260 likes | 1.02k Views
Myocardial Infarction and the ECG. Paul D. Sherry, M.D. Parkside Cardiology. Paul D. Sherry, M.D. Parkside Cardiology. Financial Disclosure 9/2/2010
E N D
Myocardial Infarction and the ECG Paul D. Sherry, M.D. Parkside Cardiology
Paul D. Sherry, M.D.Parkside Cardiology Financial Disclosure 9/2/2010 neither I, nor any member of my immediate family, within the last 12 months, have had a financial relationship with any proprietary entity producing health care goods or services.
Myocardial Infarction and the ECG • Very brief ECG basics • Definition of ST elevation • Definition of a significant Q wave • Localizing the area involved in the MI • Some ECG cases • Pseudo infarcts
Definition of Acute M.I. 2007 Joint Task Force of the European Society of Cardiology, ACC, AHA A clinical event consequent to the death of cardiac myocytes that is caused by ischemia
An acute MI can occur with a normal ECG The most important tool early on in diagnosing an MI is still the history. Diagnosis of an acute or old anterior MI with a LBBB can be difficult if not impossible Remember the value of serial ECGs in acute coronary syndromes
What is significant ST elevation? • Elevation of the origin of the ST segment at its junction (J point) with the QRS complex of ≥1 mm in two or more limb leads or precordial leads V4 to V6 • Or ≥ 2 mm in two or more precordial leads V1 to V3
Current of Injury during balloon inflation in the left anterior coronary artery Wagner, Galen: Marriott’s Practical Electrocardiography, 10th edition, page 176
What is the difference between a physiologic Q wave and one that indicates an infarction?
Physiologic Q waves are less than or equal to .02 sec Except for lead III, AVR and V1, Q waves greater than or equal to 0.4 seconds are abnormal.
Myth • Q waves always mean transmural infarct • Non Q wave infarcts always are subendocardial • Q waves tell you there has been an infarct • Q waves don’t tell you about pathology
Septal Q waves in the inferior and anterolateral leads II, III, avf, V3-V6
Reciprocal Changes The ECG recorded from one side of the electric field of the heart will be seen in an upside-down mirror image on the other
Localizing Infarcts on the 12 Lead ECG Lateral - Cx Ant – sep - LAD Anterior - LAD Lateral - Cx Inferior - RCA Lateral - Cx Ant – sep - LAD Anterior - LAD Lateral - Cx Inferior - RCA Inferior - RCA