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Controller interface

System controller

The system controller is a small computer that controls and checks the operation of the system.


The driveline is a cable that goes through the skin and connects the pump inside the body with the system controller outside the body.

Power cable connectors

The power cable connectors link the external power source (mobile power unit or two HeartMate 14 volt lithium-ion batteries) to the system controller.

User interface

The user interface features buttons, lights and a screen.

The interface is where system data, alarms and user instructions will appear.

Controller driveline connector

The controller driveline connector links the internal pump to the system controller.

Battery button

The battery button operates the battery power gauge.

Pressing and holding the battery button for five seconds will start the system controller self-test.

Display button

The information display screen can be activated by pressing the display button. The number of times the button is pressed changes the information displayed on screen as outlined below.

One press – revolutions per minute (RPM)

Pressing the display button once will present the pump speed in RPM on the display screen.

Further guidance on the pump RPM is outlined below:

  • The pump can run at speeds from 3,000-9,000 RPM
  • The speed of the pump is usually set at 4,500-6,200 RPM
  • Fluctuations of above or below 100 RPM are usual
  • If the speed is dropping it could indicate suction events which could indicate dehydration or that the right side of your heart is unwell. Take note of how much fluid you are drinking, plus any signs of swollen feet and shortness of breath

Two presses – litres per minute (LPM)

Pressing the display button for a second time will present the pump flow in LPM on the display screen.

Further information on the pump LPM is outlined below:

  • The amount of blood flow in LPM through your pump is directly related to speed and power
  • It will be an estimated reading based on pump power and speed
  • If there is an increase in power it will equal an increase in flow
  • The system controller will alarm 'low flow' if flow falls below 2.5 litres
  • If the pump power increases it could be due to problems with clots and flow readings will be inaccurately high
  • If the pump is on and running, the 'pump running' symbol will be green

Three presses – pulsatility index (PI)

Pressing the display button for a third time will show the PI on the display screen which is the left ventricle’s pulsatile contribution to the pump.

Fluctuations in the PI will be related to changes in your status. It is indicative of hydration and how well the right side of your heart is working and can also can indicate changes to the hearts natural contraction.

Four presses – power

Pressing the display button for a fourth time will present the power in watts on the display screen.

More information on pump power is listed below:

  • Power is measured using pump voltage and current
  • Power will change in relation to speed and blood flow
  • Readings of less than ten and sharp increases of two could be indicative of a clot inside the pump

Five presses – backup battery status

Pressing the display button for a fifth time will show the status of the system controller's backup battery.

The backup battery is located inside the system controller and is used to temporarily run the pump during a power emergency.

The backup battery has three charge statuses:

  • Charged – ready for use
  • Charging – actively charging
  • Fault – there is problem with the backup battery that could affect its reliability

Six presses – blank screen

Pressing the display button for a sixth time will present a blank screen that indicates the screen is off, which is normal.

Last reviewed: 24 May 2023