// MODEL NUMBER: 0344
// MODEL NAME: Rideout_PressureFlowReg
// SHORT DESCRIPTION: CV loop with baroreceptor regulation ported from
// Rideout (ACSL program PF-1-REG).
// Also in MATLAB.
import nsrunit; unit conversion on;
math Rideout_PressureFlowReg
{
// Choice Variable
choice Mode("Open Loop",
"Closed Loop") = 1;
// Independent Variable
realDomain t s; t.min = 0; t.max = 20; t.delta = .02;
// Parameters
real RP1 = 10 g/cm^4/s, // Pulm. Art. 1 Resistance
RP2 = 40 g/cm^4/s, // Pulm. Art. 2 Resistance
RP3 = 80 g/cm^4/s, // Pulm. Art. 3 Resistance
RL1 = 30 g/cm^4/s, // Pulm. Veins 1 Resistance
RL2 = 10 g/cm^4/s, // Pulm. Veins 2 Resistance
RLA = 5 g/cm^4/s, // Left Atrium Resistance
RLV = 5 g/cm^4/s, // Left Ventricle Resistance
RA1 = 10 g/cm^4/s, // Aortic 1 Resistance
RA2 = 160 g/cm^4/s, // Aortic 2 Resistance
RA3 = 1000 g/cm^4/s, // Carotid Resistance
RV1 = 90 g/cm^4/s, // Syst. Veins 1 Resistance
RV2 = 10 g/cm^4/s, // Syst. Veins 2 Resistance
RRA = 5 g/cm^4/s, // Right Atrium Resistance
RRV = 5 g/cm^4/s, // Right Ventricle Resistance
RPW1 = 10 g/cm^4/s, //
LP1 = 1 g/cm^4, // Pulm. Art. 1 Inertance
LL2 = 1 g/cm^4, // Pulm. Veins 2 Inertance
LLA = 1 g/cm^4, // Left Atrium Inertance
LLV = 1 g/cm^4, // Left Ventricle Inertance
LA1 = 1 g/cm^4, // Aortic 1 Inertance
LV2 = 1 g/cm^4, // Syst. Veins 2 Inertance
LRA = 1 g/cm^4, // Right Atrium Inertance
LRV = 1 g/cm^4, // Right Ventricle Inertance
CP1 = .0002 cm^4*s^2/g, // Pulm. Art. 1 Compliance
CP2 = .0004 cm^4*s^2/g, // Pulm. Art. 2 Compliance
CP3 = .0027 cm^4*s^2/g, // Pulm. Art. 3 Compliance
CL1 = .001 cm^4*s^2/g, // Pulm. Veins 1 Compliance
CL2 = .001 cm^4*s^2/g, // Pulm. Veins 2 Compliance
CLA = .01176 cm^4*s^2/g, // Left Atrium Compliance
CA1 = .00018 cm^4*s^2/g, // Aortic 1 Compliance
CA2 = .00023 cm^4*s^2/g, // Aortic 2 Compliance
CA3 = .00182 cm^4*s^2/g, // Carotid Compliance
CV1 = .021 cm^4*s^2/g, // Syst. Veins 1 Compliance
CV2 = .045 cm^4*s^2/g, // Syst. Veins 2 Compliance
CRA = .045 cm^4*s^2/g, // Right Atrium Compliance
PP1EDM = 7.2 mmHg, // Pulm. Art. 1 End-Diastolic Pressure
PP2EDM = 7 mmHg, // Pulm. Art. 1 End-Diastolic Pressure
PP3EDM = 6.6 mmHg, // Pulm. Art. 1 End-Diastolic Pressure
PL1EDM = 4.45 mmHg, // Pulm. Veins 1 End-Diastolic Pressure
PL2EDM = 3.62 mmHg, // Pulm. Veins 2 End-Diastolic Pressure
PLAEDM = 3.45 mmHg, // Left Atrium End-Diastolic Pressure
PLVEDM = 4 mmHg, // Left Ventricle End-Diastolic Pressure
PA1EDM = 64.3 mmHg, // Aortic 1 End-Diastolic Pressure
PA2EDM = 64 mmHg, // Aortic 2 End-Diastolic Pressure
PA3EDM = 63 mmHg, // Carotid End-Diastolic Pressure
PV1EDM = 13.5 mmHg, // Syst. Veins 1 End-Diastolic Pressure
PV2EDM = 7.2 mmHg, // Syst. Veins 2 End-Diastolic Pressure
PRAEDM = 6.64 mmHg, // Right Atrium End-Diastolic Pressure
PRVEDM = 7.4 mmHg, // Right Ventricle End-Diastolic Pressure
FP1IC = 0 ml/s, // Pulm. Art. 1 Initial Flow
FL2IC = 33 ml/s, // Pulm. Veins 2 Initial Flow
FLAIC = 0 ml/s, // Left Atrium Initial Flow
FLVIC = 0 ml/s, // Left Ventricle Initial Flow
FA1IC = 4.6 ml/s, // Aortic 1 Initial Flow
FV2IC = 95 ml/s, // Syst. Veins 2 Initial Flow
FRAIC = 0 ml/s, // Right Atrium Initial Flow
FRVIC = 6 ml/s, // Right Ventricle Initial Flow
FV2FIC = 80 ml/s, // Cardiac Output Initial Flow
FI = 0 ml/s, // Arterial Infusion Flow
QP1U = 7.8 ml, // Pulm. Art. 1 Unstressed Volume
QP2U = 23.4 ml, // Pulm. Art. 2 Unstressed Volume
QP3U = 210.5 ml, // Pulm. Art. 3 Unstressed Volume
QL1U = 69 ml, // Pulm. Veins 1 Unstressed Volume
QL2U = 69 ml, // Pulm. Veins 2 Unstressed Volume
QLAU = 814.5 ml, // Left Atrium Unstressed Volume
QLVU = 10 ml, // Left Ventricle Unstressed Volume
QA1U = 35.1 ml, // Aortic 1 Unstressed Volume
QA2U = 85 ml, // Aortic 2 Unstressed Volume
QA3U = 710 ml, // Carotid Unstressed Volume
QV1U = 909 ml, // Syst. Veins 1 Unstressed Volume
QV2U = 1948 ml, // Syst. Veins 2 Unstressed Volume
QRAU = 1948 ml, // Right Atrium Unstressed Volume
QRVU = 10 ml, // Right Ventricle Unstressed Volume
LD = 45 g/cm^4/s^2, // Diastolic L Ventricle Stiffness
LSI = 2500 g/cm^4/s^2, // Systolic L Ventricle Init. Stiffness
RD = 68 g/cm^4/s^2, // Diastolic R Ventricle Stiffness
RSI = 350 g/cm^4/s^2, // Systolic R Ventricle Init. Stiffness
DLS = -625 g/cm^4/s^2, // Sudden change in LS at t > THI
DRS = 0 g/cm^4/s^2, // Sudden change in RD at t > THI
SV1 = .9, // Stiffness first harmonic factor
SV2 = .25, // Stiffness second harmonic factor
TI = 11 s, // Time of Ventricular Infarction
TB = 3 s, // Time of Venous Bleeding
GBS = 0 cm^4*s/g, // Venous Bleeding Conductance
TFIL = 3.2 s, // Time constant for PA3 filter
PREF = 72 mmHg, // Carotid Reference Pressure
PA3FIC = 72 mmHg, // Carotid Filtered Initial Pressure
KX = .2 1/mmHg, // Carotid Filtered Pressure error gain
LLT = 0.1, // Feedback signal minimum
ULT = 1.9; // Feedback signal maximum
// Dependent Variables
real PP1(t) mmHg, // Pulm. Art. 1 Pressure
PP2(t) mmHg, // Pulm. Art. 2 Pressure
PP3(t) mmHg, // Pulm. Art. 3 Pressure
PL1(t) mmHg, // Pulm. Veins 1 Pressure
PL2(t) mmHg, // Pulm. Veins 2 Pressure
PLA(t) mmHg, // Left Atrium Pressure
PLV(t) mmHg, // Left Ventricle Pressure
PA1(t) mmHg, // Aortic 1 Pressure
PA2(t) mmHg, // Aortic 2 Pressure
PA3(t) mmHg, // Carotid Pressure
PV1(t) mmHg, // Syst. Veins 1 Pressure
PV2(t) mmHg, // Syst. Veins 2 Pressure
PRA(t) mmHg, // Right Atrium Pressure
PRV(t) mmHg, // Right Ventricle Pressure
FP1(t) ml/s, // Pulm. Art. 1 Flow
FP2(t) ml/s, // Pulm. Art. 2 Flow
FP3(t) ml/s, // Pulm. Art. 3 Flow
FL1(t) ml/s, // Pulm. Veins 1 Flow
FL2(t) ml/s, // Pulm. Veins 2 Flow
FLA(t) ml/s, // Left Atrium Flow
FLAD(t) ml/s^2, // Left Atrium Flow Derivative
FLV(t) ml/s, // Left Ventricle Flow
FLVD(t) ml/s^2, // Left Ventricle Flow Derivative
FA1(t) ml/s, // Aortic 1 Flow
FA2(t) ml/s, // Aortic 2 Flow
FA3(t) ml/s, // Carotid Flow
FV1(t) ml/s, // Syst. Veins 1 Flow
FV2(t) ml/s, // Syst. Veins 2 Flow
FV2F(t) ml/s, // Syst. Veins 2 Average Flow
FRA(t) ml/s, // Right Atrium Flow
FRAD(t) ml/s^2, // Right Atrium Flow Derivative
FRV(t) ml/s, // Right Ventricle Flow
FRVD(t) ml/s^2, // Right Ventricle Flow Derivative
FB(t) ml/s, // Venous Bleeding at t > TB
QP1(t) ml, // Pulm. Art. 1 Volume
QP1IC ml, // Pulm. Art. 1 Initial Volume
QP2(t) ml, // Pulm. Art. 2 Volume
QP2IC ml, // Pulm. Art. 2 Initial Volume
QP3(t) ml, // Pulm. Art. 3 Volume
QP3IC ml, // Pulm. Art. 3 Initial Volume
QL1(t) ml, // Pulm. Veins 1 Volume
QL1IC ml, // Pulm. Veins 1 Initial Volume
QL2(t) ml, // Pulm. Veins 2 Volume
QL2IC ml, // Pulm. Veins 2 Initial Volume
QLA(t) ml, // Left Atrium Volume
QLAIC ml, // Left Atrium Initial Volume
QLV(t) ml, // Left Ventricle Volume
QLVIC ml, // Left Ventricle Initial Volume
QA1(t) ml, // Aortic 1 Volume
QA1IC ml, // Aortic 1 Initial Volume
QA2(t) ml, // Aortic 2 Volume
QA2IC ml, // Aortic 2 Initial Volume
QA3(t) ml, // Carotid Volume
QA3IC ml, // Syst. Art. Initial Volume
QV1(t) ml, // Syst. Veins 1 Volume
QV1IC ml, // Syst. Veins 1 Initial Volume
QV2(t) ml, // Syst. Veins 2 Volume
QV2IC ml, // Syst. Veins 2 Initial Volume
QRA(t) ml, // Right Atrium Volume
QRAIC ml, // Right Atrium Initial Volume
QRV(t) ml, // Right Ventricle Volume
QRVIC ml, // Right Ventricle Initial Volume
QT ml, // Total Initial Blood Volume
QU ml, // Total Unstressed Volume
QS ml, // Stressed Volume
TH(t) s, // Heart period
TS(t) s, // Sytsolic duration
X(t), // Stiffness auxillary function
STW(t), // Stiffness triangular waveform
SSW(t), // Stiffness sinusoid waveform
ACT(t), // Stiffness actuator waveform
SLV(t) g/cm^4/s^2, // Left Ventricle Stiffness
SRV(t) g/cm^4/s^2, // Right Ventricle Stiffness
LS(t) g/cm^4/s^2, // Systolic Left Ventricle Stiffness
RS(t) g/cm^4/s^2, // Systolic Right Ventricle Stiffness
PA3F(t) mmHg, // Carotid Filtered Pressure
DPA3F(t) mmHg, // Carotid Filtered Pressure Error
Z3(t), // Dimensionlles Scaled Error Signal
Y(t); // Dimensionlles Feedback Signal
// State Variables
realState ZOH(t);
when (t = t.min) { FP1 = FP1IC; FL2 = FL2IC; FLA = FLAIC; FLV = FLVIC;
FA1 = FA1IC; FV2 = FV2IC; FRA = FRAIC; FRV = FRVIC;
FV2F = FV2FIC; PA3F = PA3FIC; ZOH = t.min;
QP1 = QP1IC; QP2 = QP2IC; QP3 = QP3IC; QL1 = QL1IC;
QL2 = QL2IC; QLA = QLAIC; QLV = QLVIC; QA1 = QA1IC;
QA2 = QA2IC; QA3 = QA3IC; QV1 = QV1IC; QV2 = QV2IC;
QRA = QRAIC; QRV = QRVIC; }
// Equations
QP1IC = QP1U + PP1EDM * CP1;
QP2IC = QP2U + PP2EDM * CP2;
QP3IC = QP3U + PP3EDM * CP3;
QL1IC = QL1U + PL1EDM * CL1;
QL2IC = QL2U + PL2EDM * CL2;
QLAIC = QLAU + PLAEDM * CLA;
QLVIC = QLVU + PLVEDM / LD;
QA1IC = QA1U + PA1EDM * CA1;
QA2IC = QA2U + PA2EDM * CA2;
QA3IC = QA3U + PA3EDM * CA3;
QV1IC = QV1U + PV1EDM * CV1;
QV2IC = QV2U + PV2EDM * CV2;
QRAIC = QRAU + PRAEDM * CRA;
QRVIC = QRVU + PRVEDM / RD;
QT = QP1IC + QP2IC + QP3IC + QL1IC + QL2IC + QLAIC + QLVIC +
QA1IC + QA2IC + QA3IC + QV1IC + QV2IC + QRAIC + QRVIC;
QU = QP1U + QP2U + QP3U + QL1U + QL2U + QLAU + QLVU +
QA1U + QA2U + QA3U + QV1U + QV2U + QRAU + QRVU;
QS = QT - QU;
LS = LSI / (0.5 * Y + 0.5) + if (t > TI) DLS else 0;
RS = RSI / (0.5 * Y + 0.5) + if (t > TI) DRS else 0;
PA3F:t = (PA3 - PA3F) / TFIL;
DPA3F = PA3F - PREF;
Z3 = if (Mode = 2) KX * DPA3F else 0;
Y = if (Z3 + 1 < LLT) LLT else if (Z3 + 1 > ULT) ULT else Z3 + 1;
TH = (0.2 + 0.6 * Y) * (1 s);
TS = 0.14 + 0.2 * TH;
event(t + t.delta / 2 - ZOH >= TH) ZOH = t;
X = t - ZOH;
STW = if (X <= TS + t.delta / 2) X else 0;
SSW = SV1 * sin(PI * STW / TS) - SV2 * sin(2 * PI * STW / TS);
ACT = if (SSW < 0) 0 else if (SSW > 1) 1 else SSW;
// Pressure-Flow equations start here
PP1 = (QP1 - QP1U) / CP1 + RPW1 * (FRV - FP1);
FP1:t = (PP1 - PP2 - RP1 * FP1) / LP1;
QP1:t = FRV - FP1;
PP2 = (QP2 - QP2U) / CP2;
FP2 = (PP2 - PP3) / RP2;
QP2:t = FP1 - FP2;
PP3 = (QP3 - QP3U) / CP3;
FP3 = (PP3 - PL1) / RP3;
QP3:t = FP2 - FP3;
PL1 = (QL1 - QL1U) / CL1;
FL1 = (PL1 - PL2) / RL1;
QL1:t = FP3 - FL1;
PL2 = (QL2 - QL2U) / CL2;
FL2:t = (PL2 - PLA - RL2 * FL2) / LL2;
QL2:t = FL1 - FL2;
PLA = (QLA - QLAU) / CLA;
FLAD = (PLA - PLV - RLA * FLA) / LLA;
FLA:t = if (FLAD < 0 and FLA <= 0) 0
else if (FLAD > 0 and FLA >= 1e4) 0
else FLAD;
QLA:t = FL2 - FLA;
SLV = LD * (1 - ACT) + LS * ACT;
PLV = (QLV - QLVU) * SLV;
FLVD = (PLV - PA1 - RLV * FLV) / LLV;
FLV:t = if (FLVD < 0 and FLV <= 0) 0
else if (FLVD > 0 and FLV >= 1e5) 0
else FLVD;
QLV:t = FLA - FLV;
PA1 = (QA1 - QA1U) / CA1 + RPW1 * (FLV - FA1);
FA1:t = (PA1 - PA2 - RA1 * FA1) / LA1;
QA1:t = FLV - FA1 + FI;
PA2 = (QA2 - QA2U) / CA2;
FA2 = (PA2 - PA3) / RA2;
QA2:t = FA1 - FA2;
PA3 = (QA3 - QA3U) / CA3;
FA3 = (PA3 - PV1) / RA3;
QA3:t = FA2 - FA3;
PV1 = (QV1 - QV1U) / CV1;
FV1 = (PV1 - PV2) / RV1;
QV1:t = FA3 - FV1;
PV2 = (QV2 - QV2U) / CV2;
FV2:t = (PV2 - PRA - RV2 * FV2) / LV2;
FV2F:t = (FV2 - FV2F) / TFIL;
FB = if (t > TB) PV2 * GBS else 0;
QV2:t = FV1 - FV2 - FB;
PRA = (QRA - QRAU) / CRA;
FRAD = (PRA - PRV - RRA * FRA) / LRA;
FRA:t = if (FRAD < 0 and FRA <= 0) 0
else if (FRAD > 0 and FRA >= 1e4) 0
else FRAD;
QRA:t = FV2 - FRA;
SRV = RD * (1 - ACT) + RS * ACT;
PRV = (QRV - QRVU) * SRV;
FRVD = (PRV - PP1 - RRV * FRV) / LRV;
FRV:t = if (FRVD < 0 and FRV <= 0) 0
else if (FRVD > 0 and FRV >= 1e5) 0
else FRVD;
QRV:t = FRA - FRV;
}
/*
FIGURE:
Refer to Rideout, Fig. 4.3.5, page 98
Legend
---------------------------
F Flow [ml/s]
P Pressure [mmHg]
Q Volume [ml]
R Resistance [g/cm^4/s]
C Compliance [cm^4*s^2/g]
S Stiffness (S=1/C)
L Inertance [g/cm^4]
A two letter suffix is used to represent various segments in the CV
loop. For example, FLV represents the left Ventricle (LV) flow (F). The
table below shows suffixes used and anatomy represented. It also shows
the values of R, L, C and QU (unstressed volume) used in this model, in
CGS untis.
Suffix Anatomy Represented R L C * 10^6 QU
-----------------------------------------------------------
P1 Pulm. Art. 1 10 1 200 7.8
P2 Pulm. Art. 2 40 400 23.4
P3 Pulm. Art. 3 80 2700 210.5
L1 Pulm. Veins 1 30 1000 69
L2 Pulm. Veins 2 10 1 1000 69
LA Left Atrium 5 1 11760 814.5
LV Left Ventricle 5 1 10
A1 Aorta 1 10 1 180 35.1
A2 Aorta 2 160 1 230 85
A3 Carotid 1000 1820 710
V1 Syst. Veins 1 90 21000 909
V2 Syst. Veins 2 10 45000 1948
RA Right Atrium 5 1 45000 1948
RV Right Ventricle 5 1 10
-----------------------------------------------------------
Total Unstressed Blood Volume: 6849.3
DETAILED DESCRIPTION:
This Pressure-Flow model of the CV loop is regulated with baroreceptor
feedback. It is similar to Rideout's uncontrolled CV loop model PF-1,
ported to JSim in model Rideout_PressureFlow1. Despite the uncontrolled
nature of that model, the Frank-Starling mechanism ensures stability.
More robust stability, however, requires regulation or feedback.
The present model simulates one of the body's important homeostatic
mechanisms to maintain blood pressure. Known as baroreflex, it is a
negative feedback loop with connections to the central nervous system
(CNS). Pressure sensors called baroreceptors are located in the carotid
(aortic) arch. Afferent nerves carry signals from these sensors to the
CNS and efferent nerves carry signals back to the heart. There are two
branches of efferent nerves with opposing effects: sympathetic which
elevate blood pressure and parasympathetic which lower it.
Baroreceptor regulation can be described as follows:
* If blood pressure increases:
- Baroreceptors activated
- Parasympathetic nerves activated, sympathetic inactivated
- Heart rate and strength of contraction decrease
- Blood pressure drops (returns to normal)
* If blood pressure drops:
- Baroreceptors inactivated
- Parasympathetic nerves inactivated, sympathetic activated
- Heart rate and strength of contraction increase
- Blood pressure increases (returns to normal)
A JSim choice variable is used to switch between open-loop (without
baroreceptor feedback) and closed-loop (with feedback). Left and right
ventricle stiffnesses SLV and SRV (S = 1 / C) in this model use a
half-sine pulse with a second harmonic added to shape the actuator more
realistically. With open-loop, these waveforms are periodic, with
systole lasting TS = 0.3 sec and diastole 0.5 sec, such that the heart
period is TH = 0.8 sec (corresponding to 75 beats/min). Peak amplitude
is LS = 2500 g/cm^4/s^2 for the left ventricle and RS = 350 g/cm^4/s^2
for the right ventricle.
With closed-loop, a feedback signal Y is derived from PA3, corresponding
approximately to carotid pressure. The following steps are taken:
1) Average PA3 using a low-pass filter. Filtered output, PA3F, tracks
PA3, but changes less rapidly.
2) Calculate an error signal, DPA3F, as the difference between PA3F and
a constant reference PREF = 72 mmHg. Error signal may be positive or
negative, according to whether the average carotid pressure is
greater or less than PREF.
3) Scale the error signal with a constant gain KX = 0.2 1/mmHg. Scaled
output, Z3, is dimensionless.
4) Apply an offset and limit the error Z3 to obtain the feedback signal
Y. Offset is 1.0, lower limit is 0.1 and upper limit 1.9. Thus, Y is
unity when there is no error and has a maximum allowed deviation of
0.9 about unity.
The goal of the feedback loop is to maintain the feedback signal Y as
close as possible to unity. Y is used to control the systolic amplitudes
LS and RS, heart period TH and systolic period TS using these equations:
LS = LSI / (0.5 + 0.5 Y) (Eq. 1)
RS = RSI / (0.5 + 0.5 Y) (Eq. 2)
TH = 0.2 + 0.6 Y (Eq. 3)
TS = 0.14 + 0.2 TH (Eq. 4)
With the feedback at unity, these values default to the open-loop
values. An increase in Y, which might result from an increase in carotid
pressure, will tend to increase heart period (decrease heart rate) and
also decrease strengths of contraction of both ventricles. The result of
these changes will tend to return arterial pressures, and thus cardiac
output, back to their original values.
This model may be used to study the effect of myocardial infarction of
one or both ventricles introduced at a chosen time. The infarction is
simulated by adding negative values DLS and DRS to the systolic
ventricle stiffnesses LS and RS respectively at a chosen time. The
model also allows study of arterial infusion or venous bleeding.
The figures examine open and closed loop behavior with total run time of
20 sec. A sudden myocardial infarction is introduced at time TI = 11 sec
in the left ventricle. By setting DLS = 625, stiffness drops 25% from
approximately 2500 g/cm^4/s^2 to 1875 g/cm^4/s^2. Figures 1 and 2 are
in open loop mode; the rest of the figures are closed loop.
Figure 1 shows ventricular volumes, QLV and QRV. Stroke volume from the
left ventricle is decreased at infarction time from approx. 68 ml to 55
ml. A slow recovery begins to occur as average volumes and pressures
increase. By Frank-Starling's Law, stroke volume rises and at t = 20 sec
it is approx. 63 ml.
Figure 2 demonstrates that without true feedback, some variables cannot
return to their pre-infarction value. The carotid pressure, for example,
drops from an approx. average of 72.5 to 70.5 mmHg.
Figures 3 and 4 show the feedback signal Y and heart period TH in closed
loop. Both plots show a dip at 11 sec. Since the error signal DPA3F is
negative, Y drops below unity. From feedback equations 3 and 4 above,
heart period and systole period drop with Y (heart rate increases).
Within approx. 4 sec, Y returns to near unity and TH returns to the
open loop stable value of 0.8 sec. Thus the feedback loop was able to
compensates for the infarction relatively rapidly.
Figures 5 and 6 show the left ventricle systolic stiffness LS and right
ventricle systolic stiffness RS. From feedback equations 1 and 2 above,
both increase when Y drops below unity. The increase in contraction
strength contributes to the recovery. As Y returns to unity, LS and RS
stablize with means near 1875 g/cm^4/s^2 and 350 g/cm^4/s^2.
Figures 7 shows ventricular volumes QLV and QRV. It is similar to the
open-loop result of Figure 1, but recovery is faster.
Figure 8 shows the filtered carotid pressure in closed-loop. Unlike the
corresponding open-loop result of Figure 2, PA3F returns near its value
before infarction, centered at the reference point of PREF = 72 mmHg.
KEY WORDS:
Cardiovascular, CV, Aorta, Carotid, Left, Right, Ventricle, Ventricular,
CNS, Central Nervous System, Baroreceptor, Negative Feedback, Regulation
Mechanism, Baroreflex, Afferent, Efferent, Nerve Signals, Closed Loop,
Controlled, Myocardial Infarction, Blood Infusion, Bleeding, Heart Rate,
Cardiac Output, Varying Elastance, Stiffness, Contraction, Muscle,
Pressure-Flow-Volume, Ohm's Law, RLC circuit, Resistance, Resistive,
Compliance, Compliant, Inertance, Frank-Starling, Stroke, Rideout
REFERENCES:
Rideout VC. Mathematical computer modeling of physiological systems.
Prentice Hall, Englewood Cliffs, NJ, 1991, Section 4.5, pp. 109-117
REVISION HISTORY:
Ported from ACSL by DH 3/15/12
JSim SOFTWARE COPYRIGHT AND REQUEST FOR ACKNOWLEDGMENT OF USE:
JSim software was developed with support from NIH grants HL088516,
and HL073598. Please cite these grants in any publication for which
this software is used and send one reprint of published abstracts or
articles to the address given below. Academic use is unrestricted.
Software may be copied so long as this copyright notice is included.
Copyright (C) 1999-2009 University of Washington.
Contact Information:
The National Simulation Resource,
Director J. B. Bassingthwaighte,
Department of Bioengineering,
University of Washington, Seattle, WA
98195-5061
*/