Online cardiac output estimation during transvalvular left ventricular assistance

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Medical Device Technology

Background:

• Ventricular assist device (VAD) therapy aims to ensure sufficient cardiac output.
• Current methods lack adequate estimation of total cardiac output from native heart and VAD.
• Accurate cardiac output monitoring is crucial for VAD management.

Purpose of the Study:

• To develop and validate a method for estimating total cardiac output.
• To utilize optical pressure sensor signals from an Impella CP pump.
• To provide a direct, physiologically meaningful feedback for VAD therapy.

Main Methods:

• Employed two parallel Kalman filters for joint estimation of aortic flow rate and aortic valve hydraulic resistance.
• Utilized a third-order nonlinear state-space cardiovascular model with ovine and human parameter sets.
• Validated the method in a hybrid mock circulatory loop and an ovine animal study.

Main Results:

• Achieved an in vitro accuracy of ±3.64% for cardiac output estimation.
• In an ovine model, the method showed 95% limits of agreement of -0.004 ± 0.897 L/min compared to pulmonary artery flow.
• Estimation errors were comparable to the accuracy of the gold standard ultrasonic flow measurement (±10%).

Conclusions:

• Online total cardiac output estimation offers direct physiological feedback for VAD speed adjustment.
• The method holds promise for physiological control in closed-loop VAD therapy.
• Enables precise VAD management and optimization of patient support.