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Biomedical subjects

K Antila

Publications and source records attributed to K Antila.

At least 19 recordsLinked to original sources
PubMed2003

Docetaxel with epirubicin--investigations on cardiac safety.

The aim was to evaluate clinical and subclinical cardiac toxicity of epirubicin-docetaxel (ET) combination. Breast cancer patients were given epirubicin (75 mg/m2 for 15 min), followed 1 h later by a 1-h infusion of docetaxel (75 mg/m2) q3w as first-line treatment. Cardiac function was monitored using a 24-h ambulatory electrocardiogram (ECG), left ventricular ejection fraction (LVEF), physical examination and chest radiography. The median LVEF did not decrease during the course of the treatment: median LVEF was 64% prior to treatment and 68% after cycle 8. The 24-h ECG did not reveal any significant changes in heart rate variability. The number of extrasystoles or cardiac arrhythmia did not increase with the ET treatment. No patient experienced congestive heart failure during treatment or the mean follow-up of 34 months. We conclude that first-line ET caused no major cardiac changes during 6 months of treatment (8 cycles) or during follow-up. Twenty-four-hour ECG, combined with echocardiography to measure LVEF, was a feasible method for the close monitoring of the cardiac effects during chemotherapy.

Adult↗
PubMed1998

Increased amplitude modulation of continuous respiration precedes sudden infant death syndrome -detection by spectral estimation of respirogram.

The immaturity of the control of the autonomic nervous system has been suggested as one of the key factors in the pathophysiology of sudden infant death syndrome (SIDS). Therefore, the attenuated control of respiration may also cause more slow oscillatory breathing among infants at risk of SIDS. In this study, patterns of respiratory activity (RAV) and heart rate variability (HRV) were examined in Medilog-records prospectively obtained from 22 tape recordings made on 16 babies subsequently suffering from SIDS and from 22 matched control babies. A total of 248 signal segments, 120 s in duration, representing the state of regular breathing were visually selected for further analysis. The digitised signal sets were detrended, Fast-Fourier-transformed and autospectra as well as cross-spectra for the HRV and HRV were computed. The RAV and HRV were examined at two spectral bands: (1) a low frequency (LF) band 0.03-0.17 Hz (1.8-10 cycles/min) and (2) a high frequency (HF) band 0.3-1.3 Hz (18-90 cycles/min). Different parameters of each band were tested in the spectral analysis of cardiorespiratory control. The LF/HF-ratio of the spectral peak area of the respiratory activity and the LF/HF-ratio of the spectral band area of the respiratory activity were greater in the SIDS group when compared to the controls. No significant intergroup differences were found in the parameters of HRV, or the cross-spectral parameters. Interestingly, the technique appeared helpful in displaying that the victims of SIDS had a significantly greater amount of slow oscillation in the continuous respiratory signal (1.05+/-1.89 vs. 0.41+/-0.57, P=0.02). In the victims of SIDS the respiratory control system seems to be less stable and cause more slow oscillatory breathing and this can be detected using spectral analysis of respiratory activity even during breathing that visually seems to be regular.

Autonomic Nervous System↗
PubMed1997

Paclitaxel changes sympathetic control of blood pressure.

Paclitaxel has become part of standard therapy in the treatment of ovarian and breast cancer. Concern has been raised about the effects of paclitaxel on cardiovascular function. Therefore, this study of the effects of paclitaxel on autonomic cardiovascular control was initiated. Eighteen women treated for ovarian or breast cancer were examined with autonomic cardiovascular function tests, once before the treatment and once after the second course of paclitaxel. Heart rate and blood pressure variability and changes in heart rate and blood pressure responses to the tests were measured. Baroreflex sensitivity was calculated from the Valsalva manoeuvre non-invasively. Paclitaxel did not change heart rate variability at rest compared with the pretreatment level. However, medium frequency variability of blood pressure was smaller after treatment with paclitaxel. Paclitaxel treatment did not impair the heart rate and blood pressure responses to the autonomic function tests. The results do imply that paclitaxel alters sympathetic control of blood pressure. Nevertheless, paclitaxel does not appear to precipitate autonomic cardiac neuropathy.

Adult↗
PubMed1995

Haemodynamic response to head-up tilt in elderly hypertensives and diabetics.

To examine the haemodynamic mechanism associated with postural hypotension (PH) in elderly people, haemodynamic response to head-up tilt was studied in 14 elderly hypertensives and 13 elderly diabetics. Hypertensives and diabetics were divided into those with or without PH, defined as > or = 10 mmHg decline in mean blood pressure in response to head-up tilt. There was no significant change in cardiac output in hypertensives or diabetics with PH, whereas there was a significant increase during tilt in hypertensives without PH (p < 0.0001) and diabetics without PH (p = 0.0054). Hypertensives without PH showed a significant decrease in total peripheral resistance in response to head-up tilt (p = 0.0043). In hypertensives with PH and in both diabetic groups, there was no change in total peripheral resistance in response to head-up tilt. There was no difference in ejection fractions or heart rate responses between subjects with and without PH in either disease group. The difference in cardiac output change was not explained by myocardial changes observed at echocardiography nor by heart rate response nor by differences in total peripheral resistance. The results suggest that an increase in cardiac output in response to changing posture may be more important than vasoconstriction in protecting elderly subjects from PH.

Aged↗
PubMed1995

The role of potassium in postural hypotension: electrolytes and neurohumoral factors in elderly hypertensive patients using diuretics.

OBJECTIVE: To study the association between postural hypotension and (i) electrolyte levels and (ii) neurohumoral factors in elderly hypertensive patients using diuretics. DESIGN: Cross-sectional study of patients and controls. SETTING: The subjects were gathered from senior citizen clubs or they were referred to the study by general practitioners. The subjects were examined on a geriatric ward in Turku City Hospital. SUBJECTS: Seven subjects with postural hypotension and 13 controls. MEASUREMENTS: Plasma electrolyte levels and neurohumoral response to head-up tilt. RESULTS: There were significantly more hypokalaemic subjects in the postural hypotension group (5/7) than in the control group (1/13) (P < 0.01). The plasma potassium level was negatively correlated to plasma aldosterone (r = -0.57; P < 0.01) and renin activity (r = -0.69; P < 0.001). Subjects with postural hypotension had higher levels of noradrenaline, both supine (P < 0.05) and during tilt (P < 0.05). There were no significant differences in supine or tilt levels of plasma adrenaline, vasopressin, atrial natriuretic peptide, aldosterone and renin activity between the groups. CONCLUSION: The results suggest that potassium depletion is associated with postural hypotension in elderly hypertensive patients using diuretics. However, it is unclear whether there is a causative link between potassium depletion and postural hypotension or whether they are both caused by some other factor, e.g. volume contraction.

Aged↗
PubMed1994

Pre-excitation syndrome in Leber's hereditary optic neuropathy.

Pre-excitation syndrome is common in families with Leber's hereditary optic neuropathy (LHON). 24 Finnish families with LHON were screened for the 11778 and the 3460 mitochondrial DNA mutations. 5 of 30 individuals with LHON and the 11778 mutation had the Wolff-Parkinson-White pre-excitation syndrome. None of 10 with the 3460 mutation or of 11 with "other" mutations had this syndrome. Overall, 5 of 51 LHON patients and 9 of 112 symptom-free maternal relatives had Wolff-Parkinson-White syndrome (9%). In paternal relatives, the frequency was 1.6%. Mitochondrial DNA causal for LHON may contribute to pre-excitation syndrome.

DNA, Mitochondrial↗
PubMed1994

Spectral analysis of heart rate variability in evaluation of sympathetic function in elderly subjects.

Plasma concentration of noradrenaline is often used as a measure of sympathetic nervous activity. Recently, the method of spectral analysis of heart rate variability has been introduced to detect autonomic dysfunction. To examine whether spectral analysis of heart rate variability is useful in evaluating sympathetic function, changes in the heart rate variability in the low-frequency spectral band were compared with the change of plasma noradrenaline in response to head-up tilt in elderly hypertensives (n = 13) and diabetics (n = 13). In hypertensive subjects, there was an increase in relative low-frequency power (p = 0.015) and an increase in plasma noradrenaline level (p = 0.040) in response to head-up tilt. Diabetics did not show corresponding changes. There was no change in absolute low-frequency power in either group. It is concluded that spectral analysis of heart rate variability can be useful in evaluating sympathetic function in elderly subjects.

Aged↗
PubMed1993

Association of breathing movements to the variability of heart rate and blood pressure in foetal lambs.

Heart rate (HR) variability and arterial blood pressure (BP) variability were analysed as functions of foetal breathing movements (FBMs) by means of power spectral analysis in seven foetal lambs during the third trimester of gestation. No evidence of FBM-related changes, either in mean HR, mean systolic or diastolic arterial pressures, were found. Mean arterial pulse pressure, HR variability, and BP variability increased during FBMs. The increase in BP variability occurred at frequencies higher than 0.35 Hz, i.e. those of FBMs. The increase in HR variability occurred at 0.07-1.0 Hz, i.e. at every frequency band except the lowest one. Thus, the increase in HR variability was not frequency-specifically related to FBMs. During FBMs the periodic variability of HR at frequencies > 0.35 Hz was only 10% of total HR variability. We suggest that the FBM-related changes of BP variability may be mediated by direct peripheral, hydraulic mechanisms. HR changes involve autonomic control systems: the vagal component of baroreflex seems to be relatively insensitive, whereas the very slow vasomotor component of HR variability is dominant.

Animals↗
PubMed1991

Effects of glycopyrrolate and atropine on heart rate variability.

Analysis of heart rate variability, combined with physiological tests (deep breathing and tilt tests) was used to characterise the effects of atropine and glycopyrrolate on the parasympathetic nervous tone of the heart in healthy male volunteers. The low dose of atropine (120 micrograms) administered as a continuous infusion in 15 min was associated with parasympatomimetic effects estimated by the slowing of the heart rate and an increase of the mean and beat-to-beat heart rate variability. The bradycardia and increase of heart rate variability following infusion of glycopyrrolate (50 micrograms) was less marked and did not differ significantly from that of placebo. The higher doses of atropine (720 micrograms) and glycopyrrolate (300 micrograms) administered as a continuous infusion in 15 min produced an equal vagal cardiac blockade characterised by significant tachycardia and a decrease in overall and beat-to-beat heart rate variability. It is concluded that at low doses the parasympatomimetic action of glycopyrrolate is less marked than that of atropine; and at higher doses only small differences exist between these two muscarinic antagonists in their effects on cardiac vagal outflow, assessed by heart rate and heart rate variability.

Adult↗
PubMed1990

Effect of posture on spontaneous and thermally stimulated cardiovascular oscillations.

STUDY OBJECTIVE: The aim of the study was to investigate the effect of posture on thermally stimulated cardiovascular oscillations. DESIGN: The effect of increased gravitational stress (rising from sitting to standing position) on the thermally stimulated cardiovascular oscillations was measured in young male volunteers. Extensive cardiovascular function data were obtained using a cardiovascular investigation protocol. SUBJECTS: The volunteers were five fit young men, aged 20-21 years. EXPERIMENTS AND MAIN RESULTS: Cardiovascular changes from sitting to standing indicated increased sympathetic and decreased parasympathetic influence on heart and skin blood vessels; mean heart rate increased, beat to beat heart rate variability diminished, high frequency periodic heart rate variability decreased, low frequency heart rate oscillations and ratio of low frequency to high frequency heart rate variability increased, mean skin blood flow and oscillations of skin blood flow decreased (all p less than 0.05). Thermal skin stimulation at 0.01-0.10 Hz frequency increased both sitting and standing 0.10 Hz periodic heart rate variability (p less than 0.05), and 0.10 Hz thermal stimulation entrained the heart rate oscillations in sitting and standing subjects (p less than 0.05). In contrast, skin blood flow oscillations in sitting subjects decreased, while in standing subjects it increased during 0.10 Hz thermal stimulation compared to the corresponding prestimulus values (p less than 0.04). CONCLUSIONS: On the basis of previous physiological experiments, these results suggest coupling between thermoregulatory and 0.10 Hz reflex activities.

Adult↗
PubMed1990

Plasma pharmacokinetics of Idarubicin and its 13-hydroxymetabolite after intravenous and oral administration under fasting and non-fasting conditions.

The plasma pharmacokinetics of Idarubicin and its 13-hydroxy-metabolite have been studied in 10 patients with solid tumours after intravenous and oral administration under fasting and non-fasting conditions in a randomized cross-over design. The plasma concentration time curves of Idarubicin after intravenous administration could be described by the open two or three compartment models. No pharmacokinetic modelling of Idarubicin was possible after oral administration. After oral administration of Idarubicin, the amount of intact drug was higher under non-fasting conditions. The extensive and long-lasting appearance of Idarubicinol suggests that this cytotoxic metabolite is of major clinical importance in i.v. and oral therapy with Idarubicin. The pharmacokinetics of Idarubicinol was not affected by food intake.

Administration, Oral↗
PubMed1990

Children in sauna: cardiovascular adjustment.

Children's circulatory adjustment to a 10-minute heat stress in a climatic chamber was studied in 61 children and 20 adolescents and young adults. The thermal conditions corresponded to those of an ordinary Finnish sauna bath. In all subjects the rectal temperature and heart rate increased during the heat exposure (P less than .001). Systolic and diastolic blood pressures remained unchanged in sauna, but the systolic and especially the diastolic blood pressure decreased (P less than .001) in children less than 10 years of age immediately after the heat exposure; two vasovagal collapses developed. Cardiac output increased in all but the less than 5-year-old children (P less than .001). This was due to a significant decrease in stroke volume (32.9%) (P less than .001) in children less than 5 years old. Stroke volume declined slightly even in the older subjects. These changes indicate that the Finnish sauna bath puts great demands on a child's circulatory regulation. To avoid possible cardiovascular side effects, particularly small children should be supervised carefully during sauna bathing.

Adolescent↗
PubMed1989

Pharmacokinetics of 4' epi-adriamycin after morning and afternoon intravenous administration.

The chronopharmacokinetics of 4' epi-adriamycin (Epi) have been studied in ten patients with gynecological malignancies. The drug (45 mg m-2) was administered as a short time (5.0 min) intravenous infusion at 7 a.m. and 7 p.m., in a randomized cross-over design. The pharmacokinetics of Epi were evaluated according to the statistical moment theory. Morning and afternoon dosing of Epi was not bioequivalent. The area under the plasma concentration-time curve (AUC), the maximum plasma concentration (Cmax), mean residence time (MRT) and the terminal half-life time (t1/2) could differ by more than 35% after morning and afternoon dosing. The inter-individual variation of AUC and Cp,max were larger after morning dosing than after afternoon dosing (P less than 0.04). The morning dose of Epi resulted in higher values of AUC in seven of the ten treated patients as compared to the afternoon dose. The terminal half-life times were shorter in eight of the patients after the morning dose.

Aged↗
PubMed1989

A non-invasive method for testing neural circulatory control in man.

Exaggerated cardiovascular responsiveness is common in young men and may cause non-specific symptoms and poor performance. Conventional autonomic function tests are not clinically useful. We have therefore designed a thermal entrainment method to evaluate sympathetic and parasympathetic cardiovascular function in subjects with dystonic symptoms and orthostatic intolerance. Oscillations of thermal gradient in the skin were produced by standardised periodic stimulation of the lower part of the arm with warm and cool water. Vasomotor activity of the skin induced oscillations of arterial blood pressure which were thought to be regulated by sympathetic and parasympathetic heart rate control and by oscillation of the sympathetically controlled peripheral vascular resistance. We tested the method in subjects with cardiovascular symptoms (n = 7) and controls (n = 7). At supine rest, the frequency response of the heart rate variability to the thermal stimulation at frequencies of 0.01, 0.02, 0.03 and 0.1 Hz was significantly different (p = 0.008) between symptomatic subjects and controls. The gain of the heart rate control was increased to 0.03 Hz [-1.3(SEM 0.5) dB v -3.8(0.8) dB, p = 0.068] and decreased at 0.1 Hz [-3.9(1.1) dB v -1.5(0.6) dB, p = 0.076] in the test group compared to the control group. At stimulus frequencies of less than 0.03 Hz the individual overall heart rate variability of the subjects with symptoms stayed below the mean control value, at 60(6) ms v 79(15) ms, p = 0.16. The cutaneous temperature oscillations at the site of stimulation, frequency response of the oscillations of the skin blood flow and respiration to the thermal stimulation, and mean heart rate were similar in the both groups. The results show that this thermal entrainment method quantifies the increased sympathetic and decreased parasympathetic cardiac control of subjects with dystonic symptoms.

Adult↗
PubMed1988

Multivariate autoregressive modeling of autonomic cardiovascular control in neonatal lamb.

The neonatal cardiovascular control system is a complicated interactive system which is under vigorous development at birth. From the measurement point of view the cardiovascular control is a closed-loop system. However, it can be examined on a beat-by-beat basis by analyzing circulatory-controlled variables with advanced signal analysis techniques. This paper proposes to use a multivariate autoregressive modeling technique in the analysis of several simultaneous physiological signals in order to examine interactions and inherent properties in the system. With the proposed multivariate autoregressive modeling technique, a signal is modeled as a linear combination of its own past and the past values of the other simultaneous signals plus a predictive error term of the model. The interactions in the system after the model identification are analyzed in frequency domain utilizing power spectrum estimates of the signals and signal contributions. The applicability of the proposed method was examined by a three-variable model between heart rate, blood pressure and respiration in the study of autonomic cardiovascular control in a chronic neonatal lamb model, in which the cardiovascular status was changed by using a beta-adrenergic autonomic nervous blockade. The study showed that the multivariate autoregressive modeling technique is a feasible technique in studying complicated interactions within the cardiovascular control system.

Animals↗
PubMed1988

Interaction of heart rate and respiration in newborn babies.

Variability of heart rate (HRV) and transthoracic electric impedance respirogram (TEZ) were examined by spectral analysis in three groups of neonates: healthy term babies (22), healthy preterm babies (21), and preterm babies with respiratory distress syndrome (RDS) (11). Heart rate, TEZ, PtcO2, and PtcCO2 were monitored during quiet sleep on the 1st, 3rd, and 5th day of postnatal life. Autospectra for trend-corrected segments of heart rate and TEZ as well as their cross-spectral density was in less than 0.2 Hz [low frequency (LF)] area (less than 12 cycles/min) in all the neonates. Intergroup comparisons of average band-integrated spectra revealed that the LF spectral density of HRV was greater in the term babies than in the preterm babies on day 3. In the babies with RDS, both LF and high-frequency (HF, greater than 0.2 Hz) were abnormally low throughout the study. In the term infants, the TEZ amplitude spectrum was flat on day 1. On later days, a peak corresponding to the average respiratory rate emerged. In the healthy preterm babies, there was a LF peak in TEZ autospectrum on all days. In the babies with RDS, the peak of ventilator frequency was initially present; finally, the respiratory activity accumulated in the LF area. In the cross-spectra of term babies, there was a LF peak on all days. On day 5, an additional HF peak appeared, representing respiratory sinus arrhythmia. In the healthy preterm babies, only a LF peak was present.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗