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Biomedical subjects

K Antila

Publications and source records attributed to K Antila.

33 records · Page 2Linked to original sources
PubMed1987

Autonomic neuropathy and vibration exposure in forestry workers.

The variation in heart rate (HRV) at rest and during deep breathing (6 cycles a minute) of 88 professional lumber jacks was studied using a computer technique. The traditional indexes of HRV (CV, CVS, MEAN) were calculated and the spectral components of the HRV were also computed. There was a significant difference (p less than 0.001) between the HRV indexes during the deep breathing test in those with the shortest (CV = 10.1 +/- 1.1) and those with the longest (CV V 6.2 +/- 0.4) exposures to vibration. The values of the HRV indexes decreased with age, but multiple regression analysis showed that the total exposure time to vibration had an independent negative association with the HRV. There were significant differences in all the frequency bands (frequency related power, FRP) of the heart rate between those with the longest and those with the shortest exposures. The HRV during a deep breathing test is associated with the activity of the parasympathetic nervous system and is decreased in autonomic neuropathies. Our results suggest that prolonged exposure to the vibration caused by a chain saw has a negative effect on the parasympathetic activity and thus causes autonomic dysfunction.

Adult↗
PubMed1986

Effects of haemodialysis on heart rate variability in chronic renal failure.

The influence of haemodialysis (HD) on the heart rate variability (HRV) was investigated in nine non-diabetic patients on maintenance haemodialysis. The R-R intervals were measured in recordings during spontaneous quiet breathing and during controlled deep breathing before and after a single HD session. The HRV was expressed as the standard deviation of the mean R-R interval in 3 min ECG recordings. Heart rate variability is the irregularity in the heart rate mainly caused by autonomic control mechanisms. The long-term HRV during quiet breathing was statistically significantly (p less than 0.05) higher after the HD than before. The HRV in the intermediate frequency range of 0.075-0.125 Hz was also significantly increased by the HD. This suggests that some metabolic agents interfering with the heart rate regulation are removed by the haemodialysis, and as a result a better function of the autonomic cardiac control is achieved in uraemic patients.

Adult↗
PubMed1986

Individual relationship between heart rate and electromechanic systole in orthostatic test during autonomic blockade.

The aim of this work was to investigate the usefulness of the individual regression coefficients between the HR and the Q-A2 when studying their relationship during simultaneous changes in afterload and preload in combination with autonomic blockade. Twelve healthy male volunteers were studied in an orthostatic test done four times: without drugs (control test), after atropinization, after beta-blockade, as well as after combined beta-blockade and atropinization. The individual regression coefficients showed great inter-individual variation, and in average they were not significantly different in the four tests. However, it was observed that during the control test four, during the atropinization eight, during the beta-blockade three and during the combined beta-blockade and atropinization five individual regression coefficients were greater than -2.1, which is the regression coefficient used for the rate correction of the Q-A2 in males in the Weissler formula. It seems to use that the individual regression coefficents are useful in the evaluation of the relationship between the HR and the Q-A2 in pharmacological or physiological interventions, in which the intra-individual variation is great, and in which the number of subjects is often so small that group regressions are not very informative.

Adolescent↗
PubMed1985

Rapid changes in rate-corrected and uncorrected systolic time intervals during cold pressor test.

The changes in heart rate and systolic time intervals were studied in a group of 10 young healthy male volunteers during immersion of their hand in ice water for 1 min. The heart rate and systolic time intervals were measured from electro-, phono-, and impedance cardiograms in the standard way. When the cold immersion was done in the supine position the left ventricular ejection time (LVET) and the electromechanic systole (Q-S2Tc) shortened, and when corrected for the heart rate the Q-S2Tc lengthened in the beginning of the immersion. In the head-up position the Q-S2T shortened in the beginning of the immersion while the rate-corrected systolic time intervals remained unchanged. Most of the changes in the systolic time intervals disappeared before the last quarter of the cold immersion. It was observed that during the cold immersion the linear regression coefficients between the heart rate and the Q-S2T in the supine position as well as between the heart rate and the LVET, Q-S2T and the PEP in the head-up position were greater than the regression coefficients used in the rate correction.

Adult↗
PubMed1984

Relationship between systolic time intervals and heart rate during four circulatory stress tests.

The linear regression equations between heart rate and systolic time intervals were calculated before and during a handgrip test, an orthostatic test, the Valsalva test and a cold pressor test. The subjects were 30 healthy men, average age 20 years. During the 1st min of orthostasis the regression line of the left ventricular ejection time (LVET) was significantly (P less than 0.05) steeper than at rest and that of the pre-ejection period (PEP) was significantly (P less than 0.01) less steep than at rest, and the regression between HR and the PEP/LVET ratio deviated significantly (P less than 0.001) from zero. During the Valsalva maneuver, the regression line of the LVET became significantly (P less than 0.001) steeper than at rest and the regression coefficient of the PEP changed from negative to positive, the difference being significant (P less than 0.001); the regression between HR and the PEP/LVET also deviated significantly (P less than 0.001) from zero. During the cold pressor test the regression line of the electromechanic systole (Q-S2 time) was significantly (P less than 0.01) less steep than at rest. It was concluded that the use of regression equations calculated for the systolic time intervals and heart rate at rest can lead to errors when applied to rate correction of systolic time intervals during an orthostatic, Valsalva, or a cold pressor test.

Adolescent↗
PubMed1984

Patterns of QT/QS2 ratio in vasomotorically labile young men.

The QT/QS2 ratio in seven 21-year-old men with a history of vasomotor lability was measured when they were resting supine and during orthostatic, Valsalva and diving reflex tests. The vasolability was characterized by an abnormal sympathicotonic heart rate (HR) response to the orthostatic test and vacillating inferoapical T waves in the ECG. The results of the vasolabile subjects were compared to those of seven fit control subjects of the same age. In spite of equal HR's in both groups the vasolabile subjects' QT/Q2 ratio constantly exceeded 1.00 during the whole test protocol and it was higher than of the controls (P = 0.04). The reversed QT/QS2 relationship in the test subjects seemed to be due both to a prolongation of the QT time and a shortening of the QS2 time. This difference prevailed throughout although the reaction pattern to autonomic stimulations was equal in both groups. We considered an inadequate neural control of the heart, possibly with metabolic and haemodynamic interactions, responsible for the prolongation of the electrical systole in relation to the electromechanical systole in the heart of the vasomotorically labile subjects.

Adult↗
PubMed1984

Relationship between the changes in heart rate and cardiac output during the Valsalva maneuver.

Ten young (average age 20 years) healthy male volunteers performed the Valsalva maneuver (40 mmHg for 15 seconds) in the supine and the upright position. The heart rate (HR), stroke volume (SV) and the cardiac index (CI) were registered using ECG and impedance cardiography. During the expiratory strain of the Valsalva maneuver the HR increased about equally in the two positions while the decreases in the SV and the CI were in the supine position significantly greater than in the upright position. The CI decreased to equal levels in both positions after 15 seconds of strain. The rise in the HR due to the expiratory strain did not correlate significantly with the decrease in the CI in either position. The correlation between the HR rise and the SV decrease was almost significant (p less than 0.05) in the supine position and significant (p less than 0.01) in the upright position after 5 seconds of strain but not after 10 or 15 seconds. These observations suggest that the relationship between the rise in the HR and the decrease in the venous return does not remain constant during 15 seconds of expiratory strain. Perhaps the cardiopulmonary baroreceptor reflexes affect the HR after five seconds of strain more than they do after 10 or 15 seconds of strain.

Adult↗
PubMed1983

Heart rate variability, cardiac mechanics, and subjectively evaluated stress during simulator flight.

The effects of a simulator flight task on the heart rate variation (HRV) and hemodynamic variables were studied in nine pilots with instrument flight ratings. An electrocardiogram (ECG), phonocardiogram (PCG), and impedance cardiogram (ICG) were recorded continuously during three successive flights. Indices of HRV, power spectra, and autocorrelograms were computed from the R-R interval signal. Stroke volume (SV), cardiac output (CO), and systolic time intervals (STI) were determined by means of the ECG, PCG, and ICG. A scaling method for a subjective evaluation of tiredness, effort, and success during the flight was used. The repeats of the flight task decreased the heart rate (HR), CO, and cardiac index (CI). The different phases of the flight altered the HR (mean 97 min-1, S.E.M. 4 min-1), total HRV (RMSM) (mean 33 ms, S.E.M. 5 ms), and the periodic HRV. Subjectively, the pilots felt only moderate stress. The subjectively evaluated tiredness was significantly associated with the STI. Moderate informative stress in the flight simulator affected the chronotropic parameters of the heart. The inotropic state of the heart was not affected by the different phases of the flight but possibly by the diminishing sympathetic drive with accommodation during the repeats.

Adult↗
PubMed1978

Decreased heart rate variation in decerebration syndrome: quantitative clinical criterion of brain death?

Heart rate variation (HRV) was measured in 12 children with brain death. Computer analysis demonstrated an overall heart rate variation (RMSM) of 3.5 to 9.6 msec (mean, 6.0 msec). The respective figures for beat-to-beat variation (RMSSD) were 4 to 16 msec (mean, 7.7 msec). Normal infants (RMSM, 20 to 30 msec) and children (RMSM, 50 to 90 msec) and infants with respiratory distress syndrome (RMSM, 10 to 20 msec) have a clearly higher HRV than those with brain death. In all subjects a periodic component of the HRV with a cycle length of 5.9 +/- 0.26 seconds was discovered. In five patients an additional periodic component was found that corresponded exactly to the rate of artificial respiration. This study demonstrated the value of accurate digital techniques in the characterization of fixed heart rate in decerebration. This phenomenon could be considered one clinical criterion of brain death.

Adolescent↗
PubMedDate not supplied

Docetaxel and autonomic cardiovascular control in anthracycline treated breast cancer patients.

BACKGROUND: Taxoids are new chemotherapeutic agents effective in the treatment of breast cancer. Paclitaxel treatment has been reported to cause some cardiac side effects and both paclitaxel and docetaxel to cause mild, mainly sensory, peripheral neuropathy. Autonomic function tests are sensitive measures of autonomic neuropathy and cardiac regulation. The purpose of this study was to find out whether docetaxel changes neural cardiovascular regulation in breast cancer patients previously treated with anthracyclines. PATIENTS AND METHODS: Nine women treated for metastatic breast cancer with docetaxel were studied prior to the docetaxel treatment and after the third or fourth course. Autonomic cardiovascular function tests were performed and heart rate and blood pressure variability were assessed with power spectrum analysis. RESULTS: Heart rate variability or the heart rate responses to the autonomic function tests did not change after docetaxel treatment. The blood pressure response to standing was enhanced and systolic blood pressure variability decreased after three to four cycles of docetaxel. CONCLUSIONS: Docetaxel treatment did not deteriorate vagal cardiac control in breast cancer patients after exposure to epirubicin. The observed changes in blood pressure responses suggest that docetaxel changes sympathetic vascular control. However, these changes seem to be related to altered cardiovascular homeostasis rather than peripheral sympathetic neuropathy.

Adult↗
PubMedDate not supplied

Plasma levels of atrial natriuretic factor and catecholamines in endotoxin shock in dogs.

Changes in arterial plasma levels of atrial natriuretic factor and catecholamine release were studied in 11 beagle dogs during pentobarbital anesthesia. Seven dogs were injected intravenously with Escherichia coli endotoxin, 0.5 mg/kg over 15 min. Four control dogs received only saline solution. The endotoxin injection resulted in cardiac depression,, hemoconcentration, acidosis and renal hypoperfusion. The central venous pressure remained relatively unchanged in both groups during the 2-hour study. The concentrations of epinephrine, norepinephrine and the norepinephrine metabolite 3,4-dihydroxyphenylglycol increased in arterial plasma during the acute hypodynamic endotoxin shock. In the control dogs the levels of these hormones remained very low and constant. Increased circulating levels of atrial natriuretic factor were observed in endotoxin shock with renal hypoperfusion, unchanged central venous pressure and no concomitant tachycardia.

Animals↗