Effect of left ventricular volume on the magnitude of functional depression by external minute vibration

We examined the effect of the left ventricular (LV) volume on the magnitude of the vibration induced functional depression (VID) using four canine cross-circulated isovolumically beating LV preparations. A sinusoidal, 50 Hz vibration (1.5 mm in amplitude) was applied to the ventricular anterior epicardium at different values of LV volume which was stepwisely increased by 1-2 ml from 0 to 30 ml. VID was estimated as the difference of the peak LV pressure between control and during external vibration. VID increased as an increment in LV volume when the volume was below 7-8 ml and when peak LV pressure was less than 70 mmHg. However, VID remained constant when the volume increased further. We concluded that VID was independent of LV volume at physiological range.