Systolic time intervals after a seven-day orbital flight.

Heart rate, systolic time intervals (pre-ejection period, left ventricular ejection time , ejection friction, stroke volume and QT interval of two cosmonauts (Leonid Popov--L.P. and Dumitru Prunariu--D.P.) were studied before, during, and after an ergometric bicycle exercise test performed before and after the seven-day Soviet-Romanian orbital flight on the Soyuz 40-Salyut 6 Complex in May 1981. For this purpose one precordial electrocardiogram (ecg) and the ear photodensitopram (den) were recorded stimulaneously. The method used permitted recording even during exercise, Ecg and den signals were stored on magnetic tape, processed in an analogue device and in a digital computer. The data obtained after landing suggest a slight cardiac deconditioning in L.P., demonstrated especially by augmentation of the pre-ejection period, which was unchanged in D.P. corresponding to a sympathoadrenergic hypertonia. The seven-day orbital flight has not produced important cardiovascular changes.

Systolic time intervals after a seven-day orbital flight.

Heart rate (HR), systolic time intervals (STI) (pre-ejection period--PEP, left ventricular ejection time--LVET, PEP/LVET ratio indirect ejection fraction--EF, stroke volume--SV and QT interval of two cosmonauts (Leonid Popov--LP and Dumitru Prunariu--DP), were studied before, during and after an ergometric bicyle exercise test performed before and after the seven-day Soviet-Romanian orbital flight on the Soyuz 40--Saliut 6 Complex in May 1981. To this purpose one precordial electrocardiogram (Ecg) and the ear densitogram (Den) were recorded simultaneously. The method used permitted clear recordings even during exercise. Ecg and Den signals were stored on magnetic tape, processed in an analogue device and in a digital computer. The data obtained after landing suggest a slight cardiac deconditioning in LP, demonstrated especially by PEP augmentation, which was unchanged in DP corresponding to a better cardiac contractility. It is concluded that the seven-day orbital flight has not produced important cardiovascular alteration.

The influence of day and night work on the circadian variations of cardiovascular performance.

Circadian variations of the pre-ejection period, Q-T interval, heart rate and oral temperature at rest and in day and night shift work were investigated. At rest, pronounced circadian variation was found in heart rate, pre-ejection period and Q-T interval. The ratio between Q-T interval and heart rate also shows a distinct circadian variation. When working, the rest rhythms of the variables were obscured. The physiological implications for shift work are discussed.

A method for continuous electrocardiodynamic monitoring.

A new method is presented for the monitoring of cardiac time intervals, e.g. in clinical and industrial work investigation. The methods yields 'on-line' the electrocardiodynamic time profile during rest as well as effort, and has applications in health care, sports and occupational medicine. By means of analog processing of an electrocardiographic signal, ear densitogram and beat-by-beat display of the measured cardiac time intervals as amplitude-modulated pulses, an 'electrocardiodynamic time profile' is obtained. In order to estimate the accuracy and the limitations of the method, a comparison with computerized methods was performed. In an ergonomic experiment carried out by a Romanian-Swedish research team, analog and digital methods for the detection of cardiac time intervals showed good agreement.

The sympatho-adrenergic response in hyperthermia.

The sympatho-adrenergic reaction was investigated in heated rats under the influence of a ganglioblocking agent--hexamethonium. The overheating at a 40 degrees environmental temperature produced in a relatively short interval (after 157 min on an average) the death of the animals. An initial bradycardia was followed by a tachycardic phase. In the prelethal phase there appeared bradyarrhythmia produced by conductibility troubles and activation of ectopic ventricular centers. The survival time was not influenced by hexamethonium in spite of its hypothermic action. In blood, heating produced an increased concentration of noradrenaline and adrenaline. Hexamethonium, which reduced the rectal temperature, markedly decreased both blood catecholamines concentration. On this background heating likewise produced a relative increase of both blood catecholamines content. The catecholamines changes in adrenal glands presented less significant modifications.

Hypergravitation and sympatho-adrenergic reactivity.

The sympatho-adrenergic reaction of the organism subjected to hypergravitation was investigated in rats exposed to +6 Gz. The electro- and cardiotachograms recorded telemetrically were correlated with the adrenal catecholamine content. The determinations were made in controls and in rats treated with hexamethonium and atropine administered separately or together. The rats reacted to acceleration initially by a short bradycardia followed by tachycardia. In one case there was a sustained bradycardic response. Hexamethonium (C6) lowered the resting heart rate, attenuated the initial bradycardia and reduced the consecutive tachycardia. In some rats during centrifugation a bradycardic and arhythmic response was found sometimes ending in cardiac arrest. Hexamethonium stored the catecholamines in the adrenals as a result of their increased concentration. Atropin brought about resting tachycardia, disappearance of bradycardia from the very beginning of centrifugation and a more accentuated tachycardia. Atropin and hexamethonium administrated together diminished the response to acceleration.