Tick Tock

Abstract

Multiple clinical findings can point to an uncharacteristically advanced presentation of a common disease. This was the case with a 20-year-old white man who had a past medical history of narcolepsy and allergic bronchial asthma. Recently, he had returned to New York after finishing a job as a camp counselor in Minnesota. The patient presented to the Emergency Department complaining of cardiac palpitations that had occurred over several hours. He had a 2-week history of headaches and migratory arthralgias, and several areas were marked by a tender macular blanching rash that exhibited central clearing. His family history consisted of hypertension in his father and myocardial infarction in his grandfather. He denied alcohol, tobacco, or recreational drug use. An electrocardiogram (ECG) was taken upon the patient's arrival in the Emergency Department, and a subsequent ECG was taken several hours later when he reported worsening palpitations (Figure 1, Figure 2). The ECG changes demonstrated the severity of the patient's condition, and that one disease process might be responsible for his signs and symptoms.Figure 2A second electrocardiogram was ordered when the patient said that his palpitations were worsening.View Large Image Figure ViewerDownload Hi-res image Download (PPT) At admission, the patient's vital signs were: temperature 37.8°C (100°F); pulse 85 beats per minute; respiratory rate 20 breaths per minute; blood pressure 112/75 mm Hg; and oxygen saturation 100% on 1.5 L/min. A macular blanching rash with central clearing was evident on several large areas (>5 cm). These were more prominent on the lower extremities. Cardiac auscultation revealed an irregular rate with normal S1 and S2. No rubs, murmurs, or gallops were noted. Results of a chest radiograph, complete metabolic panel, cerebral spinal fluid test, and urine analysis were normal. The following day, an echocardiogram revealed increased left ventricular diastolic and systolic cavity size, reduced left ventricular systolic function, a left ventricular ejection fraction of 35%, and a Doppler cardiac output of 5.15 L/min. Cardiac magnetic resonance imaging (MRI) disclosed increased signal intensity in the septum and anterior wall on T2-weighted double-inversion recovery images, a small focus of delayed enhancement in the apical septum, and no regional wall motion abnormalities. The patient's ECG changes, echocardiogram, MRI results, and dermatologic findings pointed to early disseminated Lyme disease with erythema migrans and atrioventricular (AV) conduction involvement. According to the initial ECG, the patient had a normal sinus rhythm with a PR interval of 280 ms, QRS duration of 98 ms, and heart rate of 87 beats per minute. These signs indicated first-degree AV block (Figure 1). When the patient complained of worsening palpitations several hours later, a subsequent ECG showed sinus rhythm at a rate of 100 beats per minute, as calculated by the rate of atrial depolarizations (Figure 2). This ECG also showed high-grade AV block with intervals of consecutive nonconducted P waves and a PR interval of 320 ms for conducted P waves. The overall ventricular rate was slower than the rate of atrial depolarization because of nonconducted P waves. Lyme borreliosis is the most common tick-borne infection in the Northern Hemisphere. This potentially systemic infection is caused by the spirochete, Borrelia burgdorferi, which is transmitted by the Ixodes scapularis deer tick. In parts of Minnesota, more than 20% of Ixodes scapularis ticks carry B. burgdorferi.1Wormser G.P. Dattwyler R.J. Shapiro E.D. et al.The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America.Clin Infect Dis. 2006; 43: 1089-1134Crossref PubMed Scopus (1558) Google Scholar The diagnosis was confirmed in our patient by the presence of serum Lyme immunoglobulin G (IgG) and IgM antibodies, which positively identify 40%-60% of patients in the first few weeks of infection.2Steere A.C. Taylor E. Wilson M.C. Levine J.F. Spielman A. Longitudinal assessment of the clinical and epidemiological features of Lyme disease in a defined population.J Infect Dis. 1986; 154: 295-300Crossref PubMed Scopus (182) Google Scholar However, Lyme borreliosis, in the absence of microbiologic findings, can be diagnosed on the basis of physical examination findings, history of present illness, and identifiable risk factors. Lyme disease is divided into 3 stages. Stage 1 presents most commonly 2 weeks after the initial infection with erythema migrans.1Wormser G.P. Dattwyler R.J. Shapiro E.D. et al.The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America.Clin Infect Dis. 2006; 43: 1089-1134Crossref PubMed Scopus (1558) Google Scholar Approximately two thirds of patients progress to stage 2, which can involve cardiac or neurologic abnormalities, weeks to months later.3Meyerhoff J.O. Lyme disease.http://emedicine.medscape.com/article/330178-overviewGoogle Scholar Stage 3 presents months to years later and classically involves the musculoskeletal system, with the potential for late neurologic abnormalities. Cardiac involvement is estimated to occur in approximately 4%-10% of untreated adults in the US, and it becomes clinically apparent 3 weeks after the onset of erythema migrans.4Cox J. Krajden M. Cardiovascular manifestations of Lyme disease.Am Heart J. 1991; 122: 1449-1455Abstract Full Text PDF PubMed Scopus (80) Google Scholar, 5Steere A.C. Batsford W.P. Weinberg M. et al.Lyme carditis: cardiac abnormalities of Lyme disease.Ann Intern Med. 1980; 93: 8-16Crossref PubMed Scopus (401) Google Scholar Lyme carditis is defined as acute AV conduction disturbance, usually above the bundle of His, myocarditis, or pancarditis.5Steere A.C. Batsford W.P. Weinberg M. et al.Lyme carditis: cardiac abnormalities of Lyme disease.Ann Intern Med. 1980; 93: 8-16Crossref PubMed Scopus (401) Google Scholar, 6Sigal L.H. Early disseminated Lyme disease: cardiac manifestations.Am J Med. 1995; 98: 25S-28SAbstract Full Text PDF PubMed Scopus (70) Google Scholar, 7EUCALB 1997-2005. European Union Concerted Action on Lyme Borreliosis.http://meduni09.edis.at/eucalb/cms/index.php?option=com_content&task=view&id=42&Itemid=73Google Scholar The most common presentation consists of varying degrees of AV conduction block. Patients usually complain of dizziness, shortness of breath, substernal chest pain, and palpitations.5Steere A.C. Batsford W.P. Weinberg M. et al.Lyme carditis: cardiac abnormalities of Lyme disease.Ann Intern Med. 1980; 93: 8-16Crossref PubMed Scopus (401) Google Scholar ECG findings include T-wave flattening or inversions in the lateral and inferior leads.5Steere A.C. Batsford W.P. Weinberg M. et al.Lyme carditis: cardiac abnormalities of Lyme disease.Ann Intern Med. 1980; 93: 8-16Crossref PubMed Scopus (401) Google Scholar The MRI and echocardiogram findings show a reduced left ventricular ejection fraction of 42% and 35%, respectively, which is typical for Lyme carditis; these findings are consistent with the septal and anterior wall edema seen in myocardial inflammation.5Steere A.C. Batsford W.P. Weinberg M. et al.Lyme carditis: cardiac abnormalities of Lyme disease.Ann Intern Med. 1980; 93: 8-16Crossref PubMed Scopus (401) Google Scholar The small focus of delayed enhancement and high T2 signal intensity in the myocardium on MRI has recently been reported to coincide with local myocarditis in patients affected with Lyme carditis.8Munk P.S. Ørn S. Larsen A.I. Lyme carditis: persistent local delayed enhancement by cardiac magnetic resonance imaging.Int J Cardiol. 2007; 115 (Accessed September 2009): e108-e110http://www.internationaljournalofcardiology.com/article/S0167-5273(06)00653-X/abstractAbstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar Although the cause of the AV nodal dysfunction in Lyme carditis is unknown, these MRI results correlate with autopsy findings of transmural lymphoplasmacytic infiltrate, necrosis of myocardial fibers, and spirochetes in the endomysial space of myocardial cells.9Stanek G. Klein J. Bittner R. Glogar D. Isolation of Borrelia burgdorferi from the myocardium of a patient with longstanding cardiomyopathy.N Engl J Med. 1990; 322: 249-252Crossref PubMed Scopus (213) Google Scholar Molecular mimicry by an immune-mediated reaction to myosin also has been postulated.10de Koning J. Hoogkamp-Korstanje J.A. van der Linde M.R. Crijns H.J. Demonstration of spirochetes in cardiac biopsies of patients with Lyme disease.J Infect Dis. 1989; 160: 150-153Crossref PubMed Scopus (81) Google Scholar, 11Raveche E.S. Schutzer S.E. Fernandes H. et al.Evidence of Borrelia autoimminuty-induced component of Lyme carditis and arthritis.J Clin Microbiol. 2005; 43: 850-856Crossref PubMed Scopus (44) Google Scholar The Electrophysiology service admitted the patient to the Coronary Care Unit, where he was monitored on continuous telemetry for 1 week. Progression to complete AV block, QT interval prolongation, tachyarrhythmias, and potentially, asystole, are associated with an initial presentation of first-degree AV block with a PR interval >0.3 seconds.4Cox J. Krajden M. Cardiovascular manifestations of Lyme disease.Am Heart J. 1991; 122: 1449-1455Abstract Full Text PDF PubMed Scopus (80) Google Scholar Patients who initially present with first-degree AV block may unexpectedly progress to second-degree or complete heart block within minutes.12Peters A.J. Dijkmans B.A.C. Sedney M.I. et al.Lyme borreliosis: a hidden cause of heart lock in pacemaker treated males.Poster presented at IV International Conference on Lyme Borreliosis; Stockholm, Sweden. 1990; Google Scholar Some patients also show escape rhythms, brief asystole, and fluctuating bundle branch block with transient His-Purkinje involvement.5Steere A.C. Batsford W.P. Weinberg M. et al.Lyme carditis: cardiac abnormalities of Lyme disease.Ann Intern Med. 1980; 93: 8-16Crossref PubMed Scopus (401) Google Scholar Curiously, while there is a slight predominance in the incidence of Lyme disease in men, there is a 3:1 male-to-female preponderance for Lyme carditis.13Steere A.C. Lyme disease.N Engl J Med. 1989; 321: 586-596Crossref PubMed Scopus (1347) Google Scholar AV block with left ventricular dysfunction frequently resolves over the course of 1-6 weeks, perhaps after underlying myocardium inflammation resolves. Our patient's recovery was very typical for Lyme carditis; it consisted of a gradual progression from high-grade AV block with intervals of consecutive nonconducted P waves, to Wenckebach phenomenon, and finally, to first-degree AV block with a gradually decreasing PR interval.5Steere A.C. Batsford W.P. Weinberg M. et al.Lyme carditis: cardiac abnormalities of Lyme disease.Ann Intern Med. 1980; 93: 8-16Crossref PubMed Scopus (401) Google Scholar Current recommendations dictate that hospitalized patients with AV block be treated with a parenteral antibiotic, such as ceftriaxone, 2 grams per day, followed by doxycycline, 100 mg twice per day, for up to 21 days, which was the treatment given to our patient. He also began wearing a Holter monitor.1Wormser G.P. Dattwyler R.J. Shapiro E.D. et al.The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America.Clin Infect Dis. 2006; 43: 1089-1134Crossref PubMed Scopus (1558) Google Scholar Patients who develop third-degree heart block, as observed in approximately 50% of patients with Lyme carditis, may ultimately need a temporary pacemaker.1Wormser G.P. Dattwyler R.J. Shapiro E.D. et al.The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America.Clin Infect Dis. 2006; 43: 1089-1134Crossref PubMed Scopus (1558) Google Scholar, 14McAlister H.F. Klementowicz P.T. Andrews C. Fisher J.D. Feld M. Furman S. Lyme carditis: an important cause of reversible heart block.Ann Intern Med. 1989; 110: 339-345Crossref PubMed Scopus (214) Google Scholar While conventional management of left ventricular dysfunction involves the use of beta-blockers, this is not advised in a patient with Lyme carditis because these agents may further exacerbate AV nodal dysfunction. Four weeks after being discharged from the hospital, our patient, who was still wearing the Holter monitor, continued to have first-degree AV block with intermittent changes in P-wave morphology at night. These episodes included several brief episodes of second-degree AV block. Possible long-term consequences include persistent first-degree AV block and chronic cardiomyopathy. Accurate diagnosis of Lyme carditis is challenging and requires integration of physical examination findings, laboratory data, and reported symptoms. AV block may be the first and only sign of Lyme disease. Enzyme-linked immunosorbent assay testing is preferred for early diagnosis, but most patients are seropositive for IgG antibody only after several weeks. Lyme carditis can be diagnosed accurately with historical evidence of borreliosis, presence of erythema migrans, and characteristic ECG and cardiac MRI findings.