© Springer International Publishing AG 2017Tilak D. Raj (ed.)Data Interpretation in Anesthesiadoi.org/10.1007/978-3-319-55862-2_34
34. Chest Pain Profiles
Department of Anesthesiology and Critical Care, Saint Louis University, School of Medicine, 3635 Vista Ave., PO Box 15250, St. Louis, MO 63110-0250, USA
John David SrinivasanAssistant Professor
KeywordsElevated troponinClassification of MIPerioperative MI
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A 78-year-old male underwent an open AAA repair for an 8 cm infrarenal aneurysm. His preoperative echo showed normal EF and no wall motion abnormality. During the surgery he had an episode of surgical bleeding and hypotension with transient ST depression which resolved with hypotension treatment and PRBC transfusion. On postoperative day 1, the patient developed chest pain with ST depression and elevated cardiac troponin I (cTnI) which was 15 ng/mL. An echocardiography showed severe anteroseptal hypokinesia.
Has this patient suffered an acute myocardial infarction (MI)?
What are troponins?
What is the 2012 universal classification of myocardial infarction?
What conditions can raise troponin levels other than MI?
How would you classify this patient’s perioperative MI?
What should be done next?
Yes, this patient has elevated cardiac biomarkers along with symptoms of cardiac ischemia (chest pain) with imaging evidence of regional wall motion abnormality in the anterioseptal wall. The term acute MI is used when there is evidence of myocardial necrosis in a clinical setting consistent with acute myocardial ischemia, detection of a rise and/or fall of cardiac biomarker values (preferably cardiac troponin) above the 99th percentile upper reference limit with at least one of the following:
Symptoms of cardiac ischemia
EKG changes: new significant ST-segment–T wave changes, new left bundle branch block, or development of pathological Q waves
Imaging evidence of new regional wall motion abnormality
Identification of an intracoronary thrombus by angiography or autopsy
Troponins are protein molecules that are part of cardiac and skeletal muscle. Smooth muscle cells do not contain troponins. Three types of troponins exist—troponin I, troponin T, and troponin C. Each subunit has a unique function: Troponin T binds the troponin components to tropomyosin, troponin I inhibits the interaction of myosin with actin, and troponin C contains the binding sites for Ca2+ that help initiate contraction. Raised troponin levels indicate cardiac muscle cell injury and/or death as the molecule is released into the blood upon injury to the heart. Troponins will begin to increase within 3 h following an MI. The recommended cutoff value for an elevated cardiac troponin is the 99th percentile of a control reference group. As the troponin test kits are made by many manufacturers, the cutoff values suggested by the laboratory should be used as reference .
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