Dawn's picture
Submitted by Dawn on Sat, 06/22/2013 - 22:01

 This wide complex tachycardia has an initial rate of 129/min. It is difficult to discern if P waves are present, although the ECG machine does give us a PR interval. The ECG meets most of the criteria for left bundle branch block: wide QRS, negative QRS in V1, positive QRS in Lead I and V6.The axis is leftward, which is common in LBBB.  However, it is difficult to say for certain that this is a supraventricular rhythm. Later, however, the patient's rate slowed (see top strip), revealing P waves. When the rate slowed, the left bundle branch block pattern remained. That helps confirm the original interpretation of left bundle branch block. Interestingly, the BBB is not rate-related, in that it is still present at the slower rate.

Of course, it would be helpful to have a complete 12-Lead ECG after the rate slowed, and it would also be good to see the onset and/or offset of the fast rhythm, which would help to determine if this is a sinus tachycardia or a paroxysmal supraventricular tachycardia (PSVT).  We do not have clinical data to help us determine if a sinus tachycardia with a rate of around 130 / min. would be appropriate or expected in this patient.

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Related Terms: 
Wide complex tachycardia
Left bundle branch block
LBBB
Bundle branch block
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ekgpress@mac.com's picture

Submitted by [email protected] on Sun, 06/23/2013 - 06:02

 

I looked at the 12-lead ECG first. I see a regular WCT (Wide-Complex Tachycardia) at ~135/minute without clear sign of atrial activity (despite what the computer says about the "PR interval" - ). The differential diagnosis for this is: 

  • #1,2,3-thru-8 = VT
  • #9 = SVT with aberrant conduction
  • #10 = SVT with preexisting BBB

Statistically - the odds of a regular WCT without P waves being VT are at least 80% before you look at the tracing (confirmed by studies in the literature). This goes up to >90% if the patient is older and has underlying heart disease - which is why the diagnosis should always be thought of as, "VT until proven otherwise; Treat accordingly." That said, >90% is not 100% .... - and the follow-up rhythm strip shown here proves this to be one of the <10% of regular WCTs that turned out to be supraventricular.

  • Looking at the 12-lead for additional features we see extreme axis deviation (favors VT ) - but otherwise a VERY straight downslope to the S wave in V1-thru-V4 - which can clearly be consistent with LBBB. Lead V6 is upright - which doesn't help (VT favored if V6 is all negative).
  • This patient undoubtedly has significant underlying heart disease - as QRS width (even on the follow-up rhythm strip) is extremely wide. There most probably is cardiomyopathy (ischemic or otherwise) - so the situation becomes that much more challenging when a grossly abnormal baseline tracing is complicated by tachycardia ...
  • The post-conversion rhythm strip confirms this was SVT ... 
  • Clinically - it wouldn't matter. Depending on whether the patient was alert and hemodynamically stable - one would manage as a WCT of uncertain etiology- which might entail either meds (ie, amiodarone) and/or cardioversion. 
  • BOTTOM LINE: Sometimes you just can't tell for sure what a rhythm is at the time you need to begin treating. Such is the reality and fascination of ECG arrhythmia interpretation.

For anyone with interest in Review of ECG Criteria for distinguishing between VT vs SVT (and how to treat when you are uncertain) - GO TO: https://www.kg-ekgpress.com/acls_comments-_issue_11/ -

Ken Grauer, MD  www.kg-ekgpress.com   [email protected] 

Submitted by marionurse on Sun, 06/23/2013 - 19:32

Do I see P wave v5?? Review od V5 these are waves of QRS as compared to v4

Submitted by ecgekg on Mon, 06/24/2013 - 03:39

There is a saying if LBBB AND LOOKS like LBBB then it is unlikely to be VT; atypical LBB are worrisome. secondly we dont see Q in V6.

 

KEN can you please by your huge experience and knowledge share how LBBB LOOKS help in clinching ischemic versus non ischemic  kind thanks

 

aaa

ekgpress@mac.com's picture

Submitted by [email protected] on Sat, 06/29/2013 - 16:28
Hello - If I understand your point and question - you are commenting on wide tachycardias that look like typical LBBB - and also asking how one can tell when there is LBBB if acute ischemia/infarction are also likely.
 
First - I'll refer you to my detailed discussion in my ACLS Comments #11 - that reviews distinction between VT vs SVT with either aberrancy or preexisting BBB. GO TO: https://www.kg-ekgpress.com/acls_comments-_issue_11/#Illustrative%20CASE%20PRESENTATION - which shows you the problem, as this WCT (Wide Complex Tachycardia) manifests QRS morphology totally consistent with LBBB - BUT given lack of P waves, one still has to assume VT until proven otherwise ... (My discussion walks through a practical approach to a patient with this tracing).
 
Otherwise - with regard to assessing sinus rhythm with LBBB for acute ischemia/infarction as well as to recognition of "typical" LBBB - I'll refer you to my BBB Basics web page - GO TO: https://www.kg-ekgpress.com/bundle_branch_block_pdf_file/ - You'll note several brief instructional PDFs you can download on this page - as well as links to clinical examples (You may be most interested in the pdfs under 'For the Quick Answer' ).
 
  • Please let me know after review of this material if you still have questions. THANKS for your interest!
 

Ken Grauer, MD  www.kg-ekgpress.com   [email protected] 

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