A 65-year-old man has a cardiac arrest in a shopping mall. Resuscitation is initiated in the field, and the patient is successfully defibrillated. In the emergency department, he is found to have ST segment elevations in the inferior leads and then has an episode of sustained ventricular tachycardia that is treated with intravenous amiodarone. The patient is taken to the cardiac catheterization lab and is found to have a thrombotic occlusion of the right coronary artery, which is successfully treated with percutaneous coronary intervention. On the second day of hospitalization he demonstrates full neurologic recovery and is asymptomatic. Laboratory results are as follows: The patient's laboratory results were within normal limits 1 week prior to admission. Which of the following is the most likely cause of the new findings?

Question

A 65-year-old man has a cardiac arrest in a shopping mall.  Resuscitation is initiated in the field, and the patient is successfully defibrillated.  In the emergency department, he is found to have ST segment elevations in the inferior leads and then has an episode of sustained ventricular tachycardia that is treated with intravenous amiodarone.  The patient is taken to the cardiac catheterization lab and is found to have a thrombotic occlusion of the right coronary artery, which is successfully treated with percutaneous coronary intervention.  On the second day of hospitalization he demonstrates full neurologic recovery and is asymptomatic.  Laboratory results are as follows:  The patient's laboratory results were within normal limits 1 week prior to admission.  Which of the following is the most likely cause of the new findings?

Quizplus · Accepted Answer

This patient has developed ischemic hepatitis (shock liver) resulting from myocardial infarction, ventricular tachycardia, and cardiogenic shock. Ischemic hepatitis usually occurs in the setting of global hypoperfusion and/or hypoxemia; in addition to cardiac insults, other common causes include hypovolemic and septic shock as well as respiratory failure. Histologically, hepatocyte necrosis is found predominantly in zone 3 of the liver lobule, ie, surrounding the central veins where cells are farthest from the oxygen supply coming from the hepatic artery (~40% of the liver's oxygen supply) and the portal vein (~60% of the liver's oxygen supply as partially deoxygenated blood). zone 3 Patients often develop aminotransferase levels >1000 U/L shortly after the inciting incident. Although the bilirubin level can be unaffected, it usually rises several days later. Prognosis is poor as patients are typically critically ill and often have accompanying multiorgan failure. In those who survive, the hepatic injury tends to be self-limited; aminotransferase elevations usually resolve within 7 days, and bilirubin levels normalize over the course of several weeks. (Choice A) Acalculous cholecystitis usually occurs as a complication of shock or other critical illness. Mild elevations in total bilirubin, alkaline phosphatase, and aminotransferases are typical; however, aminotransferase elevation >1000 U/L would not be consistent. (Choice B) Like ischemic hepatitis, acute viral hepatitis can cause elevations in aminotransferases >1000 U/L, most commonly from acute infection with hepatitis A or B. Acute hepatitis A, which is transmitted fecal-orally, tends to present with fever, nausea, and vomiting. Patients with acute hepatitis B often have identifiable risk factors, including intravenous drug use, recent blood transfusions, or unprotected sexual intercourse. (Choice D) This patient was exposed to amiodarone, which can cause hepatic steatosis and cholestasis. This would cause a rise in bilirubin, but marked aminotransferase elevations >1000 U/L are not typical. Acute liver failure due to amiodarone toxicity is rare. (Choice E) Aspartate aminotransferase (AST) is present in cardiac myocytes, skeletal myocytes, and intestinal smooth muscle, and serum levels can rise following injury to any of these tissues. However, alanine aminotransferase (ALT) is specific to hepatocytes and would not increase in the absence of hepatic injury. Educational objective: Ischemic hepatitis, characterized histologically by zone 3-predominant hepatocyte necrosis, occurs in the setting of global hypoperfusion and/or hypoxemia. Common causes include cardiac insults (eg, myocardial infarction, unstable arrythmias), respiratory failure, hypovolemia, and septic shock. Patients immediately develop severe aminotransferase elevations with bilirubin levels remaining unaffected or rising a few days later. References: Hepatic shock differential diagnosis and risk factors: a review article. (http://www.ncbi.nlm.nih.gov/pubmed/26587034)

A 65-Year-Old Man Has a Cardiac Arrest in a Shopping