Continuous Left Ventricular Ejection Fraction Monitoring by Aortic Pressure Waveform Analysis

Abstract

We developed a technique to monitor left ventricular ejection fraction (EF) by model-based analysis of the aortic pressure waveform. First, the aortic pressure waveform is represented with a lumped parameter circulatory model. Then, the model is fitted to each beat of the waveform to estimate its lumped parameters to within a constant scale factor equal to the arterial compliance (C (a)). Finally, the proportional parameter estimates are utilized to compute beat-to-beat absolute EF by cancelation of the C (a) scale factor. In this way, in contrast to conventional imaging, EF may be continuously monitored without any ventricular geometry assumptions. Moreover, with the proportional parameter estimates, relative changes in beat-to-beat left ventricular end-diastolic volume (EDV), cardiac output (CO), and maximum left ventricular elastance (E (max)) may also be monitored. To evaluate the technique, we measured aortic pressure waveforms, reference EF and EDV via standard echocardiography, and other cardiovascular variables from six dogs during various pharmacological influences and total intravascular volume changes. Our results showed overall EF and calibrated EDV root-mean-squared-errors of 5.6% and 4.1 mL, and reliable estimation of relative E (max) and beat-to-beat CO changes. These results demonstrate, perhaps for the first time, the feasibility of estimating EF from only a blood pressure waveform.

Continuous and less invasive central hemodynamic monitoring by blood pressure waveform analysis

“…EVALUATION. We evaluated this lumped parameter modelbased analysis technique against standard transthoracic echocardiography EF measurements from dogs during drug and volume interventions (106). The overall uncalibrated absolute EF error was 5.6%.…”

Estimating cardiac output and ejection fraction using blood pressure signal

“…This acceptance is largely due to its ability to predict death in patients with heart failure and coronary artery disease as well as to readily discriminate between systolic and diastolic dysfunction [6]. The standard clinical method for measuring EF is through imaging the left ventricular volume via echocardiography, radionuclide techniques, contrast angiography, ultra-fast computed tomography, or magnetic resonance imaging [7]. In this paper we have also simulated a noninvasive method for continuouslyestimating EF using the aortic pressure waveforms.…”

Minimally invasive, patient specific, beat-by-beat estimation of left ventricular time varying elastance

“…As such, the traditional approach to non-invasively generate a TVE curve is to fix it to a population based waveform [7, 11, 12]. Most existing work surrounding TVE curves is focused on using the TVE curve to estimate a clinical parameter, such as ejection fraction [20], and, most commonly, end-systolic elastance [7, 21, 22]. However, these studies are validated on correlations with the derived parameter, rather than on the shape and change in shape of the TVE curve itself.…”