Ventricular assist device control
A control device for a ventricular assist device (VAD) with settable speed levels. The control device includes an input configured to receive at least one measuring signal related to a physiological condition of the circulatory system of a patient receiving heart assistance by the VAD, where the control device is configured to derive an actual value of at least one characteristic parameter of the heart from one or more of the at least one measuring signal and to provide a refined actual value of the at least one characteristic parameter in which effects of physiologically caused fluctuations are eliminated or reduced. The control device further includes an output configured to output an updated setting value for the speed level, where the control device is configured to produce the updated setting value based on the refined actual value and a predeterminable set-point value.
1. A control device for a ventricular assist device (VAD) with settable speed levels, the control device comprising
an input configured to receive at least one measuring signal related to a physiological condition of the circulatory system of a patient receiving heart assistance by the VAD, wherein the control device is configured to derive an actual value of at least one characteristic parameter of the heart from one or more of the at least one measuring signal and to provide a refined actual value of the at least one characteristic parameter in which effects of physiologically caused fluctuations are eliminated or reduced; and
an output configured to output an updated setting value for a speed level, wherein the control device is configured to produce the updated setting value based on the refined actual value and a predeterminable set-point value,
wherein the at least one characteristic parameter is a filling gradient of the left ventricular pressure during the diastolic phase of a cardiac cycle between the opening of the mitral valve and closing of the mitral valve, and wherein the control device is configured to produce the updated setting values so that the filling gradient becomes or is kept positive and close to zero, and
wherein the filling gradient is defined as:
Filling
Gradient
=
Δ
Left
Ventricle
Pressure
Δ
time
|
FillingGradient
=
Left
Ventricle
Pressure
(
time
ClosingMitralValve
,
j
+
1
)
-
Left
Ventricle
Pressure
(
time
OpeningMitralValve
,
j
)
time
ClosingMitralValve
,
j
+
1
-
time
OpeningMitralValve
,
j
.
2. The control device according to claim 1 , wherein the control device is configured to process a plurality of actual values within a moving time interval that includes a current actual value and historical actual values.
3. The control device according to claim 1 , wherein the refined actual value is a moving average of a plurality of actual values or is based on a moving average of the at least one measuring signal.
4. The control device according to claim 1 , wherein the control device is configured to:
(i) process the at least one measuring signal or a sequence of actual values by applying a moving average filter having a size related to a periodicity of the physiologically caused fluctuations to be eliminated or
(ii) process the at least one measuring signal or the sequence of actual values by applying a high-pass filter having a characterizing cut-off frequency related to the physiologically caused fluctuations to be eliminated.
5. The control device according to claim 1 , wherein the at least one measuring signal includes at least one pressure in the circulatory system of the patient.
6. The control device according to claim 1 , wherein the control device is configured to:
(i) display the refined actual value on a display or
(ii) provide the refined actual value at an output.
7. The control device according to claim 1 , wherein the physiologically caused fluctuations to be eliminated or to be reduced are correlated with at least one of pressure fluctuations in the thorax of the patient, pressure fluctuations caused by autonomous or assisted breathing of the patient, pressure fluctuations caused by an intra-aortic balloon pump in the aorta of the patient, pressure fluctuations caused by an external counter-pulsation therapy applied to the patient, pressure fluctuations caused by a change of the patient's positioning, or pressure fluctuations caused by a change of the patient's positioning into a Trendelenburg position.
8. The control device according to claim 1 , wherein the at least one measuring signal includes at least one of a left ventricular pressure, an aortic pressure, a central venomous pressure, a pulmonary artery pressure, or an ECG signal of the patient.
9. The system of claim 1 , wherein the VAD is a catheter-based, non-pulsatile rotational blood pump.