A 72-year-old man with diet-controlled diabetes mellitus comes to the emergency department with chest pain for the last 4 hours. He has never had similar pain before. The pain is accompanied by nausea and epigastric discomfort. Electrocardiogram shows normal sinus rhythm and ST-segment elevation in leads II, III, and aVF. Sublingual nitroglycerine and intravenous morphine are administered and the on-call interventional cardiologist is informed. Several minutes later, the patient complains of lightheadedness, nausea, and weakness. His blood pressure is 75/45 mm Hg, pulse is 60/min, and respirations are 15/min. The patient is diaphoretic and his extremities are cold. The lungs are clear on auscultation and no murmurs are appreciated on cardiac auscultation. Which of the following is the best next step in management of this patient?

Question

A 72-year-old man with diet-controlled diabetes mellitus comes to the emergency department with chest pain for the last 4 hours.  He has never had similar pain before.  The pain is accompanied by nausea and epigastric discomfort.  Electrocardiogram shows normal sinus rhythm and ST-segment elevation in leads II, III, and aVF.  Sublingual nitroglycerine and intravenous morphine are administered and the on-call interventional cardiologist is informed.  Several minutes later, the patient complains of lightheadedness, nausea, and weakness.  His blood pressure is 75/45 mm Hg, pulse is 60/min, and respirations are 15/min.  The patient is diaphoretic and his extremities are cold.  The lungs are clear on auscultation and no murmurs are appreciated on cardiac auscultation.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: This patient has developed cardiogenic shock in the setting of acute inferior ST-elevation myocardial infarction (STEMI) after administration of nitroglycerine and morphine. This is most likely due to right ventricular MI (RVMI). RVMI is seen in 30%-50% of patients with acute inferior MI. Patients typically present with hypotension or shock, jugular vein distension, and clear lung fields. inferior MI Patients with RVMI are treated similar to other patients with acute MI with appropriate dual antiplatelet therapy, statins, and anticoagulant therapy, as well as emergency revascularization with thrombolytics or primary percutaneous intervention. Drugs that slow heart rate (beta blockers) or decrease contractility (calcium channel blockers) should be used with caution. Nitrates, diuretics, and opioids should be avoided as they decrease right ventricular preload, which in turn impairs cardiac output and can cause profound hypotension. acute MI Patients with hypotension and normal or low jugular venous pressure should be treated with a bolus of intravenous fluids (isotonic saline). This generally improves right ventricular preload and facilitates left ventricular filling. (Choice A) Transient bradycardia or atrioventricular block due to enhanced vagal tone can occur in the setting of acute inferior MI. However, this patient has adequate heart rate, and interventions to decrease in vagal tone (eg, administration of atropine) are not indicated. (Choice B) Decreasing afterload with intra-aortic balloon pump is useful in patients with cardiogenic shock due to left ventricular dysfunction. An increase in afterload would worsen the RV dysfunction and hypotension. (Choice C) Inotropic agents are used in patients with RVMI and persistent hypotension despite aggressive fluid resuscitation. Dopamine is the initial drug of choice in such settings. Dobutamine can decrease peripheral vascular resistance at higher doses and worsen hypotension. (Choice E) Emergency reperfusion with thrombolytics or primary percutaneous coronary intervention is indicated in all patients with acute STEMI, including those with RVMI. However, this patient should be given a fluid bolus initially to improve RV preload and hypotension while plans for early reperfusion are implemented. Educational objective: Nitrates, diuretics, and opioids can reduce right ventricular (RV) preload and cause hypotension in patients with acute RV myocardial infarction. Such patients with evidence of low cardiac output and hypotension should be treated initially with a bolus of intravenous fluids to improve RV preload. References: Right ventricular myocardial infarction: From pathophysiology to prognosis. (http://www.ncbi.nlm.nih.gov/pubmed/24294033)

A 72-Year-Old Man with Diet-Controlled Diabetes Mellitus Comes to the Emergency