Pediatric Cardiology

Bradycardia (Slow Heart Rate): Symptoms, Causes and Treatment Options

Posted on by Prof. Dr. İbrahim Cansaran TANIDIR

Bradycardia is the condition in which the heart’s beat rate per minute falls below the lower limit determined according to the individual’s age, in other words, a slowing of the pulse. This condition, which can affect the amount of oxygen going to the organs especially in children, directly disrupts the body’s energy balance. The most common bradycardia symptoms include weakness, getting tired quickly, dizziness, feeding difficulty, and a feeling of fainting. This picture, which occurs due to slowing in the heart’s electrical conduction system or systemic problems, means that the body’s vital functions are sounding an alarm. With early diagnosis and correct evaluation, preserving the heart’s healthy working rhythm is a vital step for long-term health.

What Is Bradycardia (Slowing of the Pulse)?

When heart rhythm is mentioned, the first thing that comes to mind is the regular beats of that flawless pump working nonstop inside the rib cage. Heart rate is called pulse in medical language and is a dynamic structure that can change within seconds according to the body’s current need. Bradycardia, in its most basic and simple definition, is the condition in which this pulse falls below the lower limit considered normal for the person’s age group and beats much more slowly than expected. When the heart slows down, the amount of fresh blood pumped to the body, especially to vital organs that need high oxygen such as the brain, decreases. This decrease in blood amount prevents the organs from working at full capacity and paves the way for various problems. Bradycardia is actually not a disease on its own, but rather a sign of a problem in the heart or another part of the body, a kind of alarm system. Although this slowing of the heart does not always mean great danger, it requires the underlying cause to be investigated very meticulously. Sometimes only a simple reflex, and sometimes a structural defect in the heart’s own electrical network, may be responsible for this slowing. Therefore, beyond getting stuck on numerical values, how the general circulatory system is affected is of great importance.

Why Is Bradycardia Seen in Children Different from Adults?

The bodies of babies and children are not just smaller copies of adult bodies. Their systems are in a constant process of growth, development, and change. This also applies to their hearts. Bradycardia seen in children displays a very different character from the pictures encountered in adults. When the pulse slows in an adult individual, the problem usually stems from wear in the heart’s own tissue, vascular occlusion, or weakening of pacemaker cells due to aging. However, in children, the main cause of pulse slowing is often not the heart itself. Even if the child’s heart is completely healthy, it slows down as a reaction to an external systemic problem such as oxygen deprivation in the body, low blood pressure, or acid accumulation in the blood.

In childhood, heart rate is in constant change. A newborn baby needs very high energy for growth and development. During this period, the sympathetic nervous system, which accelerates the body, is much more dominant, and therefore babies’ hearts beat very fast. However, as the child grows, the activity of the parasympathetic nervous system, which rests the body, begins to increase. At the same time, the muscle mass of the heart grows, the inside of the heart expands, and the amount of blood it ejects into the vessels with each contraction increases. Since the heart can now pump more blood with each beat, it no longer needs to beat as fast as before in order to meet the body’s needs. Thanks to this physiological maturation process, basal heart rate gradually and completely healthily decreases with age.

At Which Ages Are Which Pulse Values Considered the Bradycardia Limit?

There is no single clear answer to the question of what normal heart rate should be. This value varies greatly according to age, whether the child is awake at that moment, and the activity being performed. It is completely natural for the heart rate to fall quite significantly when the body enters rest mode during sleep, and this is not a situation to be feared. Normal limits according to age groups are listed below.

  • Newborns 100-190/min
  • Babies under one year 100-180/min
  • Preschool children 80-140/min
  • School-age children 75-120/min
  • Puberty period/Adolescent 60-100/min

In babies in the newborn period, that is, in the first month of life, it is normal for the pulse to be between one hundred and one hundred ninety beats per minute while awake. During sleep, this value may fall to ninety. If a newborn’s pulse drops below one hundred, this condition is evaluated as bradycardia. In babies from one month to one year of age, the upper limit decreases slightly to the one hundred eighties, but below one hundred is still considered very slow.

In small children between one and three years of age, the pulse while awake is between ninety-eight and one hundred forty, and values below eighty raise suspicion of bradycardia. Between the ages of three and five, which is the preschool period, the pulse may fall to eighty, while below seventy is interpreted as slow. In school-age children between six and twelve years of age, the awake pulse is around seventy-five, while below sixty is considered the danger limit. In adolescents older than twelve years, the situation gradually approaches adult values. Between sixty and one hundred while awake is normal, but if the pulse drops below fifty and there are some accompanying complaints, this condition may require urgent intervention.

How Does the Heart’s Electrical System Work and How Does Bradycardia Occur?

There is an electrical system that works almost flawlessly and enables the heart to contract regularly and pump blood. Thanks to this electrical network, the heart sometimes speeds up and sometimes slows down according to the body’s needs. The heart’s natural pacemaker is in the upper right chamber, and the very small electrical currents coming from here spread toward the lower chambers of the heart by following certain pathways. When this electrical current reaches muscle cells, the cells contract and blood is pumped toward the vessels.

The basic structures followed by electrical impulses within the heart are listed below.

  • Sinus node
  • Atrioventricular node
  • Conduction pathways
  • Ventricular muscles

The sinus node, the place where electricity is produced, is the main generator of the heart. The impulses coming from here arrive at a transfer station located in the middle part of the heart called the atrioventricular node. This station holds the electricity for a short moment and then quickly transmits it to the ventricles, allowing the lower chambers to contract strongly. Bradycardia occurs as a result of a defect that develops at any point of this flawless electrical line. Sometimes the main generator cannot produce electricity at a sufficient rate. Sometimes electricity is produced, but it gets stuck at the transfer station. Sometimes electricity cannot reach downward due to damage in the conduction pathways. When electricity does not reach downward completely and on time, the ventricles cannot contract and the heart rate falls.

What Are the Non-Cardiac Factors That Lead to the Development of Bradycardia in Children?

As mentioned before, a very large portion of the causes that slow the heart in children do not originate from the heart’s own tissue. Disruptions in the body’s general balance directly affect the heart and slow it down. This situation is actually part of the heart’s self-protection mechanism.

  • The most common non-cardiac factors are as follows:
  • Oxygen deprivation
  • Low body temperature
  • Thyroid hormone deficiency
  • High potassium
  • Low calcium
  • Medications used
  • Strong reflex stimuli

The first of these factors is oxygen deprivation, namely hypoxia. When the oxygen level in the body decreases for any reason, heart muscle cells cannot produce enough energy. The heart lowers its rate and enters a kind of saving mode to use its existing energy sparingly and protect itself. However, since this defense mechanism further reduces the blood going to the organs, it makes the situation more dangerous. A dangerous drop in body temperature also slows the heart by freezing its electrical activities.

The thyroid gland working sluggishly and being unable to produce enough hormone slows the general metabolic rate of the body. Like a car with a slow-running engine, the heart also beats quite slowly in this condition. Potassium being higher than normal in the blood or calcium dropping to a dangerous degree disrupts the ability of heart cells to conduct electricity and causes rhythm disorders. In addition, some blood pressure medications, rhythm regulators, or very strong painkillers may seriously reduce the pulse as a side effect. Finally, situations such as a very severe coughing attack, forceful vomiting, or procedures such as placing a tube from the nose to the stomach may excessively stimulate the nerve called the vagus and dramatically slow the heart rate within seconds.

What Are the Causes of Bradycardia Originating from the Heart’s Own Structure?

If the pulse slows despite there being no problem in the body’s general condition, the problem lies in the electrical system inside the heart itself. This condition is seen more commonly in children who have congenital heart anomalies, have undergone heart surgery, or have inflammation in the heart.

  • The causes of slowing originating from within the heart are as follows:
  • Failure of the main pacemaker
  • Conduction delay
  • Partial electrical block
  • Complete electrical block
  • Heart muscle inflammation
  • Heart membrane inflammation

Failure of the main pacemaker, namely the sinus node, is the condition in which the heart cannot produce enough impulses. Especially in children who have undergone open-heart surgery due to congenital heart holes or complex heart diseases, stitches placed during surgery or scar tissues that form over time may damage this region. This condition is also called sick sinus syndrome.

Problems in the passage of electricity from above to below are called blocks. In first-degree blocks, electricity goes downward only with a slight delay, and this usually does not create a serious problem. In second-degree blocks, electricity sometimes passes downward and sometimes cannot; this condition causes noticeable skipped beats in the pulse. Complete heart block is the most dangerous one. The electrical cables between the upper chambers and lower chambers are completely disconnected. The lower part of the heart cannot receive any impulses from above and begins to work on its own at a very slow rate out of desperation. This condition usually requires urgent pacemaker implantation. In addition, heart muscle or membrane inflammations that develop after a severe flu or a different virus may also create edema in the heart and temporarily or permanently disrupt the conduction pathways.

How Can Families Notice Symptoms Showing Bradycardia in Their Children?

The externally understandable symptoms of bradycardia vary greatly according to the degree of slowing and the child’s age. Sometimes the heart adapts to the situation so skillfully that no symptoms are seen. However, when the amount of blood going to the organs, especially the brain, falls below a critical level, some important warning signs appear.

Symptoms frequently encountered during infancy are listed below.

  • Getting tired quickly while sucking
  • Pausing during feeding
  • Cold sweating on the head
  • Bluish discoloration of the lips
  • Abnormal restlessness

Since babies cannot describe what they feel, parents’ observation is very valuable. If a baby becomes breathless after a few swallows while breastfeeding, feels the need to stop and rest frequently, and especially if excessive cold sweating occurs in the forehead area during this time, this may be an indicator that the heart is strained. At the same time, bluish discoloration around the lips also indicates that circulation is insufficient.

Symptoms observed in play-age and older children are as follows:

  • Unexplained weakness
  • Falling behind while running
  • Dizziness
  • Blackout
  • Sudden fainting
  • Attention deficit
  • Feeling of tightness in the chest
  • Having nightmares at night

If an older child constantly wants to step aside and sit while playing with friends in the park, or becomes breathless quickly while running, this condition should be taken into consideration. The most dangerous symptom requiring urgent intervention is fainting. When blood flow to the brain becomes momentarily insufficient, the child may experience blackout, lose balance, or suddenly lose consciousness and fall to the ground. If the decrease in blood going to the brain progresses very slowly but continuously, this condition may also manifest as chronic focus and memory problems by affecting the child’s school performance.

Is Bradycardia Seen in Children Who Do Sports Always a Sign of Disease?

Especially in adolescent children who actively do regular training and are involved in sports such as swimming, basketball, or athletics, a very slow pulse at rest is a fairly common condition. Families may panic greatly when they hear during a routine health screening that their child’s pulse is in the forties. However, in the vast majority of cases, this situation is not a disease but a completely healthy and physiological adaptation process.

The heart muscles of a child who trains intensely strengthen just like the muscles in the arms and legs. The cavities inside the heart expand somewhat. This strengthened and enlarged heart begins to eject much more blood into the vessels with each contraction. Since the body does not need too much blood at rest, the heart reduces the number of beats in order not to waste its energy. This condition is called athlete’s heart and is an extremely healthy structure. In athlete’s heart, the pulse accelerates within seconds according to need as soon as the child starts running or climbing stairs, and the child does not experience any weakness, dizziness, or feeling of fainting. However, this healthy slowing must be clearly distinguished from conditions that can sometimes lead to sudden heart attacks and occur with diseased thickening of the heart muscle. This distinction is possible only with detailed measurements to be made by specialist physicians.

Which Methods Provide a Definitive Diagnosis in Suspected Bradycardia in Children?

When pulse slowing is detected in a child, the technological possibilities offered by modern medicine are used to understand whether this is a harmless slowing or a structural disorder requiring urgent treatment. Establishing the correct diagnosis is the most important step for planning the correct treatment.

Methods frequently used at the diagnostic stage are as follows:

  • Standard electrocardiography
  • Portable rhythm Holter
  • Long-term event recorders
  • Small subcutaneous sensors
  • Heart ultrasound
  • Treadmill exercise test

Standard electrocardiography, namely ECG, is a painless and very fast test that maps the heart’s current electrical activity. The rhythm of the heart is recorded on paper with small adhesive pads attached to the chest. However, children’s complaints do not always occur while they are with the doctor. If complaints come intermittently during the day, portable 24-hour rhythm Holter devices are used. This device is attached to the child’s waist and records every single beat of the heart for twenty-four or forty-eight hours. When the child feels dizziness, they press a button on the device to mark that moment, thus establishing a direct connection between the complaint and the rhythm. In much rarer complaints, very small devices placed just under the skin of the chest and monitoring heart rhythm for months may be preferred. While the structure and valves of the heart are examined with echocardiography, the performance of the heart is measured with an exercise test by observing how the child’s heart accelerates while running.

Which Methods and Technologies Are Preferred in Bradycardia Treatment?

The treatment to be applied for slowing of the heart is shaped completely according to what causes this condition and whether the child is in life-threatening danger. If the slowing is caused by a medication or temporary inflammation, the rhythm corrects itself when this problem disappears.

The drug groups used to accelerate the heartbeat in emergencies are as follows:

  • Adrenaline
  • Atropine
  • Calcium supplements

If the child has lost consciousness and blood pressure is very low, these medications are given urgently through the vein. Adrenaline strongly stimulates and accelerates the heart. Atropine increases the rhythm by removing the neural brake mechanism that suppresses the heart. However, if the problem is an inherited heart block or if the electrical pathways damaged after surgery do not heal, the permanent solution is pacemakers.

Implanting a pacemaker in children requires slightly more care than in adults. Since babies’ vessels are very thin, the wires may be placed directly on the outer surface of the heart instead of being advanced through the vessel. In older children, wires are placed by entering the heart through a vessel under the collarbone. Modern pacemakers produced with today’s technology are incredibly smart. They detect the child’s movement and breathing and automatically increase the heart rate when the child runs. Thanks to these pacemakers, children with bradycardia can play in the park with their friends, participate in physical education classes, and live a completely unrestricted, normal, and healthy life.

Güncellenme Tarihi: 13.10.2026

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