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Spontaneous Resolution of Sinoatrial Exit Block and Atrioventricular Dissociation in a Child with Dengue Fever Kaushik J S, Gupta P, Rajpal S, Bhatt S

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Spontaneous Resolution of Sinoatrial Exit Block and Atrioventricular Dissociation in a Child with Dengue Fever Kaushik J S, Gupta P, Rajpal S, Bhatt S Case Report Singapore Med J 2010; 51(9) : e146 Spontaneous resolution of sinoatrial exit block and atrioventricular dissociation in a child with dengue fever Kaushik J S, Gupta P, Rajpal S, Bhatt S ABSTRACT her heart rate was regular at 92/min, respiratory rate at Cardiac rhythm abnormalities, including 22/min and blood pressure (BP) at 110/74 mmHg. There ventricular arrhythmia, atrial fibrillation and was a petechial rash over the patient’s back, trunk and atrioventricular block, have been observed upper extremities. The Hess test (tourniquet test) for during the acute stage of dengue haemorrhagic capillary fragility was positive. Systemic examination fever. Atrioventricular or complete heart did not reveal any abnormality. block can be fatal and may require a temporary Investigations revealed normal haemoglobin (12.1 pacemaker. We report a ten-year-old girl who g/dl), haematocrit (35.2%) and leucocyte (6500/cumm) presented with dengue haemorrhagic fever counts, while the platelet count was observed to be with sinoatrial block and atrioventricular low (38000/cumm). Dengue serology was reactive dissociation that had a spontaneous resolution. for immunoglobulin G (IgG) and immunoglobulin M (IgM), suggesting acute primary infection. The liver Keywords: atrioventricular block, enzymes and renal profile, including serum electrolytes, atrioventricular dissociation, dengue were normal. The patient was managed supportively haemorrhagic fever, rhythm abnormality, according to the World Health Organization (WHO) sinoatrial block recommendations for management of dengue Singapore Med J 2010; 51(8): e146-e148 haemorrhagic fever.(3) The following day, the patient was observed to have INTRODUCTION bradycardia (pulse rate 50/min, regular), with normal Dengue fever is a viral infection that is transmitted BP. The heart sounds were normal, and there were no by the mosquito, Aedes aegypti and characterised new cardiovascular findings. Electrocardiography by fever, myalgia, arthralgia, rash, leucopaenia and (ECG) revealed a rate of 44/min and varying PP Department of (1) Paediatrics, thrombocytopaenia. Cardiac rhythm abnormalities, intervals (an absence of normally expected P waves), University College of including sinus bradycardia, ST-T changes, prolonged which was suggestive of SA block, with no relation Medical Sciences, Dilshad Garden, PR interval, bundle branch block and complete heart (dissociation) between P waves (atrial activity) and Delhi 110095, India block, have been uncommonly observed in dengue QRS complex (ventricular activity) indicative of AV (2) Kaushik JS, MD haemorrhagic fever. However, sinoatrial exit block has dissociation. Chest radiography was normal, with a Registrar not been previously reported in children with dengue regular heart size. Echocardiography revealed normal Gupta P, MD, FIAP fever. We report dengue haemorrhagic fever in a child, cardiac valves, left ventricular systolic and diastolic Professor with sinoatrial (SA) block and atrioventricular (AV) functions, and cardiac chamber dimension. There was Bhatt S, MD dissociation with a structurally normal heart. no evidence of pericardial effusion or vegetations. In the Registrar presence of rhythm disturbances, the patient was further Department of Medicine, University College of CASE REPORT investigated for underlying myocarditis. The creatinine Medical Science, phosphokinase (CPK) and lactate dehydrogenase (LDH) Guru Teg Bahadur A ten-year-old girl presented to our centre during a Hospital, dengue fever outbreak in Delhi, with complaints of levels were 172 U/dL (normal ≤ 130 U/dL) and 776 Dilshad Garden, Delhi 110095, fever, abdominal pain and vomiting of one week’s U/dL (normal ≤ 330 U/dL), respectively. The serum India duration. There was no history of myalgia and bone or potassium and calcium levels were found to be normal. Rajpal S, MD joint pains, nor was there a history of rash or bleeding The patient’s heart rate during the hospital Specialist from any site. There was no past history of arrhythmia stay remained at 46–54/min, but the BP and other Correspondence to: Dr Jaya Shankar Kaushik or cardiac disease. The urine output was adequate. On haemodynamic parameters were normal. The patient Tel: (91) 98711 74069 examination, the patient was lethargic and febrile, but was asymptomatic, and her vital signs were closely Fax: (91) 11 2259 0495 Email:jayashankarkaushik not dehydrated. The vital signs were stable at admission; monitored for the development of any complications. @gmail.com Singapore Med J 2010; 51(9) : e147 She was discharged after eight days, with a heart rate ECG. To the best of our knowledge, SA exit block has of 52/min and a normal BP, and the ECG showed a not been reported in cases of dengue fever to date. persisting complete AV block. The patient was kept The presence of bradycardia and elevated cardiac on close follow-up for one week, during which her enzyme levels (LDH and CPK) was consistent with a bradycardia and complete AV block persisted. A diagnosis of myocarditis,(15) although there were no follow-up after five months showed a normal heart signs of cardiogenic shock or congestive heart failure. rate (82/min). ECG reverted to a normal sinus rhythm, The co-existence of SA block with AV dissociation on and the echocardiography was also normal. ECG could possibly explain the rhythm abnormalities associated with myocarditis in our patient. The presence DISCUSSION of fever, a positive tourniquet test, thrombocytopaenia, Dengue fever is a major cause of morbidity and and positive IgG and IgM titres for dengue virus mortality in the South East Asia region, including prompted us to suspect dengue virus as the probable in India.(4) Massive bleeding and shock are the most causative agent. AV conduction abnormalities secondary common causes of death. Cardiac manifestations of to myocarditis are also observed in infections with dengue fever may play a role in the pathogenesis of Diphtheriae, Yersinia, Borrelia (Lyme disease) and shock and could influence the outcome of the disease. Trypanosoma (Chagas disease).(16) However, the cardiac manifestations in dengue are Arboviral infection can cause myocardial damage, invariably benign, transient and self-limited, and either by direct invasion or an autoimmune reaction, are attributed to subclinical viral myocarditis.(5) which results in myocarditis.(17) Myocarditis can manifest Approximately 90% of patients with viral myocarditis with complete AV block or ventricular arrhythmias, which recover completely, and only few patients develop might manifest as syncope or palpitations.(17) However, long term sequelae. During the latent period, the our patient did not develop any cardiac symptoms. virus can trigger an autoimmune reaction that may Dengue virus-induced myocarditis could apparently progressively destroy myocardial tissue, leading to explain the SA block and AV dissociation observed in dilated cardiomyopathy. our case. Cardiac rhythm disturbances, such as bradycardia Approximately 40% patients recover from and ventricular ectopics, are known to occur during the rhythm abnormality in myocarditis.(17) It is the convalescence period.(1) ECG changes in dengue postulated that patients with fewer symptoms have haemorrhagic fever include sinus bradycardia, ST segment a better prognosis and that complete resolution can elevation and non-specific ST-T changes.(5,6) Most of these be expected, as observed in our case.(15) Acute high changes are transient and revert to normal at follow-up. SA, grade AV blocks occasionally respond to atropine AV and bundle branch blocks, AV dissociation, complete and isoproterenol.(16) These drugs were not used in heart block and premature ventricular contraction have our patient due to the dangerous slow escape rhythms been described in a series of 218 cases of biopsy-proven associated with them. In view of the inadequate viral myocarditis.(7) Rhythm abnormalities reported escape rhythms and persistent bradycardia, temporary in dengue fever include complete AV block,(6) first- cardiac pacing was advised for our patient. However, degree AV block,(8) atrial fibrillation,(9) Mobitz type I owing to cost constraints, the patient’s parents did second-degree AV block,(10) ventricular arrhythmia(11) not opt for pacemaker implantation and preferred and sinus node dysfunction.(12) Abnormal right and left conservative medical management instead. This is ventricular functions, left ventricular hypokinesia, mitral acknowledged as a known limitation of patient care in regurgitation and pericardial effusion have also been developing nations. The patient was kept under close documented in dengue fever using echocardiography.(5,13) follow-up, and spontaneous resolution was observed An SA exit block refers to a block of impulses after five months. The rhythm abnormalities in dengue from the SA node to the atria. The block can be fever tend to be benign and self-limited, and resolve physiological if the initiating impulse is premature in the majority of patients at discharge or on follow- and arrives at the cardiac site during the normal up. Patients with advanced AV blocks and who are refractoriness, or it can be pathological in cases of symptomatic rarely require a pacemaker implantation. abnormally long refractory periods or abnormally slow conduction velocity.(14) An SA node exit block REFERENCES is characterised by progressive lengthening of the 1. Halstead SB. Dengue fever and dengue hemorrhagic fever. PR interval, varying PP interval or absent P wave on In: Kliegman RM, Behrman
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