An Engineering Analysis of the Aortic Valve Dynamics in Patients with Rotary Left Ventricular Assist Devices

Faragallah, George; Simaan, Marwan A.

doi:10.1260/2040-2295.4.3.307

Cited by 17 publications

(12 citation statements)

References 20 publications

(29 reference statements)

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“…The cardiovascular-pump model as explained in Section 2.1 involves a few model parameters, which can be used to represent the physiological dynamics of the heart supported with a LVAD. As previously reported, parameters R s , R M , and heart rate (HR) can govern the behaviour of the cardiovascular-pump system [13]. Thus, we propose to investigate their effect on the dynamics of the aortic valve and the cardiac output.…”

Section: Cardiac Hemodynamicmentioning

confidence: 88%

“…Note that the coefficient in Equation 12 is set to 9.9025×10 -7 mmHg/(rpm) 2 [13]. In Equation 11, the total resistance R * and inductance L * are two parameters related to the LVAD, which can be given by the following equations as:…”

Section: Healthy Heartmentioning

confidence: 99%

“…It is assumed that the patient has a healthy and normal right ventricle and pulmonary system for simplicity. Thus, its effect on the LVAD is negligible [16,13]. Figure 1 shows a schematic of the circuit model of the cardiovascular-LVAD system.…”

Section: Cardiovascular-lvad Modelmentioning

confidence: 99%

“…Consequently, the LVAD will bypass the left ventricle and the aortic valve will be closed permanently. This can significantly change the circulation physiology and introduce complications such as thrombosis and commissural fusion [12,13]. The complications are fatal to HF patients, especially when the LVAD is used as a "bridge to recovery".…”

Section: Introductionmentioning

confidence: 99%

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Stochastic Modeling and Dynamic Analysis of the Cardiovascular System with Rotary Left Ventricular Assist Devices

Son

2019

Mathematical Problems in Engineering

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The left ventricular assist device (LVAD) has been used for end-stage heart failure patients as a therapeutic option. The aortic valve plays a critical role in heart failure and its treatment with LVAD. The cardiovascular-LVAD model is often used to investigate the physiological demands required by patients and predict the hemodynamic of the native heart supported with a LVAD. As a "bridge to recovery" treatment, it is important to maintain appropriate and active dynamics of the aortic valve and the cardiac output of the native heart, which requires that the LVAD pump must be adjusted so that a proper balance between the blood contributed through the aortic valve and the pump is maintained. In this paper, we investigate how the pump power of the LVAD pump can affect the dynamic behaviors of the aortic valve for different levels of activity and different severities of heart failure. Our objective is to identify a critical value of the pump power (i.e., breakpoint) to ensure that the LVAD pump does not take over the pumping function in the cardiovascular-pump system and share the ejected blood with left ventricle to help the heart to recover. In addition, hemodynamic often involves variability due to patients' heterogeneity and the stochastic nature of cardiovascular system. The variability poses significant challenges to understand dynamic behaviors of the aortic valve and cardiac output. A generalized polynomial chaos (gPC) expansion is used in this work to develop a stochastic cardiovascular-pump model for efficient uncertainty propagation, from which it is possible to rapidly calculate the variance in the aortic valve opening duration and the cardiac output in the presence of variability. The simulation results show that the gPC-based cardiovascular-pump model is a reliable platform that can provide useful information to understand the effect of LVAD pump on the hemodynamic of the heart.

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Section: Cardiac Hemodynamicmentioning

confidence: 88%

Section: Healthy Heartmentioning

confidence: 99%

Section: Cardiovascular-lvad Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stochastic Modeling and Dynamic Analysis of the Cardiovascular System with Rotary Left Ventricular Assist Devices

Son

2019

Mathematical Problems in Engineering

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“…As a proof of concept, we utilize a standard validated left ventricle-LVAD mathematical model based on a generic axial continuous flow rotary pump. This mathematical model is dynamic, timevarying and nonlinear and has been extensively used in prior LVAD studies [24,5,30]. It consists of six coupled time-varying differential equations that represent the relationships between the hemodynamic variables of the left ventricle, including the left ventricular pressure (LVP), the left atrial pressure (LAP), the arterial pressure (AP), the aortic pressure (AoP), the total aortic flow (Q T ) and pump flow (Q P ).…”

Section: Introductionmentioning

confidence: 99%

Aortic Valve Ejection Fraction for Monitoring Heart Contractility in Patients Supported with a Continuous Flow Left Ventricular Assist Device

Simaan¹,

Vasudevan²,

Maul³

et al. 2019

AJCTS

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Ejection Fraction (EF) is an important parameter that is used in the diagnosis of heart failure. It provides a measure of the ability of the heart to pump blood into the circulatory system. For patients implanted with a continuous flow left ventricular assist device (LVAD), the standard definition of EF provides a measure of the combined ability of both the heart to pump blood through the aortic valve and the LVAD to pump blood continuously out of the left ventricle both into the circulatory system. In this paper, we introduce a new concept of EF, labeled Aortic Valve Ejection Fraction (or AVEF) which provides an accurate measure of only the ability of the heart to pump blood through the aortic valve while the LVAD is actively running. We investigate the benefits of AVEF and its relation to the LVAD speed using a well-established mathematical model of an LVAD-assisted left ventricle. We compare the sensitivities of the new AVEF index and the standard EF index to changes in heart contractility over a wide range of after loads. Our results show that AVEF is more sensitive to changes in heart contractility than EF. At a typical LVAD speed of 4,000RPM, a 10% improvement in heart contractility over time for a patient with congestive heart failure yields 13.20% increase in AVEF, while the same increase in contractility yields only 7.52% increase in EF. The AVEF index could provide a reliable, non-invasive mechanism for monitoring improvements in heart contractility for patients implanted with LVAD.

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Control of Left Ventricular Assist Devices

Simaan¹

2020

Encyclopedia of Systems and Control

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An Engineering Analysis of the Aortic Valve Dynamics in Patients with Rotary Left Ventricular Assist Devices

Cited by 17 publications

References 20 publications

Stochastic Modeling and Dynamic Analysis of the Cardiovascular System with Rotary Left Ventricular Assist Devices

Stochastic Modeling and Dynamic Analysis of the Cardiovascular System with Rotary Left Ventricular Assist Devices

Aortic Valve Ejection Fraction for Monitoring Heart Contractility in Patients Supported with a Continuous Flow Left Ventricular Assist Device

Control of Left Ventricular Assist Devices

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