Bundle branch blocks

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Bundle branch blocks

  1. 1. Bundle Branch Blocks
  2. 3. Blood supply <ul><li>RCA (proximal)  Sinus nodal artery </li></ul><ul><li>LAD  Septal branch to proximal RBB and anterior LBB. </li></ul><ul><li>LAD (septal) & RCA (terminal)  Posterior fascicle of LBB </li></ul><ul><li>PDA  AV nodal branch and bundle of HIS supply </li></ul>
  3. 4. Right Bundle Branch Block (RBBB) <ul><li>QRS duration ≥ 120ms </li></ul><ul><li>rSR’ pattern or notched R wave in V 1 </li></ul><ul><li>Wide S wave in I and V 6 </li></ul>
  4. 5. Causes <ul><li>Normal variant in 0.2% of adults. </li></ul><ul><li>CAD  Acute anterior MI (occlusion of proximal LAD) </li></ul><ul><li>Pulmonary hypertension (COPD) </li></ul><ul><li>Acute pulmonary embolism </li></ul><ul><li>Congenital heart disease e.g. ASD, Ebstein’s anomaly </li></ul><ul><li>Rate dependent RBBB </li></ul><ul><li>Rare: Brugada syndrome </li></ul>
  5. 6. Clinical significance <ul><li>RBBB is commonly seen and is usually benign </li></ul><ul><li>RBBB in the setting of an acute MI worsens the prognosis (indicates proximal LAD occlusion) </li></ul><ul><li>Presence of RBBB on ECG is not a contraindication for TMT </li></ul>
  6. 7. Right Bundle Branch Block
  7. 9. Left Bundle Branch Block (LBBB) <ul><li>QRS duration ≥ 120ms </li></ul><ul><li>Broad R wave in I and V 6 </li></ul><ul><li>Prominent QS wave in V 1 </li></ul><ul><li>Absence of q waves (including physiologic q waves) in I and V 6 </li></ul>
  8. 10. Causes <ul><li>CAD  Acute AWMI (new onset LBBB) </li></ul><ul><li>Dilated Cardiomyopathy </li></ul><ul><li>Aortic stenosis </li></ul><ul><li>Long-standing hypertension </li></ul><ul><li>Rate dependent LBBB </li></ul><ul><li>RV paced rhythm </li></ul>
  9. 11. Clinical significance <ul><li>New onset LBBB is an indication for thrombolytic therapy </li></ul><ul><li>LBBB in the setting of an acute MI worsens the prognosis </li></ul><ul><li>Standard LVH criteria are not valid in presence of LBBB </li></ul><ul><li>LBBB may mask signs of myocardial infarction </li></ul><ul><li>LBBB on ECG is a contraindication for TMT </li></ul><ul><li>Presence of LBBB in heart failure indicates ventricular dyssynchrony </li></ul>
  10. 12. Left Bundle Branch Block
  11. 14. Diagnosis of MI in the presence of LBBB <ul><li>Sgarbossa criteria: Points </li></ul><ul><li>ST segment elevation of ≥1mm 5 concordant with QRS complex </li></ul><ul><li>ST depression ≥ 1mm in leads V1-V3 3 </li></ul><ul><li>ST segment elevation ≥5mm and 2 discordant with QRS complex </li></ul><ul><li>Score ≥ indicates Acute MI </li></ul>
  12. 15. Left anterior hemiblock (LAHB) <ul><li>Left axis deviation (> -30 degrees) </li></ul><ul><li>Duration of QRS complex < 120msec </li></ul><ul><li>qR morphology in Lead I, aVL </li></ul><ul><li>rS morphology in Leads II, III, aVF </li></ul><ul><li>‘ q1S3’ pattern </li></ul><ul><li>Slurred S waves in left precordial leads </li></ul>
  13. 16. LAHB
  14. 17. LAHB - significance <ul><li>May be normal variant </li></ul><ul><li>Occurs in HTN, Cardiomyopathy </li></ul><ul><li>May be seen in acute MI (LAD territory) </li></ul><ul><li>Masks old inferior wall MI by abolishing the diagnostic Q-waves in II, III, and aVF </li></ul><ul><li>LAHB is more common than LPHB </li></ul>
  15. 18. Left Posterior hemiblock <ul><li>The duration of the QRS complex axis is normal (<120msec) </li></ul><ul><li>QRS axis is ≥ +120° (RAD) </li></ul><ul><li>Prominent Q wave in leads II, III, and aVF </li></ul><ul><li>rS complexes in Leads I, aVL </li></ul><ul><li>‘ S1Q3’ pattern </li></ul>
  16. 19. LPHB
  17. 20. LPHB – significance <ul><li>LPHB may mimic old IWMI due to Q waves in II, III, aVF </li></ul><ul><li>LPHB in the setting of Anterior MI indicates extensive damage to the conduction system and poor prognosis </li></ul><ul><li>Other causes of RVH are to be excluded before diagnosing LPHB </li></ul>

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