S. Greenberg et al., Direct ultrasound application had no effect on cardiac hemodynamic performance in a baseline isolated rat heart model, ULTRASOUN M, 26(2), 2000, pp. 315-319
Therapeutic ultrasound (US) has been used for more than 3 decades to promot
e tissue healing in cases of tissue injury and muscle soreness. It was prev
iously suggested that US may have vasorelaxatory and inotropic properties.
However, the direct effect of therapeutic US in a whole heart model has not
yet been investigated. Our hypothesis was that application of US might enh
ance cardiac function. The Langendorf model was modified in a special manne
r to allow application of US to the heart. Using this model, 20 male rats w
ere equally divided into two groups. Group 1: the hearts were perfused for
15 min, to obtain baseline measurements, and then they were perfused for an
other 15 min in a special bath full of perfusate. Group 2: after 15 min of
baseline measurements, continuous US of 1 MHz 2 W/cm(2) was applied for ano
ther 15 min. The parameters that were measured at 5-min intervals were: lef
t ventricular pressure P(max), first derivative of the rise and fall in lef
t ventricular pressure (dP/dt(max), dP/dt(min)), and pressure-time integral
. There was no significant difference between the two groups in all paramet
ers at baseline and during US application. P(max) and dP/dt(max) remained c
onstant. After 15 min of US propagation, P(max) was 98% +/- 3 from baseline
level vs. 98% +/- 7 in the control group, and dP/dt(max) was 98% +/- 3 vs.
99% +/- 9 in the control. In dP/dt(min), a gradual decline after 15 min of
perfusion was measured. In the US- treated group, it declined to 80% +/- 1
0 vs. 83% +/- 5 in the controls. In conclusion, US radiation at the dose sp
ecified does not improve healthy isolated heart hemodynamic performance. We
established a model that may be used for further investigation. (C) 2000 W
orld Federation for Ultrasound in Medicine & Biology.