Bradycardia is the medical term for a low heart rate. In children, bradycardia is defined by age group. Neonates, or newborns and infants, are considered to have a bradycardia heart rate if their heart is beating less than 100 times per minute. As children get older, bradycardia limits lower, and in older teenagers and adults, bradycardia is considered when your heart rate is less than 60 beats per minute. Bradycardia in neonates and infants can be a serious condition, because it leads to decreased perfusion of all of your vital organs, which can lead to cell death.
Your heartbeat is based on an electrical conduction system in your heart. The electrical conduction system starts at the sinoatrial node, then goes to the atrioventricular node, the bundle of HIs, bundle branches and finally the Purkinje fibers. An electrical impulse travels through your heart and spreads through the ventricles and atria in order to contract your heart and push blood throughout your body. If any part of the electrical system is damaged, then your heart rate can be affected.
The sinus node or sinoatrial node is known as the pacemaker of the heart. This term is due to the fact that your heartbeat starts at the sinus node. The regular rate of the sinus node is 60 to 100 beats per minute. If the sinus node is damaged, then it can lead to bradycardia or a lowered heartbeat because the electrical conduction system of the heart will be shortened.
The majority of newborns and infants with bradycardia are asymptomatic. However, if bradycardia persists, then your baby may have signs and symptoms of poor cardiac output and poor perfusion. These symptoms include: poor weight gain and failure to thrive, decreased feeding, increased fatigue and sleepiness, and even decreased urine output. Your child’s physician will listen to their heart at each appointment to determine the rate and if there are any extra sounds (murmurs).
Bradycardia in neonates is caused by either dysfunction in the heart’s conduction system or due to intrinsic issues in the heart. It can also be caused by extrinsic factors such as those listed below.
Once bradycardia has been recognized in a neonate, the first step is to determine the underlying cause. The majority of neonatal bradycardia, especially in the delivery room, is due to respiratory issues and hypoxia. For this reason, bradycardia in neonates is often first treated with oxygen therapy or positive pressure therapy to help neonates breathe. If this does not work, then certain medications such as atropine can be given to raise the neonate’s heart rate.
Bradycardia is a dangerous vital change in neonates that is often due to an underlying cause such as hypoxia or metabolic acidosis. It is dangerous in neonates because it can lead to poor blood flow to vital organs including the baby’s brain. Bradycardia must be recognized early in order to be treated properly and improve the neonate’s overall prognosis.