TY - JOUR
T1 - Theoretical foundations of a Starling-like controller for rotary blood pumps
AU - Salamonsen, Robert Francis
AU - Lim, Einly
AU - Gaddum, Nicholas
AU - AlOmari, Abdul-Hakeem H
AU - Gregory, Shaun David
AU - Stevens, Michael
AU - Mason, David G
AU - Fraser, John
AU - Timms, Daniel
AU - Karunanithi, Mohan
AU - Lovell, Nigel Hamilton
PY - 2012
Y1 - 2012
N2 - A clinically intuitive physiologic controller is
desired to improve the interaction between implantable
rotary blood pumps and the cardiovascular system. This
controller should restore the Starling mechanism of the
heart, thus preventing overpumping and underpumping
scenarios plaguing their implementation.A linear Starlinglike
controller for pump flow which emulated the response
of the natural left ventricle (LV) to changes in preload was
then derived using pump flow pulsatility as the feedback
variable. The controller could also adapt the control line
gradient to accommodate longer-term changes in cardiovascular
parameters, most importantly LV contractility
which caused flow pulsatility to move outside predefined
limits.To justify the choice of flow pulsatility, four different
pulsatility measures (pump flow, speed, current, and pump
head pressure) were investigated as possible surrogates for
LV stroke work. Simulations using a validated numerical
model were used to examine the relationships between LV
stroke work and these measures. All were approximately
linear (r2 (mean SD) = 0.989 0.013, n = 30) between
the limits of ventricular suction and opening of the aortic
valve. After aortic valve opening, the four measures differed
greatly in sensitivity to further increases in LV stroke
work. Pump flow pulsatility showed more correspondence
with changes in LV stroke work before and after opening of
the aortic valve and was least affected by changes in the LV
and right ventricular (RV) contractility, blood volume,
peripheral vascular resistance, and heart rate. The system
(flow pulsatility) response to primary changes in pump flow
was then demonstrated to be appropriate for stable control
of the circulation.As medical practitioners have an instinctive
understanding of the Starling curve, which is central to
the synchronization of LV and RV outputs, the intuitiveness
of the proposed Starling-like controller will promote
acceptance and enable rational integration into patterns of
hemodynamic management.
AB - A clinically intuitive physiologic controller is
desired to improve the interaction between implantable
rotary blood pumps and the cardiovascular system. This
controller should restore the Starling mechanism of the
heart, thus preventing overpumping and underpumping
scenarios plaguing their implementation.A linear Starlinglike
controller for pump flow which emulated the response
of the natural left ventricle (LV) to changes in preload was
then derived using pump flow pulsatility as the feedback
variable. The controller could also adapt the control line
gradient to accommodate longer-term changes in cardiovascular
parameters, most importantly LV contractility
which caused flow pulsatility to move outside predefined
limits.To justify the choice of flow pulsatility, four different
pulsatility measures (pump flow, speed, current, and pump
head pressure) were investigated as possible surrogates for
LV stroke work. Simulations using a validated numerical
model were used to examine the relationships between LV
stroke work and these measures. All were approximately
linear (r2 (mean SD) = 0.989 0.013, n = 30) between
the limits of ventricular suction and opening of the aortic
valve. After aortic valve opening, the four measures differed
greatly in sensitivity to further increases in LV stroke
work. Pump flow pulsatility showed more correspondence
with changes in LV stroke work before and after opening of
the aortic valve and was least affected by changes in the LV
and right ventricular (RV) contractility, blood volume,
peripheral vascular resistance, and heart rate. The system
(flow pulsatility) response to primary changes in pump flow
was then demonstrated to be appropriate for stable control
of the circulation.As medical practitioners have an instinctive
understanding of the Starling curve, which is central to
the synchronization of LV and RV outputs, the intuitiveness
of the proposed Starling-like controller will promote
acceptance and enable rational integration into patterns of
hemodynamic management.
UR - http://onlinelibrary.wiley.com/doi/10.1111/j.1525-1594.2012.01457.x/pdf
U2 - 10.1111/j.1525-1594.2012.01457.x
DO - 10.1111/j.1525-1594.2012.01457.x
M3 - Article
VL - 36
SP - 787
EP - 796
JO - Artificial Organs
JF - Artificial Organs
SN - 0160-564X
IS - 9
ER -