ECG: LBBB and Acute MI

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ECG: LBBB and Acute MI

  1. 1. AN INTERESTING ECG <ul><li>Prof. Dr. Mageshkumar’s Unit </li></ul>
  2. 2. A 75 year old female patient, a known diabetic and hypertensive presented with sudden onset of chest pain… No other significant history An ECG done 3 months in Master health checkup before was supposed to be normal
  3. 3. <ul><li>O/E patient was </li></ul><ul><li>conscious </li></ul><ul><li>oriented </li></ul><ul><li>PR-120/min, regular </li></ul><ul><li>BP- 180/110 </li></ul><ul><li>CVS- S1S2(+) </li></ul><ul><li>RS-BAE(+), B/L NVBS(+) </li></ul>
  4. 6. <ul><li>Rate- 120/min </li></ul><ul><li>Rhythm regular </li></ul><ul><li>Left axis deviation </li></ul><ul><li>P wave- normal </li></ul><ul><li>PR interval- 0.16 </li></ul><ul><li>QRS-Duration>0.12sec </li></ul><ul><li>RR’ pattern in I, aVL, V5, V6 </li></ul><ul><li>QS in V1, V2 </li></ul><ul><li>ST segment- reciprocal changes </li></ul><ul><li>T wave- Reciprocal changes </li></ul>
  5. 7. <ul><li>Impression: </li></ul><ul><li>LBBB </li></ul><ul><li>Acute MI with proximal LAD occlusion </li></ul><ul><li>Kilip class I </li></ul><ul><li>Patient treated with INJ.HEPARIN </li></ul>
  6. 8. REPEAT ECG AFTER 24 HRS
  7. 10. <ul><li>Rate- 84/min </li></ul><ul><li>Normal axis </li></ul><ul><li>P wave- normal </li></ul><ul><li>PR interval- 0.12sec </li></ul><ul><li>QRS- </li></ul><ul><li>Duration- 0.08sec </li></ul><ul><li>Increased QRS magnitude </li></ul><ul><li>T wave- inversion in II, III, aVF, V2-V4 </li></ul>
  8. 11. <ul><li>Impression: </li></ul><ul><li>LVH </li></ul><ul><li>Anterior and inferior wall ischemia </li></ul>
  9. 12. <ul><li>CAUSES OF LBBB </li></ul>Aortic stenosis Dilated cardiomyopathy Acute myocardial infarction Extensive coronary artery disease Primary disease of the cardiac electrical conduction system hypertension
  10. 13. LEFT BUNDLE BRANCH BLOCK <ul><ul><li>Left bundle branch block (LBBB) is present in approximately 7 percent of acute infarctions </li></ul></ul><ul><ul><li>LBBB confers increased risk for mortality in the setting of suspected AMI; however, the increased risk is significantly associated with older age and co-morbidity risk factors. </li></ul></ul>
  11. 14. <ul><li>Two specific patient settings might be encountered: </li></ul><ul><li>1. When the patient has LBBB on admission and recent previous ECGs are normal, the patient is presumed to have new-onset LBBB, which in many occasions is accepted as the equivalent of electrocardiographic findings supportive of AMI </li></ul><ul><li>2. When the patient has LBBB on arrival and is known to have LBBB on previous ECGs </li></ul>
  12. 15. SGARBOSSA CRITERIA <ul><li>Used in case of a LBBB and suspicion of AMI are: </li></ul><ul><li>ST elevation > 1mm in leads with a positive QRS complex(V5-V6) (score 5) </li></ul><ul><li>ST depression > 1 mm in V1-V3 (score 3) </li></ul><ul><li>ST elevation > 5 mm in leads with a negative QRS complex(V1-V3) (score 2). </li></ul><ul><li>At a score-sum of 3, these criteria have a specificity of 90% for detecting a myocardial infarction. </li></ul>
  13. 16. 5 points for concordant 1 mm ST elevation. (any lead) 3 points for concordant 1 mm ST depression in v1 to v3 2 points for discordant 5 mm ST elevation. (any lead )
  14. 19. <ul><ul><li>Cabrera sign </li></ul></ul><ul><ul><ul><li>Prominent (>0.05 sec) notching in the ascending limb of the S wave in leads V3 –V5 </li></ul></ul></ul><ul><ul><li>Chapman sign : </li></ul></ul><ul><ul><ul><li>Prominent notching (>/= 0.05 sec ) of the ascending limb of the R wave in lead V5 or V6 </li></ul></ul></ul><ul><ul><li>These signs have a specificity that approaches 90 percent. </li></ul></ul>
  15. 20. <ul><li>ST-T changes — The sequence of repolarization is altered in LBBB, with the ST segment and T wave vectors being directed opposite to the QRS complex. These changes may mask the ST segment depression and T wave inversion induced by ischemia.   •  The presence of deep T wave inversions in leads with a predominantly negative QRS complex (eg, V1-V3) is highly suggestive of evolving ischemia or MI.   •  ST elevations in leads with a predominant R wave (as opposed to QS or rS waves) are also strongly suggestive of acute ischemia.   •  Pseudonormalization of previously inverted T waves is suggestive but not diagnostic of ischemia. </li></ul>
  16. 21. <ul><li>Several studies have evaluated the value of different ECG findings of acute MI in LBBB. </li></ul><ul><li>The most useful ECG criteria were:   •  Serial ECG changes — 67 %sensitivity   •  ST segment elevation — 54 sensitivity   •  Abnormal Q waves  — 31 percent sensitivity   •  Cabrera's sign — 27 percent sensitivity, 47 percent for anteroseptal MI   •  Initial positivity in V1 with a Q wave in V6 — 20 percent sensitivity but 100 percent specificity for anteroseptal MI </li></ul>
  17. 22. Subtypes of LEFT BUNDLE BRANCH BLOCK <ul><li>MASQUERADING </li></ul><ul><li>VARIANT LBBB </li></ul><ul><li>BUNDLE BRANCH ALTERNANS </li></ul>
  18. 23. VARIANT LEFT BUNDLE BRANCH BLOCK <ul><li>Also been called left ventricular hypertrophy with terminal conduction delay or LBBB masquerading as right bundle branch block. The major characteristic of variant LBBB is a terminal, often rightward, conduction delay similar to that in right bundle branch block. This results in marked left axis deviation and, due to the late rightward force, a terminal delayed negativity (S wave) in V6. </li></ul><ul><li>Common LBBB, in comparison, is usually associated with a normal axis or only mild left axis deviation. Marked left axis deviation in common LBBB suggests additional disease or concurrent left anterior fascicular block </li></ul>
  19. 24. MASQUERADING BUNDLE BRANCH BLOCK <ul><li>Left axis deviation in chest leads with RBBB in chest leads </li></ul>
  20. 25. <ul><li>INCOMPLETE LBBB: </li></ul><ul><li>1. Small initial q wave disappears in I, V5,V6 </li></ul><ul><li>2. Small initial r wave of rS in V1 disappears </li></ul><ul><li>3. Slurring of upstroke of QRS complex </li></ul><ul><li>LVH cannot be diagnosed in the presence of LBBB </li></ul>
  21. 26. <ul><li>THANK YOU!! </li></ul>

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