RUDN University Pediatricians found a link between bronchial asthma and arrhythmia in children

Bronchial asthma is a chronic inflammatory disease of the respiratory tract, in which the smooth muscles of the bronchi contract, and they themselves narrow, making it difficult for the patient to breathe. It is not possible to get rid of it once and for all, so therapy consists in controlling the symptoms, and the patient is recommended to avoid risk factors. Additional pathologies may prevent doctors from taking the manifestations of bronchial asthma under control. This, in turn, provokes the development of complications and concomitant disorders. Due to excessive stretching of the atrial wall, patients develop supraventricular arrhythmia — a violation of the rhythm of contractions of the heart muscle. This pattern was found in several studies in adults, and RUDN University doctors first studied it in children.

"To date, the indications of an electrocardiogram with bronchial asthma in children have not been sufficiently studied. The relationship between the features of the supraventricular component of the ECG and the patency of the bronchi, which would allow us to determine changes in the heart muscle and heart rhythm disorders in children in order to predict the development of such complications of bronchial asthma, is not described in the scientific literature," Dmitry Ovsyannikov, MD, Head of the Department of Pediatrics, RUDN University.

To search for signs of future arrhythmia, doctors studied atrioventricular conduction, as well as ECG readings. The state of the bronchi was assessed according to spirometry — speed and volume indicators of respiration. The study involved 103 patients of the Nizhny Novgorod City Clinical Hospital aged 6-17 years. At the same time, children with hypoxia, that is, with blood oxygen saturation below 98%, were excluded. According to the results of measurements, children and adolescents were divided into three groups depending on their Tiffno index — the ratio of the volume of forced exhalation to the functional vital volume of the lungs, expressed as a percentage. This indicator was supposed to demonstrate how asthma and bronchial spasms make it difficult for the subjects to breathe. The first group included 15 children with a Tiffno index of more than 85%, the second — 40 people with an index of 75-85%, the third — 48 patients with indicators below 75%.

In the ECG data, pediatricians were most interested in the PQ interval — the area between the teeth of the same name on the cardiogram. It reflects the passage of an electric pulse of excitation of the heart muscle through the atrium and further into the ventricles. The length of the PQ interval in children is normally within 0.12-0.16 seconds, in adolescents it can reach 0.18 seconds. In the subjects of the first and second groups, the length of this section on the cardiogram was 0.01-0.02 seconds less than in the third. The rPQ coefficient — the value of the length of the PQ interval of patients in relation to accepted medical standards — consistently increased with a decrease in the Tiffno index. Thus, children who showed obstruction and a decrease in bronchial patency, which was seen by an index of less than 75%, had prerequisites for the development of arrhythmia.

"With a decrease in the Tiffno index, there was a statistically significant increase in the length of the PQ interval and the rPQ coefficient, which indicates a slowdown in the passage of impulses from the atria to the ventricles with narrowing of the bronchi. Our results should not be ignored, since in adults with bronchial asthma, the disease can progress and be accompanied by arrhythmias, including severe and even fatal cases. The study should be repeated on a larger sample and supplemented with long-term observations of ECG and spirometry parameters," Dmitry Ovsyannikov, MD, Head of the Department of Pediatrics, RUDN University.

The results are published in the journal Frontiers in Pediatrics.