Objective. The article discusses the advantages of performing stress tests with pressure control at each heartbeat. The question of increasing accuracy, informativeness and safety of the test is considered. Materials and methods. We performed 30 bicycle ergometric tests with ECG measurement, beat to beat blood pressure measurement and periodic blood pressure measurement by the Korotkoff method in the shoulder. Results. It was shown that arterial pressure registered by Korotkoff sounds in the shoulder corresponded with continuous pressure at the registration moment. Because of the impossibility to measure the dynamics, the underestimation of maximum systolic arterial pressure by the Korotkoff method exceeds 20 mm Hg in every 3 tests, and exceeds 30 mm Hg in every 5 tests. Therefore, the beat to beat measurement of BP significantly improves the accuracy and informativeness value of stress tests. Conclusions. Continuous BP signal in the finger increases reliability of noisy Korotkoff sounds extraction and the results of BP measurement in the shoulder by the classical method. The increased accuracy and reliability of the measurement provides greater patient safety. Continuous pressure corrected by Korotkoff sounds during reference measurements in the shoulder gives a detailed and accurate picture of BP variations, which allows to investigate in detail features of the patient’s cardiovascular system regulation, both during and after the load, which is not available with classical BP measurement.

Все большее значение для исследований в экстремальных условиях и при моделировании космических полетов приобретает комплексная оценка сердечно-сосудистой вариабельности, которая помимо вариабельности сердечного ритма включает в себя оценку вариабельности артериального давления. Использование спироартериокардиоритмографов (САКР) позволяет синхронно регистрировать работу проводящей системы сердца (ЭКГ), артериальное давление (АД) и дыхание, а также автоматически оценивать вариабельность ритмических осцилляций частоты сердечных сокращений и периферического АД. Материалы и методы. В этой работе мы анализировали напряженность регуляции сердечно-сосудистой системы организма человека при 21-дневной антиортостатической гипокинезии (АНОГ) на приборах САКР разных поколений, оценивая их релевантность для такого анализа. Результаты. В работе показано, что измерения на приборе САКР выявляют значимое снижение общей вариабельности АД вследствие длительной моделированной микрогравитации. Причём основной вклад в эти изменения вносит очень низкочастотная составляющая вариабельности систолического АД (VLFs). Известно, что именно VLF-компонента вариабельности АД может служить показателем предрасположенности к инсультам у крыс и собак, и, предположительно, может иметь прогностическое значение для оценки вероятности развития инсультов у человека. Заключение. Результаты этой работы говорят о большой важности адекватной оценки вариабельности АД с помощью неинвазивных приборов типа САКР для выявления и оценки преморбидных состояний, а также исследований адаптации при стрессе и в экстремальных условиях космических полетов. A comprehensive assessment of cardiovascular variability, which includes an assessment of blood pressure (BP) variability in addition to heart rate variability, is becoming increasingly important for research under extreme conditions, i.e., space, and during modeling of space flight. The use of spiroarteriocardiorhythmographs (SACR) allows synchronous recording activity of the cardiac conduction system (ECG), BP, and respiration, as well as automatic assessment of the variability of rhythmic oscillations of heart rate and peripheral BP. Methods. We analyzed the intensity of regulation of the human cardiovascular system during 21-day antiorthostatic hypokinesia (ANOH) using SACR devices of different generations, and we assessed their relevance for such an analysis. Results. Measurements on the SACR device revealed a significant decrease in the overall BP variability due to prolonged, simulated microgravity. Moreover, the main contribution to these changes was made by the very low-frequency component (VLF) of systolic BP variability. It is known that specifically the VLF component of BP variability indicates a predisposition to strokes in rats and dogs, and quite possibly it has a prognostic value for assessing the risk of stroke in humans. Conclusion. These results suggest adequate assessment of BP variability using non-invasive devices (e.g. SACR) is very important for the identification and assessment of premorbid states and can be applied to studies of adaptation to the stress and extreme conditions of space flights.

Aim. Blood pressure (BP) determination in atrial fibrillation (AF) patients remains challenging due to its high inter-measurement variability. The novel methodology of precise beat-to-beat BP determination may be used to guide the hypotensive therapy selection and adjustment, but along with that provides additional opportunity for the investigation of hemodynamics in patients with chronic AF. Material and method. The study sample consisted of 60 patients with the main diagnosis of grade II-III arterial hypertension; 30 of those were on sinus rhythm and 30 had chronic non-valvular AF. In all patients HR was within the limits recommended for left ventricular ejection fraction of >40%. Beat-to-beat systolic, diastolic, and pulse BP (SBP, DBP, and PBP, respectively) assessment at each heart beat within 15 minute interval was performed with “Kardiotekhnika-SAKR” system (NAO “Incart”, St.Petersburg, Russia). Results. Mild RR-interval variations, observed on sinus rhythm, resulted in insignificant SBP, DBP, and PBP fluctuations. More prominent RR-interval irregularity, typical for AF, is accompanied by more significant SBP, DBP, and PBP deviations. As mean SBP of each patient was taken for 1,0, “normal” SBP (≥0,9) was seen in RR-intervals of 754±58 msec; “markedly decreased” ( 1,15) in 587±38 msec; “prominently increased” (>1,2) in 566±38 msec; “severely increased” (>1,2) in 539±41 msec. For PBP (mean PBP of each patient was taken for 1,0) “normal” PBP (≥0,75) was seen in RR-intervals of 770±58 msec; “markedly decreased” (<0,75) in 561±40 msec; “prominently decreased” (<0,5) in 520±33 msec; “severely decreased” (<0,25) in 510±52 msec. Proportion of heart beats with insufficient efficacy according to PBP level (sum of “markedly”, “prominently”, and “severely” decreased) was 16,4±5,1% with prominent individual deviations (5,9-25,7%). Mean range of RR-interval providing to “marked” PBP decrease was 147±26 msec, also with significant individual variations 55-235 msec. Conclusions. Beat to beat BP measurement is characterized by high level of accuracy. In addition to mean SBP and DBP, their beat-to-beat fluctuations can be determined, which might be significant in irregular rhythm. This might help in selection of individualized anti-hypertensive therapy. The study has shown that along with RR-intervals shortening the number of hemodynamically insufficient heart beats increased, which manifested by SBP decrease, DBP increase, resulting in decrease of PBP. However, this general consistent pattern masks the individual differences of heart rhythm structure in AF. This method can help to determine the optimal HR for each individual patient with AF.

Objective. To assess the clinical signifcance of auscultatory gap (AG) found by the 24-hour ambulatory blood pressure monitoring (ABPM) using the Korotkoff’s sounds (KS) and its potential causes.Design and methods. 24-hour ABPM was performed in 60 patients (mean age 51,3 years, range 22–85 years), including 24 women and 36 men. In 24 patients, hypertension was diagnosed. In total, 2333 blood pressure (BP) measurements without “noise contamination” were selected for subsequent analysis (38,9 measurements per patient; from 28 to 73 measurements). The simultaneous recording of electrocardiogram (ECG), brachial cuff pressure, and KS phonograms on the right hand, as well as continuous recording of non-invasive BP curve in the left fnger using the volume clamp technique were performed in 10 patients with AG.Results. Based on the 24-hour ABPM, AG was shown in 43 of 60 subjects (71,7%). The AG was found to be associated with a decreased amplitude of fluctuations of the cuff pressure; upon its termination, the amplitude recovered. The above synchrony of changes in KS and amplitude of pressure fluctuations was found in all 124 cases which demonstrated AG during BP measurement. We assume that AG is a true variation of BP rather than a feature of KS, as the fluctuation amplitude depends on the ratio of BP and cuff pressure but does not depend on the KS phase. To test the hypothesis, the cuff pressure and KS were compared to the continuously monitored arterial pressure. When the systolic arterial pressure exceeded the cuff pressure, the KS appeared. Later on, the BP fluctuations led to a decrease in systolic BP; the arterial pressure did not reach the cuff pressure and, therefore, KS were not recorded. Subsequent decrease in the cuff pressure led to re-appearance of KS.Conclusions. The auscultative gap phenomenon is associated with true (mostly respiratory) variations of systolic BP rather than with features of KS in individual patients. The initial and repetitive KS occur at certain systolic BP levels depensing on the BP respiratory fluctuations and may indirectly indicate the amplitude of fluctuations.