Thoratec HeartMate III, Instructions For Use Manual, Page: 257 / 458

Surgical Procedures 5
HeartMate III Left Ventricular Assist System Instructions for Use 5-49
Pump flow is dependent upon the pressure difference across the Pump, aortic pressure at the
outflow minus left ventricular pressure at the inflow, and will fluctuate throughout the cardiac
cycle.
Figure 5.40 illustrates that, when left ventricular pressure equals aortic pressure, a Pump
running at 5,000 rpm will result in a 6.5 lpm pump flow rate. At an aortic pressure of 80 mmHg
and a left ventricular pressure of 10 mmHg, a pressure difference across the Pump of 80-10=70
mmHg, a Pump running at the same speed would flow 3 lpm. By increasing the speed to 6,000
rpm, the same 70 mmHg pressure difference across the Pump would result in a 6 lpm pump flow.
This relationship demonstrates that the flow generated by the Pump is directly related to the
pressure difference across the Pump and heavily dependent upon left ventricular pressure.
Figure 5.40 Typical HeartMate III Flow Characteristics
IMPORTANT! The Pump will start when the System Controller is connected to a
Driveline and a power source if one of the following is true:
• The Fixed Speed is set to 4,000 rpm or higher.
OR
• The System Controller’s backup battery is installed and any button is pushed on the
System Controller.