Bioimpedance harmonic analysis as a tool to simultaneously assess circulation and nervous control

Abstract

Multicycle harmonic (Fourier) analysis of bioimpedance was employed to simultaneously assess circulation and neural activity in visceral (rat urinary bladder) and somatic (human finger) organs. The informative value of the first cardiac harmonic of the bladder impedance as an index of bladder circulation is demonstrated. The individual reactions of normal and obstructive bladders in response to infusion cystometry were recorded. The potency of multicycle harmonic analysis of bioimpedance to assess sympathetic and parasympathetic neural control in urinary bladder is discussed. In the human finger, bioimpedance harmonic analysis revealed three periodic components at the rate of the heart beat, respiration and Mayer wave (0.1 Hz), which were observed under normal conditions and during blood flow arrest in the hand. The revealed spectrum peaks were explained by the changes in systemic blood pressure and in regional vascular tone resulting from neural vasomotor control. During normal respiration and circulation, two side cardiac peaks were revealed in a bioimpedance amplitude spectrum, whose amplitude reflected the depth of amplitude respiratory modulation of the cardiac output. During normal breathing, the peaks corresponding to the second and third cardiac harmonics were split, reflecting frequency respiratory modulation of the heart rate. Multicycle harmonic analysis of bioimpedance is a novel potent tool to examine the interaction between the respiratory and cardiovascular system and to simultaneously assess regional circulation and neural influences in visceral and somatic organs.

Electrical Rhythms Revealed by Harmonic Analysis of a High-Resolution Cardiogram

“…3, a). Thus, the changed in M-and R-waves of ECG induced by succinylcholine chloride were reciprocal, which corroborates interpretation of their nature as predominantly adrenergic and cholinergic, respectively [15].…”

“…Resolution was further enhanced by a 100-fold decimation of primary digital signal, which reduced the sampling rate to 160 Hz and decreased the input noise of instrumentation system by 10 times. An original A5 software performed harmonic analysis of ECG, which made it possible to select the frequency bands to process ECG with software fi lters of preset type, cutoff frequency, and fi lter order [3,15]. For harmonic analysis, ECG traces were cut into the segments with duration of 12.8 or 25.6 sec.…”

“…New vistas opened up due to recording of high-resolution rheograms and the use of bioimpedance harmonic analysis, which made it possible to examine the spectrum of small bioimpedance variations at low frequencies corresponding to respiration and Mayer wave [3,4,15]. The spectral parameters had been employed to assess regional activity of autonomic nervous system (ANS) and regional circulation in patients with the diseases of urogenital system [1,2,6].…”

“…Taking into consideration the relation of regional bioimpedance oscillations to respiration [1][2][3][4]6,15], the measurements had been made in norm and under the action of myorelaxant succinylcholine chloride. By analogy to bioimpedance…”

“…Taking into consideration the relation of regional bioimpedance oscillations to respiration [1][2][3][4]6,15], the measurements had been made in norm and under the action of myorelaxant succinylcholine chloride. By analogy to bioimpedance variations in various organs [4,15], we hoped to detect in ECG the refl ection of slow processes ongoing in the myocardium at respiration and Mayer frequencies and to disclose the fi ne structure of pulsatile harmonics.…”