Introduction of fixed-flow mode in the DexAide right ventricular assist device.

BACKGROUND

Although some continuous-flow left ventricular assist device algorithms have been created to respond to varying patient physiology, very little research has been conducted on control of right ventricular support in uni- or biventricular application. The purpose of this study was to develop and evaluate a simple and reliable fixed-flow algorithm for the DexAide right ventricular assist device (RVAD). This algorithm automatically adjusts speed to maintain a target flow while preventing ventricular suction when a requested target flow exceeds available tricuspid flow.

METHODS

Fixed-flow control mode was evaluated in 17 DexAide RVAD long-term bovine studies, with a duration ranging from 14 to 90 days (33 +/- 24 days). Targeted fixed-flow levels ranged from 4.0 to 6.5 liters/min. Data were monitored on an hourly basis. Pump-flow data were also recorded on a weekly basis to document the speed increment required to increase pump flow from 5 to 8 liters/min at 0.5-liter/min increments.

RESULTS

The fixed-flow control mode was evaluated for a total duration of 5,283 hours without complications related to pump flow or left/right circulation imbalance. The pump speed varied between 2,000 and 3,220 rpm to maintain the flow constant at each target level. The average absolute mismatch between the target flow and measured flow was 0.6 +/- 0.5 liter/min.

CONCLUSIONS

Fixed-flow control mode with a pre-determined maximum automatic pump speed can be used safely and effectively in the DexAide RVAD. It can provide target flows by adjusting the pump speed while monitoring pump-flow response to automatic speed increment requests.