Key result
Diastolic vibration accelerated left ventricular relaxation and improved systolic function in canine models, with the increase in peak LVP and SV correlating with incomplete relaxation severity (r=0.82).
Why the study?
Does diastolic vibration improve systolic function in canine models of incomplete relaxation?
Does diastolic vibration improve systolic function in canine models of incomplete relaxation?
Diastolic vibration accelerates LV relaxation and improves systolic function via the Frank-Starling mechanism in a canine model of incomplete relaxation.
Does not support clinical use; leaves open translation of diastolic vibration to human diastolic dysfunction.
BACKGROUND: Incomplete relaxation of the left ventricle (LV) affects LV filling, but the subsequent effect on LV systolic function remains unclear. We attempted to improve relaxation by applying oscillatory mechanical perturbation during diastole (diastolic vibration) and examined the extent to which systolic function improved. METHODS AND RESULTS: Using 10 open-chest canine preparations, pacing tachycardia and administration of propranolol were imposed to induce various levels of incomplete relaxation. Myocardial length perturbation was induced with an oscillator attached to the LV surface (50 Hz, 1-mm amplitude) and was restricted to the period from the beginning of isovolumic relaxation to end diastole. At resting heart rates, diastolic vibration caused an immediate decrease in the time constant (T) of LV pressure fall without any influence on heart rate, LV peak systolic pressure (peak LVP), stroke volume (SV), LV peak positive dP/dt, and total systemic vascular resistance. With pacing tachycardia, diastolic vibration increased both peak LVP and SV at 160 beats per minute (before) and 120 beats per minute (after propranolol), simultaneously decreasing both T and LV diastolic pressures and increasing end-diastolic segment length. The increase in peak LVP and SV caused by diastolic vibration correlated with the T/diastolic interval (r = 0.82), the assumed index of severity of incomplete relaxation. CONCLUSIONS: These results suggest that diastolic vibration accelerates the LV relaxation rate and that this increased relaxation improves systolic function through the Frank-Starling mechanism.
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Takagi et al. (1992) studied Incomplete relaxation of the left ventricle (n=10). Diastolic vibration (oscillatory mechanical perturbation) vs. Baseline (without diastolic vibration) was evaluated on Left ventricular relaxation rate (time constant T) and systolic function (peak LVP and SV) (r = 0.82). Diastolic vibration accelerated left ventricular relaxation and improved systolic function in canine models, with the increase in peak LVP and SV correlating with incomplete relaxation severity (r=0.82).
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