tag:blogger.com,1999:blog-549949223388475481.post3425419321161052823..comments2024-03-28T14:02:08.119-05:00Comments on Dr. Smith's ECG Blog: What is the Rhythm?Unknownnoreply@blogger.comBlogger21125tag:blogger.com,1999:blog-549949223388475481.post-61032310509471869192019-02-19T16:37:31.838-06:002019-02-19T16:37:31.838-06:00@ Unknown — The ECG videos that I have made are av...@ Unknown — The ECG videos that I have made are available at http://www.videoecg.com — Demands on my time prevent me from making more ... THANKS again for your kind words! — :)ECG Interpretationhttps://www.blogger.com/profile/02309020028961384995noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-90425284345688702382019-02-04T12:02:09.023-06:002019-02-04T12:02:09.023-06:00@ R_Dhali — Thanks for the kind words — :)@ R_Dhali — Thanks for the kind words — :)ECG Interpretationhttps://www.blogger.com/profile/02309020028961384995noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-38010767980018060802019-02-04T07:30:32.818-06:002019-02-04T07:30:32.818-06:00Good to hear!Good to hear!Steve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-13101010800308558702019-02-04T01:22:44.579-06:002019-02-04T01:22:44.579-06:00Thank you for the amazing teaching on this post. L...Thank you for the amazing teaching on this post. Learned a lot.R_Dhalihttps://www.blogger.com/profile/03141818059509916965noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-26770381462351920502019-02-03T10:53:25.167-06:002019-02-03T10:53:25.167-06:00My sincere thanks to BOTH K. Wang and Jerry Jones ...My sincere thanks to BOTH K. Wang and Jerry Jones — who are each specialists in arrhythmia interpretation of national and international renown. I’m always flattered and delighted to receive input from you both! I honestly believe the 3 of us agree on this tracing much more than the minor points in which our perspectives may differ. But what counts the most is this POSITIVE discussion in which specifics of this fascinating arrhythmia can be explored to the fullest. THANK YOU BOTH once again for your comments! — :)ECG Interpretationhttps://www.blogger.com/profile/02309020028961384995noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-63711103674385153532019-02-02T20:03:30.720-06:002019-02-02T20:03:30.720-06:00You elegantly identified P waves with red arrows. ...You elegantly identified P waves with red arrows. I this patient, the base of the P wave is about 120ms wide, the QRS is 100ms wide. The P wave is clearly in front of R1, barely in front in R2, R3 occurs within the P wave, P and R4 began together, R5 within the P and the P wave is barely in front of R6. So, "Q waves are gone" because they are superimposed with P waves definitely, not maybe. Of course, slightly different parts of the P wave.<br />K. Wang.Anonymoushttps://www.blogger.com/profile/04509940285330859355noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-38123294416051202852019-02-02T18:42:53.405-06:002019-02-02T18:42:53.405-06:00Thanks for your reply, Ken. I always appreciate yo...Thanks for your reply, Ken. I always appreciate your thoughts. Although we DO have different perspectives on some aspects of this tracing, I think it is very telling that we each arrive at the same conclusion. And I agree with you TOTALLY about different ways to interpret a dysrhythmia. As evidence, just look at many of the laddergrams that Marriott or Fisch produced - sometimes 2 or 3 for the same dysrhythmia! I must say I chuckled a bit at your comment on dissociation by interference because I feel the same way. It's a lot like 2:1 AV block - it really isn't an entity unto itself but rather dissociation by default OR usurpation in a situation where one really can't decide. <br /><br />I'm glad to see your input on this blog and I look forward to many more productive discussions.<br /><br />Jerry Jerry W. Jones, MD FACEP FAAEMhttps://www.blogger.com/profile/10333187745825224414noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-88213591805875809452019-02-02T17:19:25.516-06:002019-02-02T17:19:25.516-06:00Regarding "Q waves gone" = Maybe — but h...Regarding "Q waves gone" = Maybe — but how ‘bout beat #4? And for beat #6 in which the peak of the P is gone before the onset of the QRS, shouldn’t there then be some negative deflection at the onset of the QRS? And to me, the R wave is clearly taller for the junctional beats … I wish we had a longer period of monitoring to settle these issues. THANKS again so much K for your comments, which are ALWAYS tremendously insightful! — :)ECG Interpretationhttps://www.blogger.com/profile/02309020028961384995noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-46571523277531744902019-02-02T16:52:19.401-06:002019-02-02T16:52:19.401-06:001) Yes, AV junctional rhythm is very regular rhyth...1) Yes, AV junctional rhythm is very regular rhythm, but R5-R6 interval is slightly shorter than <br /> other junctional interval preceding it, and it is occurring during inspiration. That's why I <br /> said respiration is affecting even the junctional rate in this patient. But there is no question <br /> R6 is a junctional beat because the P wave is too close to the QRS. So, we pay attention to both <br /> the RR interval as well as the PR interval to decide whether the narrow QRSs are junctional or <br /> not. Ordinarily once you find out what the junctional interval is in that patient, any QRSs <br /> occuring with a short RR interval is not junctional. <br /> Beat 7,8 and 9 are definitely sinus beats because there is too much of jump in the RR interval.<br />2) About thinking beat 8 as a PAC, it is true that the RR interval is noticeably short. But <br /> the P wave morphology of a PAC should be considerably different looking. This P wave is so <br /> identical to other P waves, and it is a sinus beat. <br />3) Yes, in this patient the junctional rate is slightly faster than ordinary intrinsic junctional <br /> rate, which should be around 40-50/m. Therefore, strictly speaking, one should say slight <br /> junctional acceleration, rather than escape.<br />4) All AV dissociation is by interference, i.e. two pacemakers interfering the progression of each <br /> other by rendering the myocardium or the conduction system physiologically refractory.<br />K. Wang<br /> Anonymoushttps://www.blogger.com/profile/04509940285330859355noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-83367008828289397422019-02-02T15:54:19.112-06:002019-02-02T15:54:19.112-06:00Hi Jerry. Thank you SO MUCH for your detailed comm...Hi Jerry. Thank you SO MUCH for your detailed commentary on this fascinating tracing. Unfortunately, this is the only ECG that we have on this patient — as I think some of the points you postulate might be much more easily resolved if we had a longer period of monitoring. While you and I do indeed agree on most points regarding this tracing — there are those points that we have different perspectives on. As you know, there is often more than a single plausible explanation for a given arrhythmia (especially when only a limited period of monitoring is available). So, there is not quite “gradual increase in the sinus rate” from beat #1-to-beat #7 (ie, the purple numbers in Figure 4 are my measured P-P intervals — and there is slight increase before decrease of these intervals). The junctional rate is right around 60/minute — Could that be the normal escape rate for this individual (I’ve always used 40-60/minute as the normal junctional rate — with 50-80/minute in a pediatric population — and this patient is a young adult … ). Moreover, distinction between AV dissociation by “default” vs “usurpation” is sometimes artificial, as it is not uncommon to have a mixture of both phenomenon. The reason I said “AV dissociation by default” in this case — is that the atrial rate IS slower than the junctional rate (purple numbers greater than blue numbers) at the time when junctional rhythm takes over. As to whether beat #8 is a PAC — We have “4 looks” at P wave morphology of beats #7 and 8 (in leads V1,2,3 and lead II) — and to me — P wave morphology in each of these 4 leads is quite similar — whereas if beat #8 was a PAC, I would have expected MORE variation in P wave morphology in at least 1 of these leads. And while your point about caution in using morphology of the QRS in a rhythm with AV dissociation to assess likelihood of conduction is an excellent one — I use this criteria VERY carefully (have done so for many years). I ONLY use differing morphology when it is truly consistent across the entire tracing — which is rare. Beat #2 is the only beat that does not fit the pattern here. Beats #3-thru-6 are all junctional beats — and NONE of them have either a small q or a shorter R comparable to R wave amplitude of other beats on this tracing. We BOTH agree that beat #7 is a capture beat (I indicated this above in my description). So while TRUE that we really do NOT know what the “true conducting PR interval is” in this case (ie, We just don’t have a long enough period of monitoring) — the inescapable findings I perceive are fairly marked sinus arrhythmia with sinus bradycardia — variability in the junctional escape rate — P waves conducting with different PR intervals — and a history of multiple episodes, some of which are presyncopal in a young adult with a positive family history of some unusual arrhythmia. To me, the most likely unifying theory would be excessive vagal tone, as in the syndrome of Vagotonic AV Block. So although there is NO evidence on this single tracing of frank AV block — the other features of this syndrome ARE present. I reference above a case on this syndrome that I wrote up (this is the link — http://ecg-interpretation.blogspot.com/2013/02/ecg-interpretation-review-61-av-block.html ). THANK YOU again for your wonderful comments. It’s always a pleasure to hear from you and debate interesting arrhythmia theories — :)ECG Interpretationhttps://www.blogger.com/profile/02309020028961384995noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-20668338010451368362019-02-02T09:58:37.903-06:002019-02-02T09:58:37.903-06:00Part II
Another issue is the sudden change in the...Part II<br /><br />Another issue is the sudden change in the H’-H’ intervals (for any newbies, H’ refers to an ectopic junctional beat). From the first beat to the seventh beat we see a gradual increase in the sinus rate (inspiration is occurring here). Let’s look at the 7th and the 8th beats. While the 8th P-QRS is very obviously early (it doesn’t take calipers to see that!), in my mind, the 7th P-QRS also appears – visibly – a bit too early for this pattern of sinus arrhythmia (though it’s not nearly as obvious as the interval that follows it). Looking at all the preceding R-R intervals, one feels that they are very close to the same interval.<br /><br />While there should be no question in anyone’s mind that, due to its earliness, beat 8 is a capture beat (which should also dispel any thoughts of 3rd degree AV block), I think that quite possibly beat 7 is also a capture beat. Which (to me) also means that beat 8 is actually a PAC that managed to conduct on through to the ventricles. Now, it should also be evident to everyone that a rather abrupt change (increase) in the junctional rate (H’-H’ interval) has taken place AFTER these two beats and, more specifically, after beat 8. I think that beat 8, in passing through the AV node and the junction managed to discharge and reset the junctional pacemaker which is now firing at a more accelerated rate. This frequently happens with junctional ectopic pacemakers and supraventricular escape beats.<br /><br />The longest sinus P-P interval on this Lead II rhythm strip barely qualifies as a sinus bradycardia and most P-P intervals do not. The ectopic junctional pacemaker is also firing right at or above 60 beats/minute which is a bit beyond the upper limit for its escape rate. I wouldn’t think of this junctional rhythm so much as an “escape” rhythm (you can see that I’ve avoided using that term here) but more as an “accelerated” junctional rhythm. Most escape rhythms tend to be in the mid- to lower range of the ectopic escape rate – but that is based on my own experience.<br /><br />I would consider this AV dissociation to be due to usurpation rather than default because it persists even as the sinus rate increases. It might also qualify as AV dissociation by interference, though the episodes of AV dissociation may be a bit long for interference which is usually of very short duration.<br /><br />It’s wonderful to have a forum such as this to exchange ideas and to LEARN! I am very thankful to you and Drs. Smith and Meyers for this opportunity.<br /><br />Jerry W. Jones, MD FACEP FAAEM<br />https://www.medicusofhouston.com<br />Jerry W. Jones, MD FACEP FAAEMhttps://www.blogger.com/profile/10333187745825224414noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-75522193443043630192019-02-02T09:57:12.562-06:002019-02-02T09:57:12.562-06:00Ken…
Part I
This is a really GREAT teaching ECG ...Ken…<br /><br />Part I<br /><br />This is a really GREAT teaching ECG and there is a huge amount to learn from it. I enjoyed Dr. K.Wang’s remarks also. If you just sit back and take in the overall picture of this rhythm strip, you can see the cyclical nature of the changes in R wave amplitude that follow a respiratory-type rhythm pattern. In addition to the buffering of the QRS voltage by the expanded lungs, there is also diaphragmatic motion that may be causing a bit of axis shift as well.<br /><br />While I certainly agree with you on most points, I do have a different take on others. First, let me say “Thank you!” for emphasizing the use of calipers in ECG interpretation. They are useful in so many ways. I include a set of calipers for every participant in my advanced ECG courses plus I take the time to show them how to use them in specific situations.<br /><br />First, I think one is going down a dangerous path in using the PR interval and P wave morphology to determine whether or not a sinus P wave has conducted in the setting of an obvious AV dissociation. In such cases, a “normal” PR interval has little meaning if the ectopic pacemaker rhythm remains regular. In fact, even those P waves that DO manage to conduct and produce escape beats often have PR intervals that are longer than whatever is “normal” for that patient. Just from this ECG, we really have no idea what this man’s typical PR interval is under more normal conditions. If his “normal” PR interval were 0.26 seconds under regular circumstances, then the “normal” PR intervals for beats 8 and 9 most assuredly did NOT conduct. There are two types of “normal” PR intervals – the statistically “normal” intervals from 0.12 – 0.20 seconds but also whatever happens to be “normal” for that particular patient. While we can generally assume that a PR interval less than 0.12 seconds most likely did NOT conduct, we can’t ALWAYS assume that a PR interval of 0.18 seconds actually DID conduct. It all depends on the “normal” PR interval for that patient.<br /><br />(continued in next post – Part II)<br /><br />Jerry W. Jones, MD FACEP FAAEMhttps://www.blogger.com/profile/10333187745825224414noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-32828118511577506342019-02-02T03:45:05.883-06:002019-02-02T03:45:05.883-06:00Excellent and full of knowledge case. Thank you ve...Excellent and full of knowledge case. Thank you very much Dr.Ken Grauer and Dr.K Wang for the iformative comments.<br /><br />Few years back, there were video lessons from Dr.Grauer and also Dr.K Wang and Dr.Smith( on this blog) on <br />regular basis which were really informative . Hope the trend continues again. Anonymoushttps://www.blogger.com/profile/10439997400025056304noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-20932586861374504962019-02-02T03:44:32.171-06:002019-02-02T03:44:32.171-06:00Excellent and full of knowledge case. Thank you ve...Excellent and full of knowledge case. Thank you very much Dr.Ken Grauer and Dr.K Wang for the iformative comments.<br /><br />Few years back, there were video lessons from Dr.Grauer and also Dr.K Wang and Dr.Smith( on this blog) on <br />regular basis which were really informative . Hope the trend continues again. Anonymoushttps://www.blogger.com/profile/10439997400025056304noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-80351409312090120282019-02-01T19:57:17.685-06:002019-02-01T19:57:17.685-06:00And beat 2 is junctional( the PR is too short).
K....And beat 2 is junctional( the PR is too short).<br />K. Wang.Anonymoushttps://www.blogger.com/profile/04509940285330859355noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-9595877167038415562019-02-01T19:54:51.223-06:002019-02-01T19:54:51.223-06:00Q waves are "gone" in beats 3,4,5 and 6 ...Q waves are "gone" in beats 3,4,5 and 6 because the P wave is there.<br />K. Wang.Anonymoushttps://www.blogger.com/profile/04509940285330859355noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-88736182760242661362019-02-01T18:16:34.590-06:002019-02-01T18:16:34.590-06:00Rate too slow for VT
Rate too slow for VT<br />Anonymoushttps://www.blogger.com/profile/03598220742341150917noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-70295221750309749342019-02-01T18:13:04.663-06:002019-02-01T18:13:04.663-06:00Against your theory is no more than minimal change...Against your theory is no more than minimal change in QRS morphology (No QRS widening) as the rate speeds up ... ECG Interpretationhttps://www.blogger.com/profile/02309020028961384995noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-83410273289477724272019-02-01T18:11:27.616-06:002019-02-01T18:11:27.616-06:00THANKS so much K for your comment. My thought had ...THANKS so much K for your comment. My thought had been that the reason for change in QRS appearance (slightly taller R waves and loss of the small initial q wave) for beats #3,4,5 and 6 — was that these were junctional beats — whereas beats #1,7, 8, 9 and 10 were sinus-conducted (some with a shorter PR interval). This left me with beat #2 about which I was less certain — as the QRS of beat #2 seem to suggest a sinus-conducted beat — but the PR interval looked too short ... In my experience, on occasion AV nodal beats will look just a little different than sinus-conducted beats — and this relationship can then be VERY helpful for determining if a certain beat is being conducted or is junctional escape. THANKS again for your informative comment!ECG Interpretationhttps://www.blogger.com/profile/02309020028961384995noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-26426330386241018402019-02-01T12:27:58.753-06:002019-02-01T12:27:58.753-06:00Good one.
With the transient AV dissociation, I in...Good one.<br />With the transient AV dissociation, I initially thought it was a short run of fascicular VT. Zia Mehmoodhttps://www.blogger.com/profile/10051455707556091399noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-24577978728941168002019-02-01T11:04:56.078-06:002019-02-01T11:04:56.078-06:00An interesting tracing where vagal tone and the ac...An interesting tracing where vagal tone and the act of respiration are affecting sinus rate with slight sinus arrhythmia, even intrinsic junctional rate slightly, QRS height and PR interval. The sinus rate slows just enough to allow junctional escape to occur, resulting the sinus P wave and the junctional QRS to occur close together during each other's physiologic refractory period, resulting in an obligatory AV dissociation, a physiologic phenomenon. If the sinus beat occur early enough, it has no problem conduction (capture beats), which proves that there is no AV block. I said the act of respiration is affecting the sinus rate and the QRS height, i.e. when the sinus rate speeds up with inspiration, that is when the QRS height shortens due to the inflated lungs buffering the heart(see beats 7,8,and 9 of the rhythm strip of lead II.) <br />K. Wang.Anonymoushttps://www.blogger.com/profile/04509940285330859355noreply@blogger.com