[Historical sketches on classical physiology of the heart: the initial phase of systole].

Crucial physiological advances in the phase analysis of cardiac performance with respect to their historical and biographical aspects are elucidated. The described period started from the early measurement of blood pressure (1733) and the first graphical representation of cardiac performance (1861), continued by the progress in recording of cardiac electrical activity and a detailed study of the consecutive events throughout the cardiac cycle (1921) and, finally, reached the recording of changes in the left ventricular dimensions and shape during the phase which precedes the start of blood ejection (1955-2005).

[Contractility of the left ventricle of the human heart noninvasive measurement in each cardiac cycle].

History of development of the method of measurement of duration of the preejection (DPE) period - characteristic of left ventricular (LV) contractility is presented. On the basis of physiological prerequisites a novel computerized method of DPE measurement in each consecutive cardiocycle has been created. Distinct features of this method are: 1) principle of measurement - tetrapolar impedancemetry, with signal electrodes located along projection of the ascending aorta, one in the center of presternum, second - 5 cm caudally; 2) starting point for DPE counting - the point on ascending portion of R wave of electrocardiogram at which the first derivative of ECG signal reaches maximum, stopping point - the point of maximum of the second derivative of the primary impedance signal on the ascending front of its pulse wave. The method has been tested on healthy people for 10 functional tests. The results are presented characterizing dynamic peculiarities of changes of LV contractility during veloergometer exercise test with staderly increasing work load and reflecting development of positive inotropic action of sympathetic nervous system. Special characteristics of this action: small concealed period, preservation of achieved elevated level during lowering of work load (before its switching off) and subsequent slow (compared with chronotropic effect) diminution, as well as turning on at low loads.

[Pre-ejection period as a cardiac cotractility index: noninvasive beat-by-beat evaluation in the human study].

Beat-by-beat evaluation of left ventricular contractility provides and insight to the current dynamics of cardiac control. In non-invasive studies, pre-ejection period is conventionally used as an index of contractility. Pulse waves of electrical impedance (deltaZ) reflect the systolic dilations of the aorta segment confined between the properly placed signal electrodes. The relation of B-wave in the differentiated signal dZ/dt to the dalation of the aortic root prior to the start of ejection is discussed. The previous findings and our own experience indicate that the conventional method of identification of the end of the pre-ejection period by the B-point is not suitable for its reliable determination in each cardiac cycle. Instead of this, we defined the start of election by the maximum of the d(2)Z/dt2 signal associated with maximum acceleration of the ascending aorta dilation during the early ejection phase. It can be reliably found beat-by-beat. The proposed technique was successfully aplied for monitoring of fine dynamics of pre-ejection period changes during Valsalva maneuver, as well as in active and passive orthostatic tests.

[Computer cardiokymography. On its way to long-term noninvasive monitoring of cardiac performance in daly life]. / Komp'iuternaia kardiokimografiia na puti k dlitel'nomu neinvazivnomu nabliudeniiu za sokratil'noi deiatel'nost'iu serdtsa cheloveka.

A functioning heart generates low-frequency and low-amplitude movements (up to 40 (mrn) of soft tissues in the percardial area. Since the 1950-s of the XX-th century cardiologists have studied these movements to employ them in the diagnostics of ischemic heart disease (IHD). Indeed, changes of the movements have found their diagnostic application in this field. If blood supply to a certain area of ventricular myocardium is insufficient the contractions in this area diminish and even ceases. After systolic increase in ventricular pressure this area dilates and forces intercostal tissues out, causing a "bulge" wave on the record. For recording the patient must be in supine position and hold the breath. High frequency electromagnetic field generator was used in an attempt to examine the heart movements. It was found that such instrument measures the thickness of the air-gap that serves as a dielectric or a "capacitor" which forms between the skin and approaching it flat inductive coil. Nevertheless, such an instrument (cardiokymograph, CKG) can reveal changes in contractions of ischemic myocardium and markedly increases the sensitivity of the exercise ECG test. However, CKG can be recorded only after termination of the test. This principal disadvantage has been overcome by software that allowed the recording of CKG during the test. A low-frequency capacitance transducer developed recently by Chinese researchers has provided a simultaneous recording of several CKG. After modifying the transducer, we have established that 1) the shape of CKGs is the same as that CKGs recorded by all our predecessors, 2) CKGs are reproducible even within a 3-month interval, 3) the enormous mechanical interference caused by respiratory movements and, to a greater extent, by the vigorous movements of the legs and trunk during veloergometry can be eliminated by digital processing of the transducer signals, and 4) pathological changes appear in CKG of patients with IHD, which enables one to stop veloergometry at lower loads, thus increasing the safety of the test. Since for large medical insurance companies very simple and inexpensive cardiokymograph are quite unprofitable, their commercially production in USA and in Germany has been stopped. However, the goal of cardiokymography: a real-time, beat-to-beat, long-term monitoring of cardiac function in daily life, remains the major factor determining the future of the method.

[Spectral analysis of heart rate fluctuations: physiological basis and complicating factors]. / Spektral'nyi analiz chastoty serdtsebienii: fiziologicheskie osnovy i oslozhniaiushchie ego iavleniia.

The main stages of investigation into the changes of the heart rate in human (HRH), are presented. A satisfactory coincidence of results of the HRH oscillation power estimation within two frequency ranges obtained with the aid of two techniques: by the Yamamoto algorithm and by search for sources of non-harmonic oscillations, was shown.

[The regulation of the lumen of the major arteries in accordance with the shear stress on the endothelium]. / Reguliatsiia prosveta magistral'nykh arterii v sootvetstvii s napriazheniem sdviga na éndotelii.

A decrease in the blood viscosity due to hemoconcentration, caused arterial dilatation. These viscosity-induced responses depended on intact endothelium. The dilatory responses caused by equal increments in flow rate, increased in systemic hemoconcentration and decreased in systemic hemodilution. The data obtained corroborate the suggestion that stress applied to endothelium is the key signal in the control of arterial lumen by the blood flow rate.

[Nitrogen oxide is not an agent of endothelium-mediated arterial dilatation to an increase in the blood flow rate]. / Oksid azota ne iavliaetsia mediatorom oposreduemoi éndoteliem dilatatsii arterii na povyshenie skorosti krovotoka.

I. v. administration of inhibitors of endothelium-mediated synthesis of the oxide of nitrogen raised the arterial blood pressure, constricted the femoral artery and decreased the acetylcholine- and ATP-induced vaso-dilatation in anesthetized cats. However, the dilatation induced by an increased blood flow velocity, was not affected. The data obtained suggest that the endothelium-dependent arterial dilatation is not mediated by oxide of nitrogen formed from L-arginine.

[The decisive role of the endothelium in stabilizing pressure losses during changes in the blood flow in small arteries]. / Opredeliaiushchaia rol' éndoteliia v stabilizatsii poter' davleniia pri izmeneniiakh krovotoka v malykh arteriiakh.

Previously we established that the pressure drop along arteries remained nearly constant during the many-fold increase of blood flow rate. In anesthetized rats, functional damage of saphenous artery endothelium eliminates this local regulation of its resistance to flow. Hence, it is determined by the sensitivity of the endothelium to the shear stress. The sensitivity threshold has been estimated to be about 50-70 dyn/sm2. This is considerable more than the values characteristic of the cultured endotheliocytes. Possible reasons of this discrepancy under in vivo and in vitro conditions are discussed.

[The effect of the stabilization of a drop in pressure in the arteries during changes in the rate of blood flow]. / Effekt stabilizatsii padeniia davleniia v arteriiakh pri izmeneniiakh skorosti techeniia krovi.

The saphenous artery was joined with the femoral vein in rats. The pressure drop was measured between the aortic arch and the distal end of the saphenous artery. The stabilization of the pressure losses during the increase of blood flow rate occurs and is determined by dilation mainly of the saphenous artery, the degree of this dilation being such that the pressure drop within the wide range of blood flow rate remain constant.

[An experimental verification of the histomechanical theory of the working hyperemia of the skeletal muscles: biomicroscopic research]. / Eksperimental'naia proverka gistomekhanicheskoi teorii rabochei giperemii skeletnykh myshts: biomikroskopicheskoe issledovanie.

The histomechanical hypothesis of working hyperemia in skeletal muscle was verified by comparison of the dynamics and values of frog submaxillary muscle arterioles dilation under: 1) 4-Hz twitch contraction and 2) imitation of mechanical component of the twitch contractions. Deformation of arterioles occurred during incomplete tetanus with the maximal effect at the peaks of twitches. The repetitive displacements of a small bunch of muscle fibers with the frequency of 4 Hz and the amplitude of 0.05 to 0.25 mm caused a dilation of the arterioles attached to the fibers. The outer diameter of the arterioles might increase up to 2.2-2.3-fold, i.e. in the same range as under twitch contractions. The data showed the similarity in latency values, in the dynamics of arteriole dilation, and the dependency of the latter on the phase of the spontaneous vasomotion preceding the compared stimuli. These findings suggest that arteriolar dilation is determined by mechanically induced inactivation of pace-makers of these vessels both during passive deformations and under twitch contractions.

[Antidromic vasodilation caused by A-delta afferents in the frog]. / Antidromnoe rasshirenie sosudov liagushki, vyzyvaemoe A-del'ta-afferentami.

In anesthetized immobilized frog we recorded changes in hind leg volume evoked by electrical stimulation of peripheral end of the sciatic nerve. The ranges of the stimulus amplitudes sufficient to induce vasodilator or vasoconstrictor reactions were estimated. In a separate set of experiments thresholds of A alpha beta, A delta and C-afferent fibers excitation were evaluated by recording waves of compound action potentials in VIII-X dorsal roots. It was found that vasodilation is elicited by the stimuli of virtually the same intensity range as the excitation of A delta afferent fibers, including low threshold one. Consequently we concluded that in frog these myelinated afferent fibers are capable of dilating the blood vessels by antidromic action. This finding is in contrast with antidromic vasodilation in mammals which is known to result mainly from the impulses of the unmyelinated afferent fibers.

[The effect of an endothelium-dependent stabilization of a pressure drop in small arteries]. / Effekt éndoteliizavisimoi stabilizatsii perepada davleniia na malykh arteriiakh.

In the experiments on rats the authors showed that the discovered effect of pressure drop stabilization in the supplying arteries in changes of the blood flow was also noted in separate subcutaneous arteries. It was also observed that in functional injury of endothelium by 0.3% solution of H2O2 this effect disappears.

[Decreased thresholds of pain sensation and defense flexor reflex in patients with ischemic heart disease]. / Snizhenie porokov bolevogo oshchushcheniia i zashchitnogo sgibate'l- nogo refleksa u bo'lnykh ishemicheskoi bolez'niu serdtsa.

It was demonstrated that patients with coronary heart disease with coronary angiographically documented stenosing coronary atherosclerosis and frequent episodes of angina pectoris had significantly higher pain threshold in response to electric skin irritation and greater defense unconditioned flexor reflex R-III threshold than healthy subjects and patients with chest pain of extracoronary genesis.