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Continuous cardiac function monitoring by aortic pressure waveform analysis

We aimed to develop and initially evaluate a new technique for continuous monitoring of cardiac function by mathematical analysis of an aortic pressure (AP) waveform. Our technique specifically applies lumped parameter modeling and least squares fitting to estimate the absolute left ventricular ejection fraction (EF) from an AP waveform. To experimentally evaluate the technique, we performed hemodynamic experiments in three adult dogs (15–25 kg). Two of the dogs were instrumented with an AP catheter as well as an aortic flow probe and ultrasonic crystals attached to the left ventricle for reference EF. These dogs were studied in the conscious state before and after chronic pacing induced heart failure so as to reduce EF. The third dog was instrumented with an AP catheter and an aortic flow probe. This dog was studied under anesthesia before and after the administration of increasing doses of dobutamine so as to increase EF. Our results showed that the EF estimated by our technique corresponded to the reference EF both before and after heart failure with an overall error of 15% and significantly increased with dobutamine dose. With further successful testing, the technique may ultimately be employed for continuous cardiac function monitoring in research and clinical settings in which an AP catheter is used.