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An In vitro Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection
Published on: December 10, 2013
Altered cardiac rhythm in infants with bronchiolitis and respiratory syncytial virus infection
Susanna Esposito1, Patrizia Salice, Samantha Bosis
1Department of Maternal and Pediatric Sciences, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy. susanna.esposito@unimi.it
Insights
Respiratory syncytial virus (RSV) infection in infants is linked to heart rhythm problems like sinoatrial blocks, even in mild cases. These cardiac issues appear to be temporary, resolving within a month.
Area of Science:
- Pediatrics
- Infectious Diseases
- Cardiology
Background:
- Respiratory syncytial virus (RSV) is a common cause of bronchiolitis in infants.
- Cardiovascular involvement is a known extra-pulmonary manifestation of RSV infection.
- Systematic data on heart function in infants with RSV-associated bronchiolitis is lacking.
Purpose of the Study:
- To determine the frequency of cardiac involvement in infants hospitalized with RSV-associated bronchiolitis.
- To investigate whether mild or moderate RSV bronchiolitis poses a risk for cardiac malfunction.
Main Methods:
- 69 infants (1-12 months) with bronchiolitis were enrolled.
- RSV detection via real-time PCR and troponin I levels were assessed.
- 24-hour Holter ECG monitoring and echocardiography were performed on admission and at 4-week follow-up.
Main Results:
- Sinoatrial blocks were found in 76.5% of RSV-positive infants vs. 2.9% of RSV-negative infants (p < 0.0001).
- RSV-positive infants showed higher heart rates and altered heart rate variability.
- Cardiac abnormalities fully resolved by the 4-week follow-up.
Conclusions:
- RSV infection in infants is associated with sinoatrial blocks and transient rhythm alterations.
- These cardiac rhythm problems can occur even with mild to moderate respiratory symptoms.
- Further research is needed to understand the mechanisms and long-term implications.
Background:
Although the most frequent extra-pulmonary manifestations of respiratory syncytial virus (RSV) infection involve the cardiovascular system, no data regarding heart function in infants with bronchiolitis associated with RSV infection have yet been systematically collected. The aim of this study was to verify the real frequency of heart involvement in patients with bronchiolitis associated with RSV infection, and whether infants with mild or moderate disease also risk heart malfunction.
Methods:
A total of 69 otherwise healthy infants aged 1-12 months with bronchiolitis hospitalised in standard wards were enrolled. Pernasal flocked swabs were performed to collect specimens for the detection of RSV by real-time polymerase chain reaction, and a blood sample was drawn to assess troponin I concentrations. On the day of admission, all of the infants underwent 24-hour Holter ECG monitoring and a complete heart evaluation with echocardiography. Patients were re-evaluated by investigators blinded to the etiological and cardiac findings four weeks after enrollment.
Results:
Regardless of their clinical presentation, sinoatrial blocks were identified in 26/34 RSV-positive patients (76.5%) and 1/35 RSV-negative patients (2.9%) (p < 0.0001). The blocks recurred more than three times over 24 hours in 25/26 RSV-positive patients (96.2%) and none of the RSV-negative infants. Mean and maximum heart rates were significantly higher in the RSV-positive infants (p < 0.05), as was low-frequency power and the low and high-frequency power ratio (p < 0.05). The blocks were significantly more frequent in the children with an RSV load of ≥100,000 copies/mL than in those with a lower viral load (p < 0.0001). Holter ECG after 28 ± 3 days showed the complete regression of the heart abnormalities.
Conclusions:
RSV seems associated with sinoatrial blocks and transient rhythm alterations even when the related respiratory problems are mild or moderate. Further studies are needed to clarify the mechanisms of these rhythm problems and whether they remain asymptomatic and transient even in presence of severe respiratory involvement or chronic underlying disease.
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