Active Orthostasis Research Articles

Pulsometric study of the functional state of cardiovascular system under conditions provoking neurogenic syncopes.

The effects of passive and active orthostatic loads on the amplitude and temporal parameters of pulse waves were studied using an original computer assisted method of differential sphygmomanometry. Changes in the cardiac rhythm reflecting impairment of the autonomic regulation of the circulatory system and preceding neurogenic cardiovascular syncope were revealed and evaluated. Comparative analysis revealed similarity between these changes under conditions of both passive and active orthostasis, which confirmed the diagnostic value of differential sphygmomanometry.

The impact of ropinirole on blood pressure and noradrenaline concentration after active orthostasis in Parkinsonian patients

Orthostatic hypotension is common in Parkinsonian patients. It is probably caused by reduced noradrenaline (NA) release. This effect is further enhanced by therapeutic use of ergot alkaloid dopamine agonists. In this trial we studied the impact of the non-ergot dopamine agonist ropinirole on blood pressure and noradrenaline release in 12 patients suffering from idiopathic parkinsonism (six female, six male, mean age 57.6+/-4.9years). Only de novo patients were included in this study. These patients were started on ropinirole monotherapy. In all patients blood pressure and serum noradrenaline levels at rest were measured supine (after lying down for 10min) and standing (9th minute after positional change). Patients with a drop in blood pressure >10mmHg were excluded from the study. Measurements were repeated after treatment with ropinirole 6mg/day. Before treatment the NA concentration (determined via HPLC) went up by 390.1pg/ml (SD 54) to the 9th minute after rising, but during management with ropinirole it went up only by 338.4+/-78pg/ml. In controls (n=27; eight women, 19 men, aged 60.6+/-10.8years) NA increased by 425+/-230pg/ml. The NA increase thus differed substantially prior to therapy compared with controls, and the difference did not change significantly during treatment. With ropinirole eight patients showed normal, four patients borderline and none of them pathologic decrease in blood pressure. These results do show a small but nonsignificant influence of the non-ergot dopamine agonist on blood pressure response and noradrenaline release, which is much less prominent than the change observed with ergot dopamine agonists.

Vegetative nervous system state in pregnants with late hestosis

The vegetative nervous system state in 60 pregnants with late hestosis (with terms of 36 40 weeks is studied. The vegetative response types using mathematical analysis of cardiac rhythm variability in rest and in test with active orthostasis and phychologic peculiarities of a person are determined. The peculiar type of vegetative response especially in vegetative provision of activity as well as revealed psychovegetative syndrome can be connected with suprasegmental part disfunction of vegetative nervous system, in particular, its ergothropic part and with intrasystemic disintegration of the brain.

The impact of bromocriptine on blood pressure, heart Rate and noradrenaline concentration after active orthostasis in Parkinson patients

Abnormal blood pressure regulation after orthostasis is a frequent symptom in Parkinson’s disease. Deficient noradrenaline excretion plays a major part in that respect. In an earlier study, we were able to show that r_-dopa (with a decarboxylase inhibitor) and selegiline had no significant effect on the noradrenaline excretion after active orthostasis [l]. In our subsequent study, we wanted to see to what extent dopamine agonists worked on heart rate, blood pressure decline, and noradrenaline excretion. We examined ten patients with idiopathic Parkinson’s disease (four women, six men, mean age 60.5 -f 9.25 yr). The patients were not selected according to such parameters as duration of illness, severity of symptoms or specific anti-parkinsonian medication. They were seen at a time of satisfactory drug management. The mean daily dose of the dopamine agonist bromocriptine was 8.5 ? 5.15 mg, the mean dose of Ldopa was 315 + 126.6 mg/day. Measurements were done after 10 min of rest (lying down) and after standing up in the first, third, fifth, seventh and ninth minutes. Testing was always carried out at the same time of the day (around 10 a.m.). Blood was taken via an indwelling cannula, which had been inserted into a vein of the forearm 30 min prior to the orthostatic test. Hormone concentrations of noradrenaline were determined by high performance liquid chromatography with electrochemical detection (HPLC-ECD). The drop in blood pressure was regular in only 3/ 10

Are heart rate responses reproducible in the tilt-table test?

Measurement of blood pressure and heart rate in active orthostasis has proven to be effective in the diagnosis of autonomic regulatory dysfunctions. The following study was carried out in order to clarify to what extent reproducible heart rate reactions also occur in passive orthostasis. 61 people with normal results in five standardized tests were examined. All 61 test persons had individually differing courses of heart rate. After an initial increase of frequency an almost straight line results from a superimposed projection of the graphs. In 20 of these cases the tilt-table test was repeated in order to detect intra-individual regularities. Even when the test was repeated, no reproducible intraindividual heart rate reactions occurred. And here as well, projection of the graphs produced an almost straight line. We could not find any quotient, such as the 30/15 ratio in active orthostasis, during our tests with the tilt-table.

Optimal frequency ranges for extracting information on autonomic activity from the heart rate spectrogram

Heart rate variability spectrum analysis provides useful quantitative indices of neural control of the SA node. This method is attractive both for its simplicity and the lack of invasive instrumentation, particularly for human investigation. The differing spectral characteristics of parasympathetic and sympathetic control of heart rate allows separate measurement. However, there are widely varying opinions as to the appropriate frequency bands to represent these two inputs. We compared the heart rate variability spectra of 16 humans in supine and upright positions. Adequate measures of parasympathetic or sympathetic activity change should correlate respectively inversely or directly with heart rate change. Frequently used spectral measures of sympathetic activation did not correlate with heart rate changes. With optimization of frequency bands, we found that restricting the sympathetic band to frequencies below 0.1 Hz and above 0.05 Hz (0.055 to either 0.086–0.098 Hz), and dividing by total spectral amplitude 0.004–0.5 Hz (to account for parasympathetic fluctuations within the sympathetic band) produced the best results. The parasympathetic band was best from 0.1 Hz to a frequency greater than that of the respiratory sinus arrhythmia. The optimization method detailed here is easily applied to circumstances other than active orthostasis, and should provide a means of empirically determining useful frequency limits.

Blood pressure response to physical activity in hypertensive subjects at different times of the day.

1. Active orthostasis causes a fall of systolic blood pressure in the morning; this fall was more extensive in severe arterial hypertension. 2. Everyday physical activity produces a marked rise of systolic blood pressure, which is higher at noon and in the evening than in the morning; the hypertensive response is somewhat greater in WHO II and III, than in WHO I, grades of hypertension. 3. In studies on blood pressure behaviour in hypertensive subjects the circadian variability not only of the blood pressure at rest but also of the blood pressure response to various stimuli has to be considered.