Objective: We observed sinus bradycardia in a small number of children with hematologic malignancies who were recovering from sepsis. Our objective was to define this symptom complex and attempt to delineate its etiology.
Design: Retrospective chart review.
Setting: A pediatric ICU in a children's oncology hospital.
Patients: Children admitted to the ICU over a 24-month period who developed persistent bradycardia (heart rate less than 5% for age for greater than 1 hr) after an episode of sepsis.
Measurements and main results: Seven children developed postsepsis bradycardia. Six patients had a primary diagnosis of acute myelogenous leukemia and one patient had acute lymphocytic leukemia. All patients had positive blood cultures (Streptococcus mitis, n = 4; Escherichia coli, n = 2; and Klebsiella pneumoniae, n = 1). All seven children were clinically recovering from sepsis when the bradycardia developed. Neither hypotension nor other symptom was associated with the bradycardia. No therapy was given for the bradycardia. Echocardiograms and ECGs were normal in all patients, except for the presence of bradycardia. Bradycardia persisted for 24 to 72 hrs. After that time, heart rates slowly increased to the normal range for age.
Conclusions: We speculate that this syndrome may result from alterations in beta-adrenergic receptor function or an unidentified humoral factor produced by the invading organism or as part of the host's response to sepsis. Prior drug therapy or the underlying illness may predispose to this condition, since all the patients had acute leukemia. As the bradycardia was clinically insignificant, invasive therapeutic or diagnostic strategies were not indicated.