Bradycardia and Syncope: An Inducing Relationship

Introduction

Bradycardia means a very low heart rate. An adult heart normally beats 60 to 100 times a minute at rest. The heart beats less than 60 times per minute in conditions like bradycardia. Problems with the sinoatrial node, which is a natural pacemaker. The conduction pathways of the heart allow electrical impulses. Even metabolic problems such as hypothyroidism can also lead to hypothyroidism. This can be a very serious issue. The individual may feel weak, tired, dizzy, and have shortness of breath.

In many cases, bradycardia does not cause any symptoms or complications. However, pacemaker implants may be needed in severe conditions to help the heart maintain an appropriate rate. Bradycardia is the main reason for syncope. Syncope is loss of consciousness, passing out “fainting.” It mainly occurs when the blood pressure becomes low. This can be a harmless condition mainly due to some underlying medical conditions.

How Does Bradycardia Lead To Syncope?

Syncope is an abrupt loss of consciousness mainly due to low blood pressure and heart rate. Bradycardia lowers the heart rate and, in turn, lowers blood pressure leading to fainting. It is best described as orthostatic intolerance. Here the constellation of symptoms occurs in the upright position, like dizziness, seizures, stroke, and hypoglycemia.

What Are the Types of Syncope?

There are different types of syncope. They are

- Reflex Syncope: This is common and happens when the reflex is not regulated properly. Reflex syncope is, in turn, classified into three types. They are

1. Vasovagal: When the body overreacts to a trigger sensation, they include distress, pain, or standing too long.

2. Situational: This happens when certain actions trigger them, are coughing, laughing, or swallowing.

3. Carotid sinus: This happens when pressure is placed on the carotid artery in the neck.

Cardiac Syncope: This occurs when a problem is a heart concern. A condition where the brain receives less blood supply. Heart issues like ischemic cardiomyopathy, dilated cardiomyopathy, and heart valve disorders. Conditions like aortic dissections and pulmonary embolisms are also common causes.

Orthostatic Syncope: This happens when blood pressure drops when the individual is standing. There are many causes, like blood loss, blood pressure medications, diabetes, antidepressants, and excess alcohol use.

Cerebrovascular Syncope: This happens when blood vessels in and around the brain are prevented from getting enough blood. The causes can be due to carotid stenosis, stroke, and aneurysms.

What Are the Symptoms of Bradycardia and Syncope?

Bradycardia can prevent the brain and other organs from getting oxygen and leading to signs and symptoms:

• Confusion and memory issues.

• Dizziness or lightheadedness.

• Chest pain.

• Fatigue.

• Shortness of breath.

• Easy tiring due to any physical activity.

• Syncope- fainting.

The symptoms of fainting are:

• Blurred vision.

• Nausea.

• Vomiting.

• Tunnel vision.

• Lightheadedness.

• Pale skin.

• Cold, clammy sweat.

What Are the Causes of Bradycardia?

Many reasons can cause bradycardia. They are:

• Inflammation of heart tissue and myocarditis.

• Heart tissue damage due to aging.

• Damage to heart tissue due to heart attack or heart disease.

• The complication of heart surgery.

• Underactive thyroid gland.

• Obstructive sleep apnea.

• Inflammatory diseases like rheumatic fever or lupus.

• Imbalance of chemicals in blood like calcium and potassium.

• Medications like opioids, sedatives, drugs that treat rhythm disorders, drugs treating high blood pressure, and medication for treating mental health issues.

How Is Diagnosis and Assessment for Syncope With Bradycardia Done?

The following methods make the diagnosis and assessment of syncope:

• Echocardiogram: Initial assessment is done by an echocardiogram, which clears clinical suspicion of heart disease due to chronic obstructive pulmonary disease or body habitus.

• Stress Test: It is recommended if the syncope is due to physical activity or stress.

• Monitoring Strategy: The studies vary on durations of ECG monitoring. It is a gold standard investigation of suspected arrhythmic syncope.

• Provocative Strategy: This test is done in a controlled environment. In reality, both monitoring and provocative tests are used to determine the frequency of syncope and risks.

• Electrocardiographic Monitoring: This test record signals of the heart and rules out any disturbances like atrial fibrillation.

• Head-up Tilt Test: Most useful test in individuals with vasovagal syncope. It is a positive sign that consists of hypotension and over-bradycardia.

• Electrophysiological Study: This test helps to identify the cause of arrhythmias.

• Adenosine Triphosphate Test: ATP modulates SA and AV node function. This helps in studying unexplained syncope.

• Neurological Investigations: Brain imaging and EEG can be done.

What Are the Treatments Provided for Syncope With Bradycardia?

The most important treatment is based on getting the individual back to normal and regularizing the vitals. Based on the cause of syncope, the treatment steps are recommended. This include:

• Medications: Medication like Fludrocortisone acetate helps with syncope, in some cases selective serotonin reuptake inhibitors can also be used

• Catheter ablation for fast arrhythmias: A thin tube is inserted through a blood vesssel

• Implanting pacemakers to regulate a slow heartbeat.

• Implantation cardioverter defibrillator helps in individuals with a risk of sudden death.

• Surgeries to treat heart valve diseases.

What Are the Steps to Prevent Syncope?

The measures to prevent an individual from fainting are:

• Drinking Plenty of Fluids - Taking plenty of fluids may prevent dehydration.

• Do Not Skip Meals - Eat smaller, more frequent meals.

• Take Time While Standing - Standing suddenly or too quickly can drop in blood pressure and prevent blood flow to the brain.

• Avoid Tight Clothes and Tight Collars - This helps to prevent carotid sinus syncope.

Conclusion

Syncope associated with bradycardia is a transient loss of consciousness due to an electrical or structural defect that prevents enough cardiac output from perfusing the brain. It is common in cardiac abnormalities. Pacemaker placement can prevent other future syncopal events due to heart issues. High clinical suspicion and effective communication between emergency care and primary care are required to provide immediate treatment to patients facing syncope with cardiac issues. Timely management of cardiac syncope can improve an individual's care and decrease mortality.