This 70 year old man in routine check up showed up this ECG.
What is it ? a quick debate ensued !
- Or Both ?
- Neither RBBB nor RVH
- Wrong lead placement
- Is it a normal ECG after all ?
I thought it was RVH. (do considered RBBB) but since lead V 2 showed tall R , I was more than sure RVH was likely . Many voted for RBBB. .Some others said RBBB can never occur in monophasic form.I said it’s possible.
Some body challenged me without Echo Imaging a monophasic RBBB can never be differentiated from RVH. After a mini argument I reluctantly agreed.Yes, it seemed there is no way to differentiate the two.
What do you think ?
Curious to know the Echo finding in the above patient ? Yes , your guess was right /wrong. There was no RVH.He had normal Echocardiogram.
How to diagnose RVH in RBBB ?
- Look at the r’ wave if its taller than initial r by more than 5mm suggest RVH (Not absolute evidence though)
- Look for other evidence like Right axis , RV strain etc.
How to diagnose RBBB in RVH ?
Sorry.I don’t know the exact answer.It could be masked within Qrs complex of RVH.RVH could convert biphasic RBBB into monophasic RBBB.
Some more about this RVH/RBBB duo
- The term incomplete RBBB is liberally used with minor rsr’ pattern.It is not advisable to do so.
- RBBB is classically multiphasic (To be precise RBBB can be complete to incomplete rsr’ with various combinations of small r and big s big R or big S).
- But more than the morphology of Qrs in V1 the S wave in lead V 6 or Lead 1 could be Important.It should be delayed slurred.
- QRS width has no great use to diagnose RBBB as it can be narrow or wide.
To diagnose monophasic RBBB( in V1 ) by itself requires some guts.However ,the entity do exist.
Finally , please recall there is a traditional list for tall R in V1 other than RVH.
- Wrong lead placement
- Some cardiomyopathy(RV myopathy)
- Systemic Duchenne’s muscular dystrophy
- Posterior MI
- Normal variant*
*Why should normal guys grow a tall R in V1 , it mystifies ! but true.
What is the rarest cause of tall R in V1 ?
Localised cardaic tumors over RVOT. Cagli K , Tok D, Basar FN .An unusual cause of tall R wave in lead V1: cardiac lipoma.Heart Asia. 2013 Mar 7;5(1):33.
Annexure : Further questions in RBBB
2.What is the blood supply of bundle branches ?
3.What is the mechanism of RBBB in ASD ?
Is it true RBBB or Right bundle delay ? Students should know there need not be conduction system pathology to cause RBBB. Simple delayed conduction in RVOT can cause a RBBB. (The concept of central RBBB vs Peripheral RBBB) This is what happens in ASD.
In fact , true pathological damage due to right bundle branch due to necrosis, Ischemia, Infiltration is much rarer than pathological LBBB.
4. What are the structural , histological difference between right and left bundle branches that has electrophysiological Importance ?
Wait . . . I am trying to collect info for this .Meanwhile ,Why don’t one of the energetic young fellows in cardiology find the answer and post here !