A 32-year-old otherwise healthy Hispanic man from Chile was brought in by Emergency Medical Services for multiple and brief episodes of spontaneous loss of consciousness, lasting 20-40 seconds each over the previous 2 days prior to admission. He denied shortness of breath, impaired exercise tolerance, diaphoresis, orthopnea, paroxysmal nocturnal dyspnea, headache, nausea, fever, chills, cough, sore throat, flu-like symptoms, skin rash, arthralgias, leg swelling, trauma, or seizures. However, he reported feeling that his heart skipped beats occasionally (irregular heartbeat) but denied chest pain and dizziness.
On further questioning, the patient admitted to have gone on a camping trip in a wooded area, but denied any tick or spider bite. Incidentally, he also recalled having been bitten by a fish on his right leg during swimming about a month ago and was treated with an antibiotic.
Social history: Patient was a furniture deliverer. Besides smoking 1/2 pack of cigarettes per day for 10 years, he also admitted to recent use of marijuana, cocaine, and alcohol. He was sexually active with one female partner and practiced safe sex.
Family history: Mother had hypertension, but denied any sudden cardiac death in the family.
Vital signs: Oral temperature, 97.7 F; pulse, 45 beats per minute (bpm); blood pressure, 139/88 (sitting and standing); respiratory rate, 16 breaths per minute; and oxygen saturation by pulse oximetry was 98% while breathing room air.
Head: Normocephalic and no trauma noted. Examination of the head, eyes, ears, nose, and throat were normal.
Neck: No jugular venous distention, rigidity, or lymphadenopathy was noted.
Lungs: Bilateral fair air entry without rales or wheezes.
Heart: Bradycardia with variable first heart sound and normal S2, but no murmurs, rubs or S3 were noted.
Abdomen: Bowel sounds present, soft and nontender. No hepatomegaly or abdominal bruits noted.
Extremities: There was no edema or clubbing. No effusion or joint tenderness noted. A residual old healed scar behind the right leg was noted. Peripheral pulses were full.
Skin: No rash or ecchymoses noted.
Neurological exam: The neurological examination was nonfocal. There was no asterexis.
On arrival in the emergency department, the patient was found to have a heart rate of 40 bpm and the initial electrocardiogram showed a bifascicular block (Figure 1). The patient continued to have transient, witnessed episodes of loss of consciousness with normal and stable blood pressure. He was hospitalized for continuous cardiac monitoring that showed progression to bifascicular block and subsequently to complete heart block with ventricular escape within the first hour. Subsequently, the patient had a brief episode of asystole, lasting for 30 seconds. He was given atropine 1 mg by IV push and continued to have asystolic episodes briefly without hemodynamic compromise.
In the first few hours of cardiac monitoring, the patient had fluctuating variable atrioventricular (AV) blocks: first degree AV block with prolonged PR interval, Wenckebach type-2, a higher degree block with 5:1 block, and a complete heart block with ventricular escape (Figure 2).
As the patient had persistent complete heart block with recurrent loss of consciousness without hemodynamic compromise, a transcutaneous pacemaker was placed and subsequently a transvenous pacemaker was placed with good capture (Figure 3).
Results of a complete blood cell count, serum chemistry panel, liver function profile, lipid profile, urine analysis, serum alcohol level, emergency toxicology, drugs of abuse urine, and cardiac enzymes for all normal. Erythrocyte sedimentation rate was 15, but C-reactive protein was elevated (Table 1).
Chest radiograph showed no active disease, infiltrates or effusion. A transthoracic echocardiogram showed concentric left ventricular hypertrophy with normal left ventricular systolic function without any pericardial effusion, possibly due to the strenuous nature of his work. However, it showed right ventricular enlargement and abnormal septal motion consistent with conduction abnormality. A gallium scan was performed that showed increased uptake, suggestive of myocarditis.
Of the various diagnostic markers in this patient (Table 2), screening for Lyme disease was positive with Lyme titer Ab elevated at 2.25. The diagnosis of Lyme carditis was confirmed on the 5th day when the Western blot results were found to be positive for Lyme disease.
The patient was started on intravenous ceftriaxone 2 gm/day with continuous cardiac monitoring. Subsequently, patient symptoms improved from complete block to 2:1 AV block, and eventually to sinus bradycardia 1st degree block. However, within 3 days of treatment with ceftriaxone, the patient had a remarkable improvement in symptoms and remained completely asymptomatic
After 14 days of intravenous ceftriaxone, continuous cardiac monitoring of the patient showed remarkable improvement with sinus bradycardia at 50 bpm with 1st degree AV block without any further episodes of asystole or complete heart block, or any symptoms of loss of consciousness (Figure 4).
The patient was discharged home on amoxicillin 500 mg PO tid for another 4 weeks. During subsequent followups at 1 month and 3 months after the antibiotic treatment, the patient showed normal sinus rhythm with 1st degree AV block.