CARDIOSIM | Intra-aortic balloon pump

Schematic Representation of the IABP (Intra-Aortic Balloon Pump) Implantation into the Patient's Aorta.

First Model

Intra-Aortic balloon pumps (IABP) are commonly used for temporary circulatory support in patients with advanced heart failure. IABP is traditionally placed percutaneously through the transfemoral artery approach. The major limitation with this approach is ambulatory restriction that can promote deconditioning, particularly in situations of prolonged circulatory support. Inflating and deflating the balloon in synchrony with the heart rate (HR) helps augment diastolic blood pressure (upper left panel) and theoretically can increase coronary arterial perfusion, thereby augmenting myocardial oxygen delivery. During systole, the balloon quickly deflates thereby reducing afterload and therefore decreasing myocardial oxygen consumption and workload. Volume shifting of approximately 40 ml per heart beat by the IABP increases left ventricular stroke volume (LVSV) and cardiac output (CO) by up to 1 litre per minute, with the largest increases seen in patients with severely reduced CO.

In: C. De Lazzari, M. Darowski, et al. (2001). Ventricular energetics during mechanical ventilation and intraaortic balloon pumping--computer simulation. J. Med. Eng. Technol., 25(3), 103-111.

In: MODELLING CARDIOVASCULAR SYSTEM AND MECHANICAL CIRCULATORY SUPPORT. Claudio De Lazzari Editor (2007). Published by Consiglio Nazionale delle Ricerche (CNR) ROMA. ISBN 978-88-8080-081-1.

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Electric Analogue of Cardiocirculatory Network with Inta-Aortic Balloon Pump (IABP).

First Model

The IABP model, inserted in the arterial tree, is considered as a source flow Q_IABP(t) in the following way: during the diastole the balloon inflates and the flow is positive, during the next systole the balloon deflates and the flow is negative. The flow source Q_IABP(t) may be replaced by a pneumatic pressure source P(t), representing the compressed gas reservoir, and by resistance (R) representing the total gas delivery resistance of the system. The pneumatic source P(t) has been modelled by describing separately the ejection and the filling phase as the air outflow from high-pressure tank, connected to the pressure source, and the air outflow from a lower-pressure tank connected to the vacuum source. In the electric analogue the behavior of the heart was implemented using the equations reported in the Numerical Heart Model (1) section.

In: C. De Lazzari, M. Darowski, et al. (2001). Ventricular energetics during mechanical ventilation and intraaortic balloon pumping--computer simulation. J. Med. Eng. Technol., 25(3), 103-111.

In: MODELLING CARDIOVASCULAR SYSTEM AND MECHANICAL CIRCULATORY SUPPORT. Claudio De Lazzari Editor (2007). Published by Consiglio Nazionale delle Ricerche (CNR) ROMA. ISBN 978-88-8080-081-1.

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Intra-Aortic Balloon Pump equations.

First Model

In: C. De Lazzari, M. Darowski, et al. (2001). Ventricular energetics during mechanical ventilation and intraaortic balloon pumping--computer simulation. J. Med. Eng. Technol., 25(3), 103-111.

In: MODELLING CARDIOVASCULAR SYSTEM AND MECHANICAL CIRCULATORY SUPPORT. Claudio De Lazzari Editor (2007). Published by Consiglio Nazionale delle Ricerche (CNR) ROMA. ISBN 978-88-8080-081-1.

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Electric Analogue of Cardiocirculatory Network with Inta-Aortic Balloon Pump (IABP).

Second Model

In this cardiocirculatory configuration the behavior of the left and right native ventricles is reproduced by the time-varying elastance model. The same theory is used to model both left and right atria and the septum. Ventricles, atria and septum activities are synchronized with the electrocardiographic (ECG) signal. The described model allows inter-ventricular and intra-ventricular dyssynchrony to be simulated . (see Numerical Heart Model (2))

The systemic arterial section is modelled using four RLC elements reproducing aortic, thoracic and abdominal tracts. RLC elements are used to implement the pulmonary circulation composed by: the mean (small) arterial section, the arteriole and capillary section and the venous section.

In: C. De Lazzari, B. De Lazzari, A. Iacovoni, S. Marconi, S. Papa, M. Capoccia, S. Papa, R. Badagliacca, C.D. Vizza. (2020). Intra-Aortic Balloon Counterpulsation Timing: A New Numerical Model for Programming and Training in the Clinical Environment. Computer Methods and Programs in Biomedicine, 194, 1-9.

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Electric Analogue of Cardiocirculatory Network with Inta-Aortic Balloon Pump (IABP).

Second Model

The pulmonary circulation is reproduced using the following compartments: main and small arterial, pulmonary arteriole and capillary and pulmunary venous. Both main and small arterial sections are modelled with 3-WM elements. Arteriole and capillary sections are reproduced with two resitances (R_par and R_pc). Pulmonary venous compartment is modelled wit a 2-WM element (Rvp and Cvp). In the network Pt is the mean intrathoracic pressure. (see Pulmonary Network 4)

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Electric Analogue of Inta-Aortic Balloon Pump (IABP) and Systemic Arterial Tree.

Second Model

The systemic bed is divided in aortic, thoracic and two abdominal tracts. When the IABP is “OFF” (SW1=ON and SW2=OFF), the aortic (thoracic) tract is modelled using resistance R_AT (R_TT), compliance C_AT (C_TT) and inertance L_AT (L_TT). The first abdominal tract behavior is reproduced by RLC elements (R_ABT1, L_ABT1 and C_ABT1) when the IABP is disabled. The second abdominal tract is modelled by R_ABT2, L_ABT2, C_ABT2 and by variable systemic arterial resistance (Ras). The switches SW1 and SW2 are set to OFF (ON) and ON (OFF) respectively, when the device is (not) working. The effect induced by the balloon is reproduced in each tract of the aorta by the presence of compliances (C_IABP1, C_IABP2 and C_IABP3) connected to P_IABP generator and resistances (R_IABP1, R_IABP2 and R_IABP3). P_IABP generator reproduces the balloon pressure and the possibility to change the IABP temporization. The resistances (compliances) R_IABP1 (C_IABP1), R_IABP2 (C_IABP2) and R_IABP3 (C_IABP3) are connected in series (parallel) to R_AT (C_AT), R_TT (C_TT) and R_ABT1 (C_ABT1) in the aortic, thoracic and first abdominal tract.

The systemic venous section consists of a compliance (C_VS) and two variable resistances (R_VS1 and R_VS2).

In: C. De Lazzari, B. De Lazzari, A. Iacovoni, S. Marconi, S. Papa, M. Capoccia, S. Papa, R. Badagliacca, C.D. Vizza. (2020). Intra-Aortic Balloon Counterpulsation Timing: A New Numerical Model for Programming and Training in the Clinical Environment. Computer Methods and Programs in Biomedicine, 194, 1-9.

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IABP Balloon Pressure Waveform.

Second Model

The software simulator allows the IABP to be synchronized with either the ECG or the arterial waveform. The frequency of balloon-assisted beats can be set from the maintenance 1:1 ratio to a weaning 1:2 ratio (every other systole is assisted). Depending on the clinician's judgment, weaning modes of 1:4 or even 1:8 may be initiated if a more gradual approach is needed. In addition, IABP driving and vacuum pressures can be changed.

The hemodynamic effects induced by the IABP may vary with assisting frequency and depend on balloon inflation/deflation timing. A range of settings T1-T7 is available in the software simulator. The IABP can be triggered to deflate during systole once the peak of the R wave is sensed. IABP inflation may be triggered to occur in the middle of the T wave, which corresponds to diastole. The simulator allows the setting of different delays. Changing IABP compliance and resistance allows the balloon volume to be modified.

In: C. De Lazzari, B. De Lazzari, A. Iacovoni, S. Marconi, S. Papa, M. Capoccia, S. Papa, R. Badagliacca, C.D. Vizza. (2020). Intra-Aortic Balloon Counterpulsation Timing: A New Numerical Model for Programming and Training in the Clinical Environment. Computer Methods and Programs in Biomedicine, 194, 1-9.

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Heart Assist Devices

Intra-aortic balloon pump