Continuous left ventricular ejection fraction monitoring by central aortic pressure waveform analysis

Left ventricular ejection fraction (EF) is perhaps the most clinically significant index of global ventricular function. EF is measured in clinical practice via imaging methods such as echocardiography. However, these methods generally require a well-trained operator and expensive capital equipment. Thus, EF measurements are only obtained in the clinical setting and are usually made few and far between. To expand the measurement of this critical hemodynamic variable, our overarching hypothesis is that EF may be continuously (i.e., automatically) monitored by mathematical analysis of routinely measured blood pressure waveforms. Here, we introduce a novel technique for estimating the absolute EF by model-based analysis of only a central aortic pressure (CAP) waveform. We then demonstrate the validity of the technique with respect to five conscious dogs in which reference EF was independently measured before and after chronic pacing induced heart failure. With further successful testing, the technique may potentially be utilized for continuous EF monitoring in research and clinical settings in which an aortic catheter is employed as well as for ambulatory EF monitoring in conjunction with recently developed implantable devices for measuring CAP.