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What is Bradycardia-Induced Syncope & How is it Treated?|Causes, Symptoms, Prevention of Bradycardia-Induced Syncope

Bradycardia is a stage generally known when a person has a heart rate of 60 beats per minute (BPM), in adults. Syncope is a transient loss of consciousness with loss of postural tone. It is necessary to understand the relation between the two. This article focusses on bradycardia induced syncope.

Bradycardia does not show any signs unless the rate drops to below 50 BPM. When it does happen to a person it causes fatigue, sweating, and it all happens gradually.

When a person sleeps, the low heartbeat of 40-50 BPM is considered to be normal.

In medical terms, fainting or passing out is designated as syncope. Syncope is different from cardiac arrest. In syncope, the person becomes unconscious and goes limp but recovers soon after that. A person suffering from cardiac arrest will lose consciousness and may expire if no medical treatment is provided. On the contrary, a person with syncope recovers quickly almost always without treatment. In syncope, there is a risk of falling and getting injured. Hence, care should be taken to prevent such injuries. In the event of early signs like lightheadedness or dizziness, you may suspect that syncope is near its occurrence. It can lead to a serious injury if no prior treatment is provided.

Pre-syncope or near-syncope is a condition when you get a feeling that you are about to faint. You may experience lightheadedness or feel nauseated, have a problem with hearing and viewing, experience palpitations and feel weak and sweaty. To help a person who faints we should move the person to allow the blood to reach the brain. If that doesn’t help start providing CPR first aid. A serious cardiovascular condition called cardiac syncope is the condition that needs immediate medical attention.

Bradycardia-Induced Syncope

The frequency of fainting defines the type of syncope. If the patient faints frequently not because of dehydration or change in posture, the patient needs to be tested for heart or vascular disease. The nature of this syncope makes it dangerous. It occurs suddenly without any pre-syncope symptoms or dizziness. The most common cause of cardiac syncope is arrhythmia and abnormal heart rhythm. In this condition, the efficiency of the heart decreases due to the unavailability of enough oxygen to circulate through the brain. Cardiac arrhythmias can be of two types bradyarrhythmias (i.e. slowing of the heartbeat) and tachyarrhythmias (i.e. heartbeat becomes too fast).

Bradycardia is a condition of reduced heart rate. In this condition, the heart rate falls below normal. As a result, the output of the blood decreases leading to the decreased blood supply to the brain which in turn, increases the heart pressure. This increased pressure leads to a decrease in heart pump rate per minute. Sinus bradycardia occurs due to an anomaly in the sinus node called sinus node dysfunction (or sinus node disease). Medications can also reduce sinus node firing. The heart usually has to stop for at least 6 to 10 seconds which is known as asystole.

Approximately 3 to 10 percent of all cases of syncope is caused due to bradyarrhythmia. This asystole or marked bradyarrhythmia may be caused due to impaired sinus node function, which is called sick sinus syndrome, high degree AV block or neurocardiogenic disorders in which case it is either carotid sinus syndrome or vasovagal syncope.

A study involved an old man who was diagnosed with a low pulse when he was checking his blood pressure at home even though he was not on any medication or history of having a cardiovascular disease. He at first was showing no symptoms of bradycardia like dizziness, syncope or weakness. In response to this, he was tested with a 12-lead ECG which showed type 1 AV (atrioventricular) block due to which he had to undergo a Holter monitoring system. He was then taken to a cardiologist. The next day he had a syncopal attack and the Holter recording was analyzed. It was observed from this study that the AV block is not always caused by asystole and can be caused by TdP. TdP is associated with some medications, which may lead to repolarization. 1,2

Symptoms of Bradycardia-Induced Syncope

Symptoms of Bradycardia-Induced Syncope

Bradycardia induced syncope does not allow sufficient oxygen to flow through the brain and other organs, due to which the following are noted as the symptoms of bradycardia-induced syncope:

  • Lightheadedness
  • Pre-syncope
  • Dizziness and fainting
  • Breathing problem
  • Pain in the chest
  • Early fatigue
  • Problem with clear thinking
  • Pain in the left portion of the body

The 60 beats per minute are normal for an individual when the person is at rest, specifically athletes, young adults. Bradycardia is not reviewed as a heart problem in such cases.

Causes of Bradycardia-Induced Syncope

The causes of bradycardia-induced syncope include many causes. Orthostatic hypotension is one of the common causes of syncope. It can occur due to variety of reasons like reduced volume or decreased volume return.3

  • Aging can cause damage to the heart tissue.
  • A cardiac arrest can cause damage to the tissue of the heart.
  • Congenital heart defect at the time of birth.
  • Myocarditis which is the condition of infection within the heart tissue
  • History of a complication during heart surgery.
  • Hyperthyroidism leading to the underactive thyroid gland.
  • Chemical imbalance within the blood
  • Rheumatic fever can cause an inflammatory disease
  • Inappropriate medications used for other disorders concerned with heart rhythm and high blood pressure.

Diagnosis of Bradycardia-Induced Syncope

The essential requirement for this diagnosis involves a link between signs and symptoms and ECG. The diagnosis of bradycardia-induced syncope can be made in the following ways.

An event recorder can also be used for this diagnosis. It is done using Holter recordings. Although a lot of tools are available these recordings have proven to be the best diagnostic tool for bradyarrhythmia-induced syncope.4

The patient needs a tilt-table test, Holter, other tests, ECG, Stress test. There is no need for electrophysiological evaluation.

The non-invasive tests do not describe the reason behind syncope which can be sinus structural heart disease, bradycardia, fascicular block, first-degree AV block due to its erroneous results when it shows positive for pathological effects. Electrophysiological studies are suggested in this regard, as they rule out the ventricular tachyarrythmias.

The presence of high-grade AV-block requires a standard ECG test for the diagnosis of bradyarrhythmia-induced syncope.

For paroxysmal arrhythmias, ambulatory ECG monitoring is advised but there is an obstruction to its interpretation due to the absence of concomitant symptoms.

Even after a proper diagnosis of syncope, there is a possibility of its recurrence with a probability of 30 percent. Various tests that can be done on the site are as under:

ECG test: In this test, various wires are connected to parts of the patient’s body to create a rhythmic graph of his heart. This test is also done while exercising which is known as an Exercise stress test.

An ultrasound test of the heart called echocardiogram.

Tilt table test which requires the measurement of heart rate and blood pressure when there is an upright tilt to the body.

Electrophysiology study: EP test involves examining the heart’s electrical activity from the inside of the body.

Certain at-home diagnosis instruments are also present, which include Holter monitor and Event monitor. A Holter monitor is a portable monitor, which measures the heart rhythm for one to seven days. On the other hand, an event monitor is worn for one to two months and only records when an abnormal heart rate is encountered.

Treatment of Bradycardia-Induced Syncope

The most effective treatment of bradycardia induced syncope is the implantation of a pacemaker but it is fairly important to select an appropriate pacemaker system as well. It is suggested to use the dual-chamber systems called DDD, which provide physiological stimulation and maintains AV synchrony. A pacemaker is a device implanted by the doctor under the patient’s skin. The wires from this device are connected to the heart where they produce impulses to regulate the heartbeat. New pacemakers are implanted within the heart itself.

The other treatments include:

Cardioverter-defibrillator: This device is surgically implanted within the patient’s skin on the chest, and is similar to the pacemaker.

Medications: These are recommended as per the physician to control the rhythmic heartbeat. Patient with a low blood fluid volume is suggested to take fludrocortisone to increase the blood volume. One other medicine that constricts the blood vessels can be used with fludrocortisone which is called Midodrine.

  • Elastic stockings – These can be worn on the feet and lower legs, for compression.
  • Catheter ablation – This can be used to cauterize the heart cells with abnormal heart rhythms.

Prevention of Bradycardia-Induced Syncope

To prevent bradycardia-induced syncope, the patient should first reduce the risk of developing any kind of heart disease. If the patient is already diagnosed with any heart disease, proper monitoring and treatment should be done.

The following steps are recommended to treat bradycardia-induced syncope:

  • Eat a healthy diet and ensure to include regular cardiovascular exercise every day.
  • Maintenance of healthy body weight is an essential element to decrease the risk of heart disease.
  • Smoking is strictly prohibited if you want to prevent this disease.
  • Drinking in moderation can help in reducing this disease.
  • Regular check-ups ensure a healthy heart.
  • Don’t use recreational drugs.
  • Stress management is an absolute necessity

If the patient is under some treatment of this disease please ensure that you strictly follow the plan devised by the doctor and report the changes immediately to him to prevent the worsening or development of new symptoms.

Change in Medications for Bradycardia-Induced Syncope

The physician will first examine the patient and confirm the treatment used by the patient. The doctor will most likely advise you some new medications and might also lower the dose of the medicines that the individual was having, which might help cure the slow heart rate. When none of the treatments work, a pacemaker is considered as a treatment of bradycardia induced syncope.

A Pacemaker in Bradycardia-Induced Syncope

A pacemaker is a machine, which works on battery and its size is roughly like a mobile phone, which is then installed via operation under the patient’s collarbone. The machine contains wires which are attached to the veins and also to the patient’s heart. The device contains electrodes that are attached to the patient’s heart tissues.

The pacemaker looks over the activity of the patient and then initiates an electrical impulse to maintain an appropriate heart rate. A wireless pacemaker has been issued by the Food and Drug Administration (FDA). This device will be helpful for patients, which require pacing in one ventricle only.


In conclusion, bradycardia is a condition, which is related to a person’s heart and its ability to pump oxygen to the different organs of the body. There are quite a few easy symptoms that one can notice to identify bradycardia such as dizziness, weakness, fainting and many more. There are multiple ways to diagnose a patient to find out the main cause of the procedure being ECG. The most effective way to tackle this disease is by implanting a pacemaker in the patient’s body.


Sheetal DeCaria, M.D.
Sheetal DeCaria, M.D.
Written, Edited or Reviewed By: Sheetal DeCaria, M.D. This article does not provide medical advice. See disclaimer
Last Modified On:November 21, 2019

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