On the Linear Theory of Thermoelasticity with Microtemperatures

In the present paper the linear theory of thermoelasticity with microtemperatures is considered. A wide class of external boundary value problems (BVPs) of steady vibrations is investigated. Sommerfeld-Kupradze type radiation conditions and the basic properties of thermoelastopotentials are established. The uniqueness and existence theorems of regular solutions of the external BVPs are proved using the potential method and the theory of singular integral equations

Potential Method in the Linear Theories of Viscoelasticity and Thermoviscoelasticity for Kelvin-Voigt Materials

In this paper the basic boundary value problems (BVPs) of steady vibrations in the linear theories of viscoelasticity and thermoviscoelasticity for Kelvin-Voigt materials are considered and some basic results of the classical theories of elasticity and thermoelasticity are generalized. The fundamental solutions of systems of equations of steady vibrations are constructed. The radiation conditions and basic properties of fundamental solutions are established. The properties of potentials of single-layer, double-layer and volume are given. The uniqueness theorems of the internal and external basic BVPs are established. Finally, the existence theorems for the internal and external basic BVPs are proved by means of the potential method and the theory of singular integral equations

Hemodynamics at different levels of salt intake in patients with hypertrophic cardiomyopathy of different age groups

Aim. To assess the relationship between the level of salt (NaCl) consumption and clinical and hemodynamic parameters in patients with hypertrophic cardiomyopathy (HCM) of different age groups.Material and methods. We examined 57 patients with HCM (mean age, 59,2±16,2 years). The patients were divided into groups according to the World Health Organization (WHO): I — young age (≤44 years old) — 12,4% of patients; II — middle (45-59 years old) — 37,2%; III — elderly (60–74 years old) — 36%; IV — senile (≥75 years old old) — 14,4%. The clinical status of patients was assessed, during which special attention was paid to syncope not related to cardiac arrhythmias. NaCl intake was assessed by the 24-hour urine sodium (Na+) level.Results. In the general cohort, in Na+ level <50 mmol/day, the lowest left ventricular stroke volume (LVSV) index was observed, which were associated with syncope (r=-0,9, p=0,03). With the urinary sodium level of 50-70 mmol/day, an increase in LVSV index was observed and the absence of syncope. At Na+ level more than 70 mmol/day, no increase in LVSV index was observed. In this regard, a predictive model was created, as a result of which it was found that with an increase in Na+ consumption by 1 mmol/day, an increase in LVSV index by 0,3 ml/m2 should be expected. There were no significant differences in the effect of NaCl intake on the studied parameters in patients with HCM of different ages. At the same time, low NaCl intake in elderly patients was associated with syncope.Conclusion. Minimal values of Na+ intake (<50 mmol/day or NaCl 3 g/day) were found, which are unfavorable for patients with HCM due to the risk syncope. The 24-hour urine sodium level to maintain a hemodynamically safe level of LVSV index in patients with HCM should be more than 70 mmol/day (NaCl 4,1 g/day). Monitoring of Na+ consumption level is especially important in elderly people with HCM

Right heart condition in patients with COVID-19 pneumonia

Aim. To assess right heart condition in patients with coronavirus disease 2019 (COVID-19) pneumonia.Material and methods. One hundred and five patients with COVID-19 pneumonia were divided into 3 groups depending on the involvement of lung parenchyma: group I — 0-25%, II — 25-50%, III — 50-75%. The clinical status of patients was assessed using the NEWS2 and SHOKS-COVID scales. A complete blood count and biochemical blood tests were performed to determine the level of N-terminal pro-brain natriuretic peptide (NT-proBNP) and troponin I. Echocardiography was performed to assess the right heart structural, hemodynamic and functional parameters.Results. In patients with COVID-19 pneumonia, with an increase in lung parenchyma involvement, the intensity of systemic inflammatory response increased: C-reactive protein, group I — (4 [1,9; 35] mg/l), in III — (70,5 [33; 144] mg/l) (pI-III=0,012); myocardial stress marker level increased: NT-proBNP, group I — 77 [48; 150] ng/l, group III — 165 [100; 287] ng/l (pI-III=0,047). The dependence of NT-proBNP on C-reactive protein level was revealed (r=0,335, p=0,03). Intergroup comparison did not reveal significant differences between the main right heart functional parameters: TAPSE, Tei index (PW and TDI), FAC of the right ventricle (RV) (p>0,05). However, differences in the tricuspid annular peaks were found as follows: group I — 0,14 [0,12; 0,14] m/s, group II — 0,14 [0,12; 0,15] m/s, group III — 0,16 [0,14; 0,17] m/s (pI-II=0,012, pI-III=0,014) and RV global longitudinal strain: group I — 19,63±7,72%, group III — 27,4±5,93% (pI-III=0,014). The relationship between the RV global longitudinal strain and SHOKS-COVID score was confirmed (r=0,381; p=0,024).Conclusion. Patients with COVID-19 pneumonia showed no signs of right heart dysfunction. The development of RV hyperfunction was noted. Most likely, this is a compensatory mechanism in response to acute RV afterload. NT-proBNP increase under conditions of an inflammatory response may indicate myocardial stress. The results obtained allow to expand our understanding of the right heart condition in patients with COVID-19 pneumonia

COVID-19-ассоциированный бивентрикулярный синдром Такоцубо, осложнившийся кардиогенным шоком (клиническое наблюдение)

Acute myocardial dysfunction (AMD) remains prominent among extrapulmonary manifestations of COVID-19. Takotsubo syndrome (TS) is one of the causes of AMD development. TS incidence in patients with COVID-19 is currently unknown. The report presents a clinical case of an elderly female patient on maintenance hemodialysis with severe COVID-19. During the session of therapeutic plasma exchange (TPE), the patient had an episode of ventricular fibrillation followed by cardiogenic shock development and ECG changes, similar to myocardial infarction. Echocardiographic (Echo) data showed a distinctive pattern of biventricular TS with a significant systolic function decrease in both ventricles. Emergency CT angiography ruled out obstructive lesions of coronary arteries. Full recovery of both ventricles systolic function, regression of ECG changes, and complete resolution of cardiogenic shock were observed within the next week. The subsequent course of the disease was complicated by sepsis and multiple organ failure which determined the lethal outcome.The autopsy findings excluded coronarogenic and viral myocardial damage. The presented case demonstrates a life-threatening TS pattern in patients with severe COVID-19. TPE procedure should be treated as a possible trigger of TS.Среди внелегочных проявлений COVID-19 важное место занимает острая миокардиальная дисфункция. Одной из причин ее развития является синдром Такоцубо (СТ). Частота встречаемости СТ у пациентов с COVID-19 неизвестна. Представлено клиническое наблюдение пожилой пациентки с тяжелым течением COVID-19, получавшей лечение программным гемодиализом. В ходе сеанса терапевтического плазмообмена развился эпизод фибрилляции желудочков с формированием клинико-инструментальной картины кардиогенного шока, сопровождавшейся инфарктоподобными изменениями ЭКГ. По данным Эхо-КГ выявлен типичный паттерн бивентрикулярного СТ с выраженным снижением систолической функции обоих желудочков. По результатам экстренной коронароангиографии обструктивного поражения коронарного русла не выявлено. В течение последующей недели лечения отмечались полное восстановление систолической функции обоих желудочков, регресс инфарктоподобных изменений ЭКГ и разрешение кардиогенного шока. Дальнейшее течение заболевания осложнилось развитием сепсиса и полиорганной недостаточности, приведших к летальному исходу. По данным аутопсии коронарогенное и вирусное поражение миокарда были исключены.Представленный случай демонстрирует развитие жизнеугрожающего варианта СТ у пациентки с COVID-19. В качестве вероятного триггера следует рассматривать процедуру терапевтического плазмообмена