A novel method using pressure responses to changes in LVAD flow can quantify left ventricular elastance and resistance in a sheep model, which may help optimize LVAD weaning.
Optimizing the procedure of weaning the left ventricle from a left ventricular assist device requires the determination of the momentaneous condition of the left ventricle. In sheep, a method was developed to momentaneously quantify the left ventricular condition. The left ventricular pump condition was quantified by the time-varying parameters elastance and resistance. They were determined from perturbations in the left ventricular pressure of two subsequent beats induced by changes in flow of the assist device. The end-diastolic volume of the ventricle was estimated without directly measuring ventricular volume. Maximum elastance and resistance were 201.3 +/- 32.7 Pa/ml and 12.3 +/- 1.6 Pa.s/ml, respectively (mean +/- SE). The ventricular time constant, defined by the ratio of resistance of elastance, was 84.6 +/- 17.1 ms (mean +/- SE).
Kunst et al. (Fri,) studied this question.