A 25-year-old man is brought to the emergency department after a syncopal event. His wife reports that they were resting in bed, watching television together, when he suddenly passed out. The patient was unconscious for approximately a minute, during which time there were a few bilateral jerks of the arms and legs. He has never had a similar episode but recently noticed some palpitations at night. The patient has no chronic medical conditions but had a fever as high as 38.3 C (100.9 F), along with a mild cough and body aches, throughout the day. Family history is significant for a male cousin who died unexpectedly in his sleep at age 37. Temperature is 38 C (100.4 F), blood pressure is 128/76 mm Hg, and pulse is 98/min. The patient is awake and alert and in no distress. The pupils are equal and reactive to light. The oropharynx is normal. Breath sounds are normal. No heart murmurs are heard. The extremities are well perfused, with symmetric strength. A rapid influenza test is positive. Which of the following is the most likely cause of this patient's syncopal episode?

Question

A 25-year-old man is brought to the emergency department after a syncopal event.  His wife reports that they were resting in bed, watching television together, when he suddenly passed out.  The patient was unconscious for approximately a minute, during which time there were a few bilateral jerks of the arms and legs.  He has never had a similar episode but recently noticed some palpitations at night.  The patient has no chronic medical conditions but had a fever as high as 38.3 C (100.9 F), along with a mild cough and body aches, throughout the day.  Family history is significant for a male cousin who died unexpectedly in his sleep at age 37.  Temperature is 38 C (100.4 F), blood pressure is 128/76 mm Hg, and pulse is 98/min.  The patient is awake and alert and in no distress.  The pupils are equal and reactive to light.  The oropharynx is normal.  Breath sounds are normal.  No heart murmurs are heard.  The extremities are well perfused, with symmetric strength.  A rapid influenza test is positive.  Which of the following is the most likely cause of this patient's syncopal episode?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d18d_7bff_bc81_1972ae5f4ac8_MD0003_00 Although most cases of syncope in healthy young individuals are benign and self-limiting (eg, vasovagal syncope, orthostatic syncope), this patient has multiple red flags for cardiac syncope due to arrhythmia. Historical clues consistent with an arrhythmic etiology include the following: Sudden onset with lack of warning symptoms suggests an abrupt, extreme drop in cardiac output, which is characteristic of tachyarrhythmia (usually ventricular tachycardia), that disrupts normal ventricular filling and/or coordinated contraction. Syncope occurs while the patient is at rest and supine; benign causes (eg, vasovagal, orthostatic) typically do not occur when the patient is in the recumbent position. Recent palpitations suggest previous transient arrhythmic episodes. Sudden death in a young family member (eg, age <40) raises suspicion for an inherited cardiac conduction syndrome that predisposes to ventricular tachycardia (eg, congenital long QT syndrome, Brugada syndrome). This patient's history may be most suggestive of Brugada syndrome, an autosomal dominant condition during which episodes of ventricular tachycardia can develop. The episodes commonly occur at night and may be triggered by fever (eg, influenza infection), due to hyperthermia-induced changes in sodium current that impact cardiac action potential. (Choice A) Fever can cause seizures (ie, febrile seizures) in children age 6 months to 5 years. This clinical diagnosis does not apply to adults. In addition, this patient's episode lacked common features of seizure activity (eg, prodromal aura, postictal period). His few extremity jerks occurred due to sudden cerebral hypoperfusion, which often causes brief myoclonus. (Choice B) Hypertrophic cardiomyopathy, which obstructs left ventricular outflow, is a potential cause of cardiac syncope. However, it typically causes syncope during exertion (vs at rest), and a systolic murmur is usually present. (Choice C) Although a febrile patient, such as this one, is prone to dehydration, which can lead to orthostatic hypotension, syncope due to orthostatic hypotension typically occurs on standing from a seated or supine position and is often preceded by light-headedness. (Choice D) Vasovagal syncope, the most common cause of syncope, is typically preceded by a trigger (eg, emotional stress, painful stimuli) and a vagal prodrome (eg, diaphoresis, nausea, warmth), neither of which occurred in this patient. Educational objective: Red-flag features suggesting an arrhythmic cause of cardiac syncope include sudden onset with lack of warning symptoms, occurrence while at rest and supine, history of palpitations, and family history of a young relative with a sudden, unexplained death. Ventricular tachycardia is the most common arrhythmic cause of syncope and sudden cardiac death. References: Syncope and the risk of sudden cardiac death: evaluation, management, and prevention (http://www.ncbi.nlm.nih.gov/pubmed/29255498)

A 25-Year-Old Man Is Brought to the Emergency Department After