Introduction

Cardiovascular diseases are very serious and can cause recurrent hospitalisation and death. Viral infections can also be very dangerous, leading to similarly serious outcomes. Given the seriousness of both these conditions, any link between the two may have the potential to be equally impactful. In this article we will explore the connection between cardiac arrhythmia (a type of cardiovascular abnormality) and viral infections.

Definition of viral infections

Before we explore if there is any connection, we should first know, what exactly is a viral infection?

Our bodies have lots of organisms that live on or in it like bacteria. There are three types of these bacteria: beneficial bacteria, which means they help our organ systems function properly; the kind of bacteria that is harmful unless our immunity drops; and of course the harmful type, which are the pathogens that harm our body. However, there is no such variety of viruses in the human body.

Viruses cause infections, which can be either a chronic infection or an acute one. 

The chronic viral infection is the one where the body is infected with the virus, yet the immune system and the virus are in an equilibrium state. On the other hand, in the case of an acute infection there is no balance between the host and the virus they: are in continuous flux until the infection is resolved, turns into a chronic infection, or leads to the death of the host (person infected with the virus).¹

Overview of common viral infections (e.g., influenza, COVID-19, HIV)

In this article we will mention specific examples of viral infections such as COVID-19, HIV and influenza. 

Influenza usually occurs annually and its vaccine needs to be updated each year to cope with the rapidly mutating nature of its causal virus. Influenza can lead to respiratory complications such as acute respiratory failure and pneumonia.

COVID-19 can cause severe respiratory complications that can eventually lead to death.

HIV (Human Immunodeficiency Virus) differs from both of these diseases as it is a long term pathogenic process causing serious complications that can eventually lead to death.²

Mechanisms of viral infection and spread

Different viruses have different ways in which they invade the host, which is in this case the human body.

Once the virus has invaded the host’s first line of defence, such as the skin, then the virus finds its own way inside of the host’s body, whether through transmission directly from cell to cell or a free transmission. Each virus has its own ability to modulate the host’s immune response and propagate and replicate inside of it.⁵

Definition of cardiac arrhythmia

Most human hearts beat within a normal range of 60 to 100 beats per minute. They are some physiological situations that can cause the decrease or increase of the heart rate, yet still remaining within the normal range (such as sleep or exercise). When the heart rate decreases below 60 heart beats per minute (bradycardia) or increases above 100 heart beats per minute (tachycardia), this is then called cardiac arrhythmia. 

Types of cardiac arrhythmias (e.g., atrial fibrillation, ventricular tachycardia)

There are several different types of cardiac arrhythmia. 

The normal heart rate or rhythm is called sinus rhythm.  When this normal cardiac rhythm, or sinus rhythm, gets interrupted or disturbed by other factors, this leads to cardiac arrhythmias. Examples of common arrhymias include  atrial fibrillation, which involves a very fast heart beat and mostly is benign, and ventricular tachycardia, which happens when the ventricle or the lower chamber of the heart beats too fast.

Basic cardiac electrophysiology

But you may be wondering, how is heart beat produced, and how does it work? To begin with, we have to know that the heart is considered a muscle called the cardiac muscle and like any muscle in our body it consists of several cells.

The process of the heart beating is considered an electrical phenomenon where ions and different electrical charges play a role.The passage of the ions across the cell membrane of the cardiac cells cause a change in the electric charges, therefore causing the heart to beat.⁷ 

Physiology of viral infections affecting the heart

Viral myocarditis

When a virus attacks the cardiac cells (heart cells), it stimulates the host’s immune system. Thiscan lead to the immune system attacking the cardiac cells, causing myocardial degeneration and dysfunction. In some studies it was found that this can lead to myocardial hypertrophy (increase in the size of the heart) and abnormal function of the heart leading to heart failure.                     

Immune response and cardiac impact

When any organism enters our body, the immune system is activated and starts to take actions to get rid of the organism and prevents any damage.⁸

Cytokine release and inflammation

Inflammation is one way our immune system works to counteract the action of the virus.

There are four types of myocardial inflammation (inflammation of the heart muscle) which are:

• Myocardial ischemia: which means a decrease in the blood flow to the heart muscle 
• Sepsis:which means that the body inappropriately reacted to the inflammation 
• Viral myocarditis
• Immune rejection 

All the types mentioned here are the body’s way to protect itself, however sometimes instead of protecting the body these processes instead damage it.

For example, if the ischemia is prolonged it can lead to tissue necrosis (death of the tissue).

Another example, sepsis, occurs when inflammation in the body leads to the secretion of inflammatory mediators and cytokines which help in containing the damage and inducing the repair. However, sometimes the prolonged existence of these inflammatory mediators and cytokines can lead to tissue damage rather than repair.⁹

Autoimmune responses

When infected by some infectious organisms like streptococcus bacteria, the body starts to defend itself. The similarity between the M protein of the streptococcus and the cardiac myosin (a type of protein found in the heart cells) can make the body confused leading to the body attacking itself causing an autoimmune response.⁸

Common viral infections linked to cardiac arrhythmia

COVID-19

Clinical findings related to arrhythmia in COVID-19 patients

Some studies were run on patients with COVID-19, which found that there was an association between the increased risk of mortality and the patients developing atrial fibrillation (irregular heartbeat), which is a type of cardiac arrhythmia.⁴

Influenza

Arrhythmic events associated with influenza

Studies on patients with influenza found that non-vaccinated patients had a higher risk of developing atrial fibrillation, and were also at greater risk of developng ventricular tachycardia than vaccinated patients.³

HIV

Incidence of arrhythmia in HIV patients

HIV has many effects on the heart; it may lead to cardiac cell death, myocardial infarction (heart attack), and can also lead to arrhythmia, with the most common type of arrhythmia caused by HIV being atrial fibrillation.¹⁰

Clinical manifestation and diagnosis

Symptoms of cardiac arrhythmia

Symptoms can range from dizziness, tachycardia (a very fast heart beat), palpitations (irregular heartbeats). Many patients die of sudden death because due to arrhythmia.⁶

Treatment and management

When treating patients with arrhythmia such as atrial fibrillation, clinicians prioritise regulating the heart rate or restoring the sinus rhythm, either with pharmacological or non-pharmacological means. In case of arrhythmia caused by viral infection, treating the infection caused by the virus is also a must.¹²

Arrhythmia management

Pharmacological interventions

Antiarrhythmic drugs are very effective in the case of an acute viral infection; they can end an arrhythmic episode in a few minutes and relieve all the symptoms with fewer adverse effects because the patient is only exposed to the drug for only a short period of time. On the other hand, in the case of chronic arrhythmia, drugs alone may not be sufficient and may carry a greater risk since the patient is exposed to the drugs for a longer period of time.¹³

Non-pharmacological interventions

There are other treatment options other than drugs, for example surgical treatment, pacemakers and cardioverter defibrillators.¹⁴

Patients who have a dysfunction in the sinus node can be treated with temporary pacemakers. Patients who suffered cardiac arrest due to ventricular tachycardia or fibrillations may need a defibrillator.¹⁵

Prevention strategies

Vaccination

Vaccines for preventing viral infections (e.g. flu vaccine, COVID-19 vaccine)

As mentioned throughout the article, there is a connection between viral infections and arrhythmia and other cardiac diseases. Therefore ensuring uptake of vaccines against viruses that can cause these diseases may decrease the chance of encountering those diseases. 

Impact of vaccination on reducing cardiac complications

Cardiovascular diseases such as ischemic heart disease, heart failure and arrhythmia are considered a leading cause of death globally.

In studies about the influenza vaccine and its role in decreasing the incidence of cardiovascular diseases, it was  found that acute myocardial infarction increases during winter, the most common season for influenza infection, and therefore it seems that influenza may increase the chance of developing a myocardial infarction or a cardiovascular disease.¹⁶

Infection control measures

Hygiene practices

Taking measures to improve hygiene and infection control may reduce the likelihood of becoming infected with viruses which may lead to any diseases, including cardiovascular diseases like arrhythmia and heart failure.

Summary

Many well known viral infections such as COVID-19, influenza and HIV may lead to cardiovascular difficulties and specifically cardiac arrhythmias. Cardiovascular diseases and arrhythmia are a leading cause of illness and death globally, and prevention of these illnesses is key to reducing the global health burden. Preventing transmission of viruses leading to cardiac arrhythmias such as atrial fibrillation and ventricular tachycardia through vaccination to causal viruses and infection control measures, and ensuring appropriate management and treatment in patients already suffering with these conditions will improve individual health outcomes.