Critical cardiac arrhythmias secondary to acute dengue fever are rare in adults
and are likely to be underestimated. We present the first case of acute dengue
fever complicated by recurrent sinus pauses and sinoatrial arrest requiring
temporary pacing in the absence of other cardiac involvement. Early intervention
to detect such arrhythmias may reduce the significant morbidity and mortality
arising from this increasingly prevalent infection.
Dengue, Cardiac Pacing, Cardiac magnetic resonance imaging
Dengue is an arthropod borne viral illness prevalent in tropical and subtropical
climates. The rising incidence of dengue infection represents an important
global health issue. Critical cardiac conduction complications complicating
dengue infection are infrequent in adults. We present a case of dengue fever
complicated by sinus arrest requiring temporary cardiac pacing.
A previously well 35-year-old male commercial airline pilot presented with a
two-day history of fevers, myalgia and macroscopic haematuria. He had returned
from Bali, Indonesia five days prior to presentation, having sustained multiple
mosquito bites during the trip. On examination, he was febrile with a
temperature of 38.6°C, heart rate was 75 bpm and blood pressure were 114/69
mmHg. A diffuse, macular, blanching rash was evident over his torso. Initial
laboratory investigations demonstrated a lymphopenia (lymphocytes 0.3 x 109/L)
and mild thrombocytopenia (platelets 141x109/L). His creatine kinase was
markedly elevated at 25,794 U/L. Liver function tests demonstrated a moderate
transaminitis (ALT 140 U/L, AST 648U/L). Infectious mononucleosis screen, thick
and thin films for malaria parasites and malaria antigen testing were negative.
He was admitted to hospital for further investigation and management.
Further investigations including blood cultures and serology for Zika virus, HIV
and Hepatitis A, B and C were negative. His dengue serology was positive for NS1
antigen and negative IgM and IgG (SD BIOLINE Dengue DUO®), with
subsequent seroconversion for dengue IgG and IgM by neutralization assay
confirming an acute and primary infection of dengue virus 3.
On day two of his admission, he had a syncopal episode post vomiting, with
preceding dizziness. His electrocardiogram demonstrated sinus bradycardia (heart
rate 48bpm) post episode. He was placed on cardiac monitoring and subsequently
experienced another syncopal episode while seated at rest. Cardiac monitoring
demonstrated a 10.2 second sinus pause [Figure 1a]. On the same day, during a
third syncopal episode while seated, cardiac monitoring demonstrated an 18.1
second episode of sinus arrest [Figure 1b]. Isoprenaline infusion was commenced,
and a temporary pacing wire was inserted, with pacing set to a VVI rate at
40min/min. Serial high sensitivity Troponin T and transthoracic echocardiography
were normal. He remained haemodynamically stable with persistent sinus
bradycardia (40-60bpm). The temporary pacing wire was removed on day five, when
no further arrhythmias or pacing were seen.
Figure 1. Electrocardiograms. (A) Cardiac monitoring
10.2 second sinus pause. (B) Cardiac monitoring demonstrated an 18.1 second
of sinus arrest.
Cardiac magnetic resonance imaging demonstrated normal cardiac size and function,
with no evidence of myocarditis or myocardial oedema. An implantable loop
recorder was inserted prior to discharge to monitor for any further cardiac
events. At discharge, his creatine kinase, white cell count and platelet count
normalised. Due to the episodes of sinus arrest with syncope, he was restricted
from driving and flying until further review.
At one year follow up, the patient experienced no further syncopal events.
Interrogation of his loop recorder did not demonstrate any further
bradyarrhythmia, and his loop recorder was subsequently removed. He resumed
driving and flying.
Although poorly recognized in adults, cardiac manifestations of dengue virus
infection are an important contributor to dengue related morbidity and mortality
 [Table 1]. These include myocarditis most commonly, but also pericarditis,
heart failure  and conduction abnormalities [2,3]. Whilst the underlying
mechanism of dengue related cardiac rhythm abnormalities is not fully
understood, it likely arises from myocardial inflammation from direct viral
infection and immune-mediated damage. The inflammatory processes involving
myocytes and the interstitium can alter membrane potentials and calcium
homeostasis . Additionally, changes in myocardial wall tension and oxygen
consumption may promote arrhythmias. Similarly, dengue related myocyte fibrosis
and atrophy may induce ectopic pacemaker activity . Host response to viral
infection and the subsequent release of cytokines are also thought to be
contributory factors in arrhythmias. Elevated tumor necrosis factor-α,
interleukins 6, 13 and 18, and cytotoxic factors that lead to increased vascular
permeability and shock , may also play a role in the development of
myocardial cell injury. Both cardiac and skeletal muscle have been identified as
sites of dengue virus replication, and there is evidence for this in our case as
our patient experienced a severe bradyarrhythmia as well as rhabdomyolysis with
a markedly elevated creatine kinase. Rhabdomyolysis and cardiac abnormalities
have been reported in dengue fever  but to our knowledge this is the first
reported case with both such manifestations simultaneously. Interestingly in our
case, sinus arrest occurred without other apparent cardiac involvement, as
manifested by a normal troponin and cardiac MRI.
Table 1. Clinical Manifestations.
- Headache, Eye pain
- Myalgia, Arthralgia, Macular Rash
- Severe complications in a small proportion of patients
- Systemic vascular leak syndrome characterized by
leakage, bleeding, shock and organ impairment
- Haemorrhagic manifestations
- Moderate-to-severe thrombocytopenia
- Recovery stage with vital signs stabilising
- Anorexia, nausea
- Abdominal pain
- Skin and/or mucosal bleeding
- Petechiae or ecchymoses
- Leukopenia and thrombocytopenia
- Sore throat
- Nasal congestion
- Heart failure
- Conduction abnormalities: sinus bradycardia, first degree AV
block, Mobitz type I and type II second-degree AV block,
complete heart block, ventricular arrhythmia and sinus node
- T wave and ST-segment abnormalities,
- Acute kidney injury
- Acute tubular necrosis
The majority of cardiac rhythm abnormalities in dengue fever have been reported
in children, with few case reports in adults. Rhythm abnormalities occur in up
to 30% of hospitalized patients, with sinus bradycardia the most frequent
abnormality . Other ECG changes include T wave and ST-segment abnormalities,
first degree AV block, Mobitz type I and type II second-degree AV block,
complete heart block, ventricular arrhythmia, and sinus node dysfunction. The
majority of these are transient in nature; one case recovered after 5 months,
and one case required a permanent pacemaker. In most cases these abnormalities
have been described in association with severe dengue and typically occur during
the recovery phase but can occur at any time during the illness. It is rare for
patients to require specific treatment for arrhythmias experienced because of
dengue fever and almost all completely recover as their illness resolves. Sinus
pauses have been described in dengue fever , but the prolonged duration of
pauses as well as the severe symptomatic nature of the pause are unique to our
case. It is also extremely rare for patients to require temporary transvenous
temporary cardiac pacing for the management of arrhythmias during dengue
infection . Our patient experienced a good long-term outcome with no
post-infection arrhythmias, avoiding the need for permanent pacemaker
implantation or change in career.
Critical cardiac arrhythmias secondary to acute dengue fever are rare in adults
and are likely to be underestimated. To our knowledge, we report the first case
of acute dengue fever complicated by recurrent sinus pauses and sinoatrial
arrest requiring temporary pacing in the absence of other cardiac involvement.
Early intervention to detect such arrhythmias may reduce the significant
morbidity and mortality arising from this increasingly prevalent infection.
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