Posts Tagged ‘lv pacing’

Pacemaker rhythms  result in classical ECG with  LBBB morphology.It is a universally understood  fact that  RV pacing would  produce LBBB and LV pacing a  RBBB pattern in surface ECG.As with any other rules in medicine , it is not 100%  perfect .(May be 70%)

In the process of oversimplification of rules  we have forgotten a simple fact , that is, interventricular  septum is  shared by both the ventricles . ( functionally and electrically )

In due course , cardiologists and electrophysiologists  have  recognised this fact. A pacemaker lead hitching on the IVS  can behave independently and disobey this  golden rule of pacing.(RV-LBBB,LV-RBBB). Depending upon the orientation of the lead and the pressure it exerts  on the tissue  and degree of penetration of the screwing lead into the septum, the resultant   ECG can  either have a complete RBBB pattern ,  partial RBBB or partial LBBBB or combination of both.

Can RBBB pacing be stable ?

Yes.,  provided the the fixity of the lead and other parameters like impedance and pacing threshold are good.

Before labelling RBBB pacing as safe one should rule out pathological RBBB pacing like septal perforation and

accidental entry into LV through foremen ovale.

Is coronary sinus pacing an acceptable alternative  for  long term permanent pacing ?

The answer is generally ” No ” ,  but it needs rethinking.

A coronary sinus pacing may happen accidentally.The leads get located  either in the main stem coronary sinus or it”s tributaries.the morphology of ECG depends upon the branch it enters.Leads when they reach LV aspect result in RBBB morphology.

Can  we do intentional coronary sinus  pacing for complete heart block ?

There are many accepted  references in literature  that terms   RV pacing as unphysiological and has high risk of precipitating or aggravating cardiac failure. So currently , alternate sites of pacing are explored.( Septum, his bundle , biventricualr etc)

It is an irony , in this era of cardiac resynchronisation therapy where we do coronary  vein pacing  , the same concept is not being tried for regular  permanent pacing in special and difficult situations.( Severe TR, Left sided SVC, AC canal defects etc)

Final message

  1. RBBB morphology following  permanent pacing  need not elicit a panic reaction provided all parameters are stable.
  2. In patients  with difficult RV anatomy* ,  who need permanent pacemaker implantation a modified  coronary sinus pacing can be a solution .But as of now no such speciifc leads are available.EP Industry should take a note on this .

*Epicardial pacing is an option in such situations .But it requires surgery.


Safe right bundle branch block pattern during permanent right ventricular pacing Journal of ElectrocardiologyJanuary 1, 2003   Yang, Yung-Nien ; Yin, Wei-Hsian ; Young, Mason Shing

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