Frequency parameters of feline left ventricular pressure under various experimental conditions.

Cardiac frequency-domain parameters of the left ventricular pressure were studied in acute experiments on cats under conditions of reflex and load stimulation and during maximum inotropic stimulation with epinephrine. A strict correlation was revealed between the upper threshold of the frequency range and the maximum value of pressure first derivative. Without epinephrine infusion, the maximum value of pressure first derivative and the upper threshold of the frequency range attained 9840 mm Hg/sec and 98.4 Hz, correspondingly. During epinephrine infusion, the corresponding values were 12911 mm Hg/sec and 145 Hz. Left ventricular pressure in cats is characterized by high-frequency parameters, which can be measured by special catheter microtransducers and only in some cases by routine pressure gauges.