Altered cardiac rhythm in infants with bronchiolitis and respiratory syncytial virus infection
1 Department of Maternal and Pediatric Sciences, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
2 Cardiology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
3 Echocardiography Laboratory, IRCCS Centro Cardiologico Monzino, Milan, Italy
4 Department of Epidemiology, Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy
5 Luigi Devoto Department of Occupational Health, Giulio A. Maccacaro Section of Medical Statistics, University of Milan, Milan, Italy
BMC Infectious Diseases 2010, 10:305 doi:10.1186/1471-2334-10-305Published: 24 October 2010
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.
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 enrolment.
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.
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.