Variability and reproducibility of arterial and venous circulation parameters in the forearm and calf measured at one-week intervals.

In 12 healthy men aged 22 to 29 years the variability of basal arterial blood flow, maximal arterial blood flow as induced by a 5-min arterial occlusion, vascular resistances, total venous capacity and venous emptying rate and the reproducibility of the measurements were studied in both the upper and lower limbs 3 times at one week's interval under strictly standardised conditions using an automatic venous occlusion plethysmograph. Means, medians, standard errors, and standard deviations were virtually identical or very similar without any statistically significant difference between the 3 study occasions; this implies that valid comparisons can be made when measurements are repeated at several days' interval provided measuring conditions are rigorously standardised. Basal and maximal arterial blood flows and venous emptying rates per 100 ml of tissue were significantly higher (p less than 0.

Temporal and spatial summation caused by aortic nerve stimulation in rabbits. Effects of stimulation frequencies and amplitudes.

Frequency-modulated stimulus patterns, controlled by heart rate or blood pressure feed-back, are proposed for therapeutic use of electrical stimulation of the carotid sinus nerves (CSNS). Continuous CSNs with equidistant pulses is applied in hypertensive or angina pectoris patients who are refractory to therapy. Frequency modulation simulates transmission properties of single baroreceptors, while modulation of stimulus amplitudes simulates recruitment of baroreceptors by pressure pulses in the carotid sinus.

The evolution strategy--a search strategy used in individual optimization of electrical parameters for therapeutic carotid sinus nerve stimulation.

Optimization problems, arising in the search for parameters and/or techniques of functional electrostimulation (FES), disproportionally increase when multiple electrodes, electrode configurations, electrical parameters, and stimulation modes may be applied. When computational or investigational effort precludes systematic studies in FES, we propose to apply and evaluate Rechenberg's evolution strategy, which in technical use and numerical optimization has been valid in comparison to more traditional methods. This strategy implements mutation and selection processes in analogy to biological evolution.

Search for optimal frequencies and amplitudes of therapeutic electrical carotid sinus nerve stimulation by application of the evolution strategy.

In humans, electrical, bipolar, bilateral carotid sinus nerve stimulation (CSNS; impulse duration 0.35 ms) was applied, using frequencies between 10 and 110 Hz and voltages between individual thresholds and maximal amplitudes of stimulation. Ten anginal patients and two hypertensive patients were studied at an interval of up to 12 years after implantation of electrodes and a radiofrequency receiver for chronic therapeutic CSNS.

Blood pressure and heart rate changes during physical activity upon heart rate feedback-controlled electrical carotid sinus nerve stimulation.

The effect of feedback-controlled electrical carotid sinus nerve stimulation on changes in blood pressure and heart rate during interventions simulating usual daily activity was studied in four anginal patients. Frequency or amplitude of stimulation was modulated pulse-synchronously and controlled by heart rate. While individual responses differed between both types of modulation, stimulation attenuated predominantly increases in blood pressure during walking and staircase climbing.