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.