A 21-year-old man is brought to the emergency department due to dizziness and palpitations that started abruptly an hour ago. He has had similar episodes provoked by fatigue or strong emotions. The patient can usually stop the episodes by squatting and taking a deep breath. However, this time these actions did not work. Blood pressure is 65/40 mm Hg and pulse is 240/min. He is diaphoretic and his extremities are cold. ECG rhythm strip shows a regular, narrow-complex tachycardia. Which of the following is the best next step in management of this patient?

Question

A 21-year-old man is brought to the emergency department due to dizziness and palpitations that started abruptly an hour ago.  He has had similar episodes provoked by fatigue or strong emotions.  The patient can usually stop the episodes by squatting and taking a deep breath.  However, this time these actions did not work.  Blood pressure is 65/40 mm Hg and pulse is 240/min.  He is diaphoretic and his extremities are cold.  ECG rhythm strip shows a regular, narrow-complex tachycardia.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

This patient has a regular, narrow-complex tachycardia (supraventricular tachycardia [SVT]) causing hemodynamic instability with hypotension and signs of poor perfusion (cool extremities). Common causes of regular, narrow-complex SVT include inappropriate sinus tachycardia, atrial tachycardia, atrial flutter, and atrioventricular nodal reentrant tachycardia. All patients with persistent tachyarrhythmia (narrow- or wide-complex) causing hemodynamic instability (eg, hypotension, signs of shock, ischemic chest discomfort, mental status changes, acute pulmonary edema) should be managed with immediate synchronized direct current cardioversion due to the risk of rapid clinical deterioration. Synchronized cardioversion involves the delivery of a low-energy electric shock synchronized to the QRS complex. Whenever possible, patients should be provided with adequate sedation and analgesia prior to cardioversion. In patients who do not have hemodynamic instability, adenosine or vagal maneuvers (eg, bearing down, squatting, breath holding) can be considered; however, these would be inappropriate in this patient with hemodynamic instability (in addition, this patient has already tried squatting and taking a deep breath). (Choices A and D) Intravenous antiarrhythmics (eg, amiodarone, procainamide) can be used in patients with stable recurrent or refractory wide-complex tachycardia. These drugs can worsen hypotension and are not recommended acutely in patients with hypotension or hemodynamic instability. (Choice B) Intravenous beta blockers (eg, metoprolol, esmolol) or calcium channel blockers (eg, verapamil, diltiazem) can be occasionally used in stable patients who fail to respond to initial vagal maneuvers and/or intravenous adenosine. They should not be used in patients with persistent hypotension and hemodynamic instability. (Choice C) Intravenous fluid resuscitation can improve blood pressure transiently. However, it will not treat the underlying cause of hypotension and may result in unnecessary delay for definitive management of this patient. (Choice F) Unsynchronized cardioversion (defibrillation), which provides a high-energy shock at a random point in the cardiac cycle, is used during resuscitation efforts in patients with pulseless cardiac arrest who have a shockable rhythm (ie, ventricular fibrillation, pulseless ventricular tachycardia). Administration of an unsynchronized shock in other circumstances (eg, in this patient with a pulse who has a regular, narrow-complex tachycardia) can lead to induction of ventricular fibrillation. Educational objective: Patients with persistent tachyarrhythmia (narrow- or wide-complex) causing hemodynamic instability should be managed with immediate synchronized cardioversion. References: Part 7: Adult Advanced Cardiovascular Life Support: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. (http://www.ncbi.nlm.nih.gov/pubmed/26472995)

A 21-Year-Old Man Is Brought to the Emergency Department Due