RBBB

This is quite an interesting ECG, and the ECG Guru would love to hear what you think about it.  What we do know is that it is a wide-complex bradycardia in a patient for whom we have no clinical data, except that she is a 51 year old female.  The rhythm is probably junctional, as no P waves are seen and the rhythm is regular.  The rate of 63 per minute would be consistent with that. Interestingly, no disassociated sinus P waves are seen.  All slow wide-complex rhythms should be evaluated for idioventricular origin, or AIVR.  The QRS in V1 shows an atypical right bundle branch block pattern.  We usually look for rSR', or "bunny ears",  but  this ECG shows an upright R wave with a smaller, slurred r wave before it.  What makes this look like RBBB is the prominent wide little S wave in V6 and in Lead I.  We question the R wave progression, too.  Do you think it is possible that the electrodes for V2 and V3 are switched?  The axis is leftward, causing Lead II to be nearly biphasic - it represents a synthesis of what is seen in Leads I and III.  This is enough left axis shift to diagnose a left anterior fascicular block (with RBBB = bifascicular block). 

This is a great ECG, and we can't wait to hear from all you ECG Gurus out there. Maybe we will need to adjust our diagnosis after we hear from you.

This ECG is from a 70 year old woman for which we have, unfortunately, no clinical information.  It shows a sinus rhythm with a rate of about 72 bpm (NSR) with AV dissociation caused by third-degree heart block.  The escape rhythm is junctional at a rate of 38 bpm.  There appears to be a right bundle branch block, based on the QRS duration of 132 ms, and a wide S wave in Leads I and V6.  The precordial leads do not show the usual RBBB pattern of rSR' in V1 and V2, and the r wave progression is poor (non-existent).  This is felt to be due to poor lead placement (a good teaching point).  Of interest, the ECG machine has reported a "severe right axis deviation" based on the tall upright R wave in aVR and the deep S in avF.  In RBBB, the first part of the QRS represents left ventricular depolarization, and the terminal wave represents the delayed right ventricle.  In effect, the two ventricles have their own electrical axes, which we can see because the ventricles are not depolarizing simultaneously.  The axis of the LV appears to be normal in this tracing.

In addition to the above, this patient has a very prolonged QT interval.  The QT is longer in bradycardic rhythms, but when corrected to a standard of 60 bpm (QTc), this patient's QT interval is still prolonged at QTc: 552 ms.  Without clinical data, we cannot speculate  as to why this patient's QTc is prolonged, but it can be a very dangerous situation.  Follow the links for more information on QT prolongation and Torsades de Pointes and Long QT Syndrome.

As always, we welcome comments from our members adding insight to this interesting ECG, and also questions you would like to ask our Guru members.

This ECG is from a healthy young man in his 20's.  He was born with a ventricular septal defect (VSD) that was surgically repaired when he was a toddler.  He now has a right bundle branch block, which could be a result of the defect, or the surgery.  This is a good ECG for the Instructors' Collection because it clearly shows all the ECG characteristics of right bundle branch block:  wide QRS in a supraventricular rhythm (in this case, NSR), rSR' pattern in V1, wide or "slurred" S waves in Leads I and V6.  There is no rhythm strip below the 12 leads in this ECG, but there is no rhythm disturbance.