Forms of physiological aliasing within the heart rate fluctuations by higher frequent respiratory movements.

In adult conscious rabbits, the respiratory frequency (RF) is almost always higher than half the heart rate (HR) Thus, no "classical" respiratory sinus arrhythmia occurred. But now, slow HR fluctuations, which were not synchronous to the respiratory rhythm but effected by it, occurred systematically. By cholinergic blockade, these slow HR fluctuations could be essentially reduced but not completely abolished. Up to now, this phenomenon was not be taken into account in the analysis of HR fluctuations. Thus misinterpretations are inevitable. During general anaesthesia, the RF decrease up to 2 RF < HR, and now classical respiratory sinus arrhythmia occurred which also could be essentially reduced but not completely abolished by vagal blockade. The possibilities of calculation of such slow HR fluctuations were shown, as those during 1/2 HR < RF < 3/2 HR and RF > 3/2 HR.