Intermittent Hypoxic-hyperoxic Training in Patients With Cardiovascular Pathology After COVID-19 Infection.

Inclusion Criteria:

1. Written informed consent to participate in the study;

2. Age 40 and over;

3. Male and female;

4. One or more cardiovascular pathologies in the anamnesis:

• a reliably confirmed diagnosis of hypertension, stage I-III (the diagnosis wasmade in accordance with the National Clinical Guidelines - 2019);

• stable angina pectoris I-III functional class, confirmed by complaints,anamnesis and physical examination and with the help of diagnostic tests (bicycle ergometry or daily electrocardiography monitoring);

• confirmed diagnosis of arrhythmias and conduction disorders based onelectrocardiography data and 24-hour Holter monitoring (prematuredepolarization, supraventricular tachycardia, atrial fibrillation, sick sinussyndrome, atrioventricular block I-II, bundle branch blocks);

• chronic heart failure stage I-IIB, I-III functional class (New York HeartAssociation Functional Classification), confirmed by the presence of clinicalsigns and at least one of two criteria: myocardial dysfunction of leftventricle or / and an increase in the level of the N-terminal fragment of brainnatriuretic peptide over 125 pg / ml;

• the presence of signs of systolic or diastolic dysfunction of the leftventricle according to echocardiography.

5. COVID-19 infection confirmed by laboratory tests (polymerase chain reaction testing,enzyme-linked immunosorbent assay (positive result at least 1 time) with a CT degreeof 3 or higher.

Non-inclusion criteria:

1. Acute infectious diseases, tuberculosis;

2. Chronic somatic diseases in the acute stage;

3. Congenital anomalies of the heart and large vessels;

4. Valvular heart defects (congenital and acquired);

5. Severe atherosclerosis of the lower extremities'vessels (chronic ischemia of thelower extremities,stage 3-4);

6. Acute decompensated heart failure (II-IV class according to Killip classification);

7. Chronic heart failure IV functional class (New York Heart Association FunctionalClassification classification);

8. Secondary arterial hypertension;

9. Acute coronary syndrome within 4 weeks before the start of the study;

10. Life-threatening rhythm and conduction disturbances;

11. Bronchial asthma with the development of respiratory failure II-III degree;

12. Acute cerebrovascular accident within the last 4 months;

13. Chronic kidney disease (glomerular filtration rate<30 ml / min / 1.73 m2 via CKD-EPI (chronic kidney disease epidemiology collaboration) formula);

14. Pregnancy;

15. Mental illness (severe dementia, schizophrenia, severe depression, manic-depressivepsychosis);

16. Oncology, diagnosed within a year or receiving a course of radiation / chemotherapyfor cancer at the present time;

17. Severe cognitive impairment (MOS) and clinically significant anxiety and / ordepression (HADS) interfering with observation;

18. Individual intolerance to oxygen deficiency.

Exclusion Criteria:

1. Refusal to further participation in the study;

2. Acute psychotic reactions arising in the process of the study;

3. Exacerbation of chronic diseases, requiring a change in patient management tacticsand preventing his or her further participation in the study.