As it was already noted in many researches, SARS-CoV-2 (the coronavirus causing a heavy acute respiratory syndrome) in certain cases causes damage of a cardiac muscle as myocarditis. The correct diagnostics of this pathology and ability to differentiate it from other heart diseases has absolute importance. About it the speech in this article will go.
Clinical manifestations of the myocarditis caused by SARS-CoV-2 can be different. They can be easy symptoms, such as fatigue and asthma, or can take place of a stethalgia or feeling of a prelum in a thorax at an exercise stress. Also fulminantny myocarditis can take place, its precursory symptoms usually remind symptoms of sepsis: at the patient fever with low pulse pressure, a cold snap or a mramornost of extremities, sinus tachycardia is often observed.
Results of blood tests of patients with myocarditis often reveal the increased level of a lactate and other inflammatory markers, including S-jet protein, a blood sedimentation rate and pro-calcitonin which usually raise in process of development of a clinical picture of a disease. It is extremely important to distinguish fulminantny myocarditis from sepsis as infusional therapy (which is included into the protocol of treatment of sepsis) aggravates fulminantny myocarditis and can lead to an overload volume. At receipt in a hospital at the patient it is necessary to determine levels of the main heart enzymes as they are usually raised at myocarditis because of acute injury of a myocardium and possible dilatation of ventricles. In particular, about increase in levels of a troponin it was reported in cases of the myocarditis caused by COVID-19. In spite of the fact that the negative take of definition of a troponin does not exclude myocarditis, especially atypical form (giant cell myocarditis) or its chronic stage, negative serial researches of a highly sensitive troponin are important in an acute phase. At myocarditis the rejections of the electrocardiogram (ECG) usually observable at a pericardis, such as elevation of a ST segment and depression of a PR-segment can be observed. However these indicators are not effective at detection of myocarditis. For example, in one case of the myocarditis caused by COVID-19 should ST segment elevation, a PR depression. At myocarditis also other rejections of the ECG can be observed, including for the first time the arisen blockade of a ventriculonector, lengthening of an interval of QT, a pseudo-heart attack, ventricular premature ventricular contraction and bradyarrhythmia with an atrioventricular block of high degree.
The differential diagnosis of myocarditis with an acute coronary syndrome is very important. The increased level of a warm troponin - a strong indication of an acute coronary syndrome, and involvement of an epicardium it is possible to exclude by means of a coronary angiography. It was reported that many patients with COVID-19 had the determined level of a troponin, even when they did not observe obvious symptoms from heart, and such result usually does not correspond to a myocardial infarction. It is possible that the increased level of a troponin is result of exacerbation of the subclinical coronary heart disease caused by sepsis which increases the need of a myocardium for oxygen. It aggravates an imbalance between intake of oxygen and the need for it that can provoke ischemia which leads to a myocardial infarction. The serial research of cardiomarkers helps to find injury of a myocardium, especially in case of a tendency to their increase.
Also it is necessary to exclude the cardiomyopathy caused by sepsis. Researches showed that at patients with COVID-19 in a critical state vazopressor often were required, and at about a third the cardiomyopathy developed. Such picture causes suspicion on existence sepsis - the induced cardiomyopathy — diseases which are characterized by reversible dysfunction of a myocardium. It is considered that in this case injury of a myocardium arises because of the increased production of nitrogen oxide which suppresses the answer of cardiomyocytes to calcium and reduces quantity β1-адренорецепторов hearts. The main signs sepsis - the induced cardiomyopathy from heart include dilatation of a left ventricle, decrease in fraction of emission and restoration (normalization) of these changes within 7–10 days.
The stress-induced cardiomyopathy (Takotsubo's cardiomyopathy, syndrome of the broken heart) — a type of not ischemic cardiomyopathy at which passing decrease in contractility of cardiomyocytes with the subsequent protrusion of a top of heart develops. Clinical manifestations are similar to symptoms of an acute coronary syndrome (for example, a stethalgia, deviations on an ECG and increase in warm markers); however Takotsubo's cardiomyopathy is usually preceded by an emotional or physical stress.