The ST-segment is the segment on the ECG right after the QRS segment and before the T wave. You may also like: “Cardiac Lab Interpretation (Troponin, CK, CK-MB, and BNP)” ISCHEMIA & INFARCTION (STEMI) ON THE ECG Where this elevation occurs will indicate which heart wall is infarcting, as well as within which coronary artery. However, the ECG does not have ST-segment elevation.Īn ST-segment Elevation Myocardial Infarction (STEMI) refers to a complete occlusion of a coronary artery that causes more significant infarction that extends the entire thickness of the myocardium (termed transmural).Ī STEMI will have ST-segment elevation in at least 2 contiguous leads on the ECG. Troponin levels will be elevated indicating myocardial cell death. However, NSTEMIs could also present with a completely normal ECG. These changes include T wave inversion or ST-segment depression with or without T wave inversion in anatomically contiguous leads.
NSTEMIs will often have nonspecific changes on the EKG. The infarction is usually limited to the inner layer of the myocardial wall. While some heart tissue dies, this is usually less extensive than a STEMI. This blood clot can completely occlude an artery – leading to infarction.Ī Non-ST segment elevation myocardial infarction (NSTEMI) refers to a complete occlusion of a coronary artery that does not cause ST-segment elevation on the ECG. This plaque can rupture, releasing contents into the bloodstream which causes a local inflammatory reaction as well as begins a coagulation cascade. This is usually caused by unhealthy eating habits, obesity, sedentary lifestyle, hyperlipidemia, smoking, and genetics. This cell death causes the release of troponin into the bloodstream, an enzyme that is not usually found in the systemic circulation.Ĭardiac ischemia is usually secondary to atherosclerosis which is a buildup of plaque within the coronary arteries. Prolonged ischemia can lead to infarction – which is cell death of the heart tissue. Whichever one does form the posterior descending artery is considered the “dominant coronary artery”.Īcute coronary syndrome (ACS) is an umbrella term referring to any condition which causes decreased blood flow to the heart – also known as ischemia. The posterior descending artery usually branches off from the RCA, although less commonly from the Cx.
The anterior 2/3 of the intraventricular septum.Anterior surface and part of the lateral surface of the left ventricle.It often extends to the inferior surface of the left ventricle in most patients. The LAD lies on the surface of the heart between the right and left ventricles. This branches off into the LAD and the Cx. The Left coronary artery begins thicker and is called the left main coronary artery.
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