Neonatal bradycardia

Heart rate monitoring has become a ubiquitous part of fetal and neonatal as sessment, and has made detection of bradycardia in the fetal and neonatal p eriods a frequent occurrence. Evaluation of a fetus or neonate with bradyca rdia requires an understanding of the mechanisms of bradycardia as well as the cardiac and non-cardiac causes of bradycardia. The mechanisms of bradyc ardia include sinus bradycardia, abnormalities of sinus node function and a bnormalities of atrioventricular conduction. In the instances where sinus b radycardia is pathologic, it usually results from non-cardiac disease. Sinu s node dysfunction is rare early in life but can arise from surgical interv entions, congenital heart disease, or endovascular manipulations. Abnormali ties of atrioventricular conduction have a similar etiology but are more co mmon than sinus node disease. Atrioventricular nodal disease can also resul t from maternal collagen vascular disease, even in the absence of symptoms in the mother. In these cases, epidemiological issues such as heart block i n subsequent pregnancies and the maternal risk of developing symptomatic co llagen vascular disease become important. The approach to treatment and lon g-term prognosis for bradycardia in the neonate is highly dependent on the underlying etiology and on the presence of concurrent factors such as struc tural heart disease. (C) 2000 Elsevier Science Ireland Ltd. All rights rese rved.