Clinical and immunological aspects of electrical instability of a structurally unchanged heart

Abstract

Introduction. The concept of "idiopathic ventricular arrhythmias" (IVA), i.e. arrhythmias that have arisen in the absence of structural disorders of the heart, is becoming more and more conventional. As for today, "idiopathic arrhythmia" is the main cause of sudden cardiac death at a young age. Unfortunately, there is no epidemiological data on vital rhythm disturbances in young people without organic heart damage in Ukraine. The active introduction into clinical practice of highly informative instrumental methods of myocardial examination, specific immunological tests and molecular genetic methods of investigation is the basis for revealing the hidden causes of their occurrence. The aim of the study was to search for clinical and instrumental signs of inflammation and markers of herpesvirus infection in persons with ventricular ectopic activity without structural damage to the cardiovascular system. Material & methods. Twenty-three patients (14 men and 9 women) were involved in the study based on the results of daily monitoring (1200 ventricular ectopic complexes per day) with no signs of an organic disease of the cardiovascular system at the age of 17-35 years (mean age 25.7 ± 6.9 years). The control group consisted of 16 practically healthy persons, comparable in age and gender ratio with the main group of subjects. All examined patients underwent daily monitoring of ECG and blood pressure by Holter using 12 channel monitors. The study used the results of magnetic resonance imaging of the heart with intravenous contrast and determination of the viral loadrepresentatives of Herpesviridae (HHV1, 2, HHV3, HHV4, HHV5, HHV6).The study was carried out using fluorescent antibodies using specific monoclonal antibodies from Santa Cruz Biotech. Inc. (USA).The levels of the main inflammatory mediators from the group of proinflammatory interleukins IL-6 and TNF-α were studied by ELISA, using commercial Thermo Scientific ™ kits (USA). Results & discussion.As a result of the study, the markers of herpesviruses in blood immunocytes, both in the form of a monoinfection and in a mixed infection, were found in 20 patients with ventricular extrasystole, which was almost 87%, while in the control group, similar markers were found in 4 subjects (25 % of cases). Moreover, the degree of viral load in the group of patients with ventricular ectopic activity averaged 1.4 - 1.8, CFU, which corresponds to the average and high level, but in the control group did not exceed 1.2 CFU, which corresponds to a low degree of viral load. Viruses: HHV_1,2, HHV₅and HHV₃were the most common representatives of Herpesviridae in 52% of patients with idiopathic ventricular arrhythmias. The obtained data of levels of pro-inflammatory cytokines suggest the presence of an inflammatory process that is not accompanied by severe clinical manifestations. So the concentration of mediators of inflammation in the blood serum of patients with idiopathic rhythm disturbances without structural damage to the heart was significantly higher than in the control group, which indicates the inflammatory process in these patients.The concentration of TNF-α in ventricular rhythm disturbances was almost 18.5 times higher than the corresponding control group, and the level of IL-6 exceeded the control one by almost 7 times. Recently, due to the introduction into clinical practice of modern methods of visualization of myocardial damage of both coronary and non-coronary genesis, it has become possible to non-invasively identify various signs of a latent inflammatory process. According to the Lake Louise Criteria (LLC), magnetic resonance imaging (MRI) is now recognized as a noninvasive diagnostic method for verifying myocarditis. When assessing early contrasting on T1-weighted images, signal strength intensification was from 3 to 5 segments in 47,8 % of patients with rhythm disturbances.Confirmation of inflammation of the myocardium is the presence of two criteria. It turned out that among patients with idiopathic ventricular arrhythmias two or more positive phenomena were registered in 10 (43.5%) patients.Obtained MRI data of individuals with ventricular arrhythmias correlate with data from studies of levels of pro-inflammatory interleukins in this group. Conclusion. Thus, the obtained results of the conducted studies indicate that the basis of non-coronarogenic ventricular ectopic activity can be ectopic foci of excitation caused by a latent herpesviral inflammatory process in the myocardium, and MRI criteria for inflammatory foci in combination with elevated levels of TNF-α and IL-6 – as additional markers of subclinical myocarditis in patients without structural heart damage.