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ECG 101 AMI with LBBB or PPM

ECG 101 AMI with LBBB or PPM. Scott E. Ewing DO Lecture #9. Review - LBBB. LBBB. LBBB – Definition. QRS duration ≥120 ms Small or absent initial R waves in right precordial leads (V1 and V2) followed by deep S waves

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ECG 101 AMI with LBBB or PPM

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  1. ECG 101AMI with LBBB or PPM Scott E. Ewing DO Lecture #9

  2. Review - LBBB

  3. LBBB

  4. LBBB – Definition • QRS duration ≥120 ms • Small or absent initial R waves in right precordial leads (V1 and V2) followed by deep S waves • Broad, notched R waves in lateral precordial leads (V5 and V6) and usually leads I and aVl • Prolonged intrinsicoid deflection (>60 ms) in V5 and V6 • Secondary ST-T wave changes

  5. LBBB Significance • Complete LBBB may be associated with a normal, leftward, or rarely rightward axis • LBBB may mask or mimic the pattern of underlying myocardial infarction • LBBB a marker of underlying organic heart disease • Hypertensive heart disease • Severe coronary disease • Cardiomyopathy • Valvular disease

  6. Acute MI and LBBB

  7. Uncomplicated LBBB • Appropriate discordance in uncomplicated LBBB (note ST elevation in leads V1 to V3)

  8. Diagnostic Criteria • If doubt persists, serial electrocardiograms may show evolving changes

  9. Examples • Inappropriate concordance in V1 in patient with LBBB • Inappropriate concordance in V6 in patient with LBBB • Exaggeration of appropriate discordance in lead V1 in patient with LBBB

  10. Acute MI and LBBB • Note ST segments are elevated V5 and V6 (inappropriate concordance) and grossly elevated (> 5 mm) V2, V3, and V4 • Note ST segment depression in leads III and aVF

  11. 68 year old Male with Chest Pain • ST segment depression in lead V3 • Example of inappropriate concordance

  12. AMI with LBBB - Examples

  13. Interpretation: Inferior AMI with LBBB • Sinus bradycardia and LBBB with primary ST-T wave changes • LBBB morphology with primary biphasic and inverted T waves in leads 2, 3 and aVF • Uncomplicated bundle branch blocks should have "secondary" T wave changes • Inverted T waves suggest that a "primary" or ischemic process is evolving in the inferior distribution • Pt had a myocardial infarction with a CK of 700 and 21% MB fraction

  14. Interpretation: Anterior AMI with LBBB • Evidence of prior and possibly evolving MI superimposed on LBBB • Prior MI is indicated by Q waves as part of a qR in I and V6 • Notching of the ascending limb of the S wave in the mid-left chest leads consistent with prior MI (Cabrera's sign) • Biphasic T waves in the mid-left chest leads raise consideration of evolving ischemia/MI • Statement that "LBBB precludes diagnosing MI" is not correct • Yet, LBBB often does mask changes of prior or acute MI

  15. 74-year-old woman with LBBB

  16. Interpretation: LBBB with Anterior AMI • Evidence of acute/evolving anterior ischemia/MI superimposed on the LBBB • Primary T wave inversions in V2-V4, rather than the expected discordant (upright) T waves in leads with negative QRS • Although this finding is not particularly sensitive for ischemia/MI with LBBB, such primary T wave changes are relatively specific • Note: prominent voltage with LAA and leftward axis here with LBBB are consistent with underlying LVH

  17. PPM Review

  18. AMI with PPM

  19. Typical VPR - altered ventricular activation from right to left, producing broad, negative QS or rS complex in leads V1-V6 • Large monophasic R wave is encountered in leads I and aVL and occasionally leads V5 and V6 • QS complexes frequently encountered in leads II, III and aVF • As with LBBB, ST-T wave configurations are discordant with QRS complex

  20. VPR demonstrating lateral AMI • Leads I and aVL demonstrate concordant ST segment elevation that is not appropriate for VPR • Dynamic changes compared to prior ECG

  21. Diagnostic Criteria • Discordant ST segment elevation > 5 mm • Concordant ST segment elevation > 1 mm • ST segment depression > 1 mm V1, V2, or V3 • Most useful criteria is discordant ST elevation of 5 mm or more

  22. 68-year-old man with dyspnea

  23. Interpretation: VPR with AMI • VPR with underlying complete heart block (P waves march through) • Superimposed current of injury with hyperacute ST-T changes inferiorly and laterally with reciprocal change V1-V3 consistent with acute infero-postero-lateral ischemia/ MI • Pacemaker patterns, like LBBB, often mask acute or chronic MI • Sometimes the ischemic changes "show through."

  24. 64-year-old-man with a dual chamber pacemaker

  25. Interpretation: VPR with Possible AMI • AV sequential pacing (see lead V1) • QRS complexes do not show a typical LBBB pattern • Instead, the lateral leads (I, aVL, V5, V6) show prominent Q waves with QR-type complexes • Persistent ST elevations in V5 and V6 • Underlying anterior MI / ventricular aneurysm-type pattern in the presence of the paced ECG • Ischemic heart disease, s/p prior MI(s), with very severe LV dysfunction, LVEF about 20%

  26. Presyncope with Dual Chamber Pacemaker

  27. Interpretation: AV Sequential Pacing with Inferior AMI • Markedly elevated J point and convex ST segment elevations inferiorly, with reciprocal changes in I, aVL, and V2 • Pacemaker is dual chamber with intermittent A-V sequential pacing alternating with A-sensed V-paced rhythm • Ventricular paced ECGs are usually not interpretable for ischemia • However, just as with an intrinsic LBBB, >5 mm ST segment elevation in right precordial or inferior leads, and especially ST depressions/T wave inversions in leads with QS or rS complexes, are highly suggestive of ischemia

  28. Review

  29. LBBB Review • QRS duration ≥120 ms • Small or absent initial R waves in right precordial leads (V1 and V2) followed by deep S waves • Broad, notched R waves in lateral precordial leads (V5 and V6) and usually leads I and aVl • Prolonged intrinsicoid deflection (>60 ms) in V5 and V6 • Secondary ST-T wave changes

  30. Interpretation: NSR With LBBB • Hypertrophic obstructive cardiomyopathy with chronic LBBB • Note evidence of LAA • Most patients with LBBB have LVH • Presence of LAA with LBBB is also strongly suggestive of underlying LVH • Note: there is some baseline artifact here that at times simulates a pacemaker stimulus--however the patient did not have an electronic pacemaker and the P waves and wide QRS are due to native conduction entirely

  31. Interpretation: SR with LBB and AMI • ST segment deviates in the same direction as the major QRS deflection (concordant) in the inferior leads • In the setting of LBBB, concordant ST segment deviation is indicative of acute infarct • Remember: ST segment deviation secondary to LBBB alone is discordant with the major QRS deflection • ST segment is depressed when the major QRS deflection is positive • elevated when the major QRS deflection is negative

  32. Questions?

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