tag:blogger.com,1999:blog-549949223388475481.post7885302789642758205..comments2024-03-26T22:42:04.176-05:00Comments on Dr. Smith's ECG Blog: A Patient with Ischemic symptoms and a Biventricular PacemakerUnknownnoreply@blogger.comBlogger3125tag:blogger.com,1999:blog-549949223388475481.post-45616216234102644512016-04-08T10:19:14.448-05:002016-04-08T10:19:14.448-05:00Thanks, Mario!Thanks, Mario!Steve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-91812273893007848962016-04-03T09:55:32.135-05:002016-04-03T09:55:32.135-05:00A really interesting case which teaches us how can...A really interesting case which teaches us how can be useful the Smith-modified Sgarbossa criteria also in VPR.<br />I have read with huge interest every single explanations on this case. This proves how stimulating is this blog.<br /><br />It is interesting to hear also that you are planning a study on this topic. I think the combination of STEMI+VPR is much more common than STEMI+LBBB given the huge number of patients with all type of pacemakers.<br />Mario<br />Mario Parrinellohttps://www.blogger.com/profile/07136945770330333718noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-9796846531409661132016-04-02T12:18:27.319-05:002016-04-02T12:18:27.319-05:00GREAT case for illustrating a series of important ...GREAT case for illustrating a series of important findings and observations during stemi evolution in a patient with a pacemaker. As per Dr. Stephen Smith — Acute STEMI can be diagnosed in some cases of paced rhythms. In addition to assessing for inappropriate discordance — the 1st ECG shown here clearly manifests primary ST segment elevation in many leads, any one of which in an older patient with new-onset worrisome chest pain should by itself be enough to strongly suggest acute evolving stemi. My “Go-To” lead is often lead aVL — which in this case shows subtle but clearly abnormal ST elevation (with beginning T wave inversion). Almost regardless of amount — this shape is highly suspicious. QRS amplitude of the paced complex in lead I is small — but the ST coving and elevation in that lead (which “neighbors” lead aVL) is clearly abnormal. ST segment assessment in the chest leads show typical ST segment shape and elevation characteristic of acute anterior STEMI, which begins in V1 and is maximal in V3,V4. The key point that I’d emphasize from this obvious acute stemi — is that ST segment appearance in any ONE of the above leads in an older adult with new-onset chest pain and a pacer should be enough to prime your suspicion of an acute evolving event.<br /><br />That the above ST segment changes noted are clearly acute becomes even more obvious with revelation of the patients baseline pacer tracing (2nd 12-lead posted).<br /><br />There follows with the 3rd and 4th ECGs posted a highly insightful example of how in some cases stemi evolution can clearly be seen on serial tracings. Electrical alternans, as seen on the 3rd 12-lead — may be seen in severe ischemia/LV dysfunction, both of which were doubtlessly present.<br /><br />Finally — the fascinating rhythm strip highlights several findings. As emphasized by Dr. Smith’s BLACK arrows — the first 3 beats are fusion beats, as the pacer spike occurs after (not before) the QRS begins. I suspect that the fusion here may be between the paced impulse with an accelerated ventricular focus (ie, AIVR) — as AIVR is a common associated rhythm with evolving stemi. And it looks like the 2nd and 3rd (but not the 1st) fusion beats manifest retrograde atrial conduction. Measurement with calipers suggests slight increase in the RP’ interval for the 3rd fusion beat compared to the 2nd fusion beat — which probably reflects retrograde Wenckebach conduction. I suspect that it is this slightly later retrograde conduction for the 3rd fusion beat that allows the pacemaker to sense atrial activity and put out a completely paced complex (ie, the 4th beat). It may be that the reason ST elevation is minimal for these first 3 fused beats is reciprocal change from opposing electrical activity (depending on the site of the AIVR rhythm) that in part cancels out the primary ST elevation.<br /><br />Of interest — a spontaneous P wave (that is upright) precedes the 5th beat. This 5th beat is also a fusion complex — but this time, the fusion is between partial conduction from this sinus P wave with the paced complex. Note there is more ST elevation for this 5th beat than there was for the first 3 fusion beats — which suggests to me that if we did see any non-paced spontaneously conducted P waves, that they might indeed show similar ST elevation as seen in the completely paced complexes on the 1st tracing.<br /><br />Finally — AIVR-and-paced fusion resumes for the last 3 beats in the rhythm strip. Note similar amount of ST elevation and similar retrograde conduction for these last 3 AIVR-paced fusion beats as was seen for the first 3 AIVR-paced fusion beats. FASCINATING!<br /><br />Thanks so much to Dr. Smith for posting this wonderful teaching tracing. Fortunately the patient’s acute evolving stemi was recognized despite permanent pacing, resulting in successful PCI.ECG Interpretationhttps://www.blogger.com/profile/02309020028961384995noreply@blogger.com