Thoratec HeartMate III, Instructions For Use Manual, Page: 25 / 458

Introduction 1
HeartMate III Left Ventricular Assist System Instructions for Use 1-15
If the LVAD speed is set too h igh, the inflow pressure may fall to the extent that it attempts to
recruit blood from the left ventricle, left atrium, and pulmonary vasculature that is not there. This
will result in the collapse of the left ventricle and potential arrhythmia. The HeartMate III LVAS
employs a feature called Suction Detection to recognize and avert this condition.
When the degree of pulsatility measured in the electrical current waveform has fallen below a
preset value, the system regards this as a risk of ventricular suction and quickly lowers the Rotor
speed to a preset, programmable Low Speed Limit. It then immediately, but gradually, returns the
Rotor to its original speed.
The HeartMate III has an intrinsic limit somewhat above 9000rpm. The system accordingly
precludes setting the speed above 9000rpm. Conversely, if the LVAD speed is set too low,
support for the failing heart may be insufficient. The HeartMate III LVAS uses the same Low
Speed Limit mentioned previously to limit how low the speed may be set. This is to avoid
profound retrograde flow (aorto-ventricular shunt). The Low Speed Limit can be set within a
range to accommodate customization for a variety of patients.
The HeartMate III employs a feature called Artificial Pulse that adds an element to the discussion
about Rotor speed (
Figure 1.4 ). Although the clinician will set only a single speed,

c
in
Figure 1.4 , the Rotor speed will periodically depart from this value to contribute a flow
disruption that in some ways mimics native cardiac contractility. This artificial pulse “beats”
30 times per minute, asynchronously with the heart. The Artificial Pulse mode is indicated on the
System Controller by the use of a (
) symbol.
Figure 1.4 Artificial Pulse