Acute MI Imposters

Course overview

Objectives Describe ECG monitoring and waveform analysis List common impostors to myocardial infarctions Content Specific conditions that occur more frequently in the elderly A Myocardial infarction 1 Patient will usually have atypical chest pain or no pain 2 May present with only dyspnea acute confusion delirium syncope weakness or nausea and vomiting Electrocardiographic ECG monitoring A Electrophysiology and wave forms 1 Origination 2 Production 3 Relationship of cardiac events to wave forms a Normal b Clinical significance 5 Segments B Leads and electrodes 1 Electrode 2 Leads a Anatomic positions b Correct placement 3 Surfaces of heart and lead systems a Inferior b Left lateral c Anterior posterior 4 Artifact C Standardization 1 Amplitude 2 Height 3 Rate a Duration b Wave form c Segment d Complex e Interval D Wave form analysis 1 Isoelectric 2 Positive 3 Negative 4 Calculation of ECG heart rate a Regular rhythm i ECG strip method ii 300 triplicate method b Irregular rhythm i ECG strip method ii 300 triplicate method E Lead systems and heart surfaces 1 ECG rhythm analysis a Value b Limitations 2 Heart surfaces a Inferior b Left lateral c Precordial 3 Acute signs of ischemia injury and necrosis a Rationale i Possible early identification of patients with acute myocardial infarction for intervention thrombolysis PTCA ii The role of out of hospital twelve lead ECG is not universally available but is appropriate in most EMS settings with proper medical oversight b Advantages disadvantages c ST segment elevation i Height depth and contour ii ST acute changes a Anterior wall significant ST elevation in V1 through V4 may indicate anterior involvement b Inferior wall significant ST elevation in II III and aVF may indicate inferior involvement iii ST segment depression in eight or more leads iv ST segment elevation in aVR and V1 d Q waves i Depth duration and significance a Greater than five millimeters and greater than zero point zero four seconds b May indicate necrosis c May indicate extensive transient ischemia Abnormal presentations The most common things that throw off a twelve lead interpretation