A 55-year-old construction worker is brought to the emergency department with sudden onset of diaphoresis and severe chest discomfort. His symptoms woke him up 3 hours earlier. On arrival, his blood pressure is 98/60 mm Hg, pulse is 86/min, and oxygen saturation is 98% on 3 L oxygen by nasal cannula. He has persistent chest discomfort, and his skin is cold and clammy. Neck veins are mildly distended. Lung fields are clear and cardiac examination is unremarkable. His initial EKG reveals 3-mm ST segment elevation in leads II, III, and aVF.
He is referred for emergency cardiac catheterization and is found to have an acute occlusion of the proximal right coronary artery. There is mild, diffuse coronary atherosclerosis present in the left coronary circulation. Left ventriculography reveals mild hypokinesis of the inferior wall with an LV ejection fraction of 55%. He undergoes primary percutaneous coronary intervention with a bare metal stent and has TIMI II flow restored at the end of the procedure. He is started on aspirin, prasugrel, atorvastatin, and intravenous eptifibatide and is transferred to the coronary care unit.
Thirty minutes later, his blood pressure drops to 80/54 mm Hg. He has minimal residual chest discomfort but no other symptoms. His physical examination is unchanged. An urgent EKG shows minimal, less than 1 mm, persistent ST-segment elevation along with small Q waves in inferior leads.
Which of the following is the next best step in management of this patient?

Question

A 55-year-old construction worker is brought to the emergency department with sudden onset of diaphoresis and severe chest discomfort.  His symptoms woke him up 3 hours earlier.  On arrival, his blood pressure is 98/60 mm Hg, pulse is 86/min, and oxygen saturation is 98% on 3 L oxygen by nasal cannula.  He has persistent chest discomfort, and his skin is cold and clammy.  Neck veins are mildly distended.  Lung fields are clear and cardiac examination is unremarkable.  His initial EKG reveals 3-mm ST segment elevation in leads II, III, and aVF.
He is referred for emergency cardiac catheterization and is found to have an acute occlusion of the proximal right coronary artery.  There is mild, diffuse coronary atherosclerosis present in the left coronary circulation.  Left ventriculography reveals mild hypokinesis of the inferior wall with an LV ejection fraction of 55%.  He undergoes primary percutaneous coronary intervention with a bare metal stent and has TIMI II flow restored at the end of the procedure.  He is started on aspirin, prasugrel, atorvastatin, and intravenous eptifibatide and is transferred to the coronary care unit.
Thirty minutes later, his blood pressure drops to 80/54 mm Hg.  He has minimal residual chest discomfort but no other symptoms.  His physical examination is unchanged.  An urgent EKG shows minimal, less than 1 mm, persistent ST-segment elevation along with small Q waves in inferior leads.
Which of the following is the next best step in management of this patient?

Quizplus · Accepted Answer

The patient's clinical presentation is consistent with cardiogenic shock due to acute right ventricular myocardial infarction (RVMI). RVMI is seen in 30-50% of patients presenting with acute inferior wall MI due to occlusion of the proximal right coronary artery before the origin of right ventricular branches. Patients typically present with hypotension or shock, jugular venous distension, and clear lung fields in the background of acute inferior MI. EKG in patients with RVMI shows > 1 mm ST-segment elevation in right-sided precordial leads V4R to V6R. Patients with RVMI are treated similarly to other patients with acute MI, with appropriate antiplatelet and anticoagulant therapy, and emergency primary percutaneous revascularization. Nitrates should be avoided as they decrease right ventricular preload and can cause profound hypotension. Patients with RVMI have reduced blood delivery to the left ventricle, which in turn decreases cardiac output despite normal LV systolic function. Such patients with evidence of low cardiac output and hypotension should be treated initially with a bolus of intravenous fluid to improve right ventricular preload and forward flow of blood to the left ventricle. (Choice A) Pericarditis and pericardial tamponade are differential diagnoses of RVMI (with chest pain, hypotension, distended neck veins, and clear lung fields). This patient had an inferior wall MI with proximal right coronary artery occlusion, which makes RVMI the most likely cause of his hypotension. (Choice C) Afterload reduction with an intra-aortic balloon pump is useful in patients with cardiogenic shock due to left ventricular dysfunction. This patient has preserved left ventricular function and will not benefit from afterload reduction with an intra-aortic balloon pump. (Choice D) Inotropic agents should be 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 and worsen hypotension. (Choice E) Retroperitoneal hematoma can cause hypotension after percutaneous coronary intervention and can lead rapidly to hypovolemic shock and death. This patient has no signs or symptoms of retroperitoneal hematoma (groin hematoma, back or abdominal pain, flat neck veins), and CT scan is not warranted at this time. Educational objective: Patients with RVMI present with hypotension, elevated jugular venous pressure, and clear lung fields in the setting of inferior wall MI. Patients with evidence of low cardiac output and hypotension should be treated initially with a bolus of intravenous fluid to improve right ventricular preload and forward flow of blood to the left ventricle. __________ References: Acute right ventricular infarction. (http://www.ncbi.nlm.nih.gov/pubmed/22548813)

A 55-Year-Old Construction Worker Is Brought to the Emergency Department