A 68-year-old man is recovering in the intensive care unit after coronary artery bypass graft surgery. Two weeks ago, he was seen in the office for progressive exertional angina and shortness of breath. The patient underwent coronary angiography, which indicated severe extensive coronary artery disease. After discussion about the risks and benefits, he agreed to proceed with open heart surgery. The patient has a family history of coronary artery disease but no sudden cardiac death, heart failure, or bleeding. On postoperative day 1, the nurses report that the patient is confused and has had reduced urine output. Temperature is 35.6 C (96 F), blood pressure is 80/50 mm Hg, pulse is 118/min and regular, and respirations are 22/min. There is no drainage from his sternal wound, and there has been no drainage in the chest tube over the last 4 hours. The lung fields are clear. No heart murmurs are appreciated. The abdomen is soft. His extremities are cool. ECG shows sinus tachycardia and nonspecific T-wave changes. Pulmonary artery catheter readings are as follows: Right atrium 20 mm Hg (normal: 2-8 mm Hg), right ventricle 35/20 mm Hg (normal: 15-30 mm Hg / 2-8 mm Hg), and pulmonary capillary wedge pressure 20 mm Hg (normal: 6-12 mm Hg). Which of the following is the most appropriate next step in management of this patient?

Question

A 68-year-old man is recovering in the intensive care unit after coronary artery bypass graft surgery.  Two weeks ago, he was seen in the office for progressive exertional angina and shortness of breath.  The patient underwent coronary angiography, which indicated severe extensive coronary artery disease.  After discussion about the risks and benefits, he agreed to proceed with open heart surgery.  The patient has a family history of coronary artery disease but no sudden cardiac death, heart failure, or bleeding.  On postoperative day 1, the nurses report that the patient is confused and has had reduced urine output.  Temperature is 35.6 C (96 F), blood pressure is 80/50 mm Hg, pulse is 118/min and regular, and respirations are 22/min.  There is no drainage from his sternal wound, and there has been no drainage in the chest tube over the last 4 hours.  The lung fields are clear.  No heart murmurs are appreciated.  The abdomen is soft.  His extremities are cool.  ECG shows sinus tachycardia and nonspecific T-wave changes.  Pulmonary artery catheter readings are as follows:  Right atrium 20 mm Hg (normal: 2-8 mm Hg), right ventricle 35/20 mm Hg (normal: 15-30 mm Hg / 2-8 mm Hg), and pulmonary capillary wedge pressure 20 mm Hg (normal: 6-12 mm Hg).  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d8a8_7c09_bc81_dbaa3e394fab_MD0003_00 IVC = inferior vena cava; JVD = jugular venous distension; LV = left ventricular; SBP = systolic blood pressure. This patient most likely has postoperative cardiac tamponade, a relatively rare but important early complication of coronary artery bypass grafting. Rapid accumulation of blood in the limited pericardial space leads to increased diastolic pressure in the chambers of the heart and severe impairment in venous return. Patients typically have evidence of shock with hypoperfusion (eg, hypotension, reduced urine output, cool extremities); the classic finding is the triad of hypotension, elevated jugular venous pressure, and distant heart sounds (Beck triad). Characteristically, there is elevation and equalization of intracardiac diastolic pressures (right atrial, right ventricular, and pulmonary capillary wedge pressure suggestive of left atrial pressure), as shown on this patient's pulmonary artery catheterization. Cardiac tamponade can rapidly lead to cardiac arrest if left untreated. Urgent echocardiography confirms the diagnosis and can identify moderate or large pericardial effusion, right atrial diastolic collapse, right ventricular diastolic collapse (highly specific for tamponade), and bowing of the interventricular septum into the left ventricle during inspiration. Immediate percutaneous or surgical (pericardial window) drainage of pericardial fluid relieves elevated intrapericardial pressures and leads to rapid improvement in symptoms and hemodynamic status. (Choice A) Blood cultures followed by empiric antibiotics are appropriate in patients with suspected septic shock; however, intracardiac pressures are typically low or normal (rather than elevated) due to the loss of intravascular volume that occurs in sepsis. (Choices B and E) Acute myocardial infarction due to failure of a bypass graft can lead to a similar presentation with cardiogenic shock and may necessitate coronary angiography for diagnosis or dobutamine infusion for inotropic left ventricular support. However, acute heart failure due to myocardial infarction does not typically cause equalization of intracardiac diastolic pressures and also is less likely in the absence of significant ECG changes. (Choice C) CT pulmonary angiography is used to diagnose acute pulmonary embolism; however, low or normal (rather than elevated) pulmonary capillary wedge pressure is expected in acute pulmonary embolism due to impaired blood flow through the pulmonary circulation to the left atrium. (Choice D) This patient's altered mental status is best explained by hypotension and shock (rather than stroke), and CT scan of the head is not indicated. Educational objective: Cardiac catheterization in patients with cardiac tamponade typically reveals elevated and equilibrated intracardiac diastolic pressures. Urgent echocardiography should be performed in patients with suspected cardiac tamponade for definitive diagnosis and management. References: Postoperative cardiac tamponade in the modern surgical era. (http://www.ncbi.nlm.nih.gov/pubmed/12400760)

A 68-Year-Old Man Is Recovering in the Intensive Care Unit