tag:blogger.com,1999:blog-549949223388475481.post8188808968641915942..comments2024-03-28T14:02:08.119-05:00Comments on Dr. Smith's ECG Blog: Paroxysmal SVT (PSVT) that repeatedly recurs in spite of successful conversion with adenosineUnknownnoreply@blogger.comBlogger18125tag:blogger.com,1999:blog-549949223388475481.post-60306637037234848942014-02-12T10:00:51.707-06:002014-02-12T10:00:51.707-06:00I don't see it. But fortunately it is academi...I don't see it. But fortunately it is academic.Steve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-33140548782869354442014-02-12T04:16:06.461-06:002014-02-12T04:16:06.461-06:00Good eye! I think the buried P-waves are indeed la...Good eye! I think the buried P-waves are indeed later than indicated, though the contour of the T-wave in III and aVF might give them a bit more size than they are due. I'm most convinced by the tiny pseudo-bifid T-wave in II whose first peak marches out in every single lead.<br /><br />It's a tough call (and I'm rubbish at telling which way is "up" with buried P-waves), but it does look to me like the P-axis is roughly around 120 degrees and seemingly inconsistent with AVNRT.<br /><br />An interesting case gets even more interesting!Vince Dhttps://www.blogger.com/profile/10636259293820649555noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-26854787123628283802014-02-04T13:26:20.338-06:002014-02-04T13:26:20.338-06:00No, that is not true. All Re-entrant tachycardias...No, that is not true. All Re-entrant tachycardias need to be initiated, and if they are converted, they can always initiate again. Many PATs are re-entrant as well (some automatic, some re-entrant). MJ Perrin (see below) thinks this might be PAT. I don't think so.Steve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-51943740424687567062014-02-04T06:26:49.363-06:002014-02-04T06:26:49.363-06:00MJ,
It's certainly possible. I'm skeptica...MJ,<br />It's certainly possible. I'm skeptical. Thanks for the great input! I guess we need a EP study to know for sure.<br />Steve SmithSteve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-76136303446532036532014-02-04T05:34:17.069-06:002014-02-04T05:34:17.069-06:00When I gave verapamil long ago, I always used calc...When I gave verapamil long ago, I always used calcium pretreatment. However, there is a good article showing no effect of calcium prior to diltiazem.Steve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-34600726089726475942014-02-03T23:28:33.308-06:002014-02-03T23:28:33.308-06:00Interesting case. I wonder if the P wave is actual...Interesting case. I wonder if the P wave is actually positive – the contour of the ST/T wave in lead III and aVF suggests this. In tachycardia the segment is predominantly positive in aVF, and clearly negative in sinus. Similarly lead III looks like it has a positive wave superimposed on the ST/T when comparing between sinus and tachycardia. If positive, it can't be AVNRT or VT. I think the arrow is pointing to late activation of the QRS – often see that with RBBB due to late RV activation.<br /><br />Then the differential is between AT and AVRT (accessory pathway). The latter is not so common in the elderly - there is a natural attrition rate for accessory pathways with each passing decade. So AT most likely? Response to amiodarone and adenosine would be consistent.<br /><br />Would be interesting to study! I think finding the P wave is the most difficult aspect of arrhythmia differentiation. I've been surprised in a couple of cases to find out at EP study that what I thought was the P wave was just a notch of the QRS or T wave, and vice versa. Perhaps I'm wrong again, but just my 2 cents.<br /><br />MJ Perrinhttps://www.blogger.com/profile/08177271615863248865noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-45129240398457631462014-02-03T20:11:32.373-06:002014-02-03T20:11:32.373-06:00do you ever use calcium gluconate before ccbs to p...do you ever use calcium gluconate before ccbs to prevent hypotension? Anonymoushttps://www.blogger.com/profile/00383107887079523606noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-5069376504371582992014-02-02T19:54:26.542-06:002014-02-02T19:54:26.542-06:00Thanks for this Great explanation. I had similar c...Thanks for this Great explanation. I had similar case before where I thought of Atrial tachycardia due to the recurrence of SVT after adenosine and electrical cardioversion but responded to Verapamil later. I kept in mind if SVT converted to sinus after adenosine (temporarily) then SVT recurs, its against re-entry mechanism and I should think of Ectopic atrial tachycardia !! is that true (narrow complex only, excluding VT just to make it simple)maateeqhttps://www.blogger.com/profile/10063793989441938455noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-51375371188835361432014-02-01T09:52:13.910-06:002014-02-01T09:52:13.910-06:00Thanks, Matthieu!Thanks, Matthieu!Steve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-22678498589561296992014-02-01T01:26:58.173-06:002014-02-01T01:26:58.173-06:00Great post as usual!
There may be a typo in the e...Great post as usual!<br /><br />There may be a typo in the esmolol dose though: I guess your loading dose is 500mcg/kg, not 500mg/kg.<br /><br />I sometime use CCB for adenosine-refractory SVT, rapid AFIB or CCB-sensitive VT. I give it by slow (20 minutes) infusion, as described in the below paper and have yet to observe a single episode of hypotension.<br /><br />Best regards.<br /><br />Lim, S. H., Anantharaman, V., Teo, W. S., & Chan, Y. H. (2009). Slow infusion of calcium channel blockers compared with intravenous adenosine in the emergency treatment of supraventricular tachycardia. Resuscitation, 80(5), 523–528. <br />http://www.ncbi.nlm.nih.gov/pubmed/19261367Matthieu G.https://www.blogger.com/profile/10403266077838003029noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-50392126312006777062014-01-31T20:00:03.125-06:002014-01-31T20:00:03.125-06:00Thanks for the feedback!Thanks for the feedback!Steve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-23898676100505159502014-01-31T19:33:36.503-06:002014-01-31T19:33:36.503-06:00Yes, thanks. Your answer squares with my practice....Yes, thanks. Your answer squares with my practice. I, too, use CCBs and BBs in afib with RVR. Not sure why some literature seems to urge caution with CCBs but not beta blockers. Thanks for your terrific blog. Jason Ryanhttps://www.blogger.com/profile/14783489586481465988noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-87410516979546790322014-01-31T19:22:43.177-06:002014-01-31T19:22:43.177-06:00Jason,
I use diltiazem freqently in atrial fib wit...Jason,<br />I use diltiazem freqently in atrial fib with RVR. It is relatively safe, but does cause hypotension a significant amount of the time. You must be careful with it. Verapamil even more so. Both Ca blockers and beta blockers equally cause negative inotropy and hypotension in these patients. That is why I used esmolol. If there are adverse effects, you can turn it off and its effect is gone in less than 10 minutes.<br />Does that answer the question?<br />SteveSteve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-4155565113720899132014-01-31T18:56:36.496-06:002014-01-31T18:56:36.496-06:00Hi Steve - You say there is "potential for si...Hi Steve - You say there is "potential for significant negative inotropic effects" with diltiazem and verapamil. Are there not also negative inotropic effects with beta blockers? You used in this case without mention of concern for negative inotropy? I ask because it is often said to avoid calcium channel blockers for rate control in tachycardias among heart failure patients. I have never been able to find solid grounding for this statement. Why would beta blockers be okay for tachycardia but not diltiazem in CHF? UpToDate says of rapid afib "both diltiazem and verapamil have negative inotropic effects...should be used with caution in heart failure." Yet it gives no reference. Is there any clinical grounds for this? Or are these statements based on animal models? Why the concern for CCBs but not BBs? Thanks in advance.Jason Ryanhttps://www.blogger.com/profile/14783489586481465988noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-40952266051433597082014-01-31T14:44:11.851-06:002014-01-31T14:44:11.851-06:00Meghan,
Yes, PSVT is usually faster, but not alwa...Meghan,<br /><br />Yes, PSVT is usually faster, but not always, especially in the elderly. Response to adenosine by itself does not make the diagnosis: there is RV outflow tract VT which is adenosine sensitive. But it has a different morphology with an inferior axis. See here: http://hqmeded-ecg.blogspot.com/2013/02/regular-wide-complex-tachycardia-what.html. RVOT VT is also rare.<br /><br />It is possible to have RBBB and LAFB morphology in VT if it originates in the posterior fascicle (posterior fascicular VT), as in this case: http://hqmeded-ecg.blogspot.com/2011/10/wide-complex-tachycardia-in-36-year-old.html. So on first glance this could be posterior fascicular VT, but it is relatively very rare, so I would only hold that possibility in the back of my mind. Also, posterior fascicular VT does not respond to adenosine, but does respond to verapamil!<br /><br />Finally, we know the diagnosis is SVT with aberrancy because we see the same QRS morphology when the rhythm is sinus.<br /><br />Thanks for the great question.<br /><br />Steve SmithSteve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-73344241130737164452014-01-31T14:34:53.889-06:002014-01-31T14:34:53.889-06:00I should say you must just be very careful because...I should say you must just be very careful because they can cause a lot of negative inotropy together, hypotension.Steve Smithhttps://www.blogger.com/profile/08027289511840815536noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-83186082752267325152014-01-31T14:07:15.262-06:002014-01-31T14:07:15.262-06:00The heart rate often adds to the differential diag...The heart rate often adds to the differential diagnosis of a tachyarrhythmia. It is interesting here, as 150 bpm is slow for an AVnRT. The rate fits VT even moreso than it does AVnRT. Moreover, VT can also be accompanied by retrograde p waves. The key is really that the rhythm converted with adenosine, prior to that, it is difficult to absolutely rule out VT (I think...) <br /><br />Help me understand this statement: "There is a definite Right Bundle Branch Block and Left Anterior Fascicular Block pattern, so this is not VT"--is that 100% correct? A Bundle Branch Reentrant VT can also have this pattern, or am I wrong?Meghanhttps://www.blogger.com/profile/15808606337703858748noreply@blogger.comtag:blogger.com,1999:blog-549949223388475481.post-64771202863674812622014-01-31T13:33:33.517-06:002014-01-31T13:33:33.517-06:00Why do you want to avoid the use of beta blockers ...Why do you want to avoid the use of beta blockers and calcium channel blockers simultaneously?Travishttps://www.blogger.com/profile/12784677165489402715noreply@blogger.com