An atypical heart rhythm, called arrhythmia, is a serious health concern for anyone. But heart rhythm disturbances in newborns, known as neonatal arrhythmias, can be especially concerning for parents and caregivers.

Certain types of arrhythmias pose no serious threat to your child and often disappear on their own. Other neonatal arrhythmias may require surgery and, at some point, a pacemaker to help ensure a healthy heartbeat.

It’s not always clear why a baby might develop an irregular heartbeat. Some known risk factors are associated with neonatal arrhythmias, including structural differences in the body, dehydration, and genetic mutations.

The condition affects an estimated 1 to 5 percent of all newborns.

If your child has received an arrhythmia diagnosis, working closely with a pediatric cardiologist can often lead to a positive outlook for the condition.

Your baby’s heart beats faster than yours

Unlike adults, who tend to have a resting heart rate between 60 and 100 beats per minute (bpm), infants usually have a much faster heart rate. A healthy newborn could have a sleeping heart rate of 90 to 160 bpm and an awake heart rate of 100 to 190 bpm — or even 205 bpm when crying.

Your baby’s heart beats quickly because of the circulation required for their rapid growth. Your baby also loses body heat more rapidly than older children and adults. A faster heart rate keeps blood circulating throughout their body and limbs to keep their temperature at a healthy level.

By adolescence, most children have a heart rate similar to that of an adult.

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In many cases, the actual cause of neonatal arrhythmia is unknown.

Certain factors are associated with a higher risk of arrhythmia in newborns. Some factors are temporary and easily treatable. Others may require long-term care.

Among the more common risk factors for neonatal arrhythmias are:

  • congenital structural difference
  • dehydration
  • electrolyte imbalance
  • inflammation
  • genetic mutation
  • medication side effect

Neonatal arrhythmias may be considered either benign or non-benign.

Benign arrhythmias are not life threatening. For this reason, they may not need significant treatment. They may even disappear as a child gets older.

Non-benign arrhythmias are more serious and may require treatment early in a child’s life and possibly for years afterward.

You can also categorize arrhythmias by the type of rhythm disturbance, such as:

  • too fast
  • too slow
  • too chaotic

If your newborn’s heart beats too fast

An atypically rapid heartbeat is known as tachycardia. There are a few different types of this arrhythmia, and some carry more risk than others.

The types of tachycardia are:

  • Supraventricular tachycardia (SVT). This is a disturbance just above the heart’s lower two chambers (ventricles). It’s the second most common arrhythmia in newborns. A 2019 study suggests that most supraventricular tachycardias in newborns resolve on their own and that medications may be enough to manage the condition.
  • Atrial flutter. This is an irregular beating of the heart’s upper chambers (atria) and a heart rate of between 280 and 500 bpm. A 2020 study suggests that while atrial flutter may be a life threatening condition, early prenatal diagnosis and prompt treatment can save lives. Electrical cardioversion uses special cardioversion pads placed on your baby’s chest to send electrical impulses that return the heart to a standard rhythm.
  • Wolff-Parkinson-White syndrome. This is a rare neonatal arrhythmia that develops due to an additional electrical pathway in the heart, which causes a potentially dangerous irregular heartbeat. Some children born with Wolff-Parkinson-White syndrome also have a structural anomaly. A procedure called ablation can sometimes eliminate the extra pathway.
  • Ventricular tachycardia. This is a rapid heartbeat that originates in the ventricles. It’s much less common than supraventricular tachycardia. When a ventricular tachycardia episode lasts a few seconds, it is usually harmless, but longer episodes can be life threatening.

If your newborn’s heart beats too slowly

An atypically slow heartbeat is known as bradycardia. These types of arrhythmias are less common than tachycardias in newborns. They include:

  • Sinus bradycardia. This is a slow heart rate caused by an irregular signal coming from the sinus node, the heart’s “pacemaker” and the origin of electrical impulses that cause the heart to contract. Sinus bradycardia in newborns is unusual. When it occurs, it’s often the result of gastroesophageal reflux or immature respiratory control that may resolve on its own.
  • Heart block. This refers to the blockage of an electrical impulse within the heart. It’s also known as atrioventricular block and may be temporary or permanent.

Genetic arrhythmias

Some arrhythmias are due to inherited genetic mutations, such as:

  • Long-QT syndrome. This causes rapid, irregular heartbeats. Long-QT syndrome occurs when the heart’s muscle walls take too long to relax.
  • Short-QT syndrome. This is when the heart muscle takes less time than usual to relax between heartbeats.
  • Catecholaminergic polymorphic ventricular tachycardia. This is a rare condition that can lead to fainting, especially when a child is excited or is physically active.

Benign arrhythmias

While news of any heart issue can be concerning, certain neonatal arrhythmias present few — if any — health concerns and often disappear after a few weeks or months. For example:

  • Sinus tachycardia. This is the most common neonatal arrhythmia in newborns. It starts in the sinus node and can lead to a heart rate of up to 170 bpm. Sinus tachycardia often requires no treatment, since it’s typically a response to pain, infection, or an emotional state.
  • Premature atrial contraction (PAC). This is a common condition that originates in the atria. PAC features extra heartbeats. Usually, no treatment is needed.
  • Premature ventricular contraction (PVC). This is a rare arrhythmia in infancy that results from extra heartbeats originating in the ventricles. PVC often disappears on its own within a few months. If treatment is needed, the short-term use of antiarrhythmic medications is usually enough.

Symptoms of neonatal arrhythmia can vary depending on the type of irregular heartbeat. But in general, possible symptoms include:

  • abnormally fast or slow heartbeat
  • breathing difficulties
  • irritability
  • feeding trouble
  • low energy
  • unusual sweating

When a doctor first listens to your baby’s heart, they may detect an arrhythmia. This may occur prior to birth, during an ultrasound.

For an accurate diagnosis of the type of arrhythmia, a doctor may perform the following tests:

  • electrocardiogram to measure the electrical activity within the heart
  • transesophageal echocardiogram, which uses a thin probe placed through the baby’s nose and down to the esophagus to create ultrasound images of the beating heart
  • Holter monitor, a wearable device that monitors a person’s heart rate 24 hours per day
  • implantable heart monitor, often done with children who experience sporadic symptoms

The right treatment for neonatal arrhythmia depends on the type of arrhythmia and your baby’s age and overall health.

Antiarrhythmic medications are often first-line treatments for certain arrhythmias. A 2022 study suggests that antiarrhythmic medications are often a safe and effective treatment for SVT in infants. In some cases, they may be enough to eliminate the arrhythmia permanently.

A procedure called ablation can sometimes eliminate the cause of an irregular heartbeat.

For some structurally caused arrhythmias, such as Wolff-Parkinson-White syndrome, catheter ablation may be helpful. This is when a doctor threads a catheter through to the heart. The tip of the catheter is fitted with a device that can destroy the atypical tissue using radiofrequency energy or by freezing it (cryoablation).

For heart block, a surgeon may need to implant a pacemaker to keep the heart’s electrical activity steady. As your child grows, they’ll need to replace the pacemaker.

When a congenital heart concern exists, doctors may perform open heart surgery to repair the heart or at least alleviate some of the risks. Some children will need multiple heart surgeries over a period of years to keep up with changes related to their growing heart.

The outlook for babies born with arrhythmia depends primarily on the type of rhythm difference they’re experiencing. It also depends on how early doctors diagnose and manage the arrhythmia.

A 2022 study suggests that, compared with infants with benign arrhythmias, babies with non-benign arrhythmias have higher rates of recurrence and mortality.

However, a report by the Pediatric Cardiac Intensive Care Society suggests that with early diagnosis and the right treatment at the outset, you can avoid many life threatening events and good quality of life can be possible.

The report also notes that short- and long-term care for a child with an arrhythmia may require several different treatments, including medications, implanted devices, and surgery or cardiac catheterization.

Some infants born with arrhythmia have no obvious symptoms. Some symptoms, such as difficulty feeding or fussiness, may not immediately trigger thoughts of a heart issue. Check with your baby’s pediatrician if you have concerns.

To help ensure your baby’s health and identify any concerns early on, be sure to keep up with doctor’s appointments. Ensure that a healthcare professional carefully listens to your baby’s heart.

Never hesitate to discuss symptoms and behaviors that concern you or any uneasy feelings you have, even if it’s a vague sense that something doesn’t seem right.

Doctors often detect neonatal arrhythmias at birth, but some aren’t apparent until later. Paying close attention to your baby’s breathing, energy level, feeding habits, and demeanor will give you the best chance of spotting a concern early.

Early detection leads to prompt treatment and the best possible outlook.