(1597) Pre-Ejection Time Proportion Correlates With Ventricular Mechanical Efficiency in Septic Patients

Introduction: Ventricular mechanical efficiency (Veff) represents the ratio between stroke work (SW) and myocardial oxygen consumption (MVO2). Veff obtention requires the invasively quantification of pressure-volume area (PVA) or the non invasively estimation of surrogates of pressure-volume (P-V) relationships. Here, a simple approach is proposed; according to Suga, all the P-V points can be represented by the time varying elastance, this elastance determines the changes in pressure during the cardiac cycle. In conditions of increased arterial load the course of ventricular pressure remains constant, however; the time of isometric contraction (pre-ejection time) will increase according to the imposed afterload, and as a consequence the time available for ejection will subsequently decrease. Therefore, we propose the relationship between pre-ejection time and systolic period (pre-ejection time proportion: PTP) as a parameter that allows the estimation of Veff.

Methods: Patients with sepsis and cardiovascular dysfunction were included. Veff was equivalent to SW/PVA quotient and was derived from echocardiographic parameters, pre-ejection time and systolic period were calculated in the signal of pulse wave doppler of the outflow tract coupled to an electrographic trace. Pearson correlation of PTP with heart rate (HR) were assessed to evaluate the HR dependency of this parameter. FInally, simple and multiple linear regressions between PTP and Veff was performed, the multiple linear regression analysis was adjusted for ejection fraction (LVEF), ventricular dead space (V0), mean arterial pressure (MAP) end diastolic and systolic volumes (EDV, ESV) and HR as covariables.

Results: 84 patients were consecutively included. The mean of Veff and PTP were: 0,59 and 0,245, respectively. There was no correlation between HR and PTP; R=0,17 (p>0,05). Univariate linear regression for PTP as a predictor of Veff yielded a R2 of 0,6108 (p < 0,0001). Multiple linear regression yielded a R2 of 0,82 (p < 0,0001), the variables related with Veff were: PTP, V0, EDV and ESV.

Conclusions: PTP was highly correlated with Veff, our regression analysis shows that PTP predicts Veff even better than LVEF. The incorporation of this echocardiographic parameter allows a fast and simple way to evaluate the Veff of septic patients.