title: 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.
authors.affiliation: Department of Electrical and Computer Engineering, Michigan State University, 2120 Engineering Building, East Lansing, MI 48824, USA.
authors.forename: Gokul
authors.initials: G
authors.lastname: Swamy
authors.forename: Jacob
authors.initials: J
authors.lastname: Kuiper
authors.forename: Madhu S R
authors.initials: MS
authors.lastname: Gudur
authors.forename: N Bari
authors.initials: NB
authors.lastname: Olivier
authors.forename: Ramakrishna
authors.initials: R
authors.lastname: Mukkamala
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology*; D001021:Aortic Valve / Q000503:physiopathology*; D001795:Blood Pressure Determination / Q000379:methods*; D002302:Cardiac Output / Q000502:physiology; D002317:Cardiovascular Agents / Q000494:pharmacology; D004280:Dobutamine / Q000494:pharmacology; D004285:Dogs; D004452:Echocardiography; D054459:Elasticity Imaging Techniques; D004562:Electrocardiography; D008955:Models, Cardiovascular; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D013318:Stroke Volume / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002317:Cardiovascular Agents; D011412:Propanolamines; D009599:Nitroprusside; D010656:Phenylephrine; D004280:Dobutamine; D014700:Verapamil; C036604:esmolol