Introduction

Respiratory Syncytial Virus (RSV) is a common virus that affects both children and adults, but children under two years old tend to experience more severe respiratory symptoms. Due to how common RSV is, approximately 80% of children have been diagnosed with RSV by the age of two. RSV does not commonly cause death; however, children with other conditions are at increased risk of severe infection potentially leading to death. Children with chronic respiratory disease, immunodeficiency, or cardiac disease have a 3-5% mortality risk. In adults, RSV displays similar rates of incidence as influenza. Transmission is through close contact with contaminated secretions such as saliva and water droplets. Direct transmission is greater than airborne transmission in spreading the disease. RSV survives on surfaces for hours, which is why it is important to wash your hands and sanitise surfaces after making contact with an infected individual.¹

Clinical manifestations of RSV

Preterm infants infected with RSV may present with poor feeding, apnoea, lethargy, or irritability. Infants may also present with rhinorrhea, cough, sneezing, fever, shortness of breath, wheezing, pharyngitis, or respiratory distress. 50% of children suffer from coughing and wheezing, whereas older children and adults present with typical cold symptoms. This includes congestion, cough, and fever, and wheezing and rhinorrhea may also be seen in adults with RSV.¹ The CDC states that in adult cases of RSV, it may lead to worsening of certain conditions: 

• Asthma
• Chronic Obstructive Pulmonary Disorder (COPD) - chronic lung disease associated with breathing difficulties and various other symptoms
• Congestive heart failure - the heart fails to pump enough oxygen and blood throughout the body.

Importance of understanding potential long-term effects of RSV

Many children with RSV have been reported to suffer from long-term complications such as recurrent wheezing episodes. In some cases, the common respiratory symptoms are associated with abnormal lung function, including bronchial hyperresponsiveness.² Most long-term effects are seen in adults with other clinical conditions who are more likely to suffer from complications. Some of the long-term complications are listed below and taken from the Cleveland Clinic:³

• Pneumonia: Although RSV may disappear within a few days, the patient may suffer with pneumonia to the point of feeling ill for weeks. Pneumonia is caused by an individual’s lungs becoming inflamed and filled with fluid after having a bacterial, viral, or fungal infection. Having pneumonia may make it hard for the patient to breathe, sometimes accompanied by a cough that is yellow, green, or contains bloody mucus. Bronchiolitis is similar to pneumonia, wherein the airways are inflamed, and it is an infection commonly associated with RSV. 
• Asthma: Research is currently being done to investigate whether RSV infections may predispose an individual into developing asthma. Asthma is a condition where the airways become swollen or blocked by mucus, which makes it difficult to breathe. 
• COPD: While RSV can worsen symptoms of COPD, studies are examining whether an RSV infection may predispose an individual to developing COPD.  
• Heart Disease: Some studies suggest that an RSV infection may increase the risk of heart disease and subsequent death, similar to the effects of influenza on older populations. Approximately 22% of adults diagnosed with RSV are also hospitalised for cardiovascular complications such as a myocardial infarction and congestive heart failure.⁴

Overview of RSV prevalence among teens

RSV is most common in young children and infants and therefore, if seen in teenagers, presents with the symptoms of a common cold: runny nose, cough, and/or a fever. Among 20% of teenagers diagnosed with asthma. They experienced an RSV infection as young adolescents and experienced severe bouts of wheezing. While rhinovirus-induced wheezing led to a 10-fold risk for asthma, RSV-induced wheezing led to a 5-fold risk for asthma. This suggests that RSV may not be the largest predictor for long-term lung complications such as asthma.⁵ However, studies observing the risk for cardiovascular complications found that RSV hospitalisation in infancy led to an increased risk for COPD in adulthood. The results do not observe the risk of cardiovascular disease prior to late adulthood.⁶ The American Heart Association reports the cardiovascular risks commonly associated with RSV, and the majority of these risks are associated with older adults rather than teenagers. 

Mechanisms of heart complications

Understanding why an RSV infection leads to a risk of heart problems may elucidate understandings of whether teenagers face potential risks. Myocarditis, inflammation of the heart muscle thereby reducing its ability to pump blood and oxygen to the rest of the body, is most commonly associated with any viral infection. Various heart problems, such as arrhythmias and bradycardia are reported alongside an RSV infection, possibly due to the weakening of the heart muscle from inflammation.⁷ Since inflammation of the heart muscle is one of the key factors contributing to heart problems, understanding age-related dysregulation of the inflammatory response may explain why adults are more susceptible to complications. As people age, the immune response is more likely to be dysregulated. This may potentially lead to a chronic inflammatory state, which, in the case of myocarditis, indicates that older patients have more difficulties returning to their original state. In addition, there are various molecular cell signalling events that facilitate this chronic inflammation, ultimately increasing the risk of developing heart problems in adulthood.⁸ 

Heart problems associated with teenagers

Although the wider literature indicates that teenagers are less likely to develop heart problems secondary to an RSV infection, there remains the potential for heart-related risks. Common heart problems associated with teenagers are listed below. Further information on their definitions and explanations may be found on the British Heart Foundation Website:⁹

• Aortic Stenosis
• Arrhythmia
• Atrial Septal Defect
• Coarctation of the aorta
• Hypoplastic Left Heart Syndrome
• Implantable Cardioverter Defibrillators (ICDs)
• Large Ventricular Septal Defect
• Long QT Syndrome (LQTS)
• Pacemakers
• Pulmonary Atresia with Intact Ventricular Septum 
• Pulmonary Stenosis
• Tetralogy of Fallot
• Transposition of the great arteries
• Tricuspid Atresia 

As can be seen above, there are many heart conditions affecting young adults and teenagers. However, not all of them are associated with complications arising from RSV infection. 

Cases of arrhythmia secondary to RSV infection

Teenagers are not often the case study for RSV infections, as it is most commonly newborns, infants, and older adults. However, it can be inferred that complications present in newborns may potentially be found in teenagers, but further investigation is needed. One study investigated the effects of RSV on heart problems such as myocarditis, bradycardia, arrhythmias, and other issues using two age categories: patients younger than 4 years old and patients older than 15 years old. Observing the 15-year-old, it was found that they experienced syncope two weeks after the RSV infection.⁷ Syncope is the condition where a patient consistently faints and/or loses consciousness due to severely low blood pressure and wherein the heart does not pump enough blood to the brain. This one study demonstrates that teenagers may potentially suffer from heart complications due to an RSV infection. However, further research is needed to support these findings and provide additional statistical support. Additionally, syncope can be caused by other heart conditions such as bradycardia, tachycardia, or complete blood flow obstruction.¹⁰

Comorbidity of viral infections and heart problems

RSV is one virus among many others that causes respiratory disorders leading to subsequent cardiovascular problems. The risk of developing myocardial infarction within a week of experiencing a viral infection is significantly high and remains high up until one month of infection. This may be due to the inflammatory processes that many viral infections activate, the increased metabolic demands placed on the body by the heart muscle, and various other factors. Infants (newborns) and older adults are severely at risk of experiencing complications with a respiratory infection for this reason. 

Summary

Viral infections and cardiovascular problems tend to co-occur due to the pro-inflammatory processes activated by an immune response. This is seen in cases of RSV where the patient is at an increased risk of cardiovascular conditions. While heart complications from an RSV infection are most commonly associated with older populations, teenagers may still be at risk for developing conditions such as arrhythmias, bradycardia, and syncope. There are various long-term effects of experiencing an RSV infection in early adolescence, and the common symptoms of RSV include a cough, runny nose, fever, and potentially wheezing. Teenagers may not be the most at-risk group when considering RSV cases. However, they should be observed closely if any extreme symptoms are noticed. A physician should always be consulted if the individual loses consciousness or rapidly deteriorates in a short span of time.