 (UTC)

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Physics

I would like to include more information about the physics of Electrocardiograms, but will probably need to spend a little more time with Partial Differential Equations before I am ready to contribute this material. As such, I am giving this article a "start" rating for physics given that it has very little information about the technical properties of electrocardiography. It is an excellent introduction to ECGs for medicine, but it does not include the physics, just to be clear I mean no insult to the persons who have written this by calling it a "start" rating for the Physics project. Bloomingdedalus (talk) 17:32, 19 June 2011 (UTC)

Scale of recording on paper

The section on ECG graph paper starts by saying it is standards to scale the y axis at 1mm per mV, but ends by saying 1mV must move the stylus 1 cm (i.e. 10 mm per mV). I believe the latter is correct. — Preceding unsigned comment added by 81.129.213.76 (talk) 12:23, 8 January 2013 (UTC)

Filters: low pass response

According to Ansi AAMI standard (EC 11 standard (1991), "Diagnostic Electrocardiographic devices") the low-pass filter must be set at least at 150Hz for diagnostic purposes. (The American Heart Association recommends that diagnostic ECGs have a frequency response up to 150 Hz.)

This avoids significant distortion on QRS-T transients that arise when low pass cut-off frequency is lower (e.g 100 Hz).

Other editors suggests that "in diagnostic mode, the low pass filter can be set to 40, 100, or 150Hz;"

The second issue is probably true on specific devices but may be misleading since 150 Hz should be set on filter to avoid impact on interpretation.

Suggestions on this issues are welcomed — Preceding unsigned comment added by Cbecc (talk • contribs) 13:32, 20 September 2013 (UTC)

Waves and Intervals -- PR segment

In the "Waves and Intervals" section it seems to me that the explanation on the 'PR segment' may be wrong, it currently reads:

The PR segment connects the P wave and the QRS complex. The impulse vector is from the AV node to the Bundle of His to the bundle branches and then to the Purkinje fibers. This electrical activity does not produce a contraction directly and is merely traveling down towards the ventricles, and this shows up flat on the ECG. The PR interval is more clinically relevant.

It has always been my understanding that during the PR segment the AV node is delaying transfer of the electrical signal from Atria to Ventricals, were the signal to be traveling down the Bundle of His that would be the very definition of electrical activity the ACG should (and does) detect, flat on ECG is no electrical activity, whether contractions happen or not can't be told from ECG alone (PEA is the perfect example for that). --Keeper of the Keys (talk) 00:28, 21 January 2015 (UTC)

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Assessment comment

The comment(s) below were originally left at Talk:Electrocardiography/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Comment(s)

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The only grades I feel at all qualified to give out are A, B, Start, and Stub. GA and FA have existing processes in place which I will not try to bypass. Having said that, my only real concerns about the article is the comparative lack of inline citations and the existing structure. I note the ECG graph paper, Leads, Precordial, Ground, Axis, Waves and intervals, P wave, PR interval, QRS complex, ST segment, T wave, Rhythm analysis, and Representation in culture sections each have no inline citations. It is possible that all this information qualifies as Wikipedia:Scientific citation guidelines#Uncontroversial knowledge, and thus not require specific referencing. I am myself not sufficient expert in the field to say one way or another. Also, I question including the "History" section so late in the article. I think generally such sections, explaining the development of the subject, come earlier, generally making it a bit easier for the reader to perhaps see how other items mentioned in the article developed over time. That, however, is just my opinion. I might find the appropriate citations for the sections above, if required, and then nominate the article for Wikipedia:Peer review for what would with any luck be more informed opinion. John Carter 13:51, 4 May 2007 (UTC)

Last edited at 05:15, 13 March 2009 (UTC). Substituted at 14:18, 29 April 2016 (UTC)

Electrodes and leads

The table in the "Electrodes and leads" section lists 10 electrodes, even though the sentence before the table reads: "The 12 leads in a 12-lead EKG are listed below". The meaning of "lead" is not defined well enough. Can an electrode have more that one lead? If so, what leads are missing from the table of electrodes? EditorAtLarge (talk) 09:54, 6 September 2016 (UTC)

Significance of "109"?

The article contains the phrase "a conventional 109 ECG", with no explanation given. What does the number refer to? is it part of a larger system of numericlature for procedures, or is it specific to ECGs? I did a quick search but didn't find an answer. MrRK (talk) 16:11, 7 September 2017 (UTC)

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Editing intro

Hello world! It's been a while since I've edited but here goes. I think the following section of the intro is not accurate and is covered better in the Theory section anyway. Here's my explanation, since this edit removes a substantial chunk I thought I should justify:

"It can also be further broken down into the following:

• O is the origin or datum point preceding the cycle (citation needed as this is not in common use)
• P is the atrial systole contraction pulse (not a great definition of P as it is usually a good idea to separate electrical and physical activity - not all electrical waves generate a systole... The standard accepted definition of P is already listed in the Theory section)
• Q is a downward deflection immediately preceding the ventricular contraction (no - it is more accurate to say that the QRS as a whole represents ventricular depolarisation. Technically, since ventricular contraction follows soon after the QRS complex the s wave might actually be the downward deflection immediately preceding ventricular contraction.)
• R is the peak of the ventricular contraction (again, not strictly true. R is a positive depolarisation wave and contraction occurs soon after (but not at the same time). Important to remember the ECG represents electrical activity and this electrical activity may not even generate a contraction at all times...)
• S is the downward deflection immediately after the ventricular contraction (inaccurate, see above)
• T is the recovery of the ventricles
• U is the successor of the T wave but it is small and not always observed"

In summary I have removed this section as it duplicates existing content in the Theory section and does not use standard accepted definitions / descriptions of these terms. It was also unreferenced.

Hope this is ok by more experienced editors! Bron (talk) 20:28, 31 March 2019 (UTC)

rECG vs cECG

Can someone please explain what a capacitively coupled electrocardiogram, a conventional galvanic reference ECG and their differences in Capacitive ECG Monitoring in Cardiac Patients During Simulated Driving. are? --46.83.142.48 (talk) 15:56, 18 September 2019 (UTC)

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Addition of normal values of the quantities PR, QRS, and QT

Could not somebody add the normal values of the quantities PR, QRS, and QT or else I would.

                                                                                          Ahmad 123456p (talk) 16:43, 29 January 2021 (UTC)

down stroke on the EKG

What is the interpretations of the down stroke in the EKG like the second half of the P wave? And what action of the electrical activity of the heart does it represents? And the same I'm wondering with the T wave? Willing student (talk) 07:16, 22 December 2021 (UTC)

Description of using of RL electrode for voltage calculation is must be.

Description of using of RL electrode for voltage calculation is must be at this article. Or the non-using of it must be indicated explicitly. Voproshatel (talk) 16:07, 7 October 2023 (UTC)

Confusing

Edit: Nevermind, my confusion was answered later in the article.