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A 19-year-old man presents to the emergency department (ED) after an episode of shortness of breath and syncope while at home. He reports having experienced recurrent episodes of irregular heartbeat and fatigue in the week before presentation. Yesterday, the patient sought medical attention for these symptoms at his pediatrician's office. The patient was sent for routine chest radiography, which was interpreted as unremarkable and without signs of cardiomegaly. The patient was sent home wearing a Holter monitor. |
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Today, the patient noticed numerous oval erythematous patches (arrows) scattered across his chest, abdomen, back, and extremities sparing the palms and soles (as shown above). While mowing the lawn, the patient again felt a sudden onset of irregular heartbeat, which was accompanied by shortness of breath and light-headedness. He went inside the house where he suddenly "passed out," according to the patient's girlfriend. The girlfriend also states that he was unresponsive for a couple of minutes and that the patient exhibited no seizurelike activity or incontinence. She noted that he was "pretty much himself" once he regained consciousness. He was then brought by ambulance to the ED. |
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En route to the ED, a rhythm strip was acquired (shown) and prophylactic transcutaneous pacer pads were subsequently placed by the paramedics. In the ED, the patient describes a racing heart with irregular forceful beats. They occur spontaneously without any clear inciting factors. He denies having any chest pain or shortness of breath at the time of questioning in the ED. He has not experienced any similar events prior to these, and he is usually active and athletic. The Holter monitor had been removed before he began to mow the lawn; therefore, no results are available. What does this rhythm strip show? A. Atrial flutter B. Premature atrial contractions C. Premature ventricular contractions D. Heart block |
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Answer: D. Heart block (given the nontransmitted P waves) On physical examination, the patient appears to be in no acute distress, but he is noted to have moderate anxiety. He appears nontoxic and alert. His vital signs include a temperature of 98.7°F (37°C), a pulse rate between 40 and 120 beats/min, a respiratory rate of 16 breaths/min, and a blood pressure of 102/46 mm Hg. His oxygen saturation is 96% on room air. His head and neck examination is unremarkable. No jugular venous distension or carotid bruits are noted. His lungs are clear to auscultation bilaterally. His cardiac examination reveals an irregular rhythm without murmur. What does this ECG (shown) obtained at the time of arrival in the ED reveal? A. First-degree atrioventricular (AV) block B. Type 1 second-degree AV block C. Type 2 second-degree AV block D. Third-degree AV block |
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Answer: D. Third-degree AV block Third-degree AV block, also referred to as third-degree heart block or complete heart block, is a disorder of the cardiac conduction system where there is no conduction through the AV node. Therefore, complete dissociation of the atrial and ventricular activity exists. The ventricular escape mechanism can occur anywhere from the AV node to the bundle branch Purkinje system. AV block results from various pathologic states causing infiltration, fibrosis, or loss of connection in portions of the healthy conduction system.[1] |
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The rest of his physical examination reveals a soft, nontender abdomen. No clubbing, cyanosis, or edema is noted in his extremities. His neurologic examination is normal. A more thorough skin examination reveals additional multiple, bilateral macular erythematous lesions with large central pallor on his thighs and a few small areas of alopecia (hair loss) to the left forearm (shown) and scalp. Which of these etiologies is associated with alopecia? A. Syphilis B. Systemic lupus erythematosus C. Tinea capitis D. Thyroid disorders E. Anemia F. All of the above |
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Answer: F. All of the above When asked specifically about outdoor activities, he reports that he had been on a hiking trip 1 month before this visit to the ED, and he remembers being bitten by a tick. He also states that a rash appeared on his legs several days later, but that he thought little of it and applied some over-the-counter cream in an effort to make it go away. At that time, he had a mild flulike illness that resolved within a week. This image shows normal (left) and engorged (right) Ixodes ticks. Which of the following tick-borne illnesses has the highest mortality if not treated? A. Tularemia B. Babesiosis C. Rocky Mountain spotted fever (RMSF) D. Lyme disease E. Ehrlichiosis |
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Answer: C. Rocky Mountain spotted fever (RMSF) RMSF is classically characterized by fever, myalgias, headache, and a petechial rash. It is the most commonly reported and most fatal tick-borne rickettsial disease in the United States. Mortality rates as high as 30% were reported for RMSF in the preantibiotic era. The current mortality rate is still 1.4%, likely due to delay in the diagnosis and treatment.[2] This image shows the palm of a patient with RMSF exhibiting the classic petechial rash associated with the disease. On the basis of the patient's skin lesions, geographic location, and ECG findings, which of the following is the most likely diagnosis? A. Tularemia B. Ehrlichiosis C. Disseminated Lyme disease D. Tertiary syphilis E. Viral myocarditis |
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Answer: C. Disseminated Lyme disease Lyme disease is an infectious, tick-borne process endemic to Wisconsin, Minnesota, and the northeastern United States. It was first recognized in 1975 after chronic infections by the spirochete Borrelia burgdorferi (shown) were discovered in 3 Connecticut communities, where an epidemic of oligoarticular arthritis was noted. The organism is transferred by theIxodes (dammini) scapularis deer tick. The incidence is approximately 6-8 cases per 100,000 people in the United States, according to estimates by the US Centers for Disease Control and Prevention; 93% of cases occur in the above-mentioned endemic areas.[3] |
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Approximately 20,000 new cases are reported every year. Patients presenting with symptoms of Lyme disease may or may not remember removing a tick from their body; the ticks often go unnoticed because they are about the size of a pencil tip (shown). With increased awareness and treatment in the first stage of Lyme disease, extracutaneous manifestations have decreased. Image courtesy of Wikimedia Commons. |
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Although Lyme disease presents with erythema chronicum migrans (ECM; shown) in 70% of cases, extracutaneous disease is well known (eg, heart block by itself occurs in < 1% of cases). The disease may involve the skin, central nervous system (CNS), heart, joints, and eyes. There are relatively few fatalities from Lyme disease; they are typically limited to those patients who are also infected with babesiosis and ehrlichiosis (also known as human granulocytic anaplasmosis).[4] |
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ECM should not be confused with erythema annulare centrifugum (left) or erythema multiforme minor (right). The image on the left shows a polycyclic lesion on the thigh of a child with a tinea capitis infection. The image on the right shows polycyclic target lesions with alternating rings of erythema and dusky desquamation on the arm. Images courtesy of McGraw-Hill. |
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There are 3 stages described in Lyme infections: early localized, early disseminated, and late. The early localized stage of the infection manifests with a nontoxic, nonspecific febrile illness and the classic ECM lesion(s) described as a red patch with central pallor (shown). These may be the only symptoms that a patient will experience; they are diagnostic and necessitate treatment even without serologic proof of the disease. The joints may be involved in early localized disease with migratory arthralgias. Image courtesy of Wikimedia Commons. Which of the following manifestations or complications is NOT typically seen in early disseminated Lyme disease? A. Peripheral neuropathies B. Myopericarditis C. Cardiac conduction defects D. Noncardiogenic pulmonary edema E. Multiple ECM lesions beyond the site of inoculation |
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Answer: D. Noncardiogenic pulmonary edema Early disseminated disease typically occurs within weeks to months following the initial infection. It manifests as multiple ECM lesions beyond the site of inoculation, with accompanying extracutaneous manifestations. The neurologic system may be affected, with patients describing headaches heralding CNS penetration and possible meningitis. A seventh cranial nerve palsy may occur, with facial nerve involvement leading to unilateral facial droop affecting the lower and upper portions of the face. Cardiac manifestations typically occur within the early disseminated stage of the infection. Approximately 8%-10% of patients with Lyme disease have cardiac involvement.[5] |
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Presenting symptoms of cardiac involvement in Lyme disease may include light-headedness, palpitations, or syncope and are typically caused by a conduction defect ranging from first-degree block to complete AV dissociation (shown). Fortunately, most conduction defects are reversible processes after treatment of the underlying infection. Finally, ocular manifestation in early disseminated disease is typically limited to conjunctivitis, described by patients as red, itchy eyes. Image courtesy of ECG Wave-Maven. Other cardiac manifestations of early disseminated Lyme disease may include which of the following? A. Myopericarditis B. Ventricular dysfunction C. Cardiomegaly D. Pericardial effusion E. Cardiac tamponade F. All of the above |
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Answer: F. All of the above Latent disease typically presents months to years later, with arthritis (frank arthritis with painful swelling and redness, typically involving the large joints; shown) or CNS complications. In this stage of the disease, any portion of the CNS and peripheral nervous system may be affected; the manifestations range from chronic encephalopathy to peripheral neuropathies or radiculopathy. |
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The disease is most often diagnosed by history, physical examination, and clinical suspicion. Serologic studies by enzyme-linked immunosorbent assay (ELISA; shown) or Western blot are typically performed, but negative results do not rule out infection. The timing of the sample is crucial to obtaining a reliable result. Early in the infection, serologic studies will often be negative. It may take several weeks for seropositivity to develop.[6] Additionally, patients inoculated in the past may have persistent seropositivity for years after inoculation; therefore, neither a positive result nor a negative result can definitively establish or rule out the presence or absence of an active infection. Image courtesy of Wikimedia Commons. |
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Other useful laboratory studies may include a complete blood cell count (CBC), serum chemistries, erythrocyte sedimentation rate, blood cultures, and specific testing for organisms such as babesiosis (arrows) and ehrlichiosis. An ECG should be obtained as part of the basic workup for any patient in whom the diagnosis of Lyme disease is being entertained. Regardless of whether the patient's history or physical examination findings support cardiac involvement, it is important to rule out any evidence of conduction system disease. Image courtesy of Wikimedia Commons. Which of the following antibiotics is NOT typically used in the treatment of Lyme disease? A. Ceftriaxone B. Amoxicillin C. Vancomycin D. Doxycycline |
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Answer: C. Vancomycin First-choice treatment for early localized infection should be amoxicillin or doxycycline for 10-21 days. For early disseminated infection without CNS infection or third-degree AV block, single-agent oral antibiotics are also appropriate (eg, 21-30 days of oral doxycycline or amoxicillin). A simple seventh cranial nerve palsy associated with B burgdorferi infection (shown) but without evidence of meningitis may be treated with a 14-day course of oral antibiotics; however, if there is evidence of CNS involvement or of a high-grade conduction defect, parenteral therapy is indicated.[4,7] The recommended first-line treatment is intravenous ceftriaxone for 14 days. Image courtesy of Wikimedia Commons. |
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Patients with high-grade heart block and hemodynamic instability should undergo transcutaneous (shown) or temporary transvenous pacing and should be monitored in an intensive care unit setting until they are not dependent on the pacemaker. Latent neurologic Lyme disease requires 2-4 weeks of ceftriaxone, whereas Lyme arthritis can be treated with an oral antibiotic for 4 weeks.[4] Persistent arthritic symptoms may necessitate parenteral therapy and should be treated in consultation with rheumatology. |
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General precautions for avoiding tick bites (shown) in endemic areas include keeping the skin covered when outdoors, using insect repellent, and examining oneself for attached ticks after outdoor activities. A tick attached for less than 24 hours has a low likelihood of transmitting infection. Prophylactic treatment for a tick bite is not routinely recommended;[6]however, for patients in hyperendemic areas who present with an engorged tick that has been attached to their skin for > 36 hours, treatment with a single dose of doxycycline 200 mg given within 72 hours of the tick bite, is highly effective in preventing the development of Lyme disease.[4,8] |
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Approximately 90% of Lyme disease cases are reported from the northeastern and upper midwestern United States (shown). The prognosis for treated Lyme disease is excellent. The patient in this case remained hemodynamically stable with a normal blood pressure in the ED, and he did not require transcutaneous pacing. He received intravenous ceftriaxone and was admitted to the cardiac care unit for Lyme disease-associated third-degree AV block. The block resolved over the treatment course, and the patient was discharged to home in good condition. |
