A 28-year-old woman comes to the office due to an episode of lightheadedness followed by a syncopal episode. She has had several days of headache, malaise, and myalgia but no vomiting or diarrhea. The patient has no history of similar symptoms. She was diagnosed with chlamydia cervicitis 3 weeks ago and received a single dose of azithromycin. The patient has no chronic medical problems or family history of sudden cardiac death. She lives in rural Massachusetts and has not traveled recently. Temperature is 37 C (98.6 F), blood pressure is 120/80 mm Hg, and pulse is 43/min. No orthostatic blood pressure changes are present. Cardiopulmonary auscultation reveals no heart murmurs. The right thigh has 2 erythematous skin lesions. ECG shows sinus rhythm with 2:1 atrioventricular block. Which of the following is the most likely cause of this patient's current condition?

Question

A 28-year-old woman comes to the office due to an episode of lightheadedness followed by a syncopal episode.  She has had several days of headache, malaise, and myalgia but no vomiting or diarrhea.  The patient has no history of similar symptoms.  She was diagnosed with chlamydia cervicitis 3 weeks ago and received a single dose of azithromycin.  The patient has no chronic medical problems or family history of sudden cardiac death.  She lives in rural Massachusetts and has not traveled recently.  Temperature is 37 C (98.6 F), blood pressure is 120/80 mm Hg, and pulse is 43/min.  No orthostatic blood pressure changes are present.  Cardiopulmonary auscultation reveals no heart murmurs.  The right thigh has 2 erythematous skin lesions.  ECG shows sinus rhythm with 2:1 atrioventricular block.  Which of the following is the most likely cause of this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d280_8ee0_bc81_4da9e3b493e9_MD0003_00 Lyme disease is a spirochetal infection caused by Borrelia burgdorferi after zoonotic transmission from the Ixodes scapularis tick. Patients in endemic areas often develop symptoms without being aware of a previous tick bite. Most infections manifest with erythema migrans (EM), a spreading, annular, erythematous rash with central clearing. However, a minority of patients have symptoms of early disseminated disease, including multiple EM lesions, carditis, and/or neurologic findings. endemic areas Lyme carditis typically occurs within the first several weeks or months of B burgdorferi infection. The most common manifestation is atrioventricular (AV) conduction block. Symptoms include lightheadedness, syncope, dyspnea, chest pain, and/or palpitations. Sudden cardiac death is rare but may occur. Diagnosis is made with B burgdorferi serology (ELISA and Western blot). Patients typically require hospitalization with telemetry and intravenous antibiotics (eg, ceftriaxone); most recover completely without sequelae. This young patient who lives in a Lyme endemic region has cardiac (lightheadedness, syncope, bradycardia, AV block), systemic (headache, malaise, myalgia), and skin (likely EM) manifestations, suggesting early disseminated Lyme disease. (Choice A) Dermatomyositis is an autoimmune disorder that may cause AV block, systemic symptoms, skin lesions (eg, Gottron papules, heliotrope eruption), and myalgias. However, most patients have significant symmetric, proximal muscle weakness. This patient in a Lyme endemic area is more likely to have Lyme disease. (Choice B) Disseminated herpes is seen primarily in immunocompromised hosts (eg, HIV with CD4 <200/mm³) and may cause encephalitis, hepatitis, and esophagitis. This young patient with new-onset AV block in a Lyme endemic area is more likely to have early disseminated Lyme disease. (Choice C) Many medications, including digitalis, amiodarone, and calcium channel blockers, can cause AV block. However, azithromycin does not typically cause AV block. (Choice D) Sarcoidosis is a multisystem granulomatous disorder that usually causes hilar lymphadenopathy, pulmonary infiltrates, and skin papules but may occasionally cause AV block. Pulmonary and/or skin symptoms are usually prominent. (Choice F) Some plants (eg, foxglove, oleander) contain digoxin-like compounds that may cause toxicity with AV block. Lyme disease is far more common than accidental or purposeful ingestion of these plants. Educational objective: Lyme disease is caused by the spirochete Borrelia burgdorferi and is endemic to the northeastern United States. Patients often develop clinical illness without knowledge of a previous tick bite. Early disease typically manifests with erythema migrans (EM), but patients may also present with multiple EM lesions, carditis, and/or neurologic manifestations. Lyme carditis most commonly causes atrioventricular block. References: Practice parameter: treatment of nervous system Lyme disease (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology. (http://www.ncbi.nlm.nih.gov/pubmed/17522387) The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. (http://www.ncbi.nlm.nih.gov/pubmed/17029130)

A 28-Year-Old Woman Comes to the Office Due to an Episode