After engaging in vigorous action, such as running, skydiving, and competitive sports, one may realise that they have a sinking feeling. This occurs as a result of decreased blood flow to the brain, and thus the brain does not get enough glucose or oxygen.¹ Bradycardia and syncope are medical conditions that commonly co-exist, and are challenging to identify and manage. Syncope may exist as an accompanying symptom of bradycardia, or sometimes an underlying disease. It's important to understand these disorders because, if left untreated, they can seriously harm a person's health and affect their quality of life.

This article will explore these disorders, their causes, symptoms, and management strategies. Please note, it is not designed to replace medical advice, and if you are concerned, please see your general practitioner (GP). 

What is bradycardia 

Bradycardia is the term for a slower-than-normal heart rate. It is often referred to as sinus bradycardia. In adults, bradycardia is defined as a slow heart rate of less than 60 beats per minute (bpm).² For some people, a slow heart rate is biologically normal, especially when in a resting state, but it might not be considered adequate for others. If you have other symptoms as well, bradycardia could be an indication of serious heart disease. However, it is important to discuss concerns with your GP.

Heart rate and age

Much research suggests that the most common cause of bradycardia is increasing age. 

During sleep, the typical heart rate (HR) drops by 14 beats per minute in those over 80 years old and by 24 beats per minute in young adults. In young adults, the average difference in heart rate between men and women between awake and sleeping is 10 beats per minute.³

Symptoms of bradycardia

Common symptoms of bradycardia include: 

• Syncope: a symptom described as fainting, blacking out, falling out 
• Presyncope
• Transient dizziness or lightheadedness 
• Fatigue 
• Dyspnea (shortness of breath) on exertion
• Heart failure symptoms
• Confusion resulting from cerebral hypoperfusion (decreased passage of fluids into the brain) ²

It is possible for some people to have no symptoms at all, which makes diagnosis difficult in the absence of medical intervention.

Causes of bradycardia 

• Age: bradycardia can develop as a person ages due to a progressive deterioration of the heart's electrical circuitry
• Athletic training: because of their well-conditioned hearts, athletes, particularly endurance athletes, may naturally have a lower resting heart rate
• Medication: the heart rate can be slowed down by taking some medicines, including beta-blockers, calcium channel blockers, corticosteroids, narcotics, anaesthetics and various antiarrhythmics
• Associated heart conditions: bradycardia can result from cardiac diseases suchas atrial fibrillation, sick sinus syndrome, and heart block
• Hypothyroidism: bradycardia can result from an underactive thyroid gland that lowers metabolic rate
• Sleep apnea: sleep disorders can be a prevalent cause of bradyarrhythmias at night
• Other causes include: seizures, genetics, systemic hypoxia

Diagnosis for bradycardia 

Diagnosis will typically involve: 

• A physical examination: which may involve the use of a stethoscope and an automated heart rate monitor
• Blood tests: for electrolytes, glucose, thyroid function, toxicology screening for drugs
• An electrocardiogram (ECG) to measure the electrical activity of the heart

What is syncope

Syncope is a condition characterized by a brief, self-limited loss of consciousness brought on by a temporary reduction in blood flow to the brain. Syncope is a symptom of an underlying medical condition, rather than an illness. It is important for syncope to be distinguished from seizure disorders such as epilepsy, posttraumatic loss of consciousness, and cataplexy (sudden muscle weakness).⁶

Symptoms of syncope

Common symptoms of syncope include:

• Lightheadedness and dizziness
• Nausea
• Blurred vision
• Feeling warm or sweaty
• Weakness and fatigue
• Pale skin
• Loss of consciousness
• Fainting or collapse
• Seizure-like event

 Causes of syncope

• Reflex syncope: this occurs in response to a situation such as engaging in strenuous event, vasovagal, orthostatic hypotension, and carotid sinus hypersensitivity⁴ 
• Neurological causes: brought on by subclavian steal syndrome, autonomic nervous system dysfunction, and cerebrovascular illness (conditions that affect the blood supply to the brain) 
• Cardiac syncope: brought on by tachyarrhythmias, bradyarrhythmias, or structural heart dysfunction
• Medications: certain medications such as blood pressure medications, antidepressants, diuretics and drugs that affect heart rhythm can cause syncope as a side effect 
• Hypoglycemia: If left untreated, low blood sugar, which is frequently observed in diabetes, can cause syncope
• Other causes include psychological issues, hyperventilation and dehydration can lead to syncope

Relationship between bradycardia and syncope

If left untreated, bradycardia may lead to a syncope. Due to decreased blood supply to the brain, bradycardia (slow heart rate), can result in syncope, or fainting. During bradycardia, the heart pumps less blood, which results in less oxygen and glucose getting to the brain. This may lead to cerebral hypoperfusion, which as a defense response may produce symptoms like lightheadedness, and finally fainting.⁵ It's critical for people with bradycardia to identify syncope symptoms and seek medical care to treat the underlying problem.

Diagnosis of bradycardia-induced syncope

A thorough assessment should be carried out to find the underlying cause for both bradycardia and syncope. This can be achieved through:

• Reviewing patient's medical history
• Physical examination  
• An electrocardiogram (ECG)- which records the electrical activity of the heart 
• An echocardiogram- which is an ultrasound scan that looks at the heart and nearby blood vessels
• Holter monitor- an ECG machine worn over an extended period i.e. 24 hours 
• Tilt table test- which measures heart rate at blood pressure at a range of elevations from lying to standing 
• Blood tests- to rule out causes such as electrolyte disturbances or hypoglycaemia²

How can bradycardia and syncope be managed?

Lifestyle changes and self-care

Changing one's lifestyle can aid in the management of syncope and bradycardia. This may entail avoiding situations that might trigger episodes of fainting, such as quickly getting up or standing for extended periods of time. Individuals should drink enough water to avoid dehydration, eat regularly follow a balanced diet, and engage in regular exercise.¹

If the cause of syncope is due to orthostatic hypotension, individuals often find it helpful to sit or lie down with their legs raised, increasing intake of salt and fluid as this raises blood pressure to normal, thereby preventing syncope.

It is also important to avoid operating machinery, driving or performing other physically demanding tasks that might set off another syncope episode until you receive the necessary care.

Medication

A cardiologist may prescribe medication to treat any underlying heart disease and control the heart rhythm if this is indicated. Some medications can induce syncope and bradycardia, so the dose of these medications might be reduced or switched to an alternative.

Pacemaker implantation

Pacemakers may be required for those with symptomatic bradycardia or certain kinds of heart blocks. A pacemaker is a tiny implant that is placed beneath the skin, commonly in the chest region. It works by stimulating the heart muscles with electrical impulses to assist in control of the heart's rhythm. 

Education and support

In order to effectively manage bradycardia and syncope, it is crucial to offer patients and their families education, counselling and support. This might contain details on how to identify symptoms when to get help from a doctor, and how crucial it is to follow treatment regimens. Follow-up with a general practitioner or cardiologist is very important to monitor symptoms and prevent further episodes.

The long-term outlook for individuals with bradycardia and syncope

Several individuals with bradycardia and syncope can significantly improve their quality of life and symptoms with the right diagnosis and treatment.

Potential complications if left untreated…

• Injuries and falls: as a result of syncope, individuals may suffer injuries from falls. These injuries become severe if the fall occurs when operating machinery¹
• Cardiovascular events: syncope may be ian ndicator of underlying cardiovascular disorders such as heart block, and arrhythmias. These disorders have the potential to worsen cardiovascular events including heart attacks, strokes, and sudden cardiac arrest if they are not addressed
• Psychological effects: having syncope on a regular basis can have serious negative psychological effects, including worry, anxiety, social withdrawal, and a reduced quality of life
• Progression of underlying conditions: if untreated, some arrhythmias or structural cardiac abnormalities, which are the causes of bradycardia and syncope, may get worse with time

Summary

Bradycardia and syncope are medical conditions characterised by a slow heart rate and temporary loss of consciousness, respectively. Dizziness, nausea, palpitations, warmth, lightheadedness, weakness, or blurred vision are some possible symptoms. Bradycardia, often referred to as sinus bradycardia, is characterised by palpitations, weakness, disorientation, and syncope and is brought on by a malfunction of the heart's natural pacemaker. For individuals with bradycardia, it is important to evaluate for structural heart problems. Thorough medical history, physical examination, and diagnostic tests (echocardiography, Holter monitor, ECG) are required to determine the root cause of the condition. For additional evaluation and therapy, consultation with experts such as cardiologists may be necessary. Depending on the underlying cause, treatment options may include medication, pacemaker installation or lifestyle changes. Working together with healthcare professionals is crucial to properly address the underlying condition.

FAQs

Is bradycardia and syncope life-threatening?

 Yes, bradycardia and syncope can occasionally be life-threatening, particularly if they happen when handling machinery or while driving. Bradycardia and syncope can lead to shock and death. The risk of harm might also be increased by recurrent syncope episodes.

How are bradycardia and syncope managed?

Medication, pacemaker implantation, lifestyle changes (including avoiding triggers), adjusting salt and hydration consumption, and taking care of underlying medical issues are some examples of approaches to management.

When must I visit my general practitioner?

If you have syncope or bradycardia symptoms, it's crucial to visit a doctor, particularly if they persist for a long time, happen frequently, or are accompanied by other worrisome symptoms like shortness of breath or chest discomfort.

Is it possible to prevent bradycardia and syncope?

Yes, it is possible to prevent bradycardia and syncope episodes by adopting certain lifestyle modifications, such as controlling underlying medical disorders, avoiding triggers, and staying hydrated, although certain events cannot be prevented.

What triggers syncope?

Many things can cause syncope, including standing up too quickly, emotional stress, dehydration, standing for extended periods of time, and certain medical diseases including orthostatic hypotension or vasovagal syncope.

Why does bradycardia occur?

Bradycardia can be brought on by a number of things, such as age-related changes, adverse drug reactions, cardiac problems, and underlying illnesses like hypothyroidism.