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Biomedical subjects

R Negoescu

Publications and source records attributed to R Negoescu.

6 recordsLinked to original sources
PubMedDate not supplied

Electrophysiological testing of sinus node function in man.

The paper reviews basic concepts, measurement principles, abnormality criteria, errors and limitations as well as technical aspects involved in the intracavitary exploration of sinus node dysfunction in man, from a standpoint connecting the cardiologist's and the clinical engineer's views.

Electrophysiology↗
PubMedDate not supplied

Conduction velocity in slower motor fibres.

Measuring conduction velocity in slower fibres (CVSF), through a partial antidromic block (Hopf-Seppäläinen method), allows estimating the dispersal of conduction velocity in motor fibres by the difference between the maximal motor conduction velocity (MCV) and CVSF. Investigations performed in workers exposed to medium concentrations of carbon disulphide show difference between MCV and CVSF as providing a more sensitive indicator for early diagnosis of peripheral neuropathies than MCV.

Adult↗
PubMedDate not supplied

Vagal involvement in sinus arrhythmia attenuation under mental load.

Experimental data document the slight increase of heart rate found during mildly stressing mental load as not being sufficient to explain concomitant sinus arrhythmia attenuation by pure sympathetic reaction. A general outlook on autonomic regulation and more specific direct and indirect arguments show heart rate response to mental load as underlain by a higher level balance of sympathetic and vagal drives. Their competition results mostly in slight increase yet sometimes in preservation or decrease of mean HR, while the consistency of sinus arrhythmia attenuation remains to reflect vagal increase specifically connected to cortex activation.

Adult↗
PubMedDate not supplied

Hypobaric hypoxia: dual sympathetic control in the light of RR and QT spectra.

ECGs of 21 candidate-pilots and 19 pilots were recorded during: 1) exposure to 5500 m hypobaric hypoxia (HH) while sitting, in the sequence: 1a) initial 7 min of adaptation (A); 1b) later 7 min of recovery (R) after short but intense tread-mill effort; and 2) final 7 min baseline (B), while sitting and requested to relax, at "0 m altitude" in the hypobaric room. RR and QT short-term variability were studied using spectral powers within Traube-Hering-Mayer (THM: 0.05-0.15 Hz) and respiratory (RESP: 0.2-0.4 Hz) bands. Mean RR proved highest capability to aggregate individual response-profiles: 15 pilots and 9 candidates entered the main (normal) cluster, featured by a comparison "triangle" set as expected: A > R < B > A. QT-THM power closely followed: 10 subjects (ss) in very normal cluster, defined as: A < R > B < A, while secondary clusters in candidates and pilots were interpreted by not-successful relaxation and exaggerated start-effects, respectively. Subjects with QT-THM normal clusters (A < R > B < A has group averages, p < = 0.05), also showed a quasi-normal "triangle" for mean RR, (A = R < B > A). During adaptation to hypoxia, pilots' QT-THM was higher than candidates' one (p < 0.02, Wilcoxon test). Study supports the emerging capability of QT-THM spectral power to index ventricular sympathetic control. Exposure to hypobaric hypoxia proved to be in these subjects a psycho-physiologic rather than a purely physiologic test.

Adaptation, Physiological↗