tailieunhanh - 150 Practice ECGs: Interpretation and Review - Part 3

Các chính chi nhánh phải động mạch vành (động mạch giảm dần sau) cung cấp bức tường kém. Các động mạch giảm dần trước là nằm trên các vách ngăn interventricular (rãnh interventricular), nó sẽ gửi đục lỗ các chi nhánh vào vách ngăn | 50 150 Practice ECGs Interpretation and Review FIGURE Coronary artery anatomy. The circumflex and right coronary arteries circle the heart in the AV groove branches of the circumflex leave the groove to supply the lateral wall. The major right coronary branch the posterior descending artery supplies the inferior wall. The anterior descending artery is located just over the interventricular septum the interventricular groove it sends perforating branches into the septum and diagonal branches to the anterior LV surface. The spatial orientation of the ECG leads allows groups of leads to reflect events in a given region of the heart see Fig as well . Table ECG Changes with Syndromes of Myocardial Ischemia Condition ECG changes Timing Pathophysiology Angina pectoris ST depression Coincidental Stenosed artery but with some with chest pain antegrade flow O2 demand exceeds supply subendocardial ischemia Coronary artery ST elevation Coincidental with Spasm may occur in a normal artery spasm angina chest pain or at the site of plaque usually total pectoris occlusion transmural ischemia temporary Non-Q MI ST depression During pain but Stenosed artery but with some T wave inversion may be antegrade flow subendocardial permanent ischemia then necrosis Q wave MI ST elevation Coincidental Total occlusion transmural ischemia with pain then necrosis T wave inversion Minutes to hours later while ST elevation persists Q wave Minutes to hours after onset of MI permanent CHAPTER 2 Morphologic Changes in P QRS ST and T 51 Subendocardial Ischemia Transmural Ischemia FIGURE Patterns of myocardial ischemia. The epicardium is the outside surface of the heart and the endocardium is the surface next to the ventricular cavity. The coronary arteries are located on the epicardial surface. Subendocardial nontransmural ischemia causes ST segment depression. If ischemia persists and there is myocardial injury there may be T wave inversion a pattern now called non-ST elevation MI but

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