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Twelve-Lead Electrocardiography phần 5

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như chúng ta đã thấy trong BBB, phì đại tâm thất trái (LVH), và AMI. Họ cũng có thể mang hình thức của biên độ rất lớn hoặc nhỏ, chẳng hạn như tăng kali máu và hạ kali máu (hình 2.9Chương 2 điện tâm đồ dạng sóng | 9 Myocardial Infarction In this chapter we will discuss what is for ACLS providers perhaps the most important and certainly the most clinically interesting subject in 12-lead electrocardiography AMI. Anatomy of the Coronary Arteries The coronary arterial circulation begins with the divergence of the right and left coronary arteries from the aorta. The left main coronary artery is very short and rapidly splits into the left anterior descending artery and the circumflex artery. The right coronary artery serves primarily the right ventricle and the inferior and true posterior walls of the left ventricle. The right coronary artery also gives off the AV nodal artery in approximately 90 of patients. The left anterior descending artery serves the anterior wall of the left ventricle and the circumflex artery serves the left lateral wall of the left ventricle. Figure 9.1 illustrates these relationships. Pathophysiology of AMI Acute myocardial infarction occurs any time that a coronary artery becomes essentially completely obstructed and the segment of myocardium served by that artery loses perfusion and begins to die. Complete obstruction usually occurs in the setting of fixed obstructive coronary lesions that are the result of coronary atherosclerosis. However the process of accumulating atherosclerotic plaque in the coronary arteries is slow and gradual. The acute nature of AMI is usually the result of a clot or thrombus forming in the immediate vicinity of an incomplete fixed obstructive lesion. The cause of clot formation is typically rupture a split of an atherosclerotic plaque which tears the overlying endothelium thereby exposing blood to the lipid-rich interior of the plaque. Many of the substances present in the 64 Electrocardiographic Hallmarks of STEMI 65 Left Main Figure 9.1. The coronary arterial circulation. plaque interior stimulate both platelet aggregation and the coagulation cascade resulting in thrombus formation. Less than complete obstruction of the .