Intraventricular conduction block.......

ECG description of Conduction Block

1. ECG: Bundle branch block & fascicular block PRESENTAR DR MD. Rifat Hasan Antor D CARD STUDENT UCC,BMU CHAIRPERSON PROF DR A T M Iqbal Hasan PROFESSOR UCC,BMU MODERATOR ASST PROF DR Khandaker Kamruzzaman UCC,BMU

2. Intraventricular conduction system Left bundle: it immediately fans into several braches including mid-septal and 2 main fascicle. LAF: LAF courses to the base of ant papillary muscle and terminating into Purkinje fibers. LPF: LPF courses to the base of post papillary muscle and terminating into Purkinje fibers.

3. Types Of Intraventricular Conduction Block Uni-fascicular block Left anterior hemiblock Left posterior hemiblock Right bundle branch block Bi-fascicular block LBBB RBBB+LAFB RBBB+LPFB Definite tri-fascicular block Alternating BBB RBBB+ alternating fascicular block RBBB+ Mobitz Type II A-V Block LBBB+ Mobitz type II A-V Block Possible tri-fascicular block Complete AV block with ventricular escape rhythm Any bi-fascicular block + 1 st /2 nd degree AV Block - RBBB+LAHB+1 st /2 nd degree AV Block - RBBB+LPHB+1 st /2 nd degree AV Block - LBBB+1 st /2 nd degree AV Block

4. Intraventricular Conduction Block- Bundle Branch Block

5. Concordant ST depression >1mm in V2-V6 with LBBB in case of anterolateral MI

6. Complete LBBB: QRS ≥ 0.12 sec. WHO/International Society and Federation for Cardiology (ISFC) Task Force Criteria for LBBB (1985) It includes: QRS duration > 120 ms. Broad and notched or slurred R waves in lead V5, V6 and aVL . Absence of Q wave in left precordial leads with possible exception of lead aVL . The R peak time(VAT) in V5 & V6 > 60ms and normal in V1 & V2 Incomplete LBBB: QRS < 0.12 sec. The WHO/ISFC task force criteria for incomplete LBBB are the same as for complete LBBB, except the QRS duration is>100ms but <120 ms. Prolongation of R peak time(VAT) > 60ms in left precordial leads QS or rS configuration in V1, Tall monophasic R waves in V6 and no septal q waves in V5, V6 and lead I

7. Complete LBBB The QRS complexes are wide ≥ 0.12 seconds. QS configuration is present in V1 Broad and notched R waves in lead V5, V6 and aVL . Septal q absent in V6 The axis of the QRS complex is normal.

8. Incomplete LBBB QRS complexes are measuring less than 0.12 seconds. QS configuration is present in V1 Tall monophasic R waves are present in V6,and no septal q waves in V6.

9. Diagnosis Of Certain Disorders In Presence Of LBBB 1) LVH & RVH 2) Acute STEMI( sgarbossa criteria)

10. LVH & RVH In LBBB LVH in LBBB A) Kafka et al criteria: - R in aVL ≥ 11 mm - S in V1+ R in V5 or V6≥ 40 mm - S in V2 ≥ 30mm and S in V3 > 25mm - Frontal QRS axis ≤ 40° (or S2 > R1) B) Klein Criteria: - R in aVL ≥ 13mm - S in LII + maximum sum of R+S in any Prec. lead > 30mm RVH in LBBB: RAD+ LBBB

11. LBBB with LVH QS configuration is present in V1 Tall monophasic R waves are present in V6,and no septal q waves in V6 S in V1+ R in V5 or V6≥ 40 mm .

12. The ST segment and T wave are normally discordant from the QRS complex when there is uncomplicated left bundle branch block. When there is myocardial disease, such as myocardial ischemia or cardiomyopathy, the ST segments and T waves become concordant and follow the direction of the QRS complex. LBBB: Concordant And Discordant T Waves

13. AMI In LBBB: Sgarbossa Criteria A total score of ≥ 3 is reported to have a specificity of 90% for diagnosing myocardial infarction.

14. AMI In LBBB: Smith modified- Sgarbossa Criteria

15. Concordant ST depression >1mm in V2-V6 with LBBB in case of anterolateral MI

16. Q wave and concordant ST segment elevation >1 mm in lead III with LBBB in case of inferior wall MI

17. Left Anterior fascicular block

18. Left Anterior fascicular block Left Anterior Fascicular Block. Hallmark of LAFB: Left Axis deviation (usually -45 to -90 degrees) qR complexes in leads I, aVL rS complexes in leads II, III, aVF Normal QRS Duration The precordial leads are not needed for the diagnosis of LAFB

19. Diagnosis of LVH in presence of LAFB LAFB Can Cause a false positive diagnosis of LVH based on voltage criteria as the QRS vector shifts in a superior and posterior direction resulting in large R wave in leads I and aVL and deep S wave in leads V5 & V6. R in aVL >13mm S in III+ maximum sum of R+S in any single precordial lead >30mm in male and > 28mm in women

20. Common Mistakes In Left Anterior Fascicular Block: LAFB mistaken for anterior infarct LAFB mistaken for inferior infarct LAFB and inferior MI occur together- Difficult to diagnose because both can cause left axis devation .

21. Left anterior fascicular block can cause small q waves in V2and V3, which can be mistaken for anterior myocardial infarction. LAFB mistaken for anterior infarct

22. LAFB Mistaken For Inferior Infarct Left anterior fascicular block should not be confused with inferior myocardial infarction (MI).In inferior MI, leads II, III, and aVF start with a q wave as shown here, rather than with a small r.

23. LAFB And Inferior MI Occur Together (A) Leads aVR and aVL are recorded simultaneously and are magnified in (B). Note that the terminal R wave in aVR (arrow) occurs later than the terminal R wave in aVL , consistent with left anterior fascicular block.Inaddition , q waves (QS) are present in lead II (A),consistent with inferior myocardial infarction.

24. Left posterior fascicular block

25. Left posterior fascicular block Left Posterior Fascicular Block. Hallmark of L P FB: Right Axis deviation (usually > 90 degrees) rS complexes in leads I qR complexes in leads III, aVF Normal QRS Duration The precordial leads are not needed for the diagnosis of LPFB

26. Twelve-lead electrocardiogram showing left posterior fascicu lar block (LPFB). The QRS complexes are not widened and the axis is shifted to +120. Before LPFB is diagnosed, other causes of right axis deviation should first be excluded.

27. Intraventricular Conduction Block- Bundle Branch Block

28. Right Bundle Branch Block In true RBBB- the impulse should be sinus or supraventricular.

29. Complete RBBB: QRS ≥ 0.12 sec. WHO/International Society and Federation for Cardiology (ISFC) Task Force Criteria for RBBB (1985) It includes: QRS duration > 120 ms. An rsr , rsR , or rSR pattern in Lead V1or V2 and occasionally a wide notched R wave. Wide S wave > 40 ms or more in leads I and V6. Normal R peak time in Leads V5 and V6, but ≥ 50 ms in V1 Incomplete RBBB: QRS < 0.12 sec. The WHO/ISFC task force criteria for incomplete RBBB are the same as for complete RBBB, except the QRS duration is < 120 ms.

30. The QRS complexes are wide ≥ 0.12 seconds. Broad and notched R wave present in V1 Wide S waves are present in leads I and V5 & V6. Complete RBBB

31. Incomplete RBBB QRS complexes are measuring less than 0.12 seconds With RSR’ in V1+V2+V3.

32. RBBB: Concordant And Discordant T Waves In uncomplicated RBBB, the ST segment and T wave are normally discordant and opposite in direction to the terminal portion of the QRS complex. These ST-T changes are secondary to the abnormal activation of the ventricles. When the ST and T waves are concordant, these changes are primary due to the presence of an intrinsic myocardial disorder such as cardiomyopathy or myocardial ischemia

33. Uncomplicated RBBB Here the ST segment & T wave in V1 is discordant to QRS complex, hence it is uncomplicated RBBB

34. Diagnosis of RVH & LVH in RBBB RVH: Barkar & Valencia Criteria: In Complete RBBB= R in V1> 15mm In incomplete RBBB= R in V1> 10mm Milnor Criteria : R/S or R/’S ratio in V1 >1, provided R or R' in V1 > 5mm LVH: Usual voltage criteria LAE & LAD with RBBB

35. Incomplete RBBB with R in V1> 10mm so acc to Barkar & Valencia Criteria it is RBB with RVH

36. Intermittent RBBB: RBBB often occurs intermittently before it becomes fixed Intermittent RBBB is usually rate related meaning that it usually occurs when the heart rate exceeds a certain level.

37. Accelerated Idioventricular Rhythm In true RBBB, the impulse should be sinus or supraventricular. When the impulse originates from the ventricles or below the bifurcation of the bundle of His, the impulse is ventricular. A ventricular impulse may demonstrate an RBBB configuration, even though RBBB is not present.

38. VT with RBBB morphology If any tachycardia has a RBBB morphology,V1 and V6 should be examined for VT. V1: Monophasic or biphasic QRS complex. V6: Any q wave (except “ qrs ”), monophasic R wave, r/S ratio <1 (r wave smaller than S wave). If a monophasic or biphasic QRS pattern is present in V1 + any of the described QRS pattern is present in V6, the diagnosis is VT

39. Brugada Syndrome This ECG showing RBBB pattern with persistent ST Segment elevation in V1+V2+V3

40. RBBB+LAFB (Bi-fascicular block) Wide QRS complexes measuring >0.12 seconds-RBBB The characteristic rR or rsR pattern is present in V1, and wide S waves are present in V6. In the frontal plane, the axis of the QRS complex is –30 with rS in lead II and tall R wave in aVL .

41. RBBB+LAFB (Bi-fascicular block) Wide QRS complexes measuring 0.12 seconds , tall R in V1 and wide S waves in V6. Left axis deviation frontal leads.

42. RBBB+LPFB (Bi-fascicular block) Wide QRS complexes measuring >0.12 seconds-RBBB The characteristic rR or rsR pattern is present in V1, and wide S waves are present in V6. In the frontal plane, the axis of the QRS complex is Right Axis Deviation > 90 degree

43. RBBB+LPFB (Bi-fascicular block) Wide QRS complexes measuring 0.12 seconds , with rR pattern in V1 and RS in V6 Right axis deviation frontal leads.

44. Intraventricular Conduction Block- Trifascicular Block Definite tri-fascicular block Alternating BBB RBBB+ alternating fascicular block RBBB+ Mobitz Type II A-V Block LBBB+ Mobitz type II A-V Block Possible tri-fascicular block Complete AV block with ventricular escape rhythm Any bi-fascicular block + 1 st /2 nd degree AV Block - RBBB+LAHB+1 st /2 nd degree AV Block - RBBB+LPHB+1 st /2 nd degree AV Block - LBBB+1 st /2 nd degree AV Block

45. A) B) LBBB RBBB +left anterior fascicular block.

46. RBBB and second-degree AV block with a fixed PR interval from Mobitz type II AV block. The presence of RBBB and Mobitz type II AV block is consistent with trifascicular block.

47. A) B) RBBB+LAFB Complete AV block with ventricular escape rhythm.

48. This 2:1 second-degree AV block combined with RBBB and LAFB is almost always a trifascicular block.

49. Take Home Massage Bundle branch blocks are best characterized on ECG by: Prolongation of the QRS > 0.12 sec Region of slowed conduction determines the orientation of the terminal QRS vector and localizes the block Hemiblocks do not typically show QRS prolongation, rather they reveal axis deviation corresponding to the RS terminal vector Ventricular conduction blocks are common and can represent a spectrum from normal variant to serious pathology