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MI Diagnosis in LBBB or paced rhythm: Difference between revisions
MI Diagnosis in LBBB or paced rhythm (view source)
Revision as of 21:33, 24 August 2007
, 24 August 2007ST segment depression in the right precordials is actually concordant, not discordant
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(ST segment depression in the right precordials is actually concordant, not discordant) |
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In case of a [[Intraventricular Conduction|left bundelbranch block (LBBB)]], infarct diagnostics based on the ECG is difficult. The ST segments | In case of a [[Intraventricular Conduction|left bundelbranch block (LBBB)]], infarct diagnostics based on the ECG is difficult. The baseline ST segments and T waves tend to be shifted in a discordant direction with LBBB, which can mask or mimic acute myocardial infarction. However, serial ECGs may show a moving ST segment during ischemia secondary to dynamic supply versus demand characteristics. A new LBBB is always pathologocal and can be a sign of myocardial infarction. The criteria (Sgarbossa <cite>LBTB</cite>) that can be used in case of a LBBB and suspicion of infarction are: | ||
*ST elevation > 1mm in leads with a positive QRS complex (concordance in ST deviation) (score 5) | *ST elevation > 1mm in leads with a positive QRS complex (concordance in ST deviation) (score 5) | ||
*ST depression > 1 mm in V1-V3 ( | *ST depression > 1 mm in V1-V3 (concordance in ST deviation) (score 3) | ||
*ST elevation > 5 mm in leads with a negative QRS complex (discordance in ST deviation) (score 2) | *ST elevation > 5 mm in leads with a negative QRS complex (inappropriate discordance in ST deviation) (score 2) | ||
At a score-sum of 3, these criteria have a specificity of 90% for detecting a myocardial infarction. | At a score-sum of 3, these criteria have a specificity of 90% for detecting a myocardial infarction. | ||