Esao 2005 Conf Left Ventricle Load Impedance Control By Apical Vad Can Help Heart Recovery And Patient Perfusion

Left Ventricle Load Impedance Control by Apical VAD Can Help Heart Recovery and Patient Perfusion †Arabia M., †Colacino F., †Moscato F. ‡Piedimonte F., †Danieli G. † University of Calabria, Mechanical Engineering Dept., Rende – Italy ‡ University of Rome “Tor Vergata” , Automation and Control Dept., Rome – Italy UNIVERSITÀ DELLACALABRIA

Dipartimento di MECCANICA

Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Aim

This study is concerning with the dependence between LV load impedance control by apical pulsatile VAD and consequent benefits.

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Cardiovascular Model Features

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RV & LV Non Linear Time Varying Elastance Model Active Atria Noordergaaf Arterial Load Model Guyton’s Venous Return Model No Bronchial Artery Automatic Circulatory Parameters Variation with Feedback Loops: Ras, Rap, Rvs, Vusv

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Cardiovascular Model: Electric Analog

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Pulsatile VAD Model Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

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Pusher Plate – Sac pump (pneumatic or electromechanic) Stroke Volume up to 80 [ml] Synchronized Counter Pulsation Diaphragm always in contact with the Piston Head Active Controlled Filling Rigid Inlet & Outlet Cannulas

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

VAD Ejection Phase

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Piston pushes all the blood outside the chamber LVAD afterload sensitivity is not controlled 6/22

Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

VAD Filling Phase

Qi _ VAD

Physical environment

Pˆlv  Pao *  Rcs *

Simulated Arterial Load 7/22

Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Pulsatile LVAD Filling Control Strategy

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

How do we choose Ras*?  EWˆ PVA

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LV and RV Pressure-Volume Loops for a case study: LV contractility 34%, HR= 90 [bpm]

Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Left Ventricle

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VED= 189 [ml] SV = 44.5 [ml] EF = 23% EW/PVA = 0.385 MPao = 86.5 [mmHg] MPla = 17.5 [mmHg] Wall Stress = 108 [mmHg]

Right Ventricle

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Mean Pap = 26 [mmHg]

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Cardiac Output and Venous Return Curves: Initial Pathological Conditions

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Controlled LV Afterload Reduction

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Cardiac Output and Venous Return Curves: Assisted Conditions

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Time Course of Mean Quantities

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Time Course of Mean Quantities

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LV and RV Pressure-Volume Loops with LVAD

Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Left Ventricle

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VED= 189 [ml] SV = 44.5 [ml] EF = 23% EW/PVA = 0.385 MAOP = 86.5 [mmHg] MLAP = 17.5 [mmHg] Wall Stress = 108 [mmHg]

Right Ventricle

 112 [ml]  62 [ml]  56%  0.730  102 [mmHg]  6 [mmHg]  48 [mmHg]

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Mean APP = 26 [mmHg]  17.5 [mmHg] SV ↑ EF ↑ 16/22

EKF: Plv, Vlv, Emax estimation 

Measurements or estimates needed for system identification:

Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

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Pvad, Fiso, QVAD,VED, EMIN

Good results were achieved considering white measurement noise affecting Pvad and VED measurements (with variance = 10 [mmHg] and 10 [ml] respectively) Almost insensitive to relative errors of 50% on EMIN

Err. ~10%

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Estimated PV Loop and Emax

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Estimated PV Loop (Preload Variations)

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Pressure and Flow Waveforms

Pressure Flow

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Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Conclusions 

Advantages   

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On-line monitoring of Heart Mechanics and Perfusion Non Invasiveness – Estimation of PLV, VLV, Emax, QoLV No impact between Piston Head and Diaphragm

Disadvantages 

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For very weak LV even reducing the afterload to 0 [mmHg] might not be enough Pump chamber dimension Estimation of Emax is poorer when LV ejects into Aorta VED must be measured (VED estimation is a work in progress) 21/22

Mechanical Engineering Dept. – F. Moscato ESAO - October 5-8, 2005 - Bologna

University of Calabria

Thank You 

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