A 47-year-old man is brought to the emergency department due to lightheadedness and palpitations. He denies chest pain, shortness of breath, or nausea. He reports a history of palpitations since he was a teenager and says he can usually stop them by bearing down. However, this maneuver did not work this time so he decided to come to the hospital. His other medical problems include type 1 diabetes mellitus and hypertension. He had a myocardial infarction 5 years ago, but has not had chest pain since then. His exercise tolerance is good.
Blood pressure is 80/40 mm Hg and his pulse is 150/min. Lungs are clear on auscultation. No heart murmurs are appreciated.
ECG is shown in the exhibit.
Which of the following is the best next step in managing this patient?

Question

A 47-year-old man is brought to the emergency department due to lightheadedness and palpitations.  He denies chest pain, shortness of breath, or nausea.  He reports a history of palpitations since he was a teenager and says he can usually stop them by bearing down.  However, this maneuver did not work this time so he decided to come to the hospital.  His other medical problems include type 1 diabetes mellitus and hypertension.  He had a myocardial infarction 5 years ago, but has not had chest pain since then.  His exercise tolerance is good.
Blood pressure is 80/40 mm Hg and his pulse is 150/min.  Lungs are clear on auscultation.  No heart murmurs are appreciated.
ECG is shown in the exhibit. 
Which of the following is the best next step in managing this patient?

Quizplus · Accepted Answer

Based on ACLS guidelines, patients with any persistent tachyarrhythmia causing hemodynamic instability should have immediate synchronized cardioversion with adequate sedation and analgesia prior to cardioversion. If the patient is hemodynamically stable, the next step is to look at QRS duration to differentiate between wide complex tachycardia (WCT) and narrow complex tachycardia (NCT). Patients with NCT likely have supraventricular tachycardia (SVT) and can be treated accordingly. ACLS guidelines 11ec193a_95d9_346c_853d_8b37cf813b61_MD0002_00 Patients with WCT likely have SVT with aberrancy (due to preexisting or functional bundle branch block), antidromic AV reentrant tachycardia, or ventricular tachycardia (VT). ECG showing evidence of AV dissociation, precordial concordance, capture beats, or fusion beats favors VT and should be treated accordingly. Capture beats occur when an atrial impulse depolarizes the ventricles through the normal conduction system and causes a narrow QRS earlier than expected (circled in above ECG). This patient's ECG shows WCT with capture beats diagnostic of VT. (Choice A) Transthoracic echocardiogram should not be the initial step in patients with clinical or hemodynamic instability. It should be performed after cardioversion to assess for left ventricular function and regional wall motion abnormalities. (Choice B) Vagal maneuvers, including Valsalva or carotid sinus massage, are commonly used in stable patients to treat reentrant SVT or to distinguish between various forms of SVT. However, VT is generally unaffected by carotid sinus pressure. (Choice C) Adenosine is frequently used in the diagnosis or treatment of stable SVT. However, in patients with VT, it can cause severe hemodynamic deterioration and induce ventricular fibrillation and cardiac arrest. (Choice D) Intravenous antiarrhythmics (eg, amiodarone, procainamide) can be used in patients with stable recurrent or refractory WCT, or in cases where it is difficult to differentiate between VT and SVT with aberrancy. Synchronized cardioversion is preferred in patients with unstable WCT. Educational objective: Immediate synchronized cardioversion is the initial treatment of choice in patients with wide complex tachycardia associated with clinical and/or hemodynamic instability. __________ References: Approach to the diagnosis and initial management of the stable adult patient with a wide complex tachycardia. (http://www.ncbi.nlm.nih.gov/pubmed/18471458)

A 47-Year-Old Man Is Brought to the Emergency Department Due