A 69-year-old man undergoes coronary artery bypass grafting and aortic valve replacement surgery. He has a history of aortic stenosis, coronary artery disease, and hypertension. The surgery is uncomplicated, and the patient is extubated and transferred to the stepdown unit on postoperative day 2. That night, he experiences sudden onset of weakness, chest tightness, and shortness of breath. On examination, he appears in moderate distress. His blood pressure is 70/30 mm Hg, pulse is 148/min, and respirations are 26/min. Lung auscultation indicates bibasilar crackles. An ECG rhythm strip is shown in the exhibit. Which of the following is the best next step in management of this patient?

Question

A 69-year-old man undergoes coronary artery bypass grafting and aortic valve replacement surgery.  He has a history of aortic stenosis, coronary artery disease, and hypertension.  The surgery is uncomplicated, and the patient is extubated and transferred to the stepdown unit on postoperative day 2.  That night, he experiences sudden onset of weakness, chest tightness, and shortness of breath.  On examination, he appears in moderate distress.  His blood pressure is 70/30 mm Hg, pulse is 148/min, and respirations are 26/min.  Lung auscultation indicates bibasilar crackles.  An ECG rhythm strip is shown in the exhibit.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d178_bb6e_bc81_6db8de6398b0_MD0003_00 This patient's ECG rhythm strip shows an irregularly irregular, narrow complex tachycardia along with fine fibrillatory waves - consistent with atrial fibrillation with rapid ventricular response (ie, pulse >100/min). This patient has developed atrial fibrillation after coronary artery bypass grafting/aortic valve replacement, leading to hemodynamic instability with signs of cardiogenic shock and acute pulmonary edema. ECG rhythm strip Based on the Advanced Cardiac Life Support guidelines, all patients with a pulse who have persistent tachyarrhythmia (narrow or wide complex) causing clinical or hemodynamic instability (hypotension, cardiogenic shock, signs of ischemia, acute heart failure) should be managed with immediate direct current cardioversion. With cardioversion, energy delivery is synchronized to the QRS complex to minimize the likelihood of the shock occurring during repolarization, which can precipitate ventricular fibrillation. By contrast, immediate defibrillation (as opposed to cardioversion) provides a high-energy shock at a random point in the cardiac cycle (unsynchronized shock) and is indicated in patients with ventricular fibrillation or pulseless ventricular tachycardia (Choice B). ventricular fibrillation (Choice A) Amiodarone is a class III antiarrhythmic drug used occasionally for acute management of ventricular arrhythmias (which would present as wide complex arrhythmias) and for maintenance of sinus rhythm in patients with atrial fibrillation. It should not be used in hemodynamically unstable patients as it can further aggravate hypotension and will delay definitive therapy with cardioversion. (Choice C) Beta blockers and/or calcium channel blockers (eg, verapamil, diltiazem) are indicated for adequate rate control in stable patients with rapid atrial fibrillation. (Choice E) Lidocaine is a class IB antiarrhythmic used for treatment of hemodynamically stable patients with ventricular arrhythmias. (Choice F) Transcutaneous pacing is most often used in management of patients with symptomatic bradyarrhythmias and/or complete heart block. complete heart block Educational objective: Immediate synchronized cardioversion is the initial treatment of choice in patients with persistent tachyarrhythmia (narrow or wide complex) associated with clinical or hemodynamic instability (hypotension, cardiogenic shock, signs of ischemia, acute heart failure). References: Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. (http://www.ncbi.nlm.nih.gov/pubmed/20956224) ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias - executive summary. (http://www.ncbi.nlm.nih.gov/pubmed/14557344)

A 69-Year-Old Man Undergoes Coronary Artery Bypass Grafting and Aortic