A new approach to generate arbitrary pulsatile pressure wave forms in mechanical circulatory support systems.

Pulsatile pressure/flow wave forms reproduction of blood in mechanical circulatory systems are still an open topic. Regarding the periodic behavior of pulsatile hemodynamics, a repetitive control algorithm was adopted as a potential methodology for rotary blood pumps. The developed algorithm was tested on a mock system including an oxygenator, a resistance, and a compliance.

Simultaneous automatic control of oxygen and carbon dioxide blood gases during cardiopulmonary bypass.

In this work an automatic control strategy is presented for the simultaneous control of oxygen and carbon dioxide blood gas partial pressures to be used during cardiopulmonary bypass surgery with heart-lung machine support. As the exchange of blood gases in the artificial extracorporeal lung is a highly nonlinear process comprising varying time delays, uncertainties, and time-varying parameters, it is currently being controlled manually by specially trained perfusionist staff. The new control strategy includes a feedback linearization routine with augmented time-delay compensation and two external linear gain-scheduled controllers, for partial oxygen and carbon dioxide pressures.

A fiber optic sensor system for control of rate-adaptive cardiac pacemakers and implantable defibrillators.

Commercially available cardiac pacemakers and implantable cardioverters/defibrillators (ICDs) predominantly use an intracardiac-derived electrocardiogram (ECG) for the detection of arrhythmias. To achieve automatic control of the heart frequency in accordance with cardiovascular strain and improved detection of life-threatening arrhythmias, it is desirable to monitor the heart by an input signal correlated with the hemodynamic state. One possible approach to derive such a signal is to measure the inotropy (mechanical contraction strength of the heart muscle).

Rate-responsive pacing based on the atrio-ventricular conduction time: comparison of different algorithms.

Rate-responsive pacing based on the atrio-ventricular conduction time is a promising therapy for restoring physiological heart rate control in chronotropic incompetent patients. This paper compares four different algorithms. Three of them had been formulated as patents, but no real test or application has been reported up to now.

Simulation and prediction of cardiotherapeutical phenomena from a pulsatile model coupled to the Guyton circulatory model.

In order to use simulation prediction for cardiotherapeutical purposes, the well-documented and physiologically validated circulatory Guyton model was coupled to a cardiac pulsatile model which comprises the hemodynamics of the four chambers including valvular effects, as well as the Hill, Frank-Starling, Laplace, and autonomic nervous system (ANS) effects. The program is written in the "C" language and available for everybody. The program system was submitted to validation and plausibility tests both as to the steady-state and the dynamic properties.

Rate-responsive pacing based on the atrio-ventricular conduction time.

Chronotropic incompetent patients are unable to adapt their heart rate adequately to the level of exertion. One treatment for this disease is a rate-responsive pacemaker that stimulates the heart at a rate proportional to an exertion-related variable derived from an implemented sensor (e.g.