Pathologic Q waves and evolving ST-T changes in leads II, III, aVF.(includes inferior, true posterior, and right ventricular MI) Inferior MI Pathologic Q waves, upright T waves (fibrosis).Pathologic Q waves, T wave inversion (necrosis and fibrosis).(Pathologic Q waves are usually defined as duration ≥ 0.04 s or ≥ 25% of R-wave amplitude).Pathologic Q waves, less ST elevation, terminal T wave inversion (necrosis).Marked ST elevation with hyperacute T wave changes (transmural injury).Hyperacute T wave changes - increased T wave amplitude and width may also see ST elevation.Pattern is quite variable and related to the size of MI, the rapidity of reperfusion (if any), and the location of the MI. Usual ECG evolution of a Q-wave MI not all of the following patterns may be seen the time from onset of MI to the final The RCAĪlso gives off the AV nodal coronary artery in 85-90% of individuals in the remaining 10-15%, this artery is a branch of the LCX. The inferior (diaphragmatic) and true posterior walls of the left ventricle, and the posterior third of the septum. The right coronary artery (RCA) supplies the right ventricle, Usually supply the posterolateral wall of the left ventricle. The left circumflex coronary artery (LCX) and its branches Of the left ventricle and the anterior two-thirds of the septum. The left anterior descending coronary artery (LAD) and its branches usually supply the anterior and anterolateral walls Additional leads on the back, V7-9 (horizontal to V6), may be used to improve the recognition In general, the more leads of the 12-lead ECG with MI changes (Q waves and ST elevation), the larger the infarct sizeĪnd the worse the prognosis. Up to 50% may also have a component of right ventricular infarction as well. In the setting of a proximal right coronary artery occlusion, however, Most MIs are located in the left ventricle. Non-Q wave MI, most having ST segment depression or T wave inversion. Two-thirds of MIs presenting to emergency rooms evolve to MIs resulting from subtotal occlusion result in more heterogeneous damage, which may be evidenced byĪ non Q-wave MI pattern on the ECG. Total coronary occlusion result in more homogeneous tissue damage and are usually reflected by a Q-wave MI pattern Sequence usually follow a well-known pattern depending on the location and size of the MI. Plaque followed by acute coronary thrombosis is the usual mechanism of acute MI. (scarring) if the blood supply isn't restored in an appropriate period of time. When myocardial blood supply is abruptly reduced or cut off to a region of the heart, a sequence of injuriousĮvents occur beginning with subendocardial or transmural ischemia, followed by necrosis, and eventual fibrosis Introduction to ECG Recognition of Myocardial Infarction
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