tag:blogger.com,1999:blog-18943510.post212036056261587726..comments2023-08-21T02:57:37.362-05:00Comments on Dr. Wes: EKG Du Jour 32: The Misfiring PacemakerDrWeshttp://www.blogger.com/profile/17438019699222125477noreply@blogger.comBlogger29125tag:blogger.com,1999:blog-18943510.post-28557451467364455232013-08-16T14:25:52.900-05:002013-08-16T14:25:52.900-05:00Great case.
Jerry from BSX (@w04f40) wins, I lo...Great case. <br /><br />Jerry from BSX (@w04f40) wins, I lose.<br /><br />Even when he showed me his correct answer, I didn't believe it because I couldn't see any atrial pacer spikes. In addition, it seemed pretty fortuitous that the patten would be so steady so long. One big coincidence captured on paper to torture us.<br /><br />Nice job, Wes and Jerry,<br /><br />Jay<br />@EJSMD<brJayhttps://www.blogger.com/profile/10897176780069403370noreply@blogger.comtag:blogger.com,1999:blog-18943510.post-42261154251330234662013-08-16T13:16:18.457-05:002013-08-16T13:16:18.457-05:00Okay, I’m sorry I have not divulged the answer soo...Okay, I’m sorry I have not divulged the answer sooner, but that darn work stuff just kept getting in the way! <br /><br />First of all, this is an EKG of an accelerated junctional rhythm at (according to the EKG) 71 beats per minute. This rate becomes important, since it represents about 845 msec (60,000 milliseconds per minute divided by 71 b/min = about 845 msec).<br /><br />Recall that the DrWeshttps://www.blogger.com/profile/17438019699222125477noreply@blogger.comtag:blogger.com,1999:blog-18943510.post-54172907485296418302013-08-16T09:44:59.840-05:002013-08-16T09:44:59.840-05:00As a pacemaker patient who doesn't understand ...As a pacemaker patient who doesn't understand any of this...I am so glad I am not THIS patient!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-81765285143551145842013-08-15T22:13:50.896-05:002013-08-15T22:13:50.896-05:00Best guess:
Isorhythmic accelerated junctional rhy...Best guess:<br />Isorhythmic accelerated junctional rhythm in a pt with a DDDR ppm with A-pacing simultaneously at near equally timed rate, causing transient continuous VSP due to timing of junctional rhythm causing V-sensed event after the Post A-blanking period. The VSP in this MDT ppm feature nominally on to prevent cross-talk inhibition, thus this is normal device operation & lead Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-17582115572505031572013-08-15T20:27:25.930-05:002013-08-15T20:27:25.930-05:00Isorhythmic AV dissociation is a such a vexing pro...Isorhythmic AV dissociation is a such a vexing problem. It's most especially vexing when the junctional rate, atrial rate and pacing rate are about the same. <br /><br />AS/VP with VP in the ERP of every other QRS complex? <br /><br />My question is: was the iso-rhythmic AV dissociation diagnosed as AV block? And therefore, was the pacemaker...never mind with that. <br /><br />Great case. John Mandrolahttp://www.drjohnm.orgnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-7184986789386694702013-08-15T20:02:17.490-05:002013-08-15T20:02:17.490-05:00I had a case with a Cardiac Contractility Modulati...I had a case with a Cardiac Contractility Modulation device from Impulse Dynamics implanted along with an ICD. The ecg looked like this:<br /><br /><a href="%E2%80%9Durl%E2%80%9D" rel="nofollow">https://dl.dropboxusercontent.com/u/32878659/Impulse%20Dynamics.jpg</a>Cam from MDTnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-74249324230229582902013-08-15T19:29:15.647-05:002013-08-15T19:29:15.647-05:00Yes, I stopped thinking MVP when he said DDD. Any...Yes, I stopped thinking MVP when he said DDD. Anyway the backup VP in MVP is 80ms after the AP. This Paced AV interval looks like the programmed one. And I dont think it is safety pacing either as that AP-VP interval is 110ms at slow rates and 70ms at fast rates.Cam from MDTnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-35033114406837081672013-08-15T16:55:06.009-05:002013-08-15T16:55:06.009-05:00MDT will be the first to tell you MVP is not DDDRMDT will be the first to tell you MVP is not DDDRAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-6374669052132063522013-08-15T15:03:26.202-05:002013-08-15T15:03:26.202-05:00The additional clue strip is 3oAVB with accelerate...The additional clue strip is 3oAVB with accelerated junctional rhythm....early on you can see the p waves marching through. With that I'm assuming the pt has no retrograde conduction. The original strip was accelerated junctional rhythm with sinus rate equal to the junctional rate. It paces the RV based on which "side" of the junctional R wave the P wave is sensed. If the R wave Scottnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-17728114645402774152013-08-15T13:19:05.844-05:002013-08-15T13:19:05.844-05:00I would guess it's V safety pacing. When a pac...I would guess it's V safety pacing. When a pacemaker senses a ventricular signal around the same time there is an atrial signal (like during a junctional rhythm) there is concern that the V signal is just farfield oversensing of an atrial signal. In someone with CHB it would be dangerous if the V lead inhibited pacing based on oversensing, so pacemakers deliver the ventricular pace just to Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-28864501729714104892013-08-15T12:36:23.671-05:002013-08-15T12:36:23.671-05:00Wes,
Even after hearing all these tech support gu...Wes,<br /><br />Even after hearing all these tech support guys pontificate in another direction, I still think your original strip is just an example of Medtronic's MVP pacing algorithm resulting in an extremely long AV interval after atrial capture. Although it's hard to see pacer spikes after every QRS, I suspect they are just not evident due to the digital signal processing of modern Jayhttps://www.blogger.com/profile/10897176780069403370noreply@blogger.comtag:blogger.com,1999:blog-18943510.post-80501136956494967322013-08-15T11:31:14.464-05:002013-08-15T11:31:14.464-05:00It looks like OOO pacing (the apparent paces on th...It looks like OOO pacing (the apparent paces on the original strip are spaced too exactly at regular intervals) so I suspect a magnet.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-11781995243251722032013-08-15T11:24:51.372-05:002013-08-15T11:24:51.372-05:00Maybe we deal with VA crosstalk during junctional ...Maybe we deal with VA crosstalk during junctional rhythm - the A channel is sensing far-field R wave, and this pseudoatrial "event" initiates PAVB (non-sensed QRS on V channel) and SAV (V pace after each QRS, non-capturing due to ventricular refractoriness)Hermine Poghosyannoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-78336307574536982232013-08-14T22:57:18.776-05:002013-08-14T22:57:18.776-05:00Okay. The strip just made it more complicated!
T...Okay. The strip just made it more complicated! <br />The A-pace happened (with no capture) then the v sense was "too quick" so device v-paced! Previous beats have a bleb before QRS (?Acessory pathway) <br /><br />Why did A pace happen??Saleh Alshalashhttps://www.blogger.com/profile/12214862849304463331noreply@blogger.comtag:blogger.com,1999:blog-18943510.post-15205960894233344912013-08-14T12:01:54.445-05:002013-08-14T12:01:54.445-05:00I think Toby is right about the junctional rhythm ...I think Toby is right about the junctional rhythm causing atrial paces to be scheduled every other beat, coinciding with the QRS. But the interval is too long to be safety pacing which is typically 110 ms. Maybe the R-wave is really narrow tip-ring egm and gets hidden by the cross chamber blanking of 30 ms in the V after an AP. This is rare, but I have seen before.Cam from Medtronicnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-64117260203931336372013-08-14T10:12:43.444-05:002013-08-14T10:12:43.444-05:00We think the A & V leads are switched (in the...We think the A & V leads are switched (in the header?) Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-62074286428680659542013-08-14T08:11:51.664-05:002013-08-14T08:11:51.664-05:00Final "clue" (that contains the answer):...Final "clue" (that contains the answer):<br /><br />Here's a <a href="http://www.medtees.com/blog/Telestrip32.jpg" rel="nofollow">link to an associated tele strip</a> of the same patient's rhythm found on their monitor that helps explain what is seen on the EKG shown. <br /><br />This is a tough one, but a few folks seem to have the right idea...DrWeshttps://www.blogger.com/profile/17438019699222125477noreply@blogger.comtag:blogger.com,1999:blog-18943510.post-88192980557197413632013-08-14T07:28:27.700-05:002013-08-14T07:28:27.700-05:00Does this person have a previous pacemaker that wa...Does this person have a previous pacemaker that was not removed? But the leads were reused in the new device? And we are seeing the output from the old device pacing unipolar at 35 bpm (they programmed a low rate trying to keep it out of the way)? Since the old device has no leads attached it cant sense the real rate, and likely the new device isn't sensing the old device's outputs even Cam from Medtronicnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-89458173830915289632013-08-13T22:11:02.595-05:002013-08-13T22:11:02.595-05:00Atrial signal is not sensed, perhaps from a PVARP ...Atrial signal is not sensed, perhaps from a PVARP that has been programmed too long. A's are not seen, V is cross sensed first in the atrial lchannel (set too sensitive) before it is sensed in the ventricle. Tracks, 150 ms later the ventricle is paced in the refractory QT interval, setting a new long PVARP. Not sure what is going on the atrium, V3 shows some noise or fib, a possibility is Andresnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-30439529801853189272013-08-13T19:39:02.933-05:002013-08-13T19:39:02.933-05:00OK, let's try another approach. Patient has a...OK, let's try another approach. Patient has a junctional rhythm (which always embarasses pacemakers) as there are no obvious P-waves. Starting from the left and looking at the continuous V5, the pacemaker senses a QRS that inhibits and resets the timing. There is a small deflection about 200 ms after the peak of the QRS that is barely visible in V1 but not other lead. there is another Tobyhttps://www.blogger.com/profile/10675782084978056510noreply@blogger.comtag:blogger.com,1999:blog-18943510.post-67330454770947398722013-08-13T12:58:43.911-05:002013-08-13T12:58:43.911-05:00Toby -
The pacemaker was a dual-chamber pacer, p...Toby - <br /><br />The pacemaker was a dual-chamber pacer, programmed DDDR with lower rate 60 b/min, upper rate 130 b/min, paced AV interval 180 msec, and sensed AV interval 150 msec.DrWeshttps://www.blogger.com/profile/17438019699222125477noreply@blogger.comtag:blogger.com,1999:blog-18943510.post-39060131070579680032013-08-13T12:26:49.436-05:002013-08-13T12:26:49.436-05:00We do not know what mode is programmed. I jumped ...We do not know what mode is programmed. I jumped too quickly and now notice atrial pacing occurs as a bigeminal rhythm. The atrial spikes are about 700 mS from the prior T-wave, possibly indicating T-wave oversensing on alternate beats. Atrial spikes linked to v-sensing might suggest a dual chamber mode, DDD, DDI, ... <br /><br />2.8 mV is a large P-wave and suspicious if measured by the Tobyhttps://www.blogger.com/profile/10675782084978056510noreply@blogger.comtag:blogger.com,1999:blog-18943510.post-89642965046857212782013-08-13T12:11:11.444-05:002013-08-13T12:11:11.444-05:00What about if there is some kind of preexcitation ...What about if there is some kind of preexcitation or some kind of accessory pathway that makes the atrial lead depolarizing both the atrium and the ventricle. But because the depolarization of the ventricle occurs during the "AV-Interval" of the pacemaker it does not sense it as an ventricular activity and thus firing again after the "AV-Interval" during the repolarization of Georg Neudertnoreply@blogger.comtag:blogger.com,1999:blog-18943510.post-51806265232476059062013-08-13T11:58:28.705-05:002013-08-13T11:58:28.705-05:00Wes,
this is a Most Vexing Problem.
Hmm.
Jay
@E...Wes,<br /><br />this is a Most Vexing Problem.<br /><br />Hmm.<br /><br />Jay<br />@EJSMDJayhttps://www.blogger.com/profile/10897176780069403370noreply@blogger.comtag:blogger.com,1999:blog-18943510.post-31291222365064079432013-08-13T11:55:36.044-05:002013-08-13T11:55:36.044-05:00Clue time!
The pacemaker was interrogated and dem...Clue time!<br /><br />The pacemaker was interrogated and demonstrated the atrial lead paced the atrium and the ventricular lead paced the ventricle. P wave amplitude was 2.8 mV, R wave 11.0 mV, and capture thresholds were normal. <br /><br />Hmmm. <br /><br />How do we explain the EKG now?DrWeshttps://www.blogger.com/profile/17438019699222125477noreply@blogger.com