What causes fast heart rate in newborns

Apnea (ap'-nee-ah) is a pause in the regular breathing of a baby lasting longer then 15-20 seconds. Normal breathing may speed up or slow down but usually does not stop for any length of time. Some infants, especially premature babies, may have times when they stop breathing for longer than normal. During the pause, the baby's heart rate may slow and, if the apnea is severe, the baby's skin color may change. The baby may look pale or blue. The pause in breathing may be just for a short time, and the baby may restart breathing without help. If the pause occurs for a longer period, the baby may need a reminder to restart breathing.
Bradycardia (bray-dee-car'-dee-ah) is the medical term for a heart rate that is too slow. How slow is too slow varies. Babies usually have heart rates faster than adults do; so a heart rate of 80 may be fine for an adult but may be low for a newborn. Also premature babies tend to have faster heart rates than full term babies do and the heart rate tends to decrease with age after birth. In general, a heart rate of 120-160 is normal for a premature and 80-140 for a full term.

What causes apnea?

Apnea is most common in premature babies because their nervous system has not finished developing. The brain has a special area, called the respiratory center, which tells the lungs to take a breath on a regular basis. If this area is not mature, the baby may forget to breathe. About 45 percent of babies weighing less than 5 ½ pounds will have at least some apnea. If the baby was less than 2 ½ pounds up to 85 percent will have apnea in the first few weeks of life. They may also have apnea if overheated or cold or just over-stimulated. Apnea can also be due to other causes, especially in term babies, so the doctors and nurses may check the baby to rule out other causes before saying the baby has Apnea of Prematurity.

What causes bradycardia?

Most infants have bradycardia for the same reasons they have apnea. And often bradycardia results from the baby having apnea. But other medical problems can sometimes be the cause; therefore, babies who have these episodes need to be evaluated.

What other things can cause apnea and bradycardia?

Most apnea and bradycardia episodes are due to prematurity but many other medical conditions can cause these problems; so infants with episodes are usually checked for these problems. This is especially true if the baby is a term infant.

Infection - infection is a fairly common cause and is often looked for if a baby develops apnea.

Low blood sugar.

Low blood oxygen.

Environmental factors - high or low body temperature, over-stressing or excessive handling of a very premature infant.

Airway problems - any kind of block in the airway or nose, including mucous, can cause problems especially in a premature.

Neurological problems

How do I know if my baby has apnea or bradycardia?

Babies that are known to be at risk for these episodes are placed on monitors that are set to alarm if the breathing or heart rate go below certain limits.

What happens if the alarm goes off?

The alarm tells the staff that the baby needs to be checked. Not every alarm means the baby is having a problem; loose wires, a lot of movement and poor connections can all cause alarms. The alarm is to let us know to check the baby.

The staff checks the breathing, heart rate, and color. If the baby is fine, then the monitor is checked to see if it is working right.

If the baby is having apnea or bradycardia, then the nurse will watch to see if the baby will restart breathing. If breathing does not restart, then the nurse may gently rub or stimulate the baby to breathe. Often this gentle action is all that is needed.

If the baby's color is blue, extra oxygen may be given.

If the baby still doesn't breathe, then the staff may help the baby breathe.

Is there any treatment for apnea and bradycardia?

First, your baby is checked for how often the events occur, how long they last, how much stimulation is needed and if there may be other causes such as infection, low oxygen, etc. If the baby has only occasional episodes that respond to gentle stimulation, no further treatment may be needed except to monitor the baby until the episodes stop happening. If the events are due to infection or other problems, then treating the problem will often clear the episodes.

If the episodes are frequent, require more than gentle stimulation, or are likely to continue for a time (as in a very premature baby), then several treatments may be tried:

Medicines such as caffeine, theophylline, or aminophylline are often used.
Continuous nasal airflow or CPAP (which is oxygen under pressure) may be blown through a plastic nosepiece or mask into the nose.
Ventilation or breathing for the baby with a machine may be needed if the events are severe.

Will apnea and bradycardia cause brain damage?

NO! While long periods of apnea and low heart rate can cause problems, the short periods that most infants have will not cause brain damage. Anyone can hold his breath for a short time without a problem. The monitors are usually set to alarm after 20 seconds; this allows the staff enough time to check the baby, and to help if needed.

Do these episodes mean my baby will have SIDS (Sudden Infant Death Syndrome)?

NO! The episodes seen in the nursery are not the same as SIDS, which is usually seen in previously healthy full term infants. Apnea of prematurity is usually due to immaturity of the respiratory center and as the baby matures so will this center. By the time your baby is ready to go home, these events will most likely have stopped. Most apnea and bradycardia due to other causes should also have stopped by the time of discharge.

What if the episodes haven't stopped when my baby is ready to go home?

Most babies will have stopped having events by the time they are ready to go home. If your baby is at risk or is still having occasional brief episodes that recover quickly, then a home apnea monitor may be an option. If your baby needs a monitor:

Most medical insurance companies will pay for home monitors.
The company providing the monitor usually teaches you how to use their particular monitor.
Infant CPR classes may be offered and are a good idea for all parents. Follow-up with an Apnea Center or physician who can read the monitor downloads is usually arranged.

Can apnea come back or can my baby develop SIDS?

Once premature babies with apnea mature, they should stop having events and usually are not at risk for the episodes to come back. However, some babies are slower to mature and some babies who have other medical conditions may be at increased risk of having on-going events. Home apnea monitoring and/or medicines may be needed for these infants.

While apnea of prematurity and SIDS are different problems, some babies who need NICU care may have a slight increased risk of later SIDS. We cannot predict which infants are at risk; there is no guarantee that a baby will not develop SIDS later. But the vast majority of infants will not be at risk and will not need monitors.

Is there anything I can do to help prevent SIDS or apnea at home?

There are several things that can be done at home to decrease any baby's risk.

BACK TO SLEEP - babies should be placed on their backs when you put them to sleep or when they are in their cribs.

DON'T SMOKE - infants of parents that smoke have increased risk of SIDS and also have more breathing problems. If you can't stop, at least don't smoke around the baby or in the house.

Breast Feed - infants who have been breastfed seem to have less SIDS.

Avoid pillows or soft mattresses in the crib and do not over bundle or over dress a baby.

Ask you baby's doctor or nurse if you have further questions about your baby.

What does it mean when a baby's heart rate is too fast?

If the heart beats too fast, contractions are shallow and not enough blood is pumped with each heartbeat. As a result, the fetus can go into heart failure. The most common form of this condition is called supraventricular tachycardia (SVT), in which the heart rate can be faster than 200 beats per minute.