Diagnostic criteria

  The QRS width is

                  120 ms or more (at least 3 small squares) in adults,

                  100 ms or more in children between 4-16 years,

                  90 ms or more in children under 4 years.

  Leads I and V6 have wide S waves: S waves are wider than R waves or wider than 40 ms.

  Leads V1 or V2 are expected to have terminal R waves.

      This may be seen as rsr', rsR' or rSR'. r' or R' waves are usually wider than the R wave.

  If there is no notch in R wave despite the presence of a big R wave, then the R peak time should be

      more than 50 ms in V1 while it is normal in V5 or V6.



RBBB Pattern - Incomplete RBBB

  The QRS width is between

                  100-120 ms in adults,

                  90-100 ms in children older than 4 years and younger than 16 years,

                  86-90 ms in children under 4 years of age.

  Other criteria of the right bundle branch block should be satisfied.




RBBB and acute myocardial infarction

  In patients with preexisting RBBB, development of ST segment depression in leads C1 to C4

      is a common finding and does not suggest a diagnosis of coronary artery disease.

  In patients with preexisting RBBB, development of ST segment depression in leads C5, C6, II and aVF

      suggests a diagnosis of coronary artery disease.




RBBB and acute myocardial infarction

  RBBB does not şnterfere with the diagnosis of acute myocardial infarction.

  Presence of RBBB shows poor prognosis in patients with coronary artery disease.

  New-onset RBBB during acute myocardial infarction has a worse prognosis than old RBBB.

      (On the contrary, in acute anterior wall myocardial infarction and left bundle branch block (LBBB),

      the mortality rate with old LBBB is higher than new-onset LBBB.
)




Some of the criteria that are suggested for the diagnosis of Left Ventricular Hypertrophy (LVH)
in the presence of right bundle branch block (RBBB) are


  The amplitude of S wave in C1 > 2mm (0.2 mV).

  The R wave amplitude in C5 or C6 > 15 mm (1.5mV).

  QRS axis is left to the -30 degrees.

  RI > 11mm (1.1mV).

  Regarding the amplitudes of S wave in lead III and R wave in any precordial lead,

      the R/S amplitude > 30 mm (3 mV)




RBBB and treadmill exercise test

  In patients with preexisting RBBB, development of ST segment depression in leads C1 to C4

      is a common finding and does not suggest a diagnosis of coronary artery disease.

  In patients with preexisting RBBB, development of ST segment depression in leads C5, C6, II and aVF

      suggests a diagnosis of coronary artery disease.




References

  Circulation 2009;119:e235-e240 .

  Am J Cardiol 1969;23:877.

  Am J Cardiol 1987;59:798.

  Circulation 1975;51:477-484.

  Circulation 1998;98:2494-2500.

  PACE 1998;21:2651.





ECG 1. Right bundle branch block is seen in the above ECG.
It is from a 67 years-old hypertensive woman with normal coronary arteries.
Negative T waves in leads V1 and V2 are not related to ischemia.

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ECG 2. Right bundle branch block pattern in an adult. The QRS width is not increased ( <120ms ). Other criteria of the right
bundle branch block are satisfied.

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ECG 3. Right bundle branch block (RBBB) and left anterior fascicular block (LAFB) in a patient with systemic arterial
hypertension and chronic obstructive pulmonary disease (COPD). RBBB is more prevalent in patients with COPD,
while LAFB is more prevalent in subjects with systemic arterial hypertension.

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ECG 4. The above ECG belongs to an 8 years old boy. He was operated for Transposition of the Great Arteries and Ventricular
Septal Defect (VSD) when he was 1 year old. VSD closure operations increase the risk of right bundle branch block.

Dr. Mahmut Gokdemir has donated this ECG to our website.

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ECG 5. Right bundle branch block in a middle-aged woman with normal coronary arteries.

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ECG 6. Right bundle branch block and nodal rhythm in a patient under Digoxin treatment.
No P waves preceed QRS complexes.

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ECG 7. The ECG above belongs to a 46 years-old hypertensive man who has echocardiographically confirmed left ventricular
hypertrophy. It shows right bundle branch block and left anterior fascicular block.
According to Gubner criteria, there is also left ventricular hypertophy pattern.

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ECG 8a. The ECG above belongs to a 59 years-old man. It was recorded in the Emergency Room. He had undergone
coronary artery bypass graft surgery 2 years ago. The ECG shows
right bundle branch block (RBBB) , ST segment elevation
and
tall T waves in inferior leads. Thrombolytic therapy with Tenecteplase was administered immediately after recording of
the above ECG. The time of onset of the RBBB in relation to infarction was uncertain in this patient.

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ECG 8b. One hour after tenecteplase, the ST segment elevation and tall T waves in inferior leads have disappeared. He does
not have chest pain now. Disappearance of chest pain with the regression of ECG signs suggest successful recanalization of
the infarct-related artery.

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