A 60-year-old man is brought to the emergency department after passing out at home. The patient was watching television while seated in an armchair when he suddenly passed out with no warning. According to his wife, he was unconscious for 1-2 minutes and displayed several muscle jerks while unconscious. The patient has never had a similar episode. Medical history includes hypertension and hyperlipidemia. The patient had a myocardial infarction 6 months ago and spent 5 days in the hospital. There have been no changes to his medications in the last few weeks. He now appears comfortable and has no symptoms. Blood pressure is 130/85 mm Hg and pulse is 80/min with frequent ectopic beats. Physical examination reveals a 2/6 holosystolic apical murmur radiating to the axilla. Which of the following is the most likely cause of this event?

Question

A 60-year-old man is brought to the emergency department after passing out at home.  The patient was watching television while seated in an armchair when he suddenly passed out with no warning.  According to his wife, he was unconscious for 1-2 minutes and displayed several muscle jerks while unconscious.  The patient has never had a similar episode.  Medical history includes hypertension and hyperlipidemia.  The patient had a myocardial infarction 6 months ago and spent 5 days in the hospital.  There have been no changes to his medications in the last few weeks. He now appears comfortable and has no symptoms.  Blood pressure is 130/85 mm Hg and pulse is 80/min with frequent ectopic beats.  Physical examination reveals a 2/6 holosystolic apical murmur radiating to the axilla.  Which of the following is the most likely cause of this event?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d190_8940_bc81_e13448b0d881_MD0003_00 Syncope is a transient loss of consciousness accompanied by a loss of postural tone with a spontaneous return to baseline neurologic function. It occurs due to global hypoperfusion of the brain and can have many causes. In many patients (eg, those with hypovolemia or vasovagal syncope), syncope is benign and self-limiting; however, it can be the initial manifestation of a life-threatening disease process (eg, cardiac syncope). This patient's syncope is most likely due to a cardiac arrhythmia. Findings consistent with an arrhythmic etiology in this patient include the following: Sudden onset with lack of prodromal symptoms Occurrence while the patient was at rest and seated (ie, no change in position) Evidence of underlying structural heart disease (eg, prior myocardial infarction, murmur of mitral regurgitation) Presence of frequent ectopic beats The most common arrhythmia causing syncope is ventricular tachycardia, which is potentially fatal. Therefore, this patient should be admitted to the hospital for continuous ECG monitoring and further cardiac workup (eg, echocardiography). (Choice B) Autonomic dysfunction resulting from degenerative changes to autonomic ganglia or CNS nuclei can result in syncope. However, it is usually seen in patients with neurodegenerative disease (eg, Parkinson disease), and syncope typically occurs on standing due to an inadequate compensatory sympathetic response (eg, vasoconstriction). (Choice C) Orthostatic (postural) hypotension refers to a drop in systolic blood pressure >20 mm Hg or diastolic blood pressure >10 mm Hg within 2-5 minutes of standing from a supine position. It is a common cause of syncope but is unlikely in this patient who was sitting in an armchair when the syncopal episode occurred. (Choice D) Seizures can cause loss of consciousness and clonic jerks; however, features more suggestive of seizure include the presence of a trigger (eg, lack of sleep, emotional stress, flashing lights), a prodromal aura, tongue lacerations, and a postictal period. The muscle jerks experienced by this patient can occur in all types of syncope because sudden cerebral hypoperfusion often causes brief myoclonus. (Choice E) Vasovagal syncope is the most common type of syncope; however, it is typically triggered by prolonged standing or emotional or painful stimuli. In addition, patients frequently experience a prodrome with nausea, pallor, dizziness, and diaphoresis prior to the syncopal episode. Educational objective: Patients with an arrhythmic cause of syncope usually have underlying structural heart disease and may not have any prodromal symptoms prior to the syncopal episode. References: Syncope: epidemiology, etiology, and prognosis (http://www.ncbi.nlm.nih.gov/pubmed/25538626) Guidelines for the diagnosis and management of syncope (version 2009). (http://www.ncbi.nlm.nih.gov/pubmed/19713422)

A 60-Year-Old Man Is Brought to the Emergency Department After