ABSTRACT
The article presents the results of studying electrophysiological changes in the myocardium of normal human subjects during 7-day dry immersion, and modification of the reaction to immersion by amlodipin and myostimulation. The dry immersion effects on the myocardium generally include a succession of electrophysiological shifts first in the ventricles and then in the left atrium due to, probably, blood pooling in the pulmonary vessels. Myostimulation and amlodipin affect the myocardium reaction visibly suggesting involvement of numerous components of the autonomous and central nervous systems. The positive effect of the pharmaceutical--alleviation of myocardium strain--is a result of amlodipin assistance to the coronary blood flow; however, it has a side-effect on orthostatic stability. The positive action of myostimulation is associated with unloading of the right heart and reflected in changed HD ECG parameters and growth of the "myocardium" index.
Subject(s)
Amlodipine/pharmacology , Electrocardiography/methods , Heart/physiopathology , Immersion/physiopathology , Muscle, Skeletal/drug effects , Vasodilator Agents/pharmacology , Adult , Electric Stimulation/methods , Electrocardiography/drug effects , Follow-Up Studies , Humans , Male , Muscle, Skeletal/physiopathology , Reference Values , Young AdultABSTRACT
Applicability of high-resolution ECG used in clinics for predicting the probability of life-threatening arrhythmias in cardiovascular patients for the space flight environment was investigated in A 7-d bedrest experiment was to verify HR ECG displayed electrophysiological shifts in myocardial atriums and ventricles. Clearly seen changes in R-amplitude and time course seem to have reflected the volumetric loading and altered sympathetic activity during bed rest QRS-complex had increased the time of low-amplitude signals at the end of the last 40 ms but was short in duration which may point to delayed ventricular depolarization. Prognostically meaningful is exaggerated electrical instability of the myocardium during the standing test on completion of the bedrest period. Results of the investigation allow recommend HR ECG integration into the spacecrew health monitoring system.