Control Strategy Design of a Microblood Pump Based on Heart-Rate Feedback

Based on the nonlinear relationship between heart rate and stroke volume, a flow model of left ventricular circulation was improved, and a variable-speed blood-pump control strategy based on heart-rate feedback was proposed. The control strategy was implemented on a system combining the rotary blood pump and blood circulation models of heart failure. The aortic flow of a healthy heart at different heart rates was the desired control goal. Changes in heart rate were monitored and pump speed was adjusted so that the output flow and aortic pressure of the system would match a normal heart in real time to achieve the best auxiliary state. After simulation with MATLAB, the cardiac output satisfied the ideal perfusion requirements at different heart rates, and aortic pressure demonstrated lifting and had good pulsatile performance when a variable-speed blood pump was used. The coupled model reflected the relationship between hemodynamic parameters at different heart rates with the use of the variable-speed blood pump, providing a theoretical basis for the blood-pump-assisted treatment of heart failure and the design of physiological control strategies.

Effects of an intra-ventricular assist device on the stroke volume of failing ventricle: Analysis of a mock circulatory system

BACKGROUND:

A novel intra-ventricular assist device (iVAD) was established as a new pulsatile assist device to address various disadvantages, such as bulky configuration and reduced arterial pulsatility, observed in conventional ventricular assist devices.

OBJECTIVE:

Analyzed the native left ventricular stroke volume (SV) after iVAD support in vitro.

METHODS:

The SV of iVAD was examined in a home-designed mock circulatory system (MCS) at different heart rates and drive pressures and the SV of a failure ventricle was examined with iVAD at 75, 90, 120 bpm and 120–180 mmHg drive pressure after iVAD support. Data pertaining to native left ventricular SV before and after iVAD support were compared.

RESULTS:

The native ventricular SV was improved by iVAD when its drive pressure (DP) was slightly greater than that of the mock system. Conversely, the native ventricular SV was decreased when DP was much greater than that (150 mmHg) of MCS. A high DP had a significant effect on SV.

CONCLUSIONS:

The proposed device improved the dysfunctional native left ventricular SV when DP of iVAD was slightly greater than that of MCS. However, iVAD reduced the SV when the drive pressure was greater than that of MCS.

Current State and Future Perspectives of Energy Sources for Totally Implantable Cardiac Devices

There is a large population of patients with end-stage congestive heart failure who cannot be treated by means of conventional cardiac surgery, cardiac transplantation, or chronic catecholamine infusions. Implantable cardiac devices, many designated as destination therapy, have revolutionized patient care and outcomes, although infection and complications related to external power sources or routine battery exchange remain a substantial risk. Complications from repeat battery replacement, power failure, and infections ultimately endanger the original objectives of implantable biomedical device therapy - eliminating the intended patient autonomy, affecting patient quality of life and survival. We sought to review the limitations of current cardiac biomedical device energy sources and discuss the current state and trends of future potential energy sources in pursuit of a lifelong fully implantable biomedical device.